Evolution of the Antarctic teleost immunoglobulin heavy chain gene

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• 作者：Maria Rosaria Coscia ; Sonia Varriale ; Concetta De Santi ; Stefano Giacomelli ; Umberto Oreste
• 关键词：Notothenioidei ; Alternative mRNA splicing ; Immunoglobulin gene structure ; Cold adaptation ; Antarctic teleost evolution
• 刊名：Molecular Phylogenetics and Evolution
• 出版年：2010
• 出版时间：April 2010
• 年：2010
• 卷：55
• 期：1
• 页码：226-233
• 全文大小：464 K

文摘

Notothenioid teleosts underwent major modifications of their genome to adapt to the cooling of the Antarctic environment. In order to identify specific features of the Antarctic teleost immunoglobulin, transcripts encoding the constant region of the IgM heavy chain from 13 Antarctic and non-Antarctic notothenioid species were sequenced. The primary mRNA splicing for the membrane form was found to be atypical in the majority of Antarctic species, because it led to exclusion of two entire constant exons, and to inclusion of 39-nucleotide exons encoding an unusually long Extracellular Membrane-Proximal Domain (EMPD). Genomic DNA analysis revealed that each 39-nucleotide exon fell within a long sequence that was the reverse complement of an upstream region. Deduced amino acid sequence analysis lead to the identification of cysteine encoding codons in the 39-nucleotide exons, but not in the respective sequence counterpart, suggesting that these residues might play an important role in the folding of the EMPD.