The application of DNA fingerprinting in the analysis of gynogenesis in tilapia
ABSTRACT The technique of DNA fingerprinting using human minisatellite probes is applied to the study of gynogenetically derived fish in two tilapia species, Oreochromis aureus and O. niloticus. In O. aureus, analysis of the progeny of a cross between two putative mitogynes provides unexpected evidence of transmission of some paternal DNA during gynogenesis. In O. niloticus, DNA fingerprinting provides confirmation of exclusively maternal transmission during gynogenesis but mitogynes and meiogynes cannot be distinguished unambiguously.
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ABSTRACT: We have successfully performed interspecific androgenesis between two cyprinid species. Gamma-ray irradiated eggs of common carp were fertilized with fresh and cryopreserved sperm of three different goldfish varieties and the haploid embryos were then heat-shocked to restore diploidy and to produce viable offspring. Androgenic diploid goldfish progenies from over a dozen different experiments were screened for four phenotypic markers several times. Color and other phenotypic markers characteristic of goldfish were found exclusively among androgenetic goldfish progenies; no markers originating from common carp were detected in over 1500 individuals investigated visually.RAPD assay was used to compare the parents and the offspring at the genomic level. The RAPD pattern of the androgenetic goldfish contained exclusively paternal bands, thereby confirming the results of the phenotypic analysis. According to our knowledge, this is the first successful interspecific androgenesis performed with two different species resulting in viable offspring.Key words: RAPD, whole genome manipulation, nuclear-mitochondrial incompatibility.Genome 02/2011; 41(4):573-579. DOI:10.1139/gen-41-4-573 · 1.56 Impact Factor
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ABSTRACT: Gynogenesis is thought to be a useful method to generate fully inbred lines in teleost fish. Endomitosis, which refers to the inhibition of first mitosis, should lead to fully homozygous offspring. In this study, the optimal conditions to induce mitogynogenesis (endomitosis) by heat shocking of the eggs were determined in the African catfish Clarias gariepinus. Comparable survival rates were obtained with a shock of 40°C applied for 1 min and a shock of 39°C applied for 1.5–2 min. Applying the shock around 20 or 37 min after activation resulted in the highest survival rates (ca. 5% relative to the positive control). The amount of inbreeding (homozygosity) and paternal contamination were assayed by using polymorphic microsatellite DNA markers. In less than 1% of the offspring paternal alleles were present, indicating a true gynogenic background for most of the progeny. Meiogynogenetic and mitogynogenetic C. gariepinus showed a fair amount of residual heterozygosity (respectively 86% and 75% for one of the markers). Heterozygous catfish obtained through mitogynogenesis were attributed to the (simultaneous) presence of meiogynogens. In addition, we prove that the sex determining system of African catfish C. gariepinus is heterogametic in the male (XY/XX).Aquaculture 05/2000; 185(1):25-42. DOI:10.1016/S0044-8486(99)00339-7 · 1.83 Impact Factor
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ABSTRACT: The Amazon molly, Poecilia formosa, is an all-female fish of hybrid origin which reproduces by gynogenesis, i.e. it depends on sperm of males of closely related species to trigger parthenogenetic development of the embryo. Therefore the offspring is clonal and identical to the mother. In rare cases the exclusion mechanism fails and paternal introgression occurs. This may result either in triploid offspring - if the whole haploid chromosome set of the sperm fuses with the diploid egg nucleus - or in siblings with microchromosomes - if only subgenomic amounts of paternal DNA are included. In one of our diploid, microchromosome-carrying laboratory stocks we observed eight triploid individuals which all developed into males. We investigated the mitotic and meiotic chromosomes, the synaptonemal complex (SC), and sperm production of these males, and compared them to males of the gonochoristic parental species (P. latipinna and P. mexicana) and their hybrids. This comparison revealed that P. formosa males are functional males with reduced effective fertility. They show a deviation from the typical 23 bivalents in the synaptonemal complexes as well as in diakinesis due to the triploid state. They produced offspring but only with gynogenetic Amazon molly females. This shows that the probably aneuploid sperm from P. formosa males can trigger parthenogenetic development of unreduced eggs.Cytogenetics and cell genetics 02/2000; 91(1-4):148-56. DOI:10.1159/000056836