Presence of an unique IgT on the IGH locus in three-spined stickleback fish (Gasterosteus aculeatus) and the very recent generation of a repertoire of VH genes

Ig heavy chain genes and their locus in grass carp Ctenopharyngodon idella

“…However, the complete composition of V H genes in the IgH loci has been reported only in zebrafish, three-spined stickleback and channel catfish, with 47, 49 and 55 V H genes identified, respectively [22,24,29]. It seems possible that the number of V H genes may vary in different species of teleost fish.…”

“…The organization of the IgH locus in rainbow trout is, in general, similar to that of zebrafish and fugu, except that two V H genes were found downstream of the Cz [23]. The IgH locus from three-spined stickleback is very complex, with three regions containing IGHM, IGHD and IGHT and a fourth region having only one IGHT [24]. The illustration of Ig genes and their loci in chromosome may enable the comparison of different Ig isotypes.…”

“…It has been suggested that some Ig isotypes may be just another name of a formerly reported Ig isotype; for example, IgZ and IgT may be of the same isotype in fish, and the newly identified IgO in platypus [4] has been considered as IgY, as it shares characteristics with IgY [5]. Furthermore, genomic organization of IgH locus has also been identified in several species of teleost fish, such as in zebrafish [22], rainbow trout [23], fugu [25], channel catfish (Ictalurus punctatus) [28,29] and three-spined sticklebacks [24]. The genome organization of IgH locus in channel catfish is a translocon arrangement, with three d genes linked to an m gene or pseudogene, and the loci in zebrafish and fugu follow the pattern of genomic organization: VneDneJneCz/s/C H eDneJneCmeCd [22,25,28,29].…”

“…[17,18]). Over the last two decades, IgD has been reported continuously in several species of teleost fish [19e21], and in this century several Ig isotypes have been identified in different species of fish, such as IgZ in zebrafish (Danio rerio) [22], IgT in rainbow trout (Oncorhynchus mykiss) [23] and three-spined sticklebacks (Gasterosteus aculeatus) [24], the novel IgH in fugu (Fugu rubripes) [25], chimeric IgMeIgZ in common carp (Cyprinus carpio) [26]. Ig isotypes in cartilaginous fish have not received much attention as in teleost fish; however, several Ig isotypes, such as IgW, IgNAR and IgNARC have been reported in cartilaginous fish.…”

Identification of Two IgD+ B Cell Populations in Channel Catfish,Ictalurus punctatus

“…This inclusion of Cm1 was hypothesized to be necessary because it permits the Igd H chain to covalently associate with catfish IgL chains. After the discovery in catfish, IgD was identified in other teleosts (6)(7)(8)(9)(10), artiodactyls (11)(12)(13), and later in dogs (14), horses (15), Xenopus (16), leopard gecko (17), green anole lizard (18), turtle (19), and more recently in the platypus (20,21). The inclusion of Cm1 has been observed in all teleost Igd transcripts; interestingly, the Cd1 domain in cow, sheep, and pig exhibits .93% amino acid identity to the respective Cm1 domain in each of these species (11)(12)(13).…”