Unigene derived SSR analysis for the Fugu rubripes and insights into the characteristics of EST-SSR distribution in tissues/organs

Abstract

A total of 11348 Unigene derived ESTs from five cDNA libraries corresponding to five different tissues/organs were screened for EST-SSR, and 1097 EST–SSRs (9.67%) were detected. There were considerable variations in the amount of EST-SSRs among the five tissues/organs. In all the tissues/organs, trinucleotide repeats (67.74%) were found to be most abundant. The trinucleotide repeats GCG were the most abundant in three tissues/organs that ranged from 80.2% in skin, 83.3% in gut, to 90.2% in fin. Dinucleotide was the second abundant repeat type (13.58%), followed by tetra-(12.38%), hexa-(5.34%), and penta-(0.96%) nucleotide repeats. Furthermore, the results of the present study also indicated that the EST-SSR motifs were not randomly distributed in tissues/organs of fugu, such as trinucleotide repeats were found to be strikingly abundant in fin, followed by skin and gut, tetra-nucleotide repeats were especially rich in muscle, while pentanucleotide repeats were less common in any tissue or organ. Most of the EST-SSRs in five tissues/organs that were assigned functions during the present study represent housekeeping genes.

Key words： Unigene; Fugu rubripes; EST-SSRs; tissues/organs