Aplicaciones lineales

This three-year project (started in 1998) is funded by the DFID Competitive Research Facility, in collaboration with ICLARM, developing the theme of the interrelations of aquaculture and biodiversity (Beardmore et al. 1997). The project aims to collect and collate data on genetic diversity of wild populations of the silver barb, Barbodes gonionotus (formerly Puntius gonionotus) throughout its natural range in order to document genetic resources. This is being achieved through the application of a suite of biochemical and molecular techniques at the laboratories at UWS, with emphasis on mtDNA and microsatellite loci. These data will be analyzed to determine the levels of genetic variability in the natural stocks of B. gonionotus and to identify those populations that can act as valuable reserves of genetic diversity. It is hoped that the degree of resolution of these techniques will be sufficient, when combined with indigenous knowledge, to determine the source of introductions of any stocks that may be feral and non-native.

Samples for B. gonionotus were collected from several sites in Indonesia and Indochina, and further sampling trips are planned. To date the control

region of the mtDNA molecule has been surveyed in four populations, two from Java, Indonesia, and two from Vietnam, with a number of fixed differences noted between the samples from the two regions.

Molecular markers are now being used to survey the populations collected so far. With the isolation of a large number of positive clones from the microsatellite libraries, a large suite of microsatellite markers is anticipated for use, in addition to those already obtained from other researchers.

Collectively, it is hoped that the techniques and approaches used in this project would represent a valuable case study investigating the genetic diversity of a commercially important species. Furthermore, it is intended that the data gathered can be used to recommend a long-term strategy for the conservation and management of this diversity in relation to future introductions and the predicted expansion of the farming of this species.

Future Directions Future Directions

Many of the research themes highlighted above will continue. DFID/FGRP projects will focus even more tightly on potential impacts of research outputs on the alleviation of poverty. It is likely that most projects will include research components evaluating important social and economic factors related to the role of increased efficiency of aquaculture production achieved through application of genetics-based technologies, on the livelihood of the poor.

Following are other areas of research currently being considered (not necessarily within the framework of the DFID/FGRP):

• In tilapia, studies on the use of clonal lines as internal controls in growth trials, comparisons and integration of different genetic improvement strategies, and research on dissemination strategies of improved fish for the benefit of the poor;

• Surveys on existing broodstock management protocols prevalent for commercially important species in developing countries and their likely impact upon seed quality;

• Strain comparisons of common carp in the tropics;

and

• Application of molecular markers in fisheries stock assessment in the Mekong basin.

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References References

Abucay, J.S., G.C. Mair, D.O.F. Skibinski. and J.A. Beardmore. 1999.

Environmental sex determination: the effect of temperature and salinity on sex ratio in Oreochromis niloticus L. Aquaculture 173: 219-234.

Beardmore, J.A. 1997. Transgenics and allotransgenics. Transgenic Res. 6: 107-108.

Beardmore, J.A., G.C. Mair and R.I. Lewis. 1997. Biodiversity in aquatic systems in relation to aquaculture. Aquacult. Res.

28(10): 829-839.

Mair, G.C., J.S. Abucay, J.A. Beardmore and D.O.F. Skibinski. 1995.

Growth performance trials of genetically male tilapia (GMT) derived from YY-males in Oreochromis niloticus L.: on station comparisons with mixed sex and sex reversed male populations. Aquaculture 137: 313-322.

Mair, G.C., J.S. Abucay, D.O.F. Skibinski, T.A. Abella and J.A.

Beardmore. 1997. Genetic manipulation of sex ratio for the large-scale production of all-male tilapia, Oreochromis niloticus.

Can. J. Fish. Aquat. Sci. 54: 396-404.

Mair, G.C., J.A. Beardmore, and D.O.F. Skibinski. 1990.

Experimental evidence for environmental sex determination in Oreochromis species, p. 555-558. In R. Hirano and I. Hanyu (eds.) The Second Asian Fisheries Forum. Asian Fisheries Society, Manila, Philippines.

Mair, G.C., A.G. Scott, D.J. Penman, J.A. Beardmore and D.O.F.

Skibinski. 1991a. Sex determination in the genus Oreochromis.

1. Sex reversal, gynogenesis and triploidy in O. niloticus (L).

Theor. Appl. Genet. 82: 144-152.

Mair, G.C., A.G. Scott, D.J. Penman, D.O.F. Skibinski and J.A.

Beardmore. 1991b. Sex determination in the genus Oreochromis.

2. Sex reversal, hybridisation, gynogenesis and triploidy in O.

aureus Steindachner. Theor. Appl. Genet. 82: 153-160.

Rahman, M.A. and N. Maclean. 1999. Growth performance of transgenic tilapia containing an exogenous piscine growth hormone gene. Aquaculture 173: 333-346.

Research on the Genetics of Aquatic Organisms at the School of Biological Sciences, University of Wales Swansea

Fish Genetics Research in Member Countries and Institutions of INGA 160

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An overview of genetics research in the Fish Culture and Fisheries Group, Department of Animal Science, Wageningen University and Research Centre, the Netherlands, is presented. The major model species for genetics research is common carp, Cyprinus carpio, L. In carp, several inbred strains have been produced by gynogenesis or androgenesis. Techniques for gynogenesis and androgenesis, hormonal sex reversal and cryopreservation, and the consequences of inbreeding and crossbreeding in terms of genetic and phenotypic variation are discussed.

Theoretical considerations for application of gynogenesis and androgenesis in selective breeding programs are illustrated with experimental results and a case study on selective breeding for stress response. The consequences of inbreeding for sex determination and differentiation are also presented.

GENETIC

GENETICS RESEARCH A S RESEARCH AT T