The Production of Unisexual Broods by Tilapia mossambica Sex-reversed with Methyl Testosterone

Clemens, Howard P.; Inslee, Theophilus

doi:10.1577/1548-8659(1968)97[18:tpoubb]2.0.co;2

Cited by 78 publications

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“…In fact, only some species exhibit morphologically differentiated sex chromosomes [6]. In the others, male or female heterogamety was first deduced from results of back crossing individuals obtained by hormonal sex reversion [7], like in tilapias Oreochromis mossambicus [8] and O. niloticus [9], or from artificial gynogenesis like in rainbow trout Oncorynchus mykiss [10]. In tilapias belonging to the genus Oreochromis, the heterogametic sex may be either the male or the female depending on the species.…”

Section: Sexualitymentioning

confidence: 99%

Particularities of reproduction and oogenesis in teleost fish compared to mammals

2005

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-Compared to mammals, teleost reproduction presents many original features. Reproductive strategies of species are diversified into numerous adaptations to a large variety of aquatic environments. This diversity may concern sexuality, spawning and parental behaviour, sensitivity to environmental factors, and specific features of gametogenesis such as the duration of vitellogenesis, and egg morphology. Sexuality presents a variety of natural modalities, from gonochorism to hermaphrodism. The absence of definitive arrest of body growth in the adult of most species gives a particular interest to the practical control of growth-reproduction interactions. Vitellogenesis, which represents an important metabolic effort for the maternal organism, involves the synthesis of vitellogenin, a specific glycolipo-phosphoprotein produced in the liver under estradiol stimulation, and its incorporation into oocytes by a receptor mediated process. Both estradiol synthesis in follicle cells and vtg uptake by vitellogenic follicles appear to be mainly controlled by FSH. Oocyte maturation is directly triggered by a progestin, or MIS (maturation inducing steroid) synthesised in follicle cells mainly under LH control, and acting through the non-genomic activation of a membrane receptor. Practical applications of some of these particularities result mainly from the external character of the fertilisation process and of embryonic development, which allows manipulating respectively egg chromosome stocks and sex differentiation. Moreover, the sensitivity of sex differentiation to exogenous factors favours the development of practical methods to control the sex of farmed populations. Finally, the sensitivity of reproductive mechanisms to xenobiotics has led to various kinds of bioassays for putative pollutants.reproductive strategies / sexuality / spawning / vitellogenesis / oocyte maturation / fertilisation

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Section: Sexualitymentioning

confidence: 99%

Particularities of reproduction and oogenesis in teleost fish compared to mammals

2005

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“…In the platyfish, female heterogamety has certainly appeared from an original male heterogametic system. Male heterogametic and female heterogametic species have also been observed within the Oreochromis genus (Hickling 1960;Clemens and Inslee 1968;Guerrero 197 5), and within the Leporinus genus (Galetti et al 1981). The morphological divergence of sex chromosomes is particularly clear in female heterogametic Leporinus species, but not visible in Oreochromis.…”

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Sex chromosome polymorphism and heterogametic males revealed by two cloned DNA probes in the ZW/ZZ fish Leporinus elongatus

et al. 1994

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Abstract. In order to study the divergence of teleost sex chromosomes, subtractive cloning was carried out between genomic DNA ofmales and females ofthe rainbow trout (XX/XY) and of Leporinus elongatus (ZW /ZZ). Inserts cloned in a plasmid vector were individually tested on Southern blots of DNA of males and females for sex specificity. No sex-specific insert was obtained from trout, but two out of ten inserts cloned from L. elongatus showed sex-specific patterns in this species: one corresponds to a sequence present on both Z and W chromosomes, while the other is W specific. Sequences of these two inserts show neither clear homology with other known sequences, nor an open reading frame. They cross-hybridize with the genomic DNA of Leporinusfriderici, but without sex-specific patterns. Twenty-four L. elongatus adults were sexed by gonadal observation, chromosomed examination and Southern hybridization with one or the other insert. Ten males and 11 females had chromosomes and hybridization patterns typical of their sex. One ZW female was recognized as a male with the W-specific probe. This was also the case for two unusual ZW males, one having a male hybridization pattern with the other probe. These three atypical individuals may result from single genetic exchanges between four regions of the Z and the W, giving rise to three atypical W chromosomes. Finding males with such atypical heterochromosomes in a female heterogametic species may indicate that a gradual transition occurs between the heterogametic systems.

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“…The primary support for these hypotheses comes from breeding animals that were sex reversed by hormone treatments, as discussed by Lee et al (2004). Male heterogametic systems were suggested in O. mossambicus and O. niloticus because crosses of sex reversed (XX) males with normal (XX) females produce only females (Clemens and Inslee 1968;Jalabert et al 1971). In O. aureus, mating between sex-reversed (ZZ) females and normal (ZZ) males usually results in 100% male offspring, but slight deviations have been observed (Hopkins et al 1979;Mair et al 1987;Lahav 1993;Rosenstein and Hulata 1994).…”

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Amh and Dmrta2 Genes Map to Tilapia (Oreochromis spp.) Linkage Group 23 Within Quantitative Trait Locus Regions for Sex Determination

et al. 2006

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Recent studies have revealed that the major genes of the mammalian sex determination pathway are also involved in sex determination of fish. Several studies have reported QTL in various species and strains of tilapia, regions contributing to sex determination have been identified on linkage groups 1, 3, and 23. Genes contributing to sex-specific mortality have been detected on linkage groups 2, 6, and 23. To test whether the same genes might control sex determination in mammals and fishes, we mapped 11 genes that are considered putative master key regulators of sex determination: Amh, Cyp19, Dax1, Dmrt2, Dmrta2, Fhl3l, Foxl2, Ixl, Lhx9, Sf1, and Sox8. We identified polymorphisms in noncoding regions of these genes and genotyped these sites for 90 individuals of an F 2 mapping family. Mapping of Dax1 joined LG16 and LG21 into a single linkage group. The Amh and Dmrta2 genes were mapped to two distinct regions of LG23. The Amh gene was mapped 5 cM from UNH879 within a QTL region for sex determination and 2 cM from UNH216 within a QTL region for sex-specific mortality. Dmrta2 was mapped 4 cM from UNH848 within another QTL region for sex determination. Cyp19 was mapped to LG1 far from a previously reported QTL region for sex determination on this chromosome. Seven other candidate genes mapped to LG4,

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The Production of Unisexual Broods by Tilapia mossambica Sex-reversed with Methyl Testosterone

Cited by 78 publications

References 0 publications

Particularities of reproduction and oogenesis in teleost fish compared to mammals

Particularities of reproduction and oogenesis in teleost fish compared to mammals

Sex chromosome polymorphism and heterogametic males revealed by two cloned DNA probes in the ZW/ZZ fish Leporinus elongatus

Amh and Dmrta2 Genes Map to Tilapia (Oreochromis spp.) Linkage Group 23 Within Quantitative Trait Locus Regions for Sex Determination

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