HGM2002 Poster Abstracts: 11. Genome Diversity
POSTER NO: 543
Evolutionary and biomedical annotation of schistosoma japonicum complementary DNA resource
1W. Hu, 1D.K. Shen, 1Q. Yan, 1F. Liu, 1X.R. Xu, 1Z.D. Zhu, 1X. Zhang, 2J.J. Wang, 2J. Sun, 2X.N. Xu, 3Z.J. Wang, 1G. Fu, 1S.Y. Wang, 3C.L. Xue, 2Z. Feng, 1Z. Chen, 1Z.G. Han
Schistosomiasis ranks as the second most serious parasitic diseases worldwide. Some 250 million people are infected with schistosome and the disease is endemic in 76 developing countries of the world. There are 0.3-0.5 million death per year. Schistosoma japonicum, one of the three major schistosome species, remains a public health problem in Asia, particularly in China. Gaining knowledge about S. japonicum genome will be important for understanding the worms in evolution and biomedicine. A better understanding of the schistosome genome will advance our ability to identify new targets for drug, vaccine and diagnosis. As a part of the S. japonicum genome project, the gene discovery program was initiated first. We constructed four cDNA libraries from its different life stages or sexes (egg, male adult worm, female adult worm, and mixed sex adult worm) and selected randomly 48,251 clones for sequencing. Total of 43,707 validated expressed sequence tags (ESTs) were obtained and integrated into 13,112 clusters (8,527 singletons), which represent probably 65.6 to 52.4% of 20,000 to 25,000 genes, estimated by comparison with C. elegans, in the S. japonicum genome. Of those ESTs, only 81(0.6%) and 102 (0.8%) ESTs match to known genes of S. japonicum and S. mansoni, respectively. A majority (80.1%) of ESTs has similarity (identity more than 25% overlapping at least 50 amino acids deduced from ESTs) with known proteins in the public database. Most highly expressed sequences are homologous to some enzymes involved in the metabolic pathways. There are a couple of genes with significant differences between the male and female worms at transcriptional level, which are potential way for the further study of biological characteristics of this parasite. Through the prediction in silico of signal peptide and transmembrane structures, 257 clones might be secretory or transmembrane proteins. These predicted proteins would be useful potential candidate targets for diagnosis and vaccine development.
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