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Research
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Virginia Sea Grant funded research Analysis of genetic variation in Crassostrea ariakensis: Evaluation of germplasm resources for broodstock development Kimberly S. Reece and Standish K. Allen Jr Our ultimate goals are 1) to be able to describe all sub populations of Crassostrea ariakensis and 2) clearly distinguish C. ariakensis from congeners. We will: 1) Develop a molecular key for the quick and reliable identification of Crassostrea species, in particular the congeners to C. ariakensis, by subjecting both mitochondrial and nuclear regions to amplification by the polymerase chain reaction (PCR) and subsequent restriction fragment length polymorphism (RFLP) analysis, and 2) Examine the population structure of C. ariakensis by identifying regions of the mitochondrial and nuclear genomes that show intraspecific variation. We will collect 50 individuals of putative C. ariakensis and subsets of co-indigenous species from each site in the presumed geographic range of C. ariakensis. Because of conflicting results using published molecular "keys" to type putative C. ariakensis samples collected to date, we are in the process of sequencing two regions of DNA from 10 20 individuals of each Crassostrea species found sympatrically with C. ariakensis. In addition, we are sequencing several (3 5) individuals from each of the putative C. ariakensis samples. Sequence analysis will be done at both the mitochondrial cytochrome oxidase I (COI) gene and the nuclear internal transcribed spacer 1 (ITS 1) region of the ribosomal RNA gene locus for phylogenetic analysis and to identify restriction enzymes that demonstrate inter and intra specific variation. Additional mitochondrial and nuclear DNA regions will be screened for polymorphisms within the C. ariakensis individuals to examine the population genetic structure of this species. Loci/restriction enzyme combinations and microsatellite regions shown to demonstrate intra specific variation will be used for a population genetic survey of C. ariakensis. We are pursuing a number of strategies for revitalizing oyster resources in Chesapeake Bay, including evaluation of native stocks for Dermo resistance, artificial selection for MSX and Dermo resistance, gene mapping in the eastern oyster, and the genetics of hatchery based restoration. Our most aggressive, and perhaps most promising, approach is sterile (triploid) non natives such as C. ariakensis for aquaculture. Almost nothing is known of the population genetics of C. ariakensis, so the genetic variability of the species is unknown. We would like to learn the range of the genetic resource and perhaps match a specific genetic entity with an ecotype that would complement the ecological features of the Chesapeake Bay. Haphazard adoption of brood stock for what could become a significant industry in the Chesapeake, is unacceptable. |
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Virginia Sea Grant • Virginia Institute of Marine Science |
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