CONSTRUCTION OF INTESTINAL cDNA LIBRARY AND ANALYSIS OF SOME EXPRESSED SEQUENCE TAGS SEQUENCING OF CTENOPHARYNGODON IDELLUS

The technology of expressed sequence tag(EST) was broadly applied in analysis of gene function and expression pattern.Based on the construction technology of non-normalized cDNA library,the cDNA libraries of grass carp's intestinal cDNA Library was constructed.This library reaches 2.3×105 in capacity;the percenyage of recombination is as high as 95%.PCR results showed that the average size of inserts was larger than 1000 bp.And a total of 1571 successful sequencing reactions yielded 1411 which expressed sequence tags(ESTs) longer than 100 bp.In addition,939 non-repetitive sequences were formed including 188 contigs and 751 singletons from these ESTs after initial assembly.Basic Local Alignment Search Tool(BLAST) analysis showed that nearly 44.5% of the sequences were assigned putative functions because they showed similarity to known genes(Evalue1.00E-10),mostly from other species,in one or more of the databases used, others suggesting a potential for further novel gene discovery.The study provides a significant number of ESTs for gene discovery and candidate genes for studying digestive system in grass carps and other carps.Furthermore,the large-scale ESTs sequencing provided a valuable resource for the functional genome research and the whole genome sequencing project of Ctenopharyngodon idellus.