The Antarctic fish belong to the Perciform suborder Notothenioidei, which constitutes the major ichthyofauna living in the freezing waters surrounding the Antarctic continent and represent one of the most successful examples of adaptive radiation in a marine environment. The development of the Antarctic Polar Front, a thermal barrier that inhibits species from migrating between sub-Antarctic and Antarctic waters, has contributed as an important biological boundary to the diversification of Notothenioidei into eight different families: five are mainly Antarctic and three occur in the coastal waters of New Zealand, Australia, and high-latitude South America. In the past few years, we have isolated and characterized the ? gene, encoding the IgT heavy chain constant region, from one or more members of each Antarctic notothenioid family, disclosing that all of them share the loss of most heavy chain second constant domain (CH2). This finding prompted us to go backwards through the phylogeny of Notothenioidei in an attempt to reconstruct the loss of the CH2 exon. To this end, we have focused on some species each representative of one of the three sub-Antarctic notothenioid families: Bovicthus diacanthus and Cottoperca gobio (family Bovichtidae), Eleginops maclovinus (family Eleginopsioidae), Pseudaphritis urvillii (family Pseudaphritioidea). These species have proved to be crucial in our investigations on the molecular changes occurred in exon-intron regions through evolution of Notothenioidei. Interestingly, based on a comparative analysis at genomic level, we highlighted that P. urvillii and G. gobio retained the whole CH2 domain like B. diacanthus. However, both species showed also some deletions in close proximity to the CH2 exon similarly to E. maclovinus that we had previously found to be devoid of almost the entire CH2 domain. Overall, our studies have shed light on key steps of genome modifications, occurred during notothenioid IgT evolutionary history.
Investigations on IgT genes of sub-Antarctic fish shed light on the CH2 exon loss.
MR Coscia
2020
Abstract
The Antarctic fish belong to the Perciform suborder Notothenioidei, which constitutes the major ichthyofauna living in the freezing waters surrounding the Antarctic continent and represent one of the most successful examples of adaptive radiation in a marine environment. The development of the Antarctic Polar Front, a thermal barrier that inhibits species from migrating between sub-Antarctic and Antarctic waters, has contributed as an important biological boundary to the diversification of Notothenioidei into eight different families: five are mainly Antarctic and three occur in the coastal waters of New Zealand, Australia, and high-latitude South America. In the past few years, we have isolated and characterized the ? gene, encoding the IgT heavy chain constant region, from one or more members of each Antarctic notothenioid family, disclosing that all of them share the loss of most heavy chain second constant domain (CH2). This finding prompted us to go backwards through the phylogeny of Notothenioidei in an attempt to reconstruct the loss of the CH2 exon. To this end, we have focused on some species each representative of one of the three sub-Antarctic notothenioid families: Bovicthus diacanthus and Cottoperca gobio (family Bovichtidae), Eleginops maclovinus (family Eleginopsioidae), Pseudaphritis urvillii (family Pseudaphritioidea). These species have proved to be crucial in our investigations on the molecular changes occurred in exon-intron regions through evolution of Notothenioidei. Interestingly, based on a comparative analysis at genomic level, we highlighted that P. urvillii and G. gobio retained the whole CH2 domain like B. diacanthus. However, both species showed also some deletions in close proximity to the CH2 exon similarly to E. maclovinus that we had previously found to be devoid of almost the entire CH2 domain. Overall, our studies have shed light on key steps of genome modifications, occurred during notothenioid IgT evolutionary history.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
