Brief Summary of Minutes of Annual Meeting

Ximing Guo Director at the Haskin Shellfish Research Laboratory, Rutgers University conducts research in three areas of molluscan genetics: selective breeding, ploidy manipulation and genomics. Guo‘s team has continued the long-term breeding program that was first established by the late Dr. Haskin in early 1960s. Recent studies have shown that the hybrid cross between the Rutgers disease-resistant strain and the Frank M. Flower‘s fast-growing variety provides the highest yield by combining disease-resistance and superior growth. In ploidy manipulation, his laboratory produced breeding populations of tetraploid and disease-resistant eastern oysters that are being used for triploid production by the oyster culture industry. Triploid oysters grow significantly faster than diploids. In genomics, Guo‘s team published a moderately-dense genetic linkage map for the eastern oyster, providing a first step toward the mapping of disease-resistant genes.

Dennis Hedgecock

A linkage map for the Pacific oyster Crassostrea gigas,which would be an invaluable tool for improving commercial stocks, has been developed using 100 microsatellite markers. Thus far, ten linkage groups have been found, a number that corresponds to the haploid number of chromosomes. The male consensus map has 89 loci and covers about 700 map units (centimorgans, cM); the female map has 86 loci and covers about 750 cM, values in good agreement with cytological observations. Significant differences have been detected in recombination rates and gene orders among families and even among siblings, which suggests polymorphism for chromosomal rearrangements exists in natural populations. The linkage map has two immediate uses, to map the location of previously detected recessive deleterious mutations in F3 and F4 populations and to map regions of the genome that contribute to variation in quantitative and economically important traits; research in both areas is in progress. The markers and maps are shared with WCC-99, providing common tools for use by members of this group.

Paul Rawson

Our laboratory is just beginning to re-establish a program for genetic improvement with the eastern oyster, Crassostrea virginica, in Maine. Although, most of the genetic improvement programs for this species have been concerned with disease-resistance, our primary concern is to develop stocks with improved cold-water growth rates. Even so, WCC-99 has proven to be invaluable to our efforts. The enhanced communication among colleagues working on oyster genetics that is engendered through WCC-99, particularly at the annual meetings held in conjunction with the National Shellfisheries Conference, has helped us to design our broodstock development program in a way that complements other on-going programs, avoid needless overlap in effort, and to develop stronger collaborations.

Christopher Langdon

1) Exchange of technical information
2) Advice for improvement of the USDA-supported Molluscan Broodstock Program
3) Design of commercial trials with selected and hybrid oyster families
4) Co-ordination of research efforts for multi-PI projects
5) Establishment of stronger links with French colleagues working on summer
mortality of Pacific oysters.

Yu, Z. and X. Guo. 2003. Genetic linkage map of the eastern oyster
Crassostrea virginica Gmelin. Biol. Bull. 204: 327-338.

Peruzzi, S. and X. Guo. 2002. Tetraploid induction by meiosis inhibition
with cytochalasin B in the dwarf surfclam, Mulinia lateralis Say: effects of
temperature. J. Shellfish Research, 21(2): 677-684.

Wang, Z., X Guo, S.K. Allen, Jr. and R. Wang. 2002. Heterozygosity and body
size in triploid Pacific oysters, Crassostrea gigas Thunberg, produced from
meiosis II inhibition and tetraploids. Aquaculture, 204(3-4):337-248.

Wang, Y., Z. Xu and X. Guo. 2001. A centromeric satellite sequence in the
Pacific oyster, Crassostrea gigas (Thunberg) identified by fluorescence in
situ hybridization. Marine Biotechnology, 3: 486-492.

Yang, H., T. Gallivan, X. Guo and S.K. Allen, Jr. 2000. A method for preserving oyster tissue samples for flow cytometry. J. Shellfish Research, 19(2):835-839.

Bucklin, K. A. 2002. Genetic Load in Two Generations of the Pacific Oyster Crassostrea gigas. Ph.D. dissertation, genetics, University of California, Davis.

Hedgecock, D., S. Hubert, G. Li and K. Bucklin. 2002. A genetic linkage map of 100 microsatellite markers for the Pacific oyster Crassostrea gigas. Journal of Shellfish Research 21:381.

Hubert, S., B. J. Landau, L. English, X. Guo, and D. Hedgecock. 2002. Genetics and linkage groups of microsatellite markers in the Pacific oyster, Crassostrea gigas using trisomics. Aquaculture 204:216. http://www.elsevier.com/locate/aquaculture

Li, G., S. Hubert, K. Bucklin, V. Ribes and D. Hedgecock. 2002. Characterization of 79 microsatellite DNA markers in the Pacific oyster Crassostrea gigas. Molecular Ecology Notes 3:228-232.

Hedgecock, D., S. Hubert and K. A. Bucklin. 2002. Linkage and gene-centromere maps of the Pacific oyster Crassostrea gigas. http://www.intl-pag.org/pag/11/abstracts/W05_W36_XI.html

Langdon, C.J., Evans, F., Jacobson, D. and Blouin, M. Yields of cultured
Pacific oysters Crassostrea gigas Thunberg improved after one generation of
selection. Aquaculture, 220: 227-244.

Brake, J., Evans, F. and C. Langdon. 2002. Evidence for genetic control of
pigmentation of shell and mantle edge in selected families of Pacific
oysters, Crasssotrea gigas. Aquaculture.