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Stock identification in lake trout using genetic markers
372 polymorphic loci potentially useful in future population studies, and (3) describe the distribution of genetic variation within and among hatchery strains. An additional 25 enzymes not previously examined were resolved and data can now be scored from an estimated 100 loci in lake trout. Among these loci 26 were observed to be polymorphic with 18 being useful for population studies among the lake trout strains examined within this study. Polymorphisms in Fum-1 and 2 and Pgm-5 and 6, previously undescribed in salmonids, were resolved. The lake trout strains examined were (omission of the work “lake” indicates a broodstock) : Lake George, Raquette Lake, Clearwater,Lake, Lake Manitou, Killala Lake, Superior, Seneca, Lake Ontario “strain” (1983 and 1984 year classes), and Gull Island Shoal. Clustering of strains based on Nei’s genetic distances matched predictions based on strain lineages. Progress is underway to determine the relative contribution of each of the stocked strains to naturally produced fry in Lake Ontario.
Inheritance of body and tail coloration in two domesticated varieties of the guppy, Poecilia reticulata
V.P.E. PHANG, A.A. FERNANDO and O.K. CHOW Department of Zoology, National University of Singapore, Kent Ridge 0511 (Singapore)
ABSTRACT Several color pattern varieties of Poecilia reticulata, a popular ornamental fish, are cultured in Singapore. The inheritance of body and tail color of the blue tail and red tail varieties of the guppy was studied by reciprocal outcrossing with the wild type straion. Body color was determined by scale melanophore, xanthophore and erythrophore counts. It was demonstrated that body coloration was determined by an autosomal gene, with the wild type dominant over the blue tail and red tail color varieties. The tail colors of the blue tail and red tail varieties were determined by Xlinked, sex-limited genes. Tail coloration was found to be affected by modifier genes.
Stock identification in lake trout using genetic markers
RUTH B. PHILLIPS’ and PETER E. IHSSEN’ ‘Department of Biological Sciences, University of Wisconsin, Milwaukee, WI (U.S.A.) ‘Ontario Ministry of Natural Resources, Maple, Ont. (Canada)
ABSTRACT Data on the frequency of isozyme alleles and chromosome banding polymorphisms were obtained from six different lake trout populations. Chromosome banding polymorphisms scored include quinacrine (Q) band size and intensity variants and nucleolar organizer region (NOR) poly-
373 morphisms as determined by chromomycin A3 (CMAS) staining. CMA3 appeared to stain both active and inactive NORs in salmonid fish. CMAS-NOR polymorphisms scored included average number of CMA3-NORs/cell, average total CMA3 band length/cell, chromosomal location of CMA3-NORs, size ofthe CMA3-NORs andpresence of adjacent Q bands. The size of chromosome bands was determined using a microcomputer-assisted image analysis system for chromosome measurement. The length of the short arm of chromosome 2 was measured in each cell and used as a standard for all other measurements. The six stocks could be divided into three groups: a Lake Superior group, a group originally from Lake Michigan and an eastern stock from Seneca Lake, New York. These three groups could be distinguished on the basis of differences in frequencies of isozyme alleles, frequencies of negatively staining Q band chromosome variants and in the total number of CMAS-NORs/cell. Each stock had a unique combination of CMA3-NOR banding variants.
Genetic resources for tilapia culture R.S.V. PULLIN’, J.M. MACARANAS’
and N. TANIGUCH13
‘ICLARM, P.O. Box 1501, Makati, Metro Manila (Philippines) 2iJniversity of the Philippines, Diliman, Quezon City (Philippines) “Dept. of Cultural Fisheries, Kochi University, Kochi 783 (Japan)
ABSTRACT Tilapia culture worldwide uses a small number of species and hybrids. The most important are Oreochromis aureus, 0. mossambicus, 0. niloticus, 0. spilurus, and various interspecific F, hybrid crosses which yield all or nearly all male progeny. There is lesser but significant interest in the culture of Tilapia rendalli, T. zillii, 0.andersonii and 0. macrochir. The red tilapias, a heterogenous group of hybrids, are also attracting attention. Despite worldwide interest in these tilapias, there are few reliable sources from which culturists can obtain founder stocks. Culture collections derived directly from founder stocks collected in Africa and checked by electrophoresis are maintained at only a few locations, for example, in Israel and the United Kingdom. Philippine and other Asian tilapia populations are currently being studied to assess their status, by electrophoresis, and their culture performance. There is disturbing evidence of interbreeding within captive populations. For example, 11 cultured populations in the Philippines, assumed to be 0. niloticus, are introgressed hybrids with 0. mossambicus. Using mean allelic frequency at six electrophoretic marker loci to estimate introgression, the range (values for least and most introgressed populations) was 0.067 rt 0.019 SE to 0.301% 0.054 SE. The mean genetic distance (Nei) between the 11 populations and Philippine 0. mossambicus is 0.2483 k 0.0058. Samples from single Taiwanese and Thai populations of 0. niloticus, kept for research, show negligible introgression: the corresponding mean allelic frequency was 0.012 +-0.009 SE for both and their mean genetic distance from Philippine 0. mossambicus was 0.3631 k 0.0058. Ongoing studies suggest that stable, well-characterized populations are rare throughout the Indo-Pacific. This emphasizes the need for the establishment of more culture collections to provide reliable material for research and production programs and the need for conservation of the wild tilapia resources of Africa and their habitats.
Inheritance of body and tail coloration in two domesticated varieties of the guppy, Poecilia reticulata
V.P.E. PHANG, A.A. FERNANDO and O.K. CHOW Department of Zoology, National University of Singapore, Kent Ridge 0511 (Singapore)
ABSTRACT Several color pattern varieties of Poecilia reticulata, a popular ornamental fish, are cultured in Singapore. The inheritance of body and tail color of the blue tail and red tail varieties of the guppy was studied by reciprocal outcrossing with the wild type straion. Body color was determined by scale melanophore, xanthophore and erythrophore counts. It was demonstrated that body coloration was determined by an autosomal gene, with the wild type dominant over the blue tail and red tail color varieties. The tail colors of the blue tail and red tail varieties were determined by Xlinked, sex-limited genes. Tail coloration was found to be affected by modifier genes.
Stock identification in lake trout using genetic markers
RUTH B. PHILLIPS’ and PETER E. IHSSEN’ ‘Department of Biological Sciences, University of Wisconsin, Milwaukee, WI (U.S.A.) ‘Ontario Ministry of Natural Resources, Maple, Ont. (Canada)
ABSTRACT Data on the frequency of isozyme alleles and chromosome banding polymorphisms were obtained from six different lake trout populations. Chromosome banding polymorphisms scored include quinacrine (Q) band size and intensity variants and nucleolar organizer region (NOR) poly-
373 morphisms as determined by chromomycin A3 (CMAS) staining. CMA3 appeared to stain both active and inactive NORs in salmonid fish. CMAS-NOR polymorphisms scored included average number of CMA3-NORs/cell, average total CMA3 band length/cell, chromosomal location of CMA3-NORs, size ofthe CMA3-NORs andpresence of adjacent Q bands. The size of chromosome bands was determined using a microcomputer-assisted image analysis system for chromosome measurement. The length of the short arm of chromosome 2 was measured in each cell and used as a standard for all other measurements. The six stocks could be divided into three groups: a Lake Superior group, a group originally from Lake Michigan and an eastern stock from Seneca Lake, New York. These three groups could be distinguished on the basis of differences in frequencies of isozyme alleles, frequencies of negatively staining Q band chromosome variants and in the total number of CMAS-NORs/cell. Each stock had a unique combination of CMA3-NOR banding variants.
Genetic resources for tilapia culture R.S.V. PULLIN’, J.M. MACARANAS’
and N. TANIGUCH13
‘ICLARM, P.O. Box 1501, Makati, Metro Manila (Philippines) 2iJniversity of the Philippines, Diliman, Quezon City (Philippines) “Dept. of Cultural Fisheries, Kochi University, Kochi 783 (Japan)
ABSTRACT Tilapia culture worldwide uses a small number of species and hybrids. The most important are Oreochromis aureus, 0. mossambicus, 0. niloticus, 0. spilurus, and various interspecific F, hybrid crosses which yield all or nearly all male progeny. There is lesser but significant interest in the culture of Tilapia rendalli, T. zillii, 0.andersonii and 0. macrochir. The red tilapias, a heterogenous group of hybrids, are also attracting attention. Despite worldwide interest in these tilapias, there are few reliable sources from which culturists can obtain founder stocks. Culture collections derived directly from founder stocks collected in Africa and checked by electrophoresis are maintained at only a few locations, for example, in Israel and the United Kingdom. Philippine and other Asian tilapia populations are currently being studied to assess their status, by electrophoresis, and their culture performance. There is disturbing evidence of interbreeding within captive populations. For example, 11 cultured populations in the Philippines, assumed to be 0. niloticus, are introgressed hybrids with 0. mossambicus. Using mean allelic frequency at six electrophoretic marker loci to estimate introgression, the range (values for least and most introgressed populations) was 0.067 rt 0.019 SE to 0.301% 0.054 SE. The mean genetic distance (Nei) between the 11 populations and Philippine 0. mossambicus is 0.2483 k 0.0058. Samples from single Taiwanese and Thai populations of 0. niloticus, kept for research, show negligible introgression: the corresponding mean allelic frequency was 0.012 +-0.009 SE for both and their mean genetic distance from Philippine 0. mossambicus was 0.3631 k 0.0058. Ongoing studies suggest that stable, well-characterized populations are rare throughout the Indo-Pacific. This emphasizes the need for the establishment of more culture collections to provide reliable material for research and production programs and the need for conservation of the wild tilapia resources of Africa and their habitats.