The heredity of sex determination in tilapias

Wohlfarth, Giora W.; Wedekind, Helmut

doi:10.1016/0044-8486(91)90016-z

Cited by 45 publications

(32 citation statements)

References 15 publications

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“…It is now commonly accepted (eg Wohlfarth and Wedekind (1991) and Trombka and Avtalion (1993)) that sex determination in tilapias is based on major (sex chromosome) genes and minor (autosomal) modifiers. The LG1 locus identified in the present work may well be the 'autosomal locus' suggested by Hammerman and Avtalion (1979), affecting sex ratios through epistatic interactions with the major WZ locus located on LG3 in O. aureus.…”

Section: Discussionmentioning

confidence: 99%

Two unlinked loci controlling the sex of blue tilapia (Oreochromis aureus)

2004

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Sex determination in the blue tilapia (Oreochromis aureus) is thought to be a WZ-ZZ (female heterogametic) system controlled by a major gene. We searched for DNA markers linked to this major gene using the technique of bulked segregant analysis. We identified 11 microsatellite markers on linkage group 3 which were linked to phenotypic sex. The putative W chromosome haplotype correctly predicts the sex of 97% of male and 85% of female individuals. Our results suggest the W locus lies within a few centimorgans of markers GM354, UNH168, GM271 and UNH131. Markers onLG1 also showed a strong association with sex, and indicate the segregation of a male-determining allele in this region. Analysis of epistatic interactions among the loci suggests the action of a dominant male repressor (the W haplotype on LG 3) and a dominant male determiner (the Y haplotype on LG1). These markers have immediate utility for studying the strength of different sex chromosome alleles, and for identifying broodstock carrying copies of the W haplotype.

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Section: Discussionmentioning

confidence: 99%

Two unlinked loci controlling the sex of blue tilapia (Oreochromis aureus)

2004

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“…There are no gross morphological differences in any chromosome pair Kornfield 1984;Crosetti et al 1988). A variety of evidence suggests that sex determination is principally monofactorial in tilapias (Wohlfarth and Wedekind 1991). The hypothesized sex-chromosome systems suggest that some species have the XX:XY system (Oreochromis mossambicus, O. niloticus) whereas other have the WZ:ZZ system (O. aureus, O. macrochir, O. urolepis hornorum).…”

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confidence: 99%

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 balance of these autosomal sex factors could influence sex chromosome expression and their effects could have increased in successive generations of pseudofemales, explaining the decrease in male percentage in progeny of the F 2 and F 3 IP pseudofemales. Complex models of sex determination, as proposed by Mair et al (1991b), cannot be applied to all species of genus Oreochromis (Mair et al, 1991a,b;Wohlfarth and Wedekind, 1991) and to all populations of a species (Shelton et al, 1983;Mair et al, 1991b; the present study). Furthermore, there are inherent differences in sex ratio variability between populations in O. niloticus (Shelton et al, 1983;Mair et al, 1991a;Pham et al, 1999) and in O. aureus (Shelton et al, 1983;Mair et al, 1991b).…”

Section: Discussionmentioning

confidence: 71%

“…This hypothesis is in part in accordance with our results, and could explain the deviating sex ratios in F 2 and F 3 pseudofemale progeny of IP which were not significantly different from 3:1. As suggested by Wohlfarth and Wedekind (1991) in O. niloticus, the variability of sex ratio in relation to monofactorial sex determination system results from autosomal loci influencing sex determination. The results on IP F 2 pseudofemale ''6'' also suggest the influence on sex determination of an additional genetic factors other than sex chromosomes (Table 1).…”

Section: Discussionmentioning

confidence: 89%

“…These deviations suggest the influence of an additional factor or factors (environmental or genetic) other than sex chromosomes also play a role in the sex determination in this species. Several authors have observed significant deviations from expected sex ratios in crosses involving O. aureus (Shelton et al, 1983;Mair et al, 1991b;Mélard, 1995), and hypotheses have been suggested to explain results, including a polygenic system of sex determination, epsitatic autosomal genes or environmental influence on sex differentiation (Majumdar and Mc Andrew, 1983;Lester et al, 1989;Mair et al, 1991b;Wohlfarth and Wedekind, 1991;Baroiller et al, 1995;Baroiller, 1996).…”

Section: Introductionmentioning

confidence: 99%

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Inheritance of sex in two ZZ pseudofemale lines of tilapia Oreochromis aureus

Desprez

Mélard

Hoareau³

et al. 2003

Aquaculture

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This paper reports a study on the sex determination system of the blue tilapia, Oreochromis aureus. Investigations were carried out using a pseudofemale line in two populations of O. aureus, known as Egyptian Population (EP) and Israel Population (IP). In O. aureus, males are the homogametic sex (ZZ/ZW), and sex reversal of fry with estradiol results in the production of some functional sexreversed fish with a female phenotype and ZZ male genotype, known as pseudofemales or D-females. Crosses between ZZ pseudofemales and ZZ males theoretically should provide monosex ZZ male progeny only. We have studied the sex ratios of progeny from 43 IP (F 2 to F 3 generations) and 51 EP (F 1 to F 5 generations), pair-matings between normal males and pseudofemales. In IP, the male percentage in progenies ranged between 83% to 100% in F 2 and 66% to 100% in F 3 . In EP, male percentage was more constant, varying from 88% to 100% in F 1 , from 96% to 100% in F 3 and from 97% to 100% in F 5 . In EP, F 2 and F 4 pseudofemales produced only monosex male progeny. This apparent difference in sex ratio frequency distributions between the two O. aureus pseudofemale lines could be due to the selection of males. EP pseudofemales were mated with their siblings for F 2 and F 3 pseudofemales or with closely related males for F 4 and F 5 pseudofemales. Conversely, IP pseudofemales were crossed with nonrelated males originating from research center broodstock, resulting in a higher proportion of females in sex ratio of progenies from successive generations of pseudofemales. The role of inbreeding is discussed in the context of predominantly monofactorial sex chromosome determination system operating in this species, influenced by other factors (genetic and environmental). The present study also shows that it is possible to fix the male sex determining factors

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The heredity of sex determination in tilapias

Cited by 45 publications

References 15 publications

Two unlinked loci controlling the sex of blue tilapia (Oreochromis aureus)

Two unlinked loci controlling the sex of blue tilapia (Oreochromis aureus)

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

Inheritance of sex in two ZZ pseudofemale lines of tilapia Oreochromis aureus

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