Plant & Animal Genomes XI Conference Plant & Animal Genomes XI ConferenceJanuary 11-15, 2003
Town & Country Convention Center
San Diego, CA
Workshop: Aquaculture
cDNA library has been versatilely using for EST analysis, expressed gene profile with microarray and linkage mapping for chromosomes. We have preliminary constructed tilapia leukocyte cDNA library to utilize microarray analysis and to make fine mapping for comparative approach to find QTL trait loci. Leukocytes were isolated by density gradient centrifugation from a male tilapia, Oreochromis niloticus. A directionally cloned cDNA library was constructed with the pDNR-LIB vector. We randomly picked E. coli clones and sequenced from the 5’ end. To accelerate the analysis, we established a semi-automated BLASTN and BLASTX informatics pipeline to identify homologous sequences in NCBI database. The sequences of 384 clones were compared with the NCBI database and 299 clones (78%) found matches using BLASTN, BLASTX or both algorithms. There were 39 genes that were found two times or more among the 384 clones. In addition to the expected complement of immune-related genes, several types of housekeeping genes, such as ribosomal protein and mitochondrial products were seen. Of particular interest is a gene composed of four immunoglobulin superfamily domains and which appears to have evolved recently. We constructing a second leukocyte cDNA library from tilapia infected with the fish pathogen, Streptococcus iniae. Abundantly expressed genes from the first library will be subtracted and the remaining unique clones used to construct a microarray. We also plan these cDNAs onto the BAC-based physical map of tilapia. The resulting comparative map will speed the positional cloning of genes controlling commerically important traits in tilapia.