Transcriptomics and Comparative Analysis of Three Antarctic Notothenioid Fishes

<div><p>For the past 10 to 13 million years, Antarctic notothenioid fish have undergone extraordinary periods of evolution and have adapted to a cold and highly oxygenated Antarctic marine environment. While these species are considered an attractive model with which to study physiology and evolutionary adaptation, they are poorly characterized at the molecular level, and sequence information is lacking. The transcriptomes of the Antarctic fishes <em>Notothenia coriiceps</em>, <em>Chaenocephalus aceratus</em>, and <em>Pleuragramma antarcticum</em> were obtained by 454 FLX Titanium sequencing of a normalized cDNA library. More than 1,900,000 reads were assembled in a total of 71,539 contigs. Overall, 40% of the contigs were annotated based on similarity to known protein or nucleotide sequences, and more than 50% of the predicted transcripts were validated as full-length or putative full-length cDNAs. These three Antarctic fishes shared 663 genes expressed in the brain and 1,557 genes expressed in the liver. In addition, these cold-adapted fish expressed more Ub-conjugated proteins compared to temperate fish; Ub-conjugated proteins are involved in maintaining proteins in their native state in the cold and thermally stable Antarctic environments. Our transcriptome analysis of Antarctic notothenioid fish provides an archive for future studies in molecular mechanisms of fundamental genetic questions, and can be used in evolution studies comparing other fish.</p> </div

Summary of full-length cDNA in the three notothenioids species.

<p>Summary of full-length cDNA in the three notothenioids species.</p

Functional annotation of proteins encoded in the transcriptomes of the three notothenioid fish based on gene ontology (GO).

<p>Functional annotation of proteins encoded in the transcriptomes of the three notothenioid fish based on gene ontology (GO).</p

Comparison of shared and unique genes identified in four notothenioid fishes.

<p>Numbers in parentheses represent the total number of enzymes in metabolic pathway analysis.</p

Statistics for pyrosequencing of the three notothenioid species.

<p>Statistics for pyrosequencing of the three notothenioid species.</p

Conservation of three notothenioid fish genes with other species.

<p>Number of notothenioid fish homologous genes annotated in GO analysis.</p

Contig distribution of three notothenioid fish transcriptome sequences.

<p>Contig distribution of three notothenioid fish transcriptome sequences.</p

Summary of microsatellite marker identification in the three notothenioid species.

<p>Summary of microsatellite marker identification in the three notothenioid species.</p

Species distribution of three notothenioid fishes based on BLAST hits from nr sequence database.

<p>Species distribution of three notothenioid fishes based on BLAST hits from nr sequence database.</p