Haem as a Maternal Factor of Ticks

Haem as a Maternal Factor of Ticks | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (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],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Haem as a Maternal Factor of Ticks Tereza Šedivá, Veronika Urbanová, Tereza Kozelková, Luise Robbertse, and 12 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9311589/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 9 You are reading this latest preprint version Graphical Abstract Abstract Ticks are obligate blood-feeding parasites that lack haem biosynthesis and must acquire haem from their hosts. Although host haem supports tick reproduction, the extent to which an individual relies on dietary haemoglobin-derived haem across immature stages is unclear. We found that host-derived haem is maternally deposited in the midgut of newly emerged larvae as vitellin-bound haem. Using an membrane-feeding system, we fed larvae and the resulting nymphs on whole blood or haemoglobin-depleted serum. Despite haemoglobin depletion, ticks engorged and moulted, indicating that immature development can proceed under reduced dietary haemoglobin. By contrast, ticks failed to feed efficiently when haemoglobin was present but could not be properly processed after its uptake into midgut digest cells. Inhibiting lysosomal cysteine cathepsins prevented full engorgement by blocking endo-lysosomal trafficking, trapping internalised cargo, and preventing haemosome formation. Together, these results show that while immature ticks can tolerate limited dietary haemoglobin, blood feeding depends on lysosomal proteolysis, identifying cysteine cathepsins as a vulnerable point for anti-tick control. ticks Ixodes ricinus haem vitellin membrane feeding RNAi cathepsins haemoglobin digestion Full Text Additional Declarations No competing interests reported. Supplementary Files Additionalfile1.xlsx Additionalfile2.docx Additionalfile3.xlsx Cite Share Download PDF Status: Under Review Version 1 posted Reviews received at journal 16 May, 2026 Reviewers agreed at journal 14 May, 2026 Reviews received at journal 06 May, 2026 Reviewers agreed at journal 26 Apr, 2026 Reviewers agreed at journal 22 Apr, 2026 Reviewers invited by journal 21 Apr, 2026 Editor assigned by journal 07 Apr, 2026 Submission checks completed at journal 06 Apr, 2026 First submitted to journal 03 Apr, 2026 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-9311589","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":629713607,"identity":"0115b368-4d7a-48d8-889a-2fb626c06369","order_by":0,"name":"Tereza Šedivá","email":"","orcid":"","institution":"Biology Centre of the Czech Academy of Sciences","correspondingAuthor":false,"prefix":"","firstName":"Tereza","middleName":"","lastName":"Šedivá","suffix":""},{"id":629713608,"identity":"dee8e929-cb24-4778-b78b-f6d4592505bb","order_by":1,"name":"Veronika Urbanová","email":"","orcid":"","institution":"Biology Centre of the Czech Academy of 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Although host haem supports tick reproduction, the extent to which an individual relies on dietary haemoglobin-derived haem across immature stages is unclear. We found that host-derived haem is maternally deposited in the midgut of newly emerged larvae as vitellin-bound haem. Using an membrane-feeding system, we fed larvae and the resulting nymphs on whole blood or haemoglobin-depleted serum. Despite haemoglobin depletion, ticks engorged and moulted, indicating that immature development can proceed under reduced dietary haemoglobin. By contrast, ticks failed to feed efficiently when haemoglobin was present but could not be properly processed after its uptake into midgut digest cells. Inhibiting lysosomal cysteine cathepsins prevented full engorgement by blocking endo-lysosomal trafficking, trapping internalised cargo, and preventing haemosome formation. 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