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: Due to non-visibility of egg nucleus, the established scheme of nuclear manipulation to clone fish may prove a difficult task. However, fishes are amenable for inter-specific androgenetic cloning. A recent discovery of using cadaveric sperm to successfully generate pro-genies has opened the possibility of adopting a simple, widely practicable method of post-mortem preserved (at – 20°C) sperm to induce androgenesis. Inactivation of maternal genome by UV-irradiation and activation of genome-inactivated homologous or heterologous egg by a single diploid or two haploid fresh or pre-served sperms are some landmark events, which have not only accelerated research activity but also focused on the importance of androgenesis in aquaculture and conservation of fish germplasm. With the absence of acrosome in the teleostean sperm, fertilization in fish is not a species-specific event. Eggs of many teleosts are amenable for heterospecific insemination. Succes-sful heterospecific insemination results in activation or fertilization of an ovum of an alien species and is the most important strategic step for induction of interspecific androgenetic cloning. Polyspermy, espe-cially dispermy occurs in nature and can be experi-mentally achieved after incubation of the milt in calcium chloride or polyethylene glycol. The paternal origin of androgenotes is verified using selected phe-notypic, protein and/or molecular markers as well as karyotyping and progeny testing. Recently, reporter genes, the green fluorescent protein gene and the Tc1 transposan-specific marker have also been used. While confirming the paternity of androgenotes, progeny testing has also indicated the unexpected occurrence of females, which are, however, shown to carry XY genotype. Survival of androgenotes can be improved using a single diploid, rather than two haploid sperms for activation. About 84% androgenotes succumb during embryonic development. Haploid genome regulates the time scale of developmental sequence in both homologous and heterologous eggs of Puntius spp., as effectively as that of diploid. A couple of research groups have restored a fish species using its preserved sperm and genome-inactivated eggs of another species. A comparison on the source, tech-nique and genomes used for generation of clones of mammals and androgenetic clones of fishes indicates that from the point of conservation and aquaculture, interspecific androgenetic cloning in fishes has an edge over that of mammals. IN biology, clones denote genetically identical progenies produced by a single parent. Clones are easily obtained in asexually-reproducing, simple organisms, plants and fungi. However, cloning does not occur in sexually-reproducing higher organisms, whose progenies are drawn from equal genomic contributions from both the parents. Consequently, their progenies need not necessarily be genetically identical copies of either of the parents. In almost all higher animals, only the egg/zygote is totipotent, i.e. the gametes have the ability to develop into a complete individual. Briefly, the unique molecular organization of egg cytoplasm alone pro-vides the signals to the nucleus, drawn from the egg/sperm or from a differentiated cell, to execute the programme of embryonic development. With an orderly series of divisions of the egg/zygote, the original totipotency of the daughter cells is progressively reduced to pluripotency and finally to unipotency. The molecular organization of cytoplasm of these daughter and grand-daughter cells is not capable of providing appropriate signals to their respective nuclei to execute the orchestrated programme that regulates the deve-lopment of a single cell into an organized multicellular entity, i.e. while the cell nucleus has the entire genetic infor-mation, its expression is controlled by signals being recei-ved from the surrounding cytoplasm (see also Lakhotia 1).85.
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ABSTRACT: The present study investigated conditions for inducing mito-gynogenetic (endomitosis) diploids by hydrostatic pressure in the large yellow croaker Pseudosciaena crocea. In haploid control groups, the development of eggs was activated with ultraviolet radiated semen. All fry presented typical haploid syndrome in the haploid control groups, and were verified as haploids using cytometry. After hydrostatic pressure treatment, morphologically normal fry reappeared at different frequencies according to the intensity and time of pressure shock. Fry with normal appearance in the pressure treated groups were verified as gynogenetic double haploids (GDHs), containing only one allele from the female parent at all four diagnostic microsatellite loci. For a fixed duration of 3 min, the optimal intensity of blocking the first mitosis was determined to be 40 Mpa, which was similar to that of blocking the second meiosis. There was a “window” of starting time, from 36.1 min to 38.1 min post-insemination at 25.0±1.0°C, within which the production of GDHs was not significantly different. Maximum production of morphologically normal fries, 9.36%±2.97% of developed eggs, was found when the eggs were shocked with hydrostatic pressure at 40 Mpa for 3 min, starting from 38.1 min post insemination at 25.0±1.0°C. Keywordgynogenesis-double haploid-large yellow croaker- Pseudosciaena crocea -microsatelliteChinese Journal of Oceanology and Limnology 04/2012; 28(4):713-719. · 0.58 Impact Factor
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ABSTRACT: It was previously shown that antidepressants are associated with diminished vagal control over the heart. Longitudinal studies are needed to test the causality of this association further. Longitudinal data were obtained in the Netherlands Study of Depression and Anxiety. At baseline and at 2-year follow-up, heart rate and cardiac vagal control as indexed by respiratory sinus arrhythmia were measured in 2114 subjects (mean age = 42.0 years; 66.2% female), who either used antidepressants at one or two time points (n = 603) or did not use antidepressants at any time point (n = 1511). Linear mixed-model analyses were conducted to compare changes in respiratory sinus arrhythmia and heart rate over time across antidepressant-naive subjects, subjects who started using an antidepressant during follow-up, subjects who stopped using an antidepressant, and persistent antidepressant users. Analyses were adjusted for demographics, health, and lifestyle factors. Compared with continuous nonusers, subjects who started the use of a tricyclic antidepressant or a serotonergic and noradrenergic antidepressant showed a significantly greater increase in heart rate and a decrease of respiratory sinus arrhythmia at 2 years. Subjects who started the use of selective serotonin reuptake inhibitors also showed a decrease in respiratory sinus arrhythmia, but their heart rate did not increase. Discontinuing antidepressants systematically caused opposite effects; levels returned in the direction of those observed among nonusers. These 2-year longitudinal results indicate that all antidepressants cause a decrease in cardiac vagal control. After discontinuing antidepressants, autonomic function recovers, suggesting that the unfavorable effects are (partly) reversible.Biological psychiatry 11/2010; 68(9):861-8. · 8.93 Impact Factor