Knowledge about the genome is a key prerequisite for any sophisticated genetic manipulation and improvement. At the present time, we know very little about the genome of oysters. It is only recently that genomic research in oysters has received some attention. Efforts are being made on marker development in a number of labs including those at the University of California at Davis, University of Delaware and Virginia Institute of Marine Science.
   Oyster molecular cytogenetics and chromosome mapping are being pursued in our genetics lab at HSRL. Our goal is to characterize, identify and label each of the 10 chromosomes of the eastern oyster (Crassostrea virginica) with fluorescence in situ hybridization (FISH) probes, linkage and physical markers. Together with Dr. James







Fluorescence in situ hybridization of the all-human telomere probe, (T₂AG₃)_n, to chromosome ends of the Pacific oyster (Crassostrea gigas).





Pierce at the Philadelphia College of Pharmacy and Science, we are currently working on several molecular approaches to characterize oyster chromosomes. First, we are testing repetitive DNA sequences for use as probes for FISH-banding of oyster chromosomes. Secondly, we are screening a P1 genomic library for clones that can be used as chromosome-specific FISH probes. We also plan to develop chromosome-specific linkage markers or sequence-tagged sites (STSs) by sequencing the ends of the assigned P1 clones. Results of this study are expected to facilitate further genomic analysis and mapping in oysters. This work is supported by a grant from the National Sea Grant Marine Biotechnology Program.