Growth‐band counts from elephantfish <i>Callorhinchus milii</i> fin spines do not correspond with independently estimated ages

Francis, Malcolm P.; Maolagáin, Caoimhghin Ó

doi:10.1111/jfb.14060

Cited by 5 publications

(2 citation statements)

References 27 publications

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“…The efish1 was 3–4 years of age, as determined by fork length [41], and was not sexually mature. Nurse sharks at 3–4 years of age are also not sexually mature but their immunity is adult in terms of their immune system components and antibody response [42].…”

Section: Resultsmentioning

confidence: 99%

Heavy chain‐only antibody genes in fish evolved to generate unique CDR3 repertoire

et al. 2021

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In addition to conventional immunoglobulin, camelids and cartilaginous fish express a special class of antibody that consists only of heavy (H) chain (HCAbs). In the holocephalan elephantfish, there are two HCAb classes, one of which has evolved surprising features. The H-chain genes in cartilaginous fish are organized as 20-200 minigenes, or clusters, each consisting of VH, 1-3 DH, JH gene segments with one set of constant region exons. We report that HHC2 (holocephalan H-chain antibody 2) evolved from IgM H-chain clusters, but its DH gene segments have diverged considerably. The three DH in HHC2 clusters are A-rich, so that one to three potential reading frames for each DH encode lysine and arginine. All three are incorporated into the rearranged VDJ, ensuring that the ligand-binding site carries multiple basic residues, as cDNA sequences demonstrate. The electropositive character in HHC2 CDR3 is accompanied by a paucity of aromatic amino acids, the latter feature at variance to the established, interactive role of tyrosine not only in ligand-binding but generally at interfaces of protein complexes. The selection for these divergent HHC2 features challenges currently accepted ideas on what determines antibody reactivity and molecular recognition.Keywords: antibody diversity r evolution r gene rearrangement r H-chain antibody r repertoire development Additional supporting information may be found online in the Supporting Information section at the end of the article.

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Section: Resultsmentioning

confidence: 99%

Heavy chain‐only antibody genes in fish evolved to generate unique CDR3 repertoire

et al. 2021

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“…The length and base width of dorsal fin spines is positively correlated with fish length (Bell, 2012), but the mineral density gradients normally indicative of growth zones were not found in dorsal fin spines of Hydrolagus colliei (Barnett, Ebert, et al., 2009). Growth rings observed in dorsal fin spines of Callorhinchus milii have been shown to be uncorrelated to age and instead are simply layers of material deposited aperiodically to strengthen the spine (Francis & Ó Maolagáin, 2019). Maximum age estimates for ghost sharks are scarce, although an Australian tagging study in 1973–1976 recaptured a male Callorhinchus milii estimated to be more than 19 years old (Coutin, 1992; Francis, 1997).…”

Section: Resultsmentioning

confidence: 99%

Ghosts of the deep – Biodiversity, fisheries, and extinction risk of ghost sharks

et al. 2020

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Ghost sharks (subclass Holocephali) remain a largely data‐poor group of cartilaginous fishes. The general paucity of attention may partially be related to identification and unresolved taxonomic issues, occurrence in the deep oceans, and their low value and interest in fisheries (which some notable exceptions). Here, we synthesize and assess the extinction risk of all known extant ghost sharks (52 species) by applying the IUCN Red List of Threatened Species Categories and Criteria. Ghost sharks have a low proportion of threatened (8%) and Near Threatened (8%) species, with most species (69%) assessed as Least Concern. The group still exhibits some data deficiency (15%), and biological information is lacking for most species. Endemism is high, with 37% of species known from only one location or one country. Species richness was highest in the Northeast Atlantic, off the northwest coast of Africa (Morocco to Mauritania), the East China Sea, New Zealand and off the northwest coast of South America (Ecuador and Peru). Ghost sharks are predominately taken as by‐catch, but some targeted fishing and/or retention for the liver oil trade occurs. Species‐specific reporting, monitoring and management are required to assess population trends, and further investigation is needed on trade and use, particularly for higher risk species including the sicklefin chimaeras (genus Neoharriotta) and the American Elephantfish (Callorhynchus callorhynchus, Callorhinidae).

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Struggling with age: Common sawsharks (Pristiophorus cirratus) defy age determination using a range of traditional methods

et al. 2020

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Growth‐band counts from elephantfish Callorhinchus milii fin spines do not correspond with independently estimated ages

Cited by 5 publications

References 27 publications

Heavy chain‐only antibody genes in fish evolved to generate unique CDR3 repertoire

Heavy chain‐only antibody genes in fish evolved to generate unique CDR3 repertoire

Ghosts of the deep – Biodiversity, fisheries, and extinction risk of ghost sharks

Struggling with age: Common sawsharks (Pristiophorus cirratus) defy age determination using a range of traditional methods

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