RESUMO
Chromosome set manipulation techniques have significant implications for research of transgenic fish. Gynogenesis can be used to generate isogenic lines, to map genes in relation to their centromeres, and to produce fish carrying extra chromosome fragments of foreign origin. Androgenesis can be used to produce isogenic lines and to recover strains from cryopreserved sperm. Triploidy can be induced in fish with heat or pressure treatment of fertilized eggs and by crossing tetraploid individuals with normal diploids. Triploid fish are typically effectively sterile. Triploid interspecific hybrids are usually more viable than the corresponding diploid hybrids. Given concerns about potential reproduction of transgenic fish in the wild, induced triploidy could facilitate application of transgenic technologies in some situations.
Assuntos
Animais Geneticamente Modificados/genética , Peixes/genética , Técnicas Genéticas , Animais , Feminino , Masculino , Salmão/genética , Truta/genéticaRESUMO
We analyzed a number of genetic characteristics in androgenetic rainbow trout (Oncorhynchus mykiss) and their progeny. The androgenetic progeny of individual androgenetic males appeared genetically identical to each other based on eight enzyme loci. Their viability was no higher than that of androgenetic progeny of outbred males. Homozygous androgenetic female rainbow trout produced very poor quality eggs. When common eggs and sperm from outbred individuals were used to produce androgenetic and gynogenetic progeny, the yield of gynogenetic progeny was higher but some were heterozygous at protein loci, while no androgenetic progeny were heterozygous. Some androgenetic diploid rainbow trout were successfully produced from cryopreserved sperm. The progeny of some androgenetic males crossed to normal females were virtually all males, while the progeny of other males were virtually all females. This suggests that both XX and YY androgenetic individuals may develop as males. Androgenesis is likely to be useful for generating homozygous clones for research and for recovering strains from cryopreserved sperm.
Assuntos
Salmão/genética , Animais , Cruzamentos Genéticos , Criopreservação , Feminino , Homozigoto , Masculino , Razão de Masculinidade , EspermatozoidesRESUMO
Pollen irradiation has recently been widely investigated as a method for differential gene transfer in plants. Using an albino color marker in rainbow trout (Salmo gairdneri), we have investigated whether irradiated sperm might be used in an analogous manner for gene transfer in fish. Our results indicate that paternal chromosome fragments are genetically active in gynogenetic offspring, but that these fragments may be lost during mitotic cell division, producing mosaic fish.
