Identification of molecular nociceptors in Octopus vulgaris through functional characterisation in Caenorhabditis elegans

Identification of molecular nociceptors in Octopus vulgaris through functional characterisation in Caenorhabditis elegans | bioRxiv /* */ /* */ <!-- <!-- /*! * yepnope1.5.4 * (c) WTFPL, GPLv2 */ (function(a,b,c){function d(a){return"[object Function]"==o.call(a)}function e(a){return"string"==typeof a}function f(){}function g(a){return!a||"loaded"==a||"complete"==a||"uninitialized"==a}function h(){var a=p.shift();q=1,a?a.t?m(function(){("c"==a.t?B.injectCss:B.injectJs)(a.s,0,a.a,a.x,a.e,1)},0):(a(),h()):q=0}function i(a,c,d,e,f,i,j){function k(b){if(!o&&g(l.readyState)&&(u.r=o=1,!q&&h(),l.onload=l.onreadystatechange=null,b)){"img"!=a&&m(function(){t.removeChild(l)},50);for(var d in y[c])y[c].hasOwnProperty(d)&&y[c][d].onload()}}var j=j||B.errorTimeout,l=b.createElement(a),o=0,r=0,u={t:d,s:c,e:f,a:i,x:j};1===y[c]&&(r=1,y[c]=[]),"object"==a?l.data=c:(l.src=c,l.type=a),l.width=l.height="0",l.onerror=l.onload=l.onreadystatechange=function(){k.call(this,r)},p.splice(e,0,u),"img"!=a&&(r||2===y[c]?(t.insertBefore(l,s?null:n),m(k,j)):y[c].push(l))}function j(a,b,c,d,f){return q=0,b=b||"j",e(a)?i("c"==b?v:u,a,b,this.i++,c,d,f):(p.splice(this.i++,0,a),1==p.length&&h()),this}function k(){var a=B;return a.loader={load:j,i:0},a}var l=b.documentElement,m=a.setTimeout,n=b.getElementsByTagName("script")[0],o={}.toString,p=[],q=0,r="MozAppearance"in l.style,s=r&&!!b.createRange().compareNode,t=s?l:n.parentNode,l=a.opera&&"[object Opera]"==o.call(a.opera),l=!!b.attachEvent&&!l,u=r?"object":l?"script":"img",v=l?"script":u,w=Array.isArray||function(a){return"[object Array]"==o.call(a)},x=[],y={},z={timeout:function(a,b){return b.length&&(a.timeout=b[0]),a}},A,B;B=function(a){function b(a){var a=a.split("!"),b=x.length,c=a.pop(),d=a.length,c={url:c,origUrl:c,prefixes:a},e,f,g;for(f=0;f<d;f++)g=a[f].split("="),(e=z[g.shift()])&&(c=e(c,g));for(f=0;f<b;f++)c=x[f](c);return c}function g(a,e,f,g,h){var i=b(a),j=i.autoCallback;i.url.split(".").pop().split("?").shift(),i.bypass||(e&&(e=d(e)?e:e[a]||e[g]||e[a.split("/").pop().split("?")[0]]),i.instead?i.instead(a,e,f,g,h):(y[i.url]?i.noexec=!0:y[i.url]=1,f.load(i.url,i.forceCSS||!i.forceJS&&"css"==i.url.split(".").pop().split("?").shift()?"c":c,i.noexec,i.attrs,i.timeout),(d(e)||d(j))&&f.load(function(){k(),e&&e(i.origUrl,h,g),j&&j(i.origUrl,h,g),y[i.url]=2})))}function h(a,b){function c(a,c){if(a){if(e(a))c||(j=function(){var a=[].slice.call(arguments);k.apply(this,a),l()}),g(a,j,b,0,h);else if(Object(a)===a)for(n in m=function(){var b=0,c;for(c in a)a.hasOwnProperty(c)&&b++;return b}(),a)a.hasOwnProperty(n)&&(!c&&!--m&&(d(j)?j=function(){var a=[].slice.call(arguments);k.apply(this,a),l()}:j[n]=function(a){return function(){var b=[].slice.call(arguments);a&&a.apply(this,b),l()}}(k[n])),g(a[n],j,b,n,h))}else!c&&l()}var h=!!a.test,i=a.load||a.both,j=a.callback||f,k=j,l=a.complete||f,m,n;c(h?a.yep:a.nope,!!i),i&&c(i)}var i,j,l=this.yepnope.loader;if(e(a))g(a,0,l,0);else if(w(a))for(i=0;i (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0];var j=d.createElement(s);var dl=l!='dataLayer'?'&l='+l:'';j.src='//www.googletagmanager.com/gtm.js?id='+i+dl;j.type='text/javascript';j.async=true;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-M677548'); Skip to main content Home About Submit ALERTS / RSS Search for this keyword Advanced Search New Results Identification of molecular nociceptors in Octopus vulgaris through functional characterisation in Caenorhabditis elegans View ORCID Profile Eleonora Maria Pieroni , View ORCID Profile Vincent O’Connor , View ORCID Profile Lindy Holden-Dye , Pamela Imperadore , View ORCID Profile Graziano Fiorito , View ORCID Profile James Dillon doi: https://doi.org/10.1101/2025.08.19.670888 Eleonora Maria Pieroni 1 School of Biological Sciences, University of Southampton , Southampton SO17 1BJ, UK 2 Association for Cephalopod Research ‘CephRes’ ETS , Napoli, Italy Find this author on Google Scholar Find this author on PubMed Search for this author on this site ORCID record for Eleonora Maria Pieroni Vincent O’Connor 1 School of Biological Sciences, University of Southampton , Southampton SO17 1BJ, UK Find this author on Google Scholar Find this author on PubMed Search for this author on this site ORCID record for Vincent O’Connor Lindy Holden-Dye 1 School of Biological Sciences, University of Southampton , Southampton SO17 1BJ, UK Find this author on Google Scholar Find this author on PubMed Search for this author on this site ORCID record for Lindy Holden-Dye Pamela Imperadore 3 Department of Biology and Evolution of Marine Organisms , Stazione Zoologica Anton Dohrn, Napoli, Italy Find this author on Google Scholar Find this author on PubMed Search for this author on this site Graziano Fiorito 3 Department of Biology and Evolution of Marine Organisms , Stazione Zoologica Anton Dohrn, Napoli, Italy Find this author on Google Scholar Find this author on PubMed Search for this author on this site ORCID record for Graziano Fiorito James Dillon 1 School of Biological Sciences, University of Southampton , Southampton SO17 1BJ, UK Find this author on Google Scholar Find this author on PubMed Search for this author on this site ORCID record for James Dillon For correspondence: jcd{at}soton.ac.uk Abstract Full Text Info/History Metrics Supplementary material Preview PDF Abstract Nociception, a phenomenon crucial for animal survival, deploys evolutionarily conserved molecular mechanisms. Among invertebrate species, cephalopods are of particular interest as they possess a well-developed brain speculated to be able to encode pain-like states. This has led to their inclusion in the Directive 2010/63 EU for welfare protection. However, the molecular mechanisms of nociception in cephalopods are still poorly characterised and it is important to address this knowledge gap to better understand cephlapods’ capacity to express pain states. Here we describe a bioinformatic pipeline utilising conserved nociceptive genes, to identify the orthologous candidates in the Octopus vulgaris transcriptome. We identified 51 genes we predict to function in nociception. These add to the mechanosensory TRPN and the unique chemotactile receptors recently identified in octopus suckers, thus expanding the set of genes that merit further functional characterisation in cephalopods. We therefore selected 38 orthologues in Caenorhabditis elegans, a tractable experimental platform and tested loss of function mutant strains of distinct functional gene classes (e.g., osm-9, egl-3, frpr-3 ) in a low pH avoidance paradigm. This identified 18 nociceptive-related genes to be prioritised for further functional characterisation in O. vulgaris . Introduction The ability to detect potential noxious stimuli in the environment involves the triggering of specialised sensory neurons called nociceptors which activate a simple reflex response that organises a withdrawal behaviour of the animal from a potential threat ( Sherrington, 1906 ; Dubin and Patapoutian, 2010 ). The number and type of modalities of noxious stimuli detected by these cells is encoded by the molecular determinants which define the transduction and integration of such environmental cues ( Wood, 2006 ; Dubin and Patapoutian, 2010 ). The crucial adaptive value of nociception in contributing to increase the individual survival, made it a conserved feature across Eumetazoa ( Smith and Lewin, 2009 ). In cephalopods, evidence of nociception is found in ex vivo and in vivo experimental observations in which noxious cues delivered to the arms or mantle of the animal, is able to trigger withdrawal responses and associated neurophysiological features such as post-injury sensitization ( Hague et al., 2013 ; Crook et al., 2013 ; Alupay et al., 2014 ; Crook et al., 2014 ; Howard et al., 2019 ). This interpretation is reinforced in studies where a complex response is suggested to be organised in the central brain to produce secondary protective behaviours such as grooming and concealing of the arm after noxious exposure ( Crook, 2021 ). The increasing interest in nociception and its processing in these cephalopods derives from the recognition of their sophisticated neuroanatomical central organization. This likely entails a top-down regulation of modulatory nerve signalling underlying the potential to exhibit pain pathways. Due to this possibility, as a precautionary principle, cephalopods are currently subject to legislation that protects their welfare when used in research ( European Parliament and Council of the European Union, 2010 ; Smith et al., 2013 ; Birch et al., 2021 ). However, to fully address the question around pain perception, a broader understanding of the molecular determinants of nociception in cephalopods is required. To date, only two molecular classes of sensory detectors have been experimentally identified in O. bimaculoides ( van Giesen et al., 2020 ) and Sepioloidea lineolata ( Kang et al., 2023 ). These are located in the sensory epithelium surrounding the suckers which harbours putative cellular nociceptors that morphologically resemble mammalian sensory neurons ( Rossi and Graziadei, 1956 ). One was identified as a NOPMC (TRPN) orthologue, activated by mechanical stimulation whilst the other class was found to be a phylum-specific ion channel, sensitive to both attractants and aversive cues ( Kang et al., 2023 ). This provides evidence of both conserved and exclusive molecular components of sensory detection in cephalopod ( van Giesen et al., 2020 ). Most of the direct investigation of nociceptive processing in cephalopods is constrained by their limited experimental genetic tractability. These limitations derive from a series of challenges posed by culturing these animals, especially considering the very delicate early life stages ( Iglesias et al., 2007 ; Vidal et al., 2014 ) and the strict requirements this species needs in terms of accommodation, nutrients, and temperature supplies ( Ponte et al., 2022 ). Therefore, currently most of the work carried out on O. vulgaris is based on animals that are caught from the wild in a non-standardised way ( Pieroni et al., 2022 ; Sykes et al., 2023 ). This generates two major issues, one is the complete absence of control over their genetic background and the second one is represented by the variable animal welfare status after capture and transport. However, the highly conserved genetic basis of nociception across the animal phyla provides an opportunity to take an indirect, but nonetheless, informative approach. Here we conducted an in silico analysis to identify molecular candidates for nociception in the O. vulgaris transcriptome. To provide insight into their function we identified their C. elegans orthologues and tested loss of function mutants for deficits in a simple assay of chemical nociception by exposing mutant nematode strains to low pH, a common noxious cue in both species ( Sambongi et al., 2000 ; Hague et al., 2013 ; Crook, 2021 ). This approach highlighted 18 nociceptive-related genes prioritised for functional characterisation, reinforcing the molecular conservation of gene families in distinct organisms and mapping out a platform through which experimentally intractable cephalopod genes can be investigated in C. elegans . Materials and Methods In silico analysis Resources to produce a list of conserved Eumetazoan nociceptive related genes An in-depth literature review of conserved molecular nociceptors was performed by surveying around 400 peer reviewed journal articles on animal nociception from well-characterised vertebrate and invertebrate Eumetazoa. This work was complemented with information taken from databases focussed on human pain genetics: 1) Human Pain Genes Database ( Meloto et al., 2018 ) a collection of nociceptive relevant genes resulted from 294 studies reporting 434 associations between genetic variants and pain phenotypes; 2) Pain Research Forum , curated by the International Association for the Study of Pain (IASP) and 3) Pain Genetics MOGILAB (McGill University, Montreal, Canada). Finally, the queries “pain perception” and “opioid activity” were searched within Gene Ontology (GO) Resource ( Carbon et al., 2009 ). The latter was included on the basis that this search term would highlight candidate molecular components that mediate or modulate anti-nociceptive pathways. The results under the “genes and gene products” label were selected for further analysis. Gene blast against O. vulgaris transcriptome and manual curation of sequences The search for orthologue nociceptive and antinociceptive candidate genes in O. vulgaris was performed by iterating the Uniprot amino acid sequence ( The UniProt, 2025 ) against O. vulgaris transcriptome ( Petrosino et al., 2015 ; Petrosino et al., 2022 ). A standard e-value of 10e −5 was used as a cut-off for the BLAST search except for neuropeptide precursors for which it was set as 10e −2 . The rationale for the latter reduced stringency is due to the known propeptide variation relative to highly conserved and short length mature and active peptide component ( Baggerman et al., 2005 ; Akhtar et al., 2011). When multiple hits were found, we considered the contig sequences with the e-value closest to 0 and a high query coverage (at least 40%) for further analysis. Incomplete sequences from the BLAST research that we failed to reconstruct were discarded. A set of bioinformatic tools was utilised to check the quality of the pre-existing automated annotations by manually curating the sequences. The nearest species with a sequence matching the candidate provided was retrieved from NCBI Blast ( Altschul et al., 1990 ). A prediction of the protein function pathways (GO terms for “Biological Process”, “Molecular Function” and “Cellular Component”) was obtained via InterProScanSearch ( Blum et al., 2021 ) following translation of the target transcript on Expasy Translate ( Gasteiger et al., 2003 ). The analysis of the conserved domain, the family and shared structure of the protein was also performed, using NCBI conserved domain ( Lu et al., 2020 ) and HHPRed ( Hildebrand et al., 2009 ). Refinement of candidate O. vulgaris nociceptive genes Refinement of the final O. vulgaris sequences to be blasted against the C. elegans genome was performed by taking into account the available relative gene expression of the candidates in O. vulgaris ( Petrosino et al., 2015 ; Petrosino et al., 2022 ). To this end, specific tissues were considered, based on their relevance in neurosensory pathways: tip of the arm (TIP), selected due to previous studies showing it is enriched in sensory receptors including those involved in nociceptive responses ( Graziadei, 1964 ; van Giesen et al., 2020 ); supra-oesophageal mass (SEM), sub-oesophageal mass (SUB) and optic lobe (OL), constituting the central brain mass fundamental in information processing and thus potentially implicated in the elaboration of nociceptive and anti-nociceptive responses. This process led to the selection of a specific representative for each gene when multiple plausible hits were found. Identification of C. elegans orthologues for candidate O. vulgaris nociceptive genes C. elegans orthologues of the hits derived from the approaches described above, were retrieved from Wormbase resource ( Davis et al., 2022 ) through the available BLAST tool (version WS288, Bioproject PRJNA13758). To compare the degree of molecular conservation between O. vulgaris and C. elegans , the respective predicted protein translations were aligned using Clustal omega ( Madeira et al., 2022 ) and the identity of the protein functional domains was compared with Expasy-SIM tool using BLOSUM62 as the comparison matrix ( Huang and Miller, 1991 ). Where multiple hits were found, the selection was made based on literature evidence for their implication in sensory responses or on their expression in sensory neurons (e.g., npr-17 as allatostatin C receptor representative within its suggested 13 orthologues; Beets et al., 2023 ). C. elegans strains and husbandry The following nematode strains were utilised in this study: CB1124 che-3 (e1124); CB75 mec-2 (e75) [STOM]; TU253 mec-4 (u253 ) [ASIC]; CB1611 mec-4 (e1611) [ASIC]; CB1515 mec-10 (e1515) [ASIC]; acd-1/deg-1 (bz90/u38u421) [FaNaC]; TQ5 trp-1 (sy690) [TRPC]; RB1052 trpa-1 (ok999) [TRPA]; TQ6 trp-4 (sy695) [TRPN]; CX10 osm-9 (ky10) [TRPV]; CX4544 ocr-2 (ak47) [TRPV]; FG125 ocr-2 (ak47), osm-9 (ky10), ocr-1 (ak46) [TRPV]; EJ1158 gon-2 (q388) [TRPM2]; LH202 gtl-2 (tm1463) [TRPM3]; PT8 pkd-2 (sy606) [TRPP]; AG405 pezo-1 (av143) [PIEZO]; RB883 kqt-2 (ok732) [KCNQ]; TM542 kqt-3 (tm542) [KCNQ]; RB1392 shk-1 (ok1581) [KCNA]; twk-46 (tm10925) [KCNK]; CB251 unc-36 (e251) [CACNA2D3]; VC48 kpc-1 (gk8) [PCSK1]; MT150 egl-3 (n150) [PCSK2]; MT1218 egl-3 (n588) [PCSK2]; VC671 egl-3 (ok979) [PCSK2]; MT1071 egl-21 (n476) [CPE] ; acn-1 (tm12662) [ACE] ; acn-1 (tm8421) [ACE]; BR2815 nep-1 (by159) [NEP]; JN356 nep-2 (pe356) [NEP]; VC2171 tkr-1 (ok2886) [TKR]; RB1340 nlp-1 (ok1469) [TK]; VC2565 frpr-3 (ok3302) [FMRFaR]; NY7 flp-1 (yn2) [FMRFa]; NY16 flp-1 (yn4) [FMRFa] ; npr-17 (tm3210) [AstCR/OPRL]; RB2030 nlp-3 (ok2688) [AST/OP-like]; FX03023 nlp-3 (tm3023) [AST/OP-like] ; anoh-1 (tm4762) [ANO]; CX14295 pdfr-1 (ok3425) [CGRPR]; RB1546 tmc-1 (ok1859) [TMC]; FK100 tax-2 (ks10) [CNG]; PR671 tax-2 (p671) [CNG]; PR678 tax-4 (p678) [CNG]; BR5514 tax-2/tax-4 (p671/p678) [CNG]; VC9 nca-2 (gk5) [NALCN]. The Bristol N2 was used as the wild-type strain. C. elegans were cultured and maintained as described in Brenner (1974) . Single colonies of saturated LB broth cultures containing Escherichia coli OP50 were used to seed 15 mL nematode growth medium (NGM) agar plates (50 μL per 55 mm diameter plate). Plates containing C. elegans were then sealed with parafilm to prevent contamination and kept at 20°C. Three days prior to any assay, gravid adult worms were put on culturing plates to lay eggs for 4h and then removed to produce an age-synchronised population to be tested at the L4+1 day (young adult) stage. Drop assay to test acidic aversion in C. elegans On the experimental day, ten L4+1 day old worms were transferred onto a 9 cm unseeded NGM plate (20mL) and left undisturbed for 20 min, in order to favour the transition from local area search (with high levels of reversal) to dispersal behaviour with low reversals and forward movements ( Gray et al., 2005 ). A small drop of noxious cue was delivered in front of a moving worm through a small electrophysiology glass capillary (1.0mmOD, Harvard Apparatus, USA) attached to a 3 mL plastic syringe (Fisherbrand™). The number of reversals exhibited by the worm within 5s of exposure to the cue was recorded. A binary score was assigned with a positive response (1) scored for worms reaching the threshold displayed by the WT N2 (at least three complete reversals within 5s from the exposure to the substance), otherwise a negative response (0) was assigned. Worms for each strain for each condition were tested by exposing them to the drop only once. The resulting response score was calculated and compared to the WT N2 performance. Strains with known or observed strong impaired movements were not included in the study as they could have potentially affected the locomotory readout on which the assay is based. To trigger low pH response, acetic acid (CAS No. 64-19-7, Fisher Chemicals™) was dissolved in M9 buffer to reach a final pH of 3 (M9, pH3). This cue was compared to the exposure of M9 buffer alone (M9, pH7). The experimenter was blind to the genotype being tested and exposure to cues was randomised. Data were analysed using either one-way or two-way parametric analysis of variance (ANOVA) with different substances (M9, pH3 vs M9 pH7, Na acetate vs M9) and strains vs WT N2 as between-subjects. Post-hoc comparisons were performed using Dunnett’s multiple comparisons test for one-way ANOVA and Tukey’s multiple comparisons test for the two-way ANOVA. A level of probability set at p<0.05 was used as statistically significant. Statistics were performed with GraphPad Prism version 10 for Windows (GraphPad Software, Boston, Massachusetts, USA). Results Resolution of a query set of conserved Eumetazoan nociceptive-related genes Our bioinformatic pipeline, identified a total number of 474 nociceptive related genes collectively retrieved from literature analysis (141), databases (200) and GO search (133). A considerable number of retrieved genes (152 entries) was found multiple times across the different sources or under synonyms. These duplications were removed, resulting in a total number of 322 distinct candidates ( Fig. 1A and Table S1A). Download figure Open in new tab Fig. 1. Summary of in silico analysis leading to the selection of O. vulgaris putative molecular nociceptive determinants to be modelled in C. elegans . (A) Literature analysis of well-characterised Eumetazoan nociceptors was complemented with information from databases on human pain genetics (Human Pain Genetic Database, IASP Pain research, MOGILab) and GO “gene and gene products” to produce 474 distinct candidate genes. We manually filtered to exclude overlapping entries among resources (152), genes involved in multiple pathways (165), neurotransmitters and their receptors (29) and those involved in the inflammatory component of pain (29). We additionally pooled together (10) different representatives of the same subfamily (e.g., ASIC1-3, TRPV1-8 etc.) (B) The resulting 89 candidates were blasted against O. vulgaris transcriptome to retrieve the closest orthologues which were then manually curated, leading to 51 candidate genes. We prioritised genes based on available tissue expression levels in octopus sensory and nervous tissues (TIP, SEM, SUB, OL – for details see Table S2). (C) To promote the functional characterisation in C. elegans, mutant strains for the orthologue genes were selected This filtering led to a final number of 37 genes across 45 strains. We then filtered down this list by focusing on essential nociceptive and anti-nociceptive determinants, such as receptors directly gated by noxious stimuli or known modulators of sensory detection. This was done with a view of excluding categories of proteins involved in multiple physiological pathways or with a rather secondary/diffuse role in nociception. Among these, neurotransmitters, and their receptors (29 genes), transcription factors, large families of enzymes involved in widespread cellular activities (165 genes) and molecules contributing to the inflammatory responses were excluded (29 genes). Furthermore, given the challenge posed by some candidates in distinguishing between isoforms of the same gene or different representatives of the same subfamily we pooled related genes (e.g., TRPV1-6 have been pooled into TRPVs, ASIC1-3, into ASICs, PIEZO1-2 into PIEZO) for a total of 10 genes. Altogether, this filtering produced a final number of 89 potential candidate genes that were blasted against O. vulgaris transcriptome ( Fig. 1A and Table S1B). O. vulgaris shares most of the conserved protein families implicated in nociception Each selected protein sequence from the query set was blasted against O. vulgaris transcriptome to find orthologue genes ( Fig. 1B ). The search of the 89 genes in O. vulgaris transcriptome led to a total number of 228 transcripts. We then manually curated each of them to remove incomplete sequences, identical sequences, and we managed to reconstruct two transcripts from fragments. This refinement led to a total number of 171 complete transcript sequences (Table S2). The corresponding 51 distinct genes encoded for proteins belonging to more than 30 different families (and 50 subfamilies) of receptors and modulators associated with sensory detection of chemical, mechanical and/or thermal stimuli. The results were organised into different categories based on the putative biological role of these proteins: 1) Classical activators of nociception, 2) Voltage-gated ion channels/subunits, 3) Proteins related to neuropeptide and lipid metabolism, 4) Other modulators of nociception (Table S2). Belonging to the first category, orthologues of well-characterised proteins such as transient receptor potential (TRPs) and amiloride sensitive (ASCs) ion channels were identified with 9 and 3 representatives (within multiple isoforms) respectively. The presence of specific subunits of ion channels implicated in nociception, such as the calcium voltage-gated channel subunit α2δ subunit 3 (CACNA2D3), known for its role in thermosensation was found, whilst other known channels specifically involved in nociception triggering such as Na v 1.7-Na v 1.9, were not clearly identified, mostly leading to Na v 1.1 (SCNA1) and Ca v 1.1 (CACNA1S) orthologues (Table S2). Genes implicated in canonical analgesic pathways are missing from O. vulgaris transcriptome Out of the 89 selected genes, 38 were not found in O. vulgaris transcriptome. These include opioid precursors and derivatives, classical opioid receptors, and endocannabinoid receptors. However, receptors that share strongest homologies with those receptors, such as Allatostatin C receptor (AstCR) with an assigned “opioid receptor” protein family membership (IPR001418) in InterProScan, and an Opioid growth factor receptor (OGFR) were identified. Furthermore, enzymes such as neprilysin (NEP), carboxypeptidase (CPE), neuroendocrine convertase (PCSKs) in the case of neuropeptides-related proteins or diacylglycerol lipase (DAGL) and N-acyl-phosphatidylethanolamine-hydrolysing phospholipase D (NAPE-PLD) in the case of lipid modulators were found. This shows the existence of conserved pathway for the biosynthesis, processing, and metabolism of neuropeptides and lipids that have a broader physiological role that may include nociception modulation and its physiological mitigation. C. elegans mutants of O. vulgaris orthologue genes were selected for characterisation in a chemical aversion assay Following the identification and manual curation of O. vulgaris candidates, we looked at the data on available tissue distribution and prioritised the analysis of genes showed to be enriched in neurosensory tissues (TIP, SEM, SUB and OL) especially when more than one hit resulted in a plausible orthologue candidate of the putative nociceptive gene (Table S3). As we intended to model the response triggered by these genes in C. elegans , each resulting O. vulgaris protein sequence was blasted against C. elegans genome database to find, where present (Table S3), the closest nematode orthologue ( Fig. 1C ). The result of this final refinement led to 37 C. elegans genes, for which we selected 45 different strains ( Table 1 ). View this table: View inline View popup Table 1. List of C. elegans loss of function mutant strains for the selected nociceptive related genes selected from O. vulgaris transcriptome after manual filtration of the in silico analysis. For each gene, the first four columns report the gene proposed function based on literature, the O. vulgaris candidate gene (based on the assembled transcriptome Petrosino et al., 2015 and Petrosino et al., 2022 ) and assigned NCBI Accession number. Columns 5-10 refer to the orthologue gene of C. elegans , the strain and alleles selected to be tested for chemoaversion impairments and the pre-existing knowledge on the behavioural phenotype of the mutant, as well as the known localisation of the gene in worms tissues. In some cases, a mutation in more than one allele encompassing the same gene was tested. The last column refers to the degree of identity and similarity found between the two species genes when comparing their functional domains (Expasy-SIM tool, BLOSUM62 comparison matrix). Based on the recurring evidence showing nociceptive responses triggered in octopuses through acetic acid administration ( O. vulgaris , Hague et al. 2013 , O. bocki, Crook, 2021 ), we selected low pH (M9, pH 3) as the exemplar cue and systematically tested against selected C. elegans strains using the chemoaversion drop assay. The drop assay is a sensitive test to study chemoaversion in C. elegans We analysed WT N2 and selected mutants in the assay and benchmarked the results against previously published data to validate our approach. The results, in agreement with published data ( Sambongi et al., 2000 ) and showed that low pH elicited a significant aversive response in N2 (M9, pH3 average number of reversals = 3.990 ± 0.115) when compared to the control (M9, pH 7, average number of reversals = 0.432 ± 0.033). This allowed us to set the threshold for measuring responsiveness (1 for avoidance, 0 for defective avoidance) to at least 3 reversals for M9 pH3 (Fig. S1). We then verified the sensitivity of the drop assay in discriminating the responsiveness of different strains of worms. We first tested the well-characterised che-3 (e1124), a strain with ultrastructural defects in the ciliated dendritic endings of the amphid sensory neurons that play an essential role in chemosensation and compared its performance to the WT N2 ( Perkins et al., 1986 ; Wicks et al., 2000 ). As previously published for che mutant strains ( Sambongi et al., 2000 ), che-3 (e1124) showed a poor avoidance performance to acidic pH when compared to the WT N2 (p<0.0001) with less than 30% responsiveness to low pH (M9, pH 3 average number of reversals 2.293 ± 0.130), a difference of more than 50% with the WT N2 (around 80% responsiveness Fig. S1). Additionally, we analysed C. elegans responsiveness to 200mM Na acetate (C₂H₃NaO₂) to check which chemical component of acetic acid was responsible for triggering the aversive response. Worms showed no sensitivity to sodium acetate (200 mM Na acetate vs Ctrl M9 pH7, p = 0.9802 in WT N2, p = 0.9924 in che-3 (e1124) ) demonstrating that the repulsive response of M9, pH3 was elicited by the protons (H + ) rather than by the acetate ion (Fig. S1). C. elegans is a discriminating platform for characterising conserved molecular nociceptors Once we established the drop assay as a valuable test to discriminate the responsiveness of the strains, we analysed the performance of all the 45 strains of C. elegans mutants that came out of the list of 37 orthologues of O. vulgaris putative nociceptive genes ( Fig. 2 ). The drop assay identified 18 distinct genes across the four different categories that seem implicated in the detection or processing of acidic pH. Download figure Open in new tab Fig. 2. Functional investigation of C. elegans orthologues of O. vulgaris genes implicated in nociception. The bars represent the average score performed by the total number of worms per strain tested ± SD. The putative genes involved in nociception were grouped into distinct categories (A-D) and the acidic aversion of mutant strains for each gene was compared to the controls, WT N2 and che-3 (e1124 ). In each experiment, worms were exposed to a drop of acetic acid (pH 3) only once and the response was recorded and classified according to the designated criteria described in the text. Data were subjected to one-way ANOVA followed by Dunnett’s multiple comparisons test. Category A: “Classical activators of nociception”, refers to all the genes that were found recurringly across all the resources we interrogated (e.g., TRPs, ASCs, PIEZOs), Category B: “Ion channel and subunits involved in nociception” is self-explanatory, Category C “Proteins related to neuropeptide and lipid metabolism” was originally meant to include representatives from the opioid and endocannabinoid systems but given we couldn’t find any obvious orthologues, we focused on the enzymes involved in the synthesis, maturation or catabolism or neuropeptides and lipids that might still have a fundamental role for counteracting nociception. Category D: “Other modulators of nociception” refers to a broader range of genes that encode for enzymes and receptors that have been known to be implicated in nociception processing. *p<0.05, **p<0.01, ***p<0.001, **** p<0.0001 refers to the comparison against the WT N2 performance; n represents the number of individuals tested. Each strain was tested in at least two independent experiments. Seven out of 18 genes belong to the “classical activators of nociception” category with impaired strains, all showing an average number of reversals below the set threshold for responsiveness ( Fig. 3 ). Download figure Open in new tab Fig. 3. C. elegans highlights potential molecular determinants involved in O. vulgaris nociception. Data for the drop assay is reported here as the number of actual reversals after exposure to the noxious cue (M9, pH 3). The heat map shows a colour coded indication of the strains’ sensitivity to M9, pH 3 from non-sensitive che-3 (e1124) -like (magenta) to sensitive WT N2-like (green). Each colour block represents the average number of reversals across all the worms tested per strain. The WT N2 performance was characterised by at least 3 body reversals within 5s of contact with the drop and was used to set our criteria for responsiveness. Mutant strains belonging to the TRP channel subfamilies, including the TRPVs osm-9 (p<0.0001) and ocr-2 (p<0.0001), the TRPA trpa-1 (p<0.0001) and the TRPMs gon-2 (p<0.0001) and gtl-2 (p<0.0001), all showed a significant impairment in the detection of acidic pH ( Fig. 2A ). Representatives of TRPN ( trp-4 ), TRPC ( trp-1 ) and TRPP ( pkd-2 ) TRP subfamilies, however, did not show any defect in pH 3 aversion. Worm strains of the orthologues of other families of classical pH detectors such as ASCs, did not show any defect in chemoaversion as it might be expected by acidic sensing ion channel representatives. In fact, mec-4 and mec-10 strains exhibited on average more than three reversals (3.2000 mec-4 (u253) , 3.1000 mec-4 (e1611) , 5.1000 mec-10 (e1515) , Fig. 3 ). The only strain showing lack of response to pH 3, was the neuronal and glial ASC double mutant acd-1 (bz90)/deg-1(u38u421) (p<0.0001). An impaired response to pH3 was also found among specific strains representative of the “voltage-gated ion channels/subunits” category. This included kqt-3 (p<0.0001) and shk-1 (p0.9999 with an average of 3.2500 reversals, Fig. 3 ) were altered in their withdrawal response. unc-36 (p<0.0001), orthologue of the CACNA2D3 subunit, showed a defective response when challenged with the noxious pH3 cue ( Fig. 2B ). Strains with mutations in genes that encode for “proteins related to neuropeptide and lipid metabolism”, showed defects in the detection of acetic acid ( Fig. 2C ). The nlp-3 (ok2688) strain showed a clear impairment in response to the repellent (p<0.0001), whilst mutant strains of FMRFamide-like peptide orthologues (flp-1) were responsive. Among the FMRFamide receptors frpr-3 , showed a loss of response (p<0.0001, average number of reversals 0.9500, Fig. 3 ). Considering C. elegans orthologues of the enzymes involved in the biosynthesis (egl-21) , maturation (kpc-1, egl-3, acn-1) and degradation (nep-1, nep-2) of neuropeptides, the PCSK2 egl-3 representatives (p<0.0001), the CPE egl-21 (p = 0.0109) and the ACE acn-1 (p = 0.0209) mutant strains showed a reduced response when exposed to the pH3 repellent ( Fig. 2C ). Belonging to a broader category of “other nociception modulators”, only mutants in the peptide nlp-1 , the stomatin-like protein mec-2 and the calcitonin gene-related peptide receptor (CGRP) pdfr-1, seemed to be involved in pH 3 avoidance (p = 0.0427, p = 0.076 and p = 0.010 respectively). Finally, most of the genes in this category did not show defects in this specific aversive response. This includes CNG representatives tax-2 and tax-4 , the anoctamin-1 orthologue anoh-1 , all eliciting a WT-like performance (> 3 reversals) when exposed to acetic acid ( Fig. 2D and Fig.3 ). Discussion Core conserved molecular nociceptors in O. vulgaris can be identified using functional characterization in C. elegans The in silico pipeline revealed that a large number of genes showing conservation to known nociceptive genes in other species are present in O. vulgaris. In particular, at least two representatives were found to belong to the acid sensing ion channels (ASICs), including the classical molluscan FMRFamide-gated Na + channel ( Cottrell et al., 1983 ; Cottrell et al., 1990 ; Cottrell et al., 1997 ), two genes belonging to the PIEZO family, whilst for TRPs, 9 members (with multiple isoforms) were identified (Table S2). These include two TRPA1 channels, two TRPCs, two TRPMs, one TRPP, one TRPN and one TRPV channel, showing less variety of members when compared to vertebrates ( Peng et al., 2015 ). This suggests either the vertebrate TRPs underwent specialisation during evolution (e.g., gene duplication and divergence) or that the fewer invertebrate representatives play multiple physiological functions as in the original ancestral gene ( Valencia-Montoya et al., 2024 ). When tested in C. elegans , one of the strongest behavioural impairments was found in mutant strains for the TRPV channel representatives osm-9 and ocr-2. ( Fig. 2A ). These results are in line with previous studies showing their role in acidic pH sensation in C. elegans ( Sambongi et al., 2000 ) reinforced by the essential role that orthologues play in vertebrate noxious responses ( Dhaka et al., 2009 ). Interestingly, other TRP channel orthologues were defective in chemoaversion implicating them in the acidic response. These include trpa-1 and the TRPM representatives gon-2 and gtl-2 . The former has been previously found to be implicated in mechanical and thermal responses in C. elegans whilst a WT response was elicited when exposed to ASH-dependent noxious chemical cues tested (i.e. copper chloride, 1M glycerol, denatonium; Kindt et al., 2007 ). Our results could therefore depend on the complexity of the low pH response circuitry, which does not exclusively rely on ASH neurons but on a series of amphids response ( Sambongi et al., 2000 ; Bergamasco and Bazzicalupo, 2006 ). To the best of our knowledge, the TRPMs have never been tested for chemical sensitivity but have been mostly studied for their role in reproduction ( Sun and Lambie, 1997 ; Teramoto et al., 2010 ). Despite the low expression levels of gon-2 in amphids and the selective expression of gtl-2 in pharynx and excretory cells, the phenotype observed might indicate some indirect effect of these TRP proteins in the chemosensation executed by exposure to low pH. The only ASC strain to show defects when exposed to acidic pH was the double mutant acd-1/deg-1 which carries mutation in both neuronal and glial ASC proteins, suggesting a glial role in the processing of low pH in C. elegans , similarly to what previously reported in vertebrates ( Chesler, 2003 ; Erlichman et al., 2004 ; Wang et al., 2008 ; Gourine and Dale, 2022 ). The octopus arm, the main structure involved in sensory interaction with environmental cues, includes different types of neurons and glial-like cells that might highlight the potential role of this cell type in acidic nociception as well ( Young, 1971 ; Winters-Bostwick et al., 2024 ). The lack of impairment in the rest of the ASC protein family members tested here is in line with previous studies showing a main role in mechanical detection ( Suzuki et al., 2003 ; Zhang et al., 2004 ; Árnadóttir et al., 2011 ; Schafer, 2015 ; Al-Sheikh and Kang, 2020 ). O. vulgaris lacks canonical vertebrate opioid signalling According to Bateson’s criteria (1991) for eligibility to feel pain, animals must be endowed not just with nociceptors connected to a central brain mass but they should also possess a system able to counteract the inner disruption of the organism homeostasis, namely analgesic pathways. Therefore, we included candidates for opioid and cannabinoid receptors, and their ligand precursors. Blasting of ‘classical’ vertebrate opioid receptors (i.e. mu-, kappa-, delta-) produced two matches. The first one was the opioid growth factor receptor (OGFR), which has no structural resemblance to the classical opioid receptors and constitutes a different protein family ( Zagon et al., 2002 ). The second and closest homology was to the allatostatin C receptor (AstCR), the protostome orthologue of the vertebrate somatostatin receptor ( Koch et al., 2022 ). Opioid receptors are thought to have evolved from a duplication of the AstCRs ( Thiel et al., 2021 ) and a few studies have reported a role of AstC in nociception and immunity in invertebrates ( Bachtel et al., 2018 ; Li et al., 2021 ), in addition to growth and feeding regulation ( Mizoguchi, 2016 ; Stay and Tobe, 2007 ). This raises the intriguing possibility that AstC signalling might underpin anti-nociceptive signalling in phyla that lack an opioid system. In line with this, we selected the opioid-like/allatostatin C-like receptor npr-17 as the best candidate to be tested in C. elegans ( Beets et al., 2023 ). Previous work has shown that the receptor NPR-17 and the neuropeptides NLP-3 and NLP-24 are essential in the morphine-mediated 1-octanol avoidance response and that the impaired response of the npr-17 null mutant could be rescued by the human κ-opioid receptor ( Mills et al., 2016 ). However, in our experiment, mutant strains for all three genes were not impaired in low pH chemoaversion, confirming a more complex peptidergic modulation of the aversive response. A recent large-scale de-orphanisation of C. elegans GPCR identified an additional 12 AstCRs which might be worth analysing in the appropriate noxious context ( Beets et al., 2023 ). C. elegans orthologues of enzymes involved in the biosynthesis (i.e., the CPE egl-21) , and processing of neuropeptides (i.e., the PCSK2 egl-3) , showed disrupted responses to the low pH cue. Mutations in egl-3 and egl - 21 were already known to show defects in mechanosensory and thermosensory avoidance responses ( Kass et al., 2001 ; Nkambeu et al., 2019 ). Such defects can be related to the disrupted production of neuropeptides as highlighted by mass spectrometry experiments ( Husson et al., 2006 ; Husson et al., 2007 ). Collectively, these data point out the importance of neuropeptide signaling in the processing of nociception ( Dickinson and Fleetwood-Walker, 1998 ) but do not constitute evidence of the presence of the classical analgesic pathways. Indeed, even in the case of the opioid sensitive analgesic pathway there is a broader functional consequence of this signaling extending to underpinnings of appetite, gut function and systemic homeostasis ( Yuan et al., 2012 ). Our in silico findings are somewhat in line with previous phylogenetic and bioinformatic analysis suggesting opioids and endocannabinoids as vertebrate exclusive proteins ( Thiel et al., 2021 ). This does not necessarily mean that invertebrates do not possess a system to counteract noxious stimuli as they could have more ancient or unique solutions to the same problem. FMRFamide has been considered the equivalent of opioid molecules in invertebrates as the sequence (Phe-Met-Arg-Phe-NH2) shows some similarities to the heptapeptide Met-enkephalin (Tyr-Gly-Gly-Phe-Met-Arg-Phe). Among the wider physiological functions these peptides were found to modulate in molluscs and more generally in invertebrates, there are a few showing an induced suppression of primary nociceptors in Aplysia ( Belardetti et al., 1987 ; Mackey et al., 1987 ). The mutant of the C. elegans FMRFa orthologue we selected, flp-1 did not show impairment in acidic response but has been found involved in high osmolarity aversion ( Nelson et al., 1998 ; Li et al., 1999 ) suggesting a more selective chemosensory role. The orthologue of the FMRFamide receptor, frpr-3 on the other hand, showed a strong impairment in pH 3 response, and thus represents a strong candidate for further analysis. Lipid signalling is an important component of nociception modulation across phyla In the case of the endocannabinoid pathway, our in silico analysis identified different O. vulgaris genes encoding proteins implicated in fatty acid metabolism, such as DAGL, NAPE-PLD or Fatty acid-binding proteins (FABPs) (Table S2). However, we did not find molecular homologies to sign post any classical receptors of these signaling cascades within the octopus genomes. Although we found no evidence for the canonical endocannabinoid receptors in octopus, the lipids that act on them have established physiological effects on other proteins such as allatostatin receptors and TRPVs. Interestingly, one of the proposed “ancestors” of the endocannabinoid system is the TRPV channel, previously shown to mediate reduced nocifensive response when activated by anandamide and 2-acyl-gycerol in the medicinal leech Hirudo verbana ( Summers et al., 2017 ). Specifically in the case of C. elegans , bioinformatic analysis coupled with thermal proteomic profile, identified the AstCR npr-32 , and the TRPV ocr-2 as responsible for modulating the nocifensive response in a thermal avoidance assay, confirming these molecular determinants as key players in the detection and modulation of nociceptive responses ( Abdollahi et al., 2024 ). Limitations and potential confound of the study Our in silico approach was biased towards the selection of pre-existing, conserved molecular determinants, thus excluding potentially phylum-specific proteins as recently demonstrated by the identified chemotactile receptors in octopus and squid ( van Giesen et al., 2020 ; Kang et al., 2023 ). Our study found a large number of conserved candidates in the transcriptome of O. vulgaris ( Petrosino et al., 2015 ; Petrosino et al., 2022 ). However, the database available is not refined and therefore manual curation led to either the exclusion of incomplete or misannotated transcripts or required manual reconstruction (e.g., TRPV) to be fully investigated. The availability of the recently published chromosome-level genome could potentially improve the quality of this pipeline ( Destanović et al., 2023 ). Some limitations in the translation of our results to C. elegans warrant discussion. In fact, a few O. vulgaris gene families representative of nociception signaling could not be modelled in the nematode due to the absence of corresponding orthologues. This is exemplified by the purinergic receptors (P2X) and voltage gated sodium (Na v s) channels ( Bargmann, 1998 ; Harte and Ouzounis, 2002 ; Hobert, 2005-2018 ; Burnstock and Verkhratsky, 2009 ; Table S3). Furthermore, both the phylogenetic distance and the distinct environments in which the two species evolved should be considered, as the diverse modalities and variety of ecological stimuli could have driven shared proteins to diverge and acquire different adaptations ( van Giesen et al., 2020 ; Allard et al., 2023 ). Future directions By performing a chemosensory assay on C. elegans mutants for the orthologue of O. vulgaris putative nociceptive genes, we have highlighted candidates that are involved in the acidic pH avoidance response. Two main categories of proteins deserve priority for further investigation: One is the classical activators of nociception, such as the TRPV channel subfamily, whose role in nociception is widely conserved across phyla, and the other is the neuropeptide-related proteins, such as FMRFa, AstC, their receptors and the enzymes involved in neuropeptide processing. A functional role of these candidates in nociception could be explored further by complementation of C. elegans lost sensory functions by the O. vulgaris orthologous gene. Overall, we highlighted an intersecting bioinformatic model hopping approach that facilitates understanding of nociception in O. vulgaris and which has key relevance for an evolutionary perspective on the phenomenon of pain. Competing interests No competing interests declared Author contributions Conceptualization: E.M.P., L.H., V.O., G.F., J.D.; Methodology: E.M.P., L.H., V.O., J.D.; In silico analysis: E.M.P. P.I.; Experimental investigation: E.M.P.; Resources: L.H., V.O., J.D.; Writing-original draft: E.M.P., L.H., V.O., J.D.; Supervision: L.H., V.O., J.D.; Project administration: L.H., V.O., J.D.; Funding acquisition: L.H., V.O., G.F. Funding E.M.P. is funded by the Association for Cephalopod Research ‘CephRes’ ETS, Napoli, Italy and the HSA-Ceph 1/2019 grant to ‘CephRes’, and The Gerald Kerkut Charitable Trust, UK Data and resource availability All relevant data and details of resources can be found within the article and its supplementary information Acknowledgments We thank Prof Laura Bianchi (University of Miami, Miami, FL) for kindly providing the double mutant acd-1/deg-1 (bz90/u38) and Dr Xiaofei Bai (University of Florida, Gainesville, FL) for kindly sharing AG405 pezo-1 (av143) strain. The rest of the strains were provided either by the Caenorhabditis Genetic Center (CGC), funded by NIH Office of Research Infrastructure Programs (P40 OD010440) or the National Bioresource Project (NBRP), funded by the AMED (Japan Agency for Medical Research and Development). Funder Information Declared Association for Cephalopod Research, Naples, IT , HSA-Ceph 1/2019 Gerald Kerkut Charitable Trust, https://ror.org/04hwsx993 References ↵ Abdollahi , M. , Castaño , J. D. , Salem , J. B. and Beaudry , F . ( 2024 ). Anandamide modulates thermal avoidance in Caenorhabditis elegans through vanilloid and cannabinoid receptor interplay . Neurochem Res 49 , 2423 – 2439 . OpenUrl PubMed ↵ Al-Sheikh , U. and Kang , L . ( 2020 ). Mechano-gated channels in C. elegans . J Neurogenet 34 , 363 – 368 . OpenUrl ↵ Allard , C. A. H. , Kang , G. , Kim , J. J. , Valencia-Montoya , W. A. , Hibbs , R. E. and Bellono , N. W . ( 2023 ). Structural basis of sensory receptor evolution in octopus . Nature 616 , 373 – 377 . OpenUrl CrossRef PubMed ↵ Altschul , S. F. , Gish , W. , Miller , W. , Myers , E. W. and Lipman , D. J . ( 1990 ). Basic local alignment search tool . J Mol Biol 215 , 403 – 10 . OpenUrl CrossRef PubMed Web of Science ↵ Alupay , J. S. , Hadjisolomou , S. P. and Crook , R. J . ( 2014 ). Arm injury produces long-term behavioral and neural hypersensitivity in octopus . Neurosci Lett 558 , 137 – 142 . OpenUrl CrossRef PubMed ↵ Árnadóttir , J. , O’Hagan , R. , Chen , Y. , Goodman , M. B. and Chalfie , M . ( 2011 ). The DEG/ENaC protein MEC-10 regulates the transduction channel complex in Caenorhabditis elegans touch receptor neurons . J Neurosci 31 , 12695 – 12704 . OpenUrl Abstract / FREE Full Text ↵ Bachtel , N. D. , Hovsepian , G. A. , Nixon , D. F. and Eleftherianos , I . ( 2018 ). Allatostatin C modulates nociception and immunity in Drosophila . Sci Rep 8 , 7501 . OpenUrl CrossRef ↵ Baggerman , G. , Liu , F. , Wets , G. and Schoofs , L . ( 2005 ). Bioinformatic analysis of peptide precursor proteins . Ann NY Acad Sci 1040 , 59 – 65 . OpenUrl CrossRef PubMed Bai , X. , Bouffard , J. , Lord , A. , Brugman , K. , Sternberg , P. W. , Cram , E. J. and Golden , A . ( 2020 ). Caenorhabditis elegans PIEZO channel coordinates multiple reproductive tissues to govern ovulation . Elife 9 , e53603 . OpenUrl CrossRef PubMed ↵ Bargmann , C. I . ( 1998 ). Neurobiology of the Caenorhabditis elegans genome . Science 282 , 2028 – 2033 . OpenUrl Abstract / FREE Full Text Barr , M. M. and Sternberg , P. W . ( 1999 ). A polycystic kidney-disease gene homologue required for male mating behaviour in C. elegans . Nature 401 , 386 – 389 . OpenUrl CrossRef PubMed Web of Science Barrett , P. L . ( 1999 ). tkr-1, a Caenorhabditis elegans tachykinin receptor homolog: Harvard University. Basbaum , A. I. , Bautista , D. M. , Scherrer , G. and Julius , D . ( 2009 ). Cellular and molecular mechanisms of pain . Cell 139 , 267 – 284 . OpenUrl CrossRef PubMed Web of Science Bateson , P . ( 1991 ). Assessment of pain in animals . Anim Behav 42 , 827 – 839 . OpenUrl CrossRef Web of Science Bauer , R. , Nebenfuehr , B. and Golden , A . ( 2019 ). Resolving a contradiction: full gene deletion of kqt-3 by CRISPR does not lead to pharyngeal pumping defects . microPubl Biol 2019 , 10 – 17912 . OpenUrl ↵ Beets , I. , Zels , S. , Vandewyer , E. , Demeulemeester , J. , Caers , J. , Baytemur , E. , Courtney , A. , Golinelli , L. , Hasakioğulları , İ. and Schafer , W. R. ( 2023 ). System-wide mapping of peptide-GPCR interactions in C. elegans . Cell Rep 42 . ↵ Belardetti , F. , Kandel , E. R. and Siegelbaum , S. A . ( 1987 ). Neuronal inhibition by the peptide FMRFamide involves opening of S K+ channels . Nature 325 , 153 – 156 . OpenUrl CrossRef PubMed Web of Science Benemei , S. , Nicoletti , P. , Capone , J. G. and Geppetti , P . ( 2009 ). CGRP receptors in the control of pain and inflammation . Curr Opin Pharmacol 9 , 9 – 14 . OpenUrl CrossRef PubMed ↵ Bergamasco , C. and Bazzicalupo , P . ( 2006 ). Signaling in the Chemosensory Systems: Chemical sensitivity in Caenorhabditis elegans . Cell Mol Life Sci 63 , 1510 – 1522 . OpenUrl CrossRef PubMed Web of Science ↵ Birch , J. , Burn , C. , Schnell , A. , Browning , H. and Crump , A . ( 2021 ). Review of the Evidence of Sentience in Cephalopod Molluscs and Decapod Crustaceans . LSE Consulting . ↵ Blum , M. , Chang , H.-Y. , Chuguransky , S. , Grego , T. , Kandasaamy , S. , Mitchell , A. , Nuka , G. , Paysan-Lafosse , T. , Qureshi , M. , Raj , S. et al. ( 2021 ). The InterPro protein families and domains database: 20 years on . Nucleic Acids Res 49 , D344 – D354 . OpenUrl CrossRef PubMed ↵ Brenner , S . ( 1974 ). The genetics of Caenorhabditis elegans . Genetics 77 , 71 – 94 . OpenUrl Abstract / FREE Full Text Brooks , D. R. , Appleford , P. J. , Murray , L. and Isaac , R. E . ( 2003 ). An essential role in molting and morphogenesis of Caenorhabditis elegans for ACN-1, a novel member of the angiotensin-converting enzyme family that lacks a metallopeptidase active site . J Biol Chem 278 , 52340 – 52346 . OpenUrl Abstract / FREE Full Text Buntschuh , I. , Raps , D. A. , Joseph , I. , Reid , C. , Chait , A. , Totanes , R. , Sawh , M. and Li , C . ( 2018 ). FLP-1 neuropeptides modulate sensory and motor circuits in the nematode Caenorhabditis elegans . PloS One 13 , e0189320 . OpenUrl CrossRef PubMed ↵ Burnstock , G. and Verkhratsky , A . ( 2009 ). Evolutionary origins of the purinergic signalling system . Acta Physiol 195 , 415 – 447 . OpenUrl ↵ Carbon , S. , Ireland , A. , Mungall , C. J. , Shu , S. , Marshall , B. , Lewis , S. , the Ami , G. O. H. and the Web Presence Working, G . ( 2009 ). AmiGO: online access to ontology and annotation data . Bioinformatics 25 , 288 – 289 . OpenUrl CrossRef PubMed Web of Science Caterina , M. J. , Schumacher , M. A. , Tominaga , M. , Rosen , T. A. , Levine , J. D. and Julius , D . ( 1997 ). The capsaicin receptor: a heat-activated ion channel in the pain pathway . Nature 389 , 816 – 824 . OpenUrl CrossRef PubMed Web of Science Chatzigeorgiou , M. , Bang , S. , Hwang , S. W. and Schafer , W. R . ( 2013 ). tmc-1 encodes a sodium-sensitive channel required for salt chemosensation in C. elegans . Nature 494 , 95 – 99 . OpenUrl CrossRef PubMed Web of Science Chatzigeorgiou , M. , Yoo , S. , Watson , J. D. , Lee , W.-H. , Spencer , W. C. , Kindt , K. S. , Hwang , S. W. , Miller Iii , D. M. , Treinin , M. and Driscoll , M . ( 2010 ). Specific roles for DEG/ENaC and TRP channels in touch and thermosensation in C. elegans nociceptors . Nat Neurosci 13 , 861 – 868 . OpenUrl CrossRef PubMed Web of Science ↵ Chesler , M . ( 2003 ). Regulation and modulation of pH in the brain . Physiol Rev 83 , 1183 – 1221 . OpenUrl CrossRef PubMed Web of Science Chew , Y. L. , Tanizawa , Y. , Cho , Y. , Zhao , B. , Alex , J. Y. , Ardiel , E. L. , Rabinowitch , I. , Bai , J. , Rankin , C. H. and Lu , H . ( 2018 ). An Afferent Neuropeptide System Transmits Mechanosensory Signals Triggering Sensitization and Arousal in C. elegans . Neuron 99 , 1233 – 1246 . OpenUrl CrossRef PubMed Cho , H. , Yang , Y. D. , Lee , J. , Lee , B. , Kim , T. , Jang , Y. , Back , S. K. , Na , H. S. , Harfe , B. D. and Wang , F . ( 2012 ). The calcium-activated chloride channel anoctamin 1 acts as a heat sensor in nociceptive neurons . Nat Neurosci 15 , 1015 – 1021 . OpenUrl CrossRef PubMed Choi , J.-G. , Choi , S.-R. , Kang , D.-W. , Kim , J. , Park , J. B. and Kim , H.-W . ( 2021 ). Inhibition of angiotensin converting enzyme induces mechanical allodynia through increasing substance P expression in mice . Neurochem Int 146 , 105020 . OpenUrl Coburn , C. M. ( 1996 ). tax-2 : A putative cyclic nucleotide-gated channel required for sensory neuron function and development in Caenorhabditis elegans , vol. PhD thesis: University of California, San Francisco . Colbert , H. A. , Smith , T. L. and Bargmann , C. I . ( 1997 ). OSM-9, A novel protein with structural similarity to channels, is required for olfaction, mechanosensation, and olfactory adaptation in Caenorhabditis elegans . J Neurosci 17 , 8259 – 8269 . OpenUrl Abstract / FREE Full Text ↵ Cottrell , G. A . ( 1997 ). The first peptide-gated ion channel . J Exp Biol 200 , 2377 – 2386 . OpenUrl Abstract ↵ Cottrell , G. A. , Green , K. A. and Davies , N. W . ( 1990 ). The neuropeptide Phe-Met-Arg-Phe-NH2 (FMRFamide) can activate a ligand-gated ion channel in Helix neurons . Pflüg Arch 416 , 612 – 614 . OpenUrl ↵ Cottrell , G. A. , Schot , L. P. C. and Dockray , G. J . ( 1983 ). Identification and probable role of a single neurone containing the neuropeptide Helix FMRFamide . Nature 304 , 638 – 640 . OpenUrl CrossRef PubMed ↵ Crook , R. J . ( 2021 ). Behavioral and neurophysiological evidence suggests affective pain experience in octopus . iScience 24 , 102229 . OpenUrl ↵ Crook , R. J. , Dickson , K. , Hanlon , R. T. and Walters , E. T . ( 2014 ). Nociceptive sensitization reduces predation risk . Curr Biol 24 , 1121 – 1125 . OpenUrl CrossRef PubMed ↵ Crook , R. J. , Hanlon , R. T. and Walters , E. T . ( 2013 ). Squid have nociceptors that display widespread long-term sensitization and spontaneous activity after bodily injury . J Neurosci 33 , 10021 – 10026 . OpenUrl Abstract / FREE Full Text ↵ Davis , P. , Zarowiecki , M. , Arnaboldi , V. , Becerra , A. , Cain , S. , Chan , J. , Chen , W. J. , Cho , J. , da Veiga Beltrame , E. , Diamantakis , S. et al. ( 2022 ). WormBase in 2022—data, processes, and tools for analyzing Caenorhabditis elegans . Genetics 220 , iyac003 . OpenUrl CrossRef PubMed Deng , J. , Zhou , H. , Lin , J.-K. , Shen , Z.-X. , Chen , W.-Z. , Wang , L.-H. , Li , Q. , Mu , D. , Wei , Y.-C. and Xu , X.-H . ( 2020 ). The parabrachial nucleus directly channels spinal nociceptive signals to the intralaminar thalamic nuclei, but not the amygdala . Neuron 107 , 909 – 923 . OpenUrl CrossRef PubMed ↵ Destanović , D. , Schultz , D. T. , Styfhals , R. , Cruz , F. , Gómez-Garrido , J. , Gut , M. , Gut , I. , Fiorito , G. , Simakov , O. and Alioto , T. S . ( 2023 ). A chromosome-level reference genome for the common octopus, Octopus vulgaris (Cuvier, 1797) . G3-Genes Genom Genet , 2023-05. Deval , E. and Lingueglia , E . ( 2015 ). Acid-Sensing Ion Channels and nociception in the peripheral and central nervous systems . Neuropharmacology 94 , 49 – 57 . OpenUrl CrossRef PubMed ↵ Dhaka , A. , Uzzell , V. , Dubin , A. E. , Mathur , J. , Petrus , M. , Bandell , M. and Patapoutian , A . ( 2009 ). TRPV1 is activated by both acidic and basic pH . J Neurosci 29 , 153 – 158 . OpenUrl Abstract / FREE Full Text ↵ Dickinson , T. and Fleetwood-Walker , S. M . ( 1998 ). Neuropeptides and nociception: recent advances and therapeutic implications . Trends Pharmacol Sci 19 , 346 – 348 . OpenUrl CrossRef PubMed Dong , X. , Chiu , H. , Park , Y. J. , Zou , W. , Zou , Y. , Özkan , E. , Chang , C. and Shen , K . ( 2016 ). Precise regulation of the guidance receptor DMA-1 by KPC-1/Furin instructs dendritic branching decisions . eLife 5 , e11008 . OpenUrl CrossRef PubMed Driscoll , M. and Chalfie , M . ( 1991 ). The mec-4 gene is a member of a family of Caenorhabditis elegans genes that can mutate to induce neuronal degeneration . Nature 349 , 588 – 593 . OpenUrl CrossRef PubMed Web of Science ↵ Dubin , A. E. and Patapoutian , A . ( 2010 ). Nociceptors: the sensors of the pain pathway . J Clin Invest 120 , 3760 – 3772 . OpenUrl CrossRef PubMed Web of Science Eigenbrod , O. , Debus Karlien , Y. , Reznick , J. , Bennett Nigel , C. , Sánchez-Carranza , O. , Omerbašić , D. , Hart Daniel , W. , Barker Alison , J. , Zhong , W. , Lutermann , H. et al. ( 2019 ). Rapid molecular evolution of pain insensitivity in multiple African rodents . Science 364 , 852 – 859 . OpenUrl Abstract / FREE Full Text ↵ Erlichman , J. S. , Cook , A. , Schwab , M. C. , Budd , T. W. and Leiter , J. C . ( 2004 ). Heterogeneous patterns of pH regulation in glial cells in the dorsal and ventral medulla . Am J Physiol-Reg I 286 , R289 – R302 . OpenUrl CrossRef PubMed Web of Science ↵ European Parliament and Council of the European Union . ( 2010 ). Directive 2010/63/EU of the European Parliament and of the Council of 22 September 2010 on the protection of animals used for scientific purposes , vol. 2010. Strasbourg : Council of Europe . Feng , Z. , Li , W. , Ward , A. , Piggott , B. J. , Larkspur , E. R. , Sternberg , P. W. and Xu , X. Z. S . ( 2006 ). A C. elegans model of nicotine-dependent behavior: regulation by TRP-family channels . Cell 127 , 621 – 633 . OpenUrl CrossRef PubMed Web of Science Fricker , L. D . ( 1993 ). Opioid peptide processing enzymes . In Opioids , pp. 529 – 545 . Handb Exp Pharmacol: Springer . Frøkjær-Jensen , C. , Kindt , K. S. , Kerr , R. A. , Suzuki , H. , Melnik-Martinez , K. , Gerstbreih , B. , Driscol , M. and Schafer , W. R. ( 2006 ). Effects of voltage-gated calcium channel subunit genes on calcium influx in cultured C. elegans mechanosensory neurons . J Neurobiol 66 , 1125 – 1139 . OpenUrl CrossRef PubMed Web of Science Gao , S. and Zhen , M . ( 2011 ). Action potentials drive body wall muscle contractions in Caenorhabditis elegans . P Natl Acad Sci USA 108 , 2557 – 2562 . OpenUrl Abstract / FREE Full Text ↵ Gasteiger , E. , Gattiker , A. , Hoogland , C. , Ivanyi , I. , Appel , R. D. and Bairoch , A . ( 2003 ). ExPASy: The proteomics server for in-depth protein knowledge and analysis . Nucleic Acids Res 31 , 3784 – 8 . OpenUrl CrossRef PubMed Web of Science Giamarchi , A. , Padilla , F. , Coste , B. , Raoux , M. , Crest , M. , Honoré , E. and Delmas , P . ( 2006 ). The versatile nature of the calcium-permeable cation channel TRPP2 . EMBO Rep 7 , 787 – 793 . OpenUrl Abstract / FREE Full Text Goodman , M. B. and Schwarz , E. M . ( 2003 ). Transducing touch in Caenorhabditis elegans . Annu Rev Physiol 65 , 429 – 452 . OpenUrl CrossRef PubMed Web of Science ↵ Gourine , A. V. and Dale , N . ( 2022 ). Brain H+/CO2 sensing and control by glial cells . Glia 70 , 1520 – 1535 . OpenUrl CrossRef PubMed ↵ Gray , J. M. , Hill , J. J. and Bargmann , C. I . ( 2005 ). A circuit for navigation in Caenorhabditis elegans . P Natl Acad Sci USA 102 , 3184 – 3191 . OpenUrl Abstract / FREE Full Text ↵ Graziadei , P . ( 1964 ). Electron microscopy of some primary receptors in the sucker of Octopus vulgaris . Z Zellforsch Mik Ana 64 , 510 – 522 . OpenUrl Gu , G. , Caldwell , G. A. and Chalfie , M . ( 1996 ). Genetic interactions affecting touch sensitivity in Caenorhabditis elegans . P Natl Acad Sci USA 93 , 6577 – 6582 . OpenUrl Abstract / FREE Full Text ↵ Hague , T. , Florini , M. and Andrews , P. L. R . ( 2013 ). Preliminary in vitro functional evidence for reflex responses to noxious stimuli in the arms of Octopus vulgaris . J Exp Mar Biol Ecol 447 , 100 – 105 . OpenUrl Hao , J. , Padilla , F. , Dandonneau , M. , Lavebratt , C. , Lesage , F. , Noël , J. and Delmas , P . ( 2013 ). Kv1.1 channels act as mechanical brake in the senses of touch and pain . Neuron 77 , 899 – 914 . OpenUrl CrossRef PubMed Web of Science Harris , G. , Mills , H. , Wragg , R. , Hapiak , V. , Castelletto , M. , Korchnak , A. and Komuniecki , R. W . ( 2010 ). The monoaminergic modulation of sensory-mediated aversive responses in Caenorhabditis elegans requires glutamatergic/peptidergic cotransmission . J Neurosci 30 , 7889 – 7899 . OpenUrl Abstract / FREE Full Text Harrison , L. M. , Kastin , A. J. , Weber , J. T. , Banks , W. A. , Hurley , D. L. and Zadina , J. E . ( 1994 ). The opiate system in invertebrates . Peptides 15 , 1309 – 1329 . OpenUrl CrossRef PubMed Web of Science ↵ Harte , R. and Ouzounis , C. A . ( 2002 ). Genome-wide detection and family clustering of ion channels . FEBS Lett 514 , 129 – 134 . OpenUrl CrossRef PubMed ↵ Hildebrand , A. , Remmert , M. , Biegert , A. and Söding , J . ( 2009 ). Fast and accurate automatic structure prediction with HHpred . Proteins:Struct Funct Bioinf 77 , 128 – 132 . OpenUrl ↵ Hobert , O. ( 2005-2018 ). The neuronal genome of Caenorhabditis elegans . In: WormBook: The Online Review of C. elegans Biology. In WormBook . Pasadena (CA) : WormBook . Hong , K. , Mano , I. and Driscoll , M . ( 2000 ). In Vivo Structure–Function Analyses of Caenorhabditis elegans MEC-4, a Candidate Mechanosensory Ion Channel Subunit . J Neurosci 20 , 2575 – 2588 . OpenUrl Abstract / FREE Full Text ↵ Howard , R. B. , Lopes , L. N. , Lardie , C. R. , Perez , P. P. and Crook , R. J. ( 2019 ). Early-life injury produces lifelong neural hyperexcitability, cognitive deficit and altered defensive behaviour in the squid Euprymna scolopes . Philos T R Soc B 374 , 20190281 . OpenUrl CrossRef PubMed Huang , M. and Chalfie , M . ( 1994 ). Gene interactions affecting mechanosensory transduction in Caenorhabditis elegans . Nature 367 , 467 – 470 . OpenUrl CrossRef PubMed Web of Science ↵ Huang , X. and Miller , W . ( 1991 ). A time-efficient, linear-space local similarity algorithm . Adv Appl Math 12 , 337 – 357 . OpenUrl CrossRef Web of Science ↵ Husson , S. J. , Clynen , E. , Baggerman , G. , Janssen , T. and Schoofs , L . ( 2006 ). Defective processing of neuropeptide precursors in Caenorhabditis elegans lacking proprotein convertase 2 (KPC-2/EGL-3): mutant analysis by mass spectrometry . J Neurochem 98 , 1999 – 2012 . OpenUrl CrossRef PubMed Web of Science ↵ Husson , S. J. , Mertens , I. , Janssen , T. , Lindemans , M. and Schoofs , L . ( 2007 ). Neuropeptidergic signaling in the nematode Caenorhabditis elegans . Prog Neurobiol 82 , 33 – 55 . OpenUrl CrossRef PubMed Web of Science ↵ Iglesias , J. , Sánchez , F. J. , Bersano , J. G. F. , Carrasco , J. F. , Dhont , J. , Fuentes , L. , Linares , F. , Muñoz , J. L. , Okumura , S. and Roo , J . ( 2007 ). Rearing of Octopus vulgaris paralarvae: present status, bottlenecks and trends . Aquaculture 266 , 1 – 15 . OpenUrl CrossRef Web of Science Immke , D. C. and Gavva , N. R . ( 2006 ). The TRPV1 receptor and nociception . Seminars in cell & developmental biology 17 , 582 – 591 . OpenUrl CrossRef PubMed Web of Science Johanning , K. , Juliano , M. A. , Juliano , L. , Lazure , C. , Lamango , N. S. , Steiner , D. F. and Lindberg , I . ( 1998 ). Specificity of prohormone convertase 2 on proenkephalin and proenkephalin-related substrates . J Biol Chem 273 , 22672 – 22680 . OpenUrl Abstract / FREE Full Text Julius , D . ( 2013 ). TRP channels and pain . Annu Rev Cell Dev Bi 29 , 355 – 384 . OpenUrl CrossRef PubMed ↵ Kang , G. , Allard , C. A. H. , Valencia-Montoya , W. A. , van Giesen , L. , Kim , J. J. , Kilian , P. B. , Bai , X. , Bellono , N. W. and Hibbs , R. E. ( 2023 ). Sensory specializations drive octopus and squid behaviour . Nature 616 , 378 – 383 . OpenUrl CrossRef PubMed ↵ Kass , J. , Jacob , T. C. , Kim , P. and Kaplan , J. M . ( 2001 ). The EGL-3 proprotein convertase regulates mechanosensory responses of Caenorhabditis elegans . J Neurosci 21 , 9265 – 9272 . OpenUrl Abstract / FREE Full Text Kavaliers , M. , Hirst , M. and Teskey , G. C . ( 1985 ). The effects of opioid and FMRF-amide peptides on thermal behavior in the snail . Neuropharmacology 24 , 621 – 626 . OpenUrl PubMed ↵ Kindt , K. S. , Viswanath , V. , Macpherson , L. , Quast , K. , Hu , H. , Patapoutian , A. and Schafer , W. R . ( 2007 ). Caenorhabditis elegans TRPA-1 functions in mechanosensation . Nat Neurosci 10 , 568 – 577 . OpenUrl CrossRef PubMed ↵ Koch , T. L. , Ramiro , I. B. L. , Flórez Salcedo , P. , Engholm , E. , Jensen , K. J. , Chase , K. , Olivera , B. M. , Bjørn-Yoshimoto , W. E. and Safavi-Hemami , H . ( 2022 ). Reconstructing the origins of the somatostatin and allatostatin-C signaling systems using the accelerated evolution of biodiverse cone snail toxins . Mol Biol Evol 39 , msac075 . OpenUrl Komandur , A. , Fazyl , A. , Stein , W. and Vidal-Gadea , A. G . ( 2023 ). The mechanoreceptor pezo-1 is required for normal crawling locomotion in the nematode C. elegans . microPubl Biol 2023 , 10 – 17912 . OpenUrl Komatsu , H. , Mori , I. , Rhee , J.-S. , Akaike , N. and Ohshima , Y . ( 1996 ). Mutations in a cyclic nucleotide–gated channel lead to abnormal thermosensation and chemosensation in C. elegans . Neuron 17 , 707 – 718 . OpenUrl CrossRef PubMed Web of Science Kumar , S. , Kundra , P. , Ramsamy , K. and Surendiran , A . ( 2019 ). Pharmacogenetics of opioids: a narrative review . Anaesthesia 74 , 1456 – 1470 . OpenUrl PubMed Kwan , K. Y. , Allchorne , A. J. , Vollrath , M. A. , Christensen , A. P. , Zhang , D.-S. , Woolf , C. J. and Corey , D. P . ( 2006 ). TRPA1 contributes to cold, mechanical, and chemical nociception but is not essential for hair-cell transduction . Neuron 50 , 277 – 289 . OpenUrl CrossRef PubMed Web of Science Lai , C. C. , Hong , K. , Kinnell , M. , Chalfie , M. and Driscoll , M . ( 1996 ). Sequence and transmembrane topology of MEC-4, an ion channel subunit required for mechanotransduction in Caenorhabditis elegans . J Cell Biol 133 , 1071 – 1081 . OpenUrl Abstract / FREE Full Text Lainé , V. , Frøkjær-Jensen , C. , Couchoux , H. and Jospin , M . ( 2011 ). The α1 subunit EGL-19, the α2/δ subunit UNC-36, and the β subunit CCB-1 underlie voltage-dependent calcium currents in Caenorhabditis elegans striated muscle . J Biol Chem 286 , 36180 – 36187 . OpenUrl Abstract / FREE Full Text Lambie , E. J. , Bruce Iii , R. D. , Zielich , J. and Yuen , S. N . ( 2015 ). Novel alleles of gon-2 , a C. elegans ortholog of mammalian TRPM6 and TRPM7, obtained by genetic reversion screens . PloS One 10 , e0143445 . OpenUrl Lee , C.-H. and Chen , C.-C . ( 2018 ). Roles of ASICs in nociception and proprioception: Springer . ↵ Li , C. , Nelson , L. S. , Kim , K. , Nathoo , A. and Hart , A. C . ( 1999 ). Neuropeptide Gene Families in the Nematode Caenorhabditis elegans . Ann NY Acad Sci 897 , 239 – 252 . OpenUrl CrossRef PubMed Web of Science Li , W. , Feng , Z. , Sternberg , P. W. and Shawn Xu , X. Z . ( 2006 ). A C. elegans stretch receptor neuron revealed by a mechanosensitive TRP channel homologue . Nature 440 , 684 – 687 . OpenUrl CrossRef PubMed Web of Science Li , W. , Kang , L. , Piggott , B. J. , Feng , Z. and Xu , X. Z . ( 2011 ). The neural circuits and sensory channels mediating harsh touch sensation in Caenorhabditis elegans . Nat Commun 2 , 1 – 9 . OpenUrl CrossRef Li , X.-Y. and Toyoda , H . ( 2015 ). Role of leak potassium channels in pain signaling . Brain Res Bull 119 , 73 – 79 . OpenUrl CrossRef PubMed ↵ Li , Z. , Cardoso , J. C. R. , Peng , M. , Inácio , J. P. S. and Power , D. M . ( 2021 ). Evolution and potential function in molluscs of neuropeptide and receptor homologues of the insect allatostatins . Front Endocrinol 12 , 725022 . OpenUrl Li , Z. , Venegas , V. , Nagaoka , Y. , Morino , E. , Raghavan , P. , Audhya , A. , Nakanishi , Y. and Zhou , Z . ( 2015 ). Necrotic cells actively attract phagocytes through the collaborative action of two distinct PS-exposure mechanisms . PLoS Genet 11 , e1005285 . OpenUrl CrossRef PubMed Lingueglia , E. , Champigny , G. , Lazdunski , M. and Barbry , P . ( 1995 ). Cloning of the amiloride-sensitive FMRFamide peptide-gated sodium channel . Nature 378 , 730 – 733 . OpenUrl CrossRef PubMed Web of Science Liu , M. and Wood , J. N . ( 2011 ). The roles of sodium channels in nociception: implications for mechanisms of neuropathic pain . Pain Med 12 , S93 – S99 . OpenUrl Liu , Q. , Kidd , P. B. , Dobosiewicz , M. and Bargmann , C. I . ( 2018 ). C. elegans AWA olfactory neurons fire calcium-mediated all-or-none action potentials . Cell 175 , 57 – 70 . OpenUrl CrossRef PubMed ↵ Lu , S. , Wang , J. , Chitsaz , F. , Derbyshire , M. K. , Geer , R. C. , Gonzales , N. R. , Gwadz , M. , Hurwitz , D. I. , Marchler , G. H. , Song , J. S. et al. ( 2020 ). CDD/SPARCLE: the conserved domain database in 2020 . Nucleic Acids Res 48 , D265 – d268 . OpenUrl CrossRef PubMed Luo , J. and Portman , D. S . ( 2021 ). Sex-specific, pdfr-1-dependent modulation of pheromone avoidance by food abundance enables flexibility in C. elegans foraging behavior . Curr Biol 31 , 4449 – 4461 . OpenUrl CrossRef PubMed ↵ Mackey , S. L. , Glanzman , D. L. , Small , S. A. , Dyke , A. M. , Kandel , E. R. and Hawkins , R. D . ( 1987 ). Tail shock produces inhibition as well as sensitization of the siphon-withdrawal reflex of Aplysia : possible behavioral role for presynaptic inhibition mediated by the peptide Phe-Met-Arg-Phe-NH2 . P Natl Acad Sci USA 84 , 8730 – 8734 . OpenUrl Abstract / FREE Full Text ↵ Madeira , F. , Pearce , M. , Tivey , A. R. N. , Basutkar , P. , Lee , J. , Edbali , O. , Madhusoodanan , N. , Kolesnikov , A. and Lopez , R . ( 2022 ). Search and sequence analysis tools services from EMBL-EBI in 2022 . Nucleic Acids Res 50 , W276 – W279 . OpenUrl CrossRef PubMed McDiarmid , T. A. , Ardiel , E. L. and Rankin , C. H . ( 2015 ). The role of neuropeptides in learning and memory in Caenorhabditis elegans . Curr Opin Behav Sci 2 , 15 – 20 . OpenUrl ↵ Meloto , C. B. , Benavides , R. , Lichtenwalter , R. N. , Wen , X. , Tugarinov , N. , Zorina-Lichtenwalter , K. , Chabot-Doré , A.-J. , Piltonen , M. H. , Cattaneo , S. and Verma , V . ( 2018 ). Human pain genetics database: a resource dedicated to human pain genetics research . Pain 159 , 749 – 763 . OpenUrl CrossRef Mikhailov , N. , Leskinen , J. , Fagerlund , I. , Poguzhelskaya , E. , Giniatullina , R. , Gafurov , O. , Malm , T. , Karjalainen , T. , Gröhn , O. and Giniatullin , R . ( 2019 ). Mechanosensitive meningeal nociception via Piezo channels: Implications for pulsatile pain in migraine? Neuropharmacology 149 , 113 – 123 . OpenUrl Millet , J. R. M. , Romero , L. O. , Lee , J. , Bell , B. and Vásquez , V . ( 2021 ). C. elegans PEZO-1 is a mechanosensitive ion channel involved in food sensation . J Gen Physiol 154 , e202112960 . OpenUrl ↵ Mills , H. , Ortega , A. , Law , W. , Hapiak , V. , Summers , P. , Clark , T. and Komuniecki , R . ( 2016 ). Opiates modulate noxious chemical nociception through a complex monoaminergic/peptidergic cascade . J Neurosci 36 , 5498 – 5508 . OpenUrl Abstract / FREE Full Text Mills , H. J. ( 2014 ). Opioid signaling contributes to the complex, monoaminergic modulation of nociception in Caenorhabditis elegans , vol. PhD thesis: University of Toledo . ↵ Y. Takei H. Ando and K. Tsutsui Mizoguchi , A . ( 2016 ). Chapter 49 - Allatostatin-C . In Handbook of Hormone:Comparative Endocrinology for Basic and Clinical Research , eds. Y. Takei H. Ando and K. Tsutsui ), pp. 385 – e49-1 . San Diego : Academic Press . Moshourab , R. A. , Wetzel , C. , Martinez-Salgado , C. and Lewin , G. R. ( 2013 ). Stomatin-domain protein interactions with acid-sensing ion channels modulate nociceptor mechanosensitivity . J Physiol 591 , 5555 – 5574 . OpenUrl CrossRef PubMed Nathoo , A. N. , Moeller , R. A. , Westlund , B. A. and Hart , A. C . ( 2001 ). Identification of neuropeptide-like protein gene families in Caenorhabditis elegans and other species . P Natl Acad Sci USA 98 , 14000 – 14005 . OpenUrl Abstract / FREE Full Text Neely , G. G. , Hess , A. , Costigan , M. , Keene , A. C. , Goulas , S. , Langeslag , M. , Griffin , R. S. , Belfer , I. , Dai , F. and Smith , S. B . ( 2010 ). A genome-wide Drosophila screen for heat nociception identifies α2δ3 as an evolutionarily conserved pain gene . Cell 143 , 628 – 638 . OpenUrl CrossRef PubMed Web of Science ↵ Nelson , L. S. , Kim , K. , Memmott , J. E. and Li , C . ( 1998 ). FMRFamide-related gene family in the nematode, Caenorhabditis elegans . Mol Brain Res 58 , 103 – 111 . OpenUrl CrossRef PubMed Nishimori , T. , Naono-Nakayama , R. and Ikeda , T . ( 2013 ). New tachykinin peptides and nociception . Jpn Dent Sci Rev 49 , 27 – 34 . OpenUrl Nkambeu , B. , Ben Salem , J. and Beaudry , F . ( 2021 ). Eugenol and other vanilloids hamper Caenorhabditis elegans response to noxious heat . Neurochem Res 46 , 252 – 264 . OpenUrl PubMed ↵ Nkambeu , B. , Salem , J. B. , Leonelli , S. , Marashi , F. A. and Beaudry , F . ( 2019 ). EGL-3 and EGL-21 are required to trigger nocifensive response of Caenorhabditis elegans to noxious heat . Neuropeptides 73 , 41 – 48 . OpenUrl Okahata , M. , Wei Aguan , D. , Ohta , A. and Kuhara , A . ( 2019 ). Cold acclimation via the KQT-2 potassium channel is modulated by oxygen in Caenorhabditis elegans . Sci Adv 5 , eaav3631 . OpenUrl FREE Full Text Papaioannou , S. , Holden-Dye , L. and Walker , R . ( 2008 ). The actions of Caenorhabditis elegans neuropeptide-like peptides (NLPs) on body wall muscle of Ascaris suum and pharyngeal muscle of C. elegans . Acta Biol Hung 59 , 189 – 197 . OpenUrl CrossRef PubMed ↵ Peng , G. , Shi , X. and Kadowaki , T . ( 2015 ). Evolution of TRP channels inferred by their classification in diverse animal species . Mol Phylogenet Evol 84 , 145 – 157 . OpenUrl CrossRef PubMed ↵ Perkins , L. A. , Hedgecock , E. M. , Thomson , J. N. and Culotti , J. G . ( 1986 ). Mutant sensory cilia in the nematode Caenorhabditis elegans . Dev Biol 117 , 456 – 487 . OpenUrl CrossRef PubMed Web of Science ↵ Petrosino , G. , Ponte , G. , Volpe , M. , Zarrella , I. , Ansaloni , F. , Langella , C. , Di Cristina , G. , Finaurini , S. , Russo , M. T. and Basu , S. ( 2022 ). Identification of LINE retrotransposons and long non-coding RNAs expressed in the octopus brain . BMC Biol 20 , 116 . OpenUrl CrossRef PubMed ↵ Petrosino , G. , Zarrella , I. , Ponte , G. , Basu , S. , Calogero , R. , Fiorito , G. and Sanges , R. ( 2015 ). De-novo assembly of the octopus transcriptome integrating custom and public sequencing data . In BIOINFO-BITS . Available at: https://bioinformatics.hsanmartino.it/bits_library/library/01652.pdf . ↵ Pieroni , E. M. , Sykes , A. V. , Galligioni , V. , Estefanell , J. , Hetherington , S. , Brocca , M. , Correia , J. , Ferreira , A. and Fiorito , G . ( 2022 ). Review on the methods of capture and transport of cephalopods for scientific purposes: Outcomes of FELASA Working Group ‘Capture and Transport of Cephalopods’ . A CephRes & FELASA Publication . ↵ Ponte , G. , Roumbedakis , K. , FA, C. A., Galligioni , V. , Dickel , L. , Bellanger , C. , Pereira , J. , Vidal , E. A. G. , Grigoriou , P. , Alleva , E. , et al. ( 2022 ). General and species-specific recommendations for minimal requirements for the use of cephalopods in scientific research . Lab Anim , 00236772221111261 . Price , M. P. , Thompson , R. J. , Eshcol , J. O. , Wemmie , J. A. and Benson , C. J . ( 2004 ). Stomatin modulates gating of acid-sensing ion channels . J Biol Chem 279 , 53886 – 53891 . OpenUrl Abstract / FREE Full Text Ramsey , I. S. , Delling , M. and Clapham , D. E . ( 2006 ). An introduction to TRP channels . Annu Rev Physiol 68 , 619 – 647 . OpenUrl CrossRef PubMed Web of Science ↵ Rossi , F. and Graziadei , P . ( 1956 ). Nouvelles Contributions à la connaissance du systême nerveux du tentacule des céphalopodes. II . Cells Tissues Organs 26 , 165 – 174 . OpenUrl Salim , C. , Kan , A. K. , Batsaikhan , E. , Patterson , E. C. and Jee , C . ( 2022 ). Neuropeptidergic regulation of compulsive ethanol seeking in C. elegans . Sci Rep 12 , 1804 . OpenUrl CrossRef PubMed Salzberg , Y. , Ramirez-Suarez , N. J. and Bülow , H. E . ( 2014 ). The proprotein convertase KPC-1/furin controls branching and self-avoidance of sensory dendrites in Caenorhabditis elegans . PLoS Genet 10 , e1004657 . OpenUrl CrossRef PubMed ↵ Sambongi , Y. , Takeda , K. , Wakabayashi , T. , Ueda , I. , Wada , Y. and Futai , M . ( 2000 ). Caenorhabditis elegans senses protons through amphid chemosensory neurons: proton signals elicit avoidance behavior . Neuroreport 11 , 2229 – 2232 . OpenUrl CrossRef PubMed Web of Science ↵ Schafer , W. R . ( 2015 ). Mechanosensory molecules and circuits in C. elegans . Pflug Arch Eur J Phy 467 , 39 – 48 . OpenUrl Schinkmann , K. and Li , C . ( 1994 ). Comparison of two Caenorhabditis genes encoding FMRFamide (Phe-Met-Arg-Phe-NH2)-like peptides . Mol Brain Res 24 , 238 – 246 . OpenUrl PubMed Setty , H. , Salzberg , Y. , Karimi , S. , Berent-Barzel , E. , Krieg , M. and Oren-Suissa , M . ( 2022 ). Sexually dimorphic architecture and function of a mechanosensory circuit in C. elegans . Nat Commun 13 , 6825 . OpenUrl ↵ Sherrington , C. S. ( 1906 ). The integrative action of the nervous system : Yale University Press . Skidgel , R. A. and Erdös , E. G. ( 2004 ). Angiotensin converting enzyme (ACE) and neprilysin hydrolyze neuropeptides: a brief history, the beginning and follow-ups to early studies . Peptides 25 , 521 – 525 . OpenUrl CrossRef PubMed Web of Science ↵ Smith , E. S. J. and Lewin , G. R . ( 2009 ). Nociceptors: a phylogenetic view . J Comp Physiol A 195 , 1089 – 1106 . OpenUrl CrossRef PubMed Smith , E. S. J. , Park , T. J. and Lewin , G. R . ( 2020 ). Independent evolution of pain insensitivity in African mole-rats: origins and mechanisms . Journal of Comparative Physiology A 206 , 313 – 325 . OpenUrl CrossRef PubMed ↵ Smith , J. A. , Andrews , P. L. R. , Hawkins , P. , Louhimies , S. , Ponte , G. and Dickel , L . ( 2013 ). Cephalopod research and EU Directive 2010/63/EU: Requirements, impacts and ethical review . J Exp Mar Biol Ecol 447 , 31 – 45 . OpenUrl CrossRef Spanier , B. , Stürzenbaum , S. R. , Holden-Dye , L. M. and Baumeister , R . ( 2005 ). Caenorhabditis elegans Neprilysin NEP-1: an Effector of Locomotion and Pharyngeal Pumping . J Mol Biol 352 , 429 – 437 . OpenUrl PubMed ↵ Stay , B. and Tobe , S. S . ( 2007 ). The role of allatostatins in juvenile hormone synthesis in insects and crustaceans . Annu Rev Entomol 52 , 277 – 299 . OpenUrl CrossRef PubMed Web of Science Stefano , G. B. and Salzet , M . ( 1999 ). Invertebrate opioid precursors: evolutionary conservation and the significance of enzymatic processing . Int Rev Cytol 187 , 261 – 286 . OpenUrl CrossRef PubMed Web of Science Storm , H. , Støen , R. , Klepstad , P. , Skorpen , F. , Qvigstad , E. and Raeder , J . ( 2013 ). Nociceptive stimuli responses at different levels of general anaesthesia and genetic variability . Acta Anaesth Scand 57 , 89 – 99 . OpenUrl CrossRef PubMed ↵ Summers , T. , Hanten , B. , Peterson , W. and Burrell , B . ( 2017 ). Endocannabinoids Have Opposing Effects On Behavioral Responses To Nociceptive And Non-nociceptive Stimuli . Sci Rep 7 , 5793 . OpenUrl ↵ Sun , A. Y. and Lambie , E. J . ( 1997 ). gon-2 , a gene required for gonadogenesis in Caenorhabditis elegans . Genetics 147 , 1077 – 1089 . OpenUrl Abstract / FREE Full Text Sun , Z.-C. , Ma , S.-B. , Chu , W.-G. , Jia , D. and Luo , C . ( 2020 ). Canonical transient receptor potential (TRPC) channels in nociception and pathological pain . Neural Plast 2020. ↵ Suzuki , H. , Kerr , R. , Bianchi , L. , Frøkjær-Jensen , C. , Slone , D. , Xue , J. , Gerstbrein , B. , Driscoll , M. and Schafer , W. R . ( 2003 ). In vivo imaging of C. elegans mechanosensory neurons demonstrates a specific role for the MEC-4 channel in the process of gentle touch sensation . Neuron 39 , 1005 – 1017 . OpenUrl CrossRef PubMed Web of Science ↵ Sykes , A. V. , Galligioni , V. , Estefanell , J. , Hetherington , S. , Brocca , M. , Correia , J. , Ferreira , A. , Pieroni , E. M. and Fiorito , G . ( 2023 ). FELASA Working Group report: Capture and transport of live cephalopods–recommendations for scientific purposes . Lab Anim , 00236772231176347 . Tan , C.-H. and McNaughton , P. A . ( 2016 ). The TRPM2 ion channel is required for sensitivity to warmth . Nature 536 , 460 – 463 . OpenUrl CrossRef PubMed Teramoto , T. , Lambie , E. J. and Iwasaki , K . ( 2005 ). Differential regulation of TRPM channels governs electrolyte homeostasis in the C. elegans intestine . Cell Metab 1 , 343 – 354 . OpenUrl CrossRef PubMed Web of Science ↵ Teramoto , T. , Sternick , L. A. , Kage-Nakadai , E. , Sajjadi , S. , Siembida , J. , Mitani , S. , Iwasaki , K. and Lambie , E. J . ( 2010 ). Magnesium excretion in C. elegans requires the activity of the GTL-2 TRPM channel . PloS One 5 , e9589 . OpenUrl CrossRef PubMed ↵ The UniProt, C . ( 2025 ). UniProt: the Universal Protein Knowledgebase in 2025 . Nucleic Acids Res 53 , D609 – D617 . OpenUrl CrossRef PubMed ↵ Thiel , D. , Yanez-Guerra , L. A. , Franz-Wachtel , M. , Hejnol , A. and Jékely , G . ( 2021 ). Nemertean, brachiopod, and phoronid neuropeptidomics reveals ancestral spiralian signaling systems . Mol Biol Evol 38 , 4847 – 4866 . OpenUrl CrossRef Tobin , D. M. , Madsen , D. M. , Kahn-Kirby , A. , Peckol , E. L. , Moulder , G. , Barstead , R. , Maricq , A. V. and Bargmann , C. I . ( 2002 ). Combinatorial expression of TRPV channel proteins defines their sensory functions and subcellular localization in C. elegans neurons . Neuron 35 , 307 – 318 . OpenUrl CrossRef PubMed Web of Science Turner , H. N. , Armengol , K. , Patel , A. A. , Himmel , N. J. , Sullivan , L. , Iyer , S. C. , Bhattacharya , S. , Iyer , E. P. R. , Landry , C. and Galko , M. J . ( 2016 ). The TRP channels Pkd2, NompC, and Trpm act in cold-sensing neurons to mediate unique aversive behaviors to noxious cold in Drosophila . Curr Biol 26 , 3116 – 3128 . OpenUrl CrossRef PubMed ↵ Valencia-Montoya , W. A. , Pierce , N. E. and Bellono , N. W . ( 2024 ). Evolution of sensory receptors . Annual review of cell and developmental biology 40 . ↵ van Giesen , L. , Kilian , P. B. , Allard , C. A. H. and Bellono , N. W. ( 2020 ). Molecular basis of chemotactile sensation in octopus . Cell 183 , 594 – 604 . OpenUrl CrossRef PubMed ↵ Vidal , E. A. G. , Villanueva , R. , Andrade , J. P. , Gleadall , I. G. , Iglesias , J. , Koueta , N. , Rosas , C. , Segawa , S. , Grasse , B. and Franco-Santos , R. M . ( 2014 ). Cephalopod culture: current status of main biological models and research priorities . Adv Mar Biol 67 , 1 – 98 . OpenUrl Wakabayashi , T. , Sakata , K. , Togashi , T. , Itoi , H. , Shinohe , S. , Watanabe , M. and Shingai , R . ( 2015 ). Navigational choice between reversal and curve during acidic pH avoidance behavior in Caenorhabditis elegans . BMC Neurosci 16 , 79 . OpenUrl CrossRef Walters , E. T . ( 2018 ). Nociceptive Biology of Molluscs and Arthropods: Evolutionary Clues About Functions and Mechanisms Potentially Related to Pain . Front Physiol 9 . Wang , X. , Li , G. , Liu , J. , Liu , J. and Xu , X. Z. S . ( 2016 ). TMC-1 mediates alkaline sensation in C. elegans through nociceptive neurons . Neuron 91 , 146 – 154 . OpenUrl ↵ Wang , Y. , Apicella Jr , A. , Lee , S. K. , Ezcurra , M. , Slone , R. D. , Goldmit , M. , Schafer , W. R. , Shaham , S. , Driscoll , M. and Bianchi , L . ( 2008 ). A glial DEG/ENaC channel functions with neuronal channel DEG-1 to mediate specific sensory functions in C. elegans . EMBO J 27 , 2388 – 2399 . OpenUrl Abstract / FREE Full Text Wang , Z. Y. and Ragsdale , C. W. ( 2019 ). Cephalopod nervous system organization . In Oxford Research Encyclopedia of Neuroscience . ↵ Wicks , S. R. , de Vries , C. J. , van Luenen , H. G. A. M. and Plasterk , R. H. A. ( 2000 ). CHE-3, a cytosolic dynein heavy chain, is required for sensory cilia structure and function in Caenorhabditis elegans . Dev Biol 221 , 295 – 307 . OpenUrl CrossRef PubMed Web of Science ↵ Winters-Bostwick , G. C. , Giancola-Detmering , S. E. , Bostwick , C. J. and Crook , R. J . ( 2024 ). Three-dimensional molecular atlas highlights spatial and neurochemical complexity in the axial nerve cord of octopus arms . Curr Biol 34 , 4756 – 4766 .e6. OpenUrl CrossRef PubMed ↵ Wood , J. N . ( 2006 ). Molecular mechanisms of nociception and pain . Handb Clin Neurol 81 , 49 – 59 . OpenUrl PubMed Xiao , R. and Xu , X. Z . ( 2009 ). Function and regulation of TRP family channels in C. elegans . Pflug Arch Eur J Phy 458 , 851 – 860 . OpenUrl Yamada , K. , Hirotsu , T. , Matsuki , M. , Butcher , R. A. , Tomioka , M. , Ishihara , T. , Clardy , J. , Kunitomo , H. and Iino , Y . ( 2010 ). Olfactory plasticity is regulated by pheromonal signaling in Caenorhabditis elegans . Science 329 , 1647 – 1650 . OpenUrl Abstract / FREE Full Text Yamazoe-Umemoto , A. , Fujita , K. , Iino , Y. , Iwasaki , Y. and Kimura , K. D . ( 2015 ). Modulation of different behavioral components by neuropeptide and dopamine signalings in non-associative odor learning of Caenorhabditis elegans . Neurosci Res 99 , 22 – 33 . OpenUrl CrossRef PubMed Yan , Z. , Zhang , W. , He , Y. , Gorczyca , D. , Xiang , Y. , Cheng , L. E. , Meltzer , S. , Jan , L. Y. and Jan , Y. N . ( 2013 ). Drosophila NOMPC is a mechanotransduction channel subunit for gentle-touch sensation . Nature 493 , 221 – 225 . OpenUrl CrossRef PubMed Web of Science Yeh , E. , Ng , S. , Zhang , M. , Bouhours , M. , Wang , Y. , Wang , M. , Hung , W. , Aoyagi , K. , Melnik-Martinez , K. and Li , M . ( 2008 ). A putative cation channel, NCA-1, and a novel protein, UNC-80, transmit neuronal activity in C. elegans . PLoS Biol 6 , e55. Yemini , E. , Jucikas , T. , Grundy , L. J. , Brown , A. E. X. and Schafer , W. R . ( 2013 ). A database of Caenorhabditis elegans behavioral phenotypes . Nat Methods 10 , 877 – 879 . OpenUrl CrossRef PubMed Web of Science ↵ Young , J. Z . ( 1971 ). The anatomy of the nervous system of Octopus vulgaris: Oxford University Press . ↵ Yuan , F. , Xiaozhou , H. , Yilin , Y. , Dongman , C. , Lawrence , H. L. and Ying , X . ( 2012 ). Current Research on Opioid Receptor Function . Curr Drug Targets 13 , 230 – 246 . OpenUrl CrossRef PubMed Web of Science ↵ Zagon , I. S. , Verderame , M. F. and McLaughlin , P. J . ( 2002 ). The biology of the opioid growth factor receptor (OGFR) . Brain Res Rev 38 , 351 – 376 . OpenUrl CrossRef PubMed Zhang , D. and Wei , Y . ( 2024 ). Role of sodium leak channel (NALCN) in sensation and pain: an overview . Front Pharmacol 14 , 1349438 . OpenUrl ↵ Zhang , S. , Arnadottir , J. , Keller , C. , Caldwell , G. A. , Yao , C. A. and Chalfie , M . ( 2004 ). MEC-2 is recruited to the putative mechanosensory complex in C. elegans touch receptor neurons through its stomatin-like domain . Curr Biol 14 , 1888 – 1896 . OpenUrl CrossRef PubMed Web of Science Zhou , C. , Zhou , Q. , He , X. , He , Y. , Wang , X. , Zhu , X. , Zhang , Y. and Ma , L . ( 2022 ). Differential modulation of C. elegans motor behavior by NALCN and two-pore domain potassium channels . PLoS Genet 18 , e1010126 . OpenUrl CrossRef PubMed View the discussion thread. Back to top Previous Next Posted August 23, 2025. 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Share Identification of molecular nociceptors in Octopus vulgaris through functional characterisation in Caenorhabditis elegans Eleonora Maria Pieroni , Vincent O’Connor , Lindy Holden-Dye , Pamela Imperadore , Graziano Fiorito , James Dillon bioRxiv 2025.08.19.670888; doi: https://doi.org/10.1101/2025.08.19.670888 Share This Article: Copy Citation Tools Identification of molecular nociceptors in Octopus vulgaris through functional characterisation in Caenorhabditis elegans Eleonora Maria Pieroni , Vincent O’Connor , Lindy Holden-Dye , Pamela Imperadore , Graziano Fiorito , James Dillon bioRxiv 2025.08.19.670888; doi: https://doi.org/10.1101/2025.08.19.670888 Citation Manager Formats BibTeX Bookends EasyBib EndNote (tagged) EndNote 8 (xml) Medlars Mendeley Papers RefWorks Tagged Ref Manager RIS Zotero Tweet Widget Facebook Like Google Plus One Subject Area Neuroscience Subject Areas All Articles Animal Behavior and Cognition (7635) Biochemistry (17690) Bioengineering (13892) Bioinformatics (41936) Biophysics (21451) Cancer Biology (18588) Cell Biology (25499) Clinical Trials (138) Developmental Biology (13378) Ecology (19899) Epidemiology (2067) Evolutionary Biology (24320) Genetics (15609) Genomics (22506) Immunology (17736) Microbiology (40394) Molecular Biology (17181) Neuroscience (88603) Paleontology (666) Pathology (2832) Pharmacology and Toxicology (4824) Physiology (7641) Plant Biology (15152) Scientific Communication and Education (2045) Synthetic Biology (4294) Systems Biology (9825) Zoology (2271)