RELATIVE MERITS OF STRATEGIES FOR COMPARATIVE MAPPING OF FISHES

Department of Zoology & Program in Genetics, 216 Rudman Hall, 46 College Road, University of New Hampshire, Durham, NH 03824 USA

Recent evidence suggests it will be feasible to construct comparative maps between the genomes of fish and mammals. Further, because the rate of chromosomal evolution in fishes is slow relative to that in mammals, conservation of gene order among fishes is expected to be high. We studied the relative efficiency of several methods for constructing comparative maps of tilapia (Oreochromis niloticus). One approach is to develop microsatellite or SSCP markers for genetic mapping. This approach has already yielded identified synteny for prolactin between tilapia linkage group 4 and human chromome 6. Nonetheless, physical mapping appears a more efficient approach. To that end we are developing a panel of tilapia radiation hybrids. This method requires the development of PCR primers for amplifying tilapia genes with recognizable homology to particular human genes. We are comparing the efficiency of two approaches for developing these primers. Sequencing of tilapia cDNAs is the most direct route for identifying such primers, and we can expect homologies for most tilapia genes to be identified as the human sequence is completed. Alternatively, we can mine the public databases for sequences from Fugu, salmonids or zebrafish, and attempt to design primers with broad utility. Ongoing analyses will determine which approach is most cost-effective. (www.tilapia.unh.edu).