Evidence for two unlinked “sex reversal” loci in the Nile tilapia, Oreochromis niloticus, and for linkage of one of these to the red body colour gene

Karayücel, İsmihan; Ezaz, Tariq; Karayücel, Sedat; McAndrew, Brendan; Penman, David J.

doi:10.1016/j.aquaculture.2003.12.016

Cited by 23 publications

(16 citation statements)

References 24 publications

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“…However, other factors may influence sex determination and differentiation. In O. niloticus , genes on LG 3 [11] and LG 23 [12], [13], and temperature [14] can affect sex ratio. Crosses between YY males and XX females generally give less than to 100% male progeny predicted from a simple XX/XY system [15].…”

Section: Introductionmentioning

confidence: 99%

Mapping and Validation of the Major Sex-Determining Region in Nile Tilapia (Oreochromis niloticus L.) Using RAD Sequencing

et al. 2013

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Sex in Oreochromis niloticus (Nile tilapia) is principally determined by an XX/XY locus but other genetic and environmental factors also influence sex ratio. Restriction Associated DNA (RAD) sequencing was used in two families derived from crossing XY males with females from an isogenic clonal line, in order to identify Single Nucleotide Polymorphisms (SNPs) and map the sex-determining region(s). We constructed a linkage map with 3,802 SNPs, which corresponded to 3,280 informative markers, and identified a major sex-determining region on linkage group 1, explaining nearly 96% of the phenotypic variance. This sex-determining region was mapped in a 2 cM interval, corresponding to approximately 1.2 Mb in the O. niloticus draft genome. In order to validate this, a diverse family (4 families; 96 individuals in total) and population (40 broodstock individuals) test panel were genotyped for five of the SNPs showing the highest association with phenotypic sex. From the expanded data set, SNPs Oni23063 and Oni28137 showed the highest association, which persisted both in the case of family and population data. Across the entire dataset all females were found to be homozygous for these two SNPs. Males were heterozygous, with the exception of five individuals in the population and two in the family dataset. These fish possessed the homozygous genotype expected of females. Progeny sex ratios (over 95% females) from two of the males with the “female” genotype indicated that they were neomales (XX males). Sex reversal induced by elevated temperature during sexual differentiation also resulted in phenotypic males with the “female” genotype. This study narrows down the region containing the main sex-determining locus, and provides genetic markers tightly linked to this locus, with an association that persisted across the population. These markers will be of use in refining the production of genetically male O. niloticus for aquaculture.

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Section: Introductionmentioning

confidence: 99%

Mapping and Validation of the Major Sex-Determining Region in Nile Tilapia (Oreochromis niloticus L.) Using RAD Sequencing

et al. 2013

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“…A number of studies have found associations of DNA markers with sex in tilapia species and their hybrids [Shirak et al, 2002;Lee et al, 2003Lee et al, , 2004Cnaani et al, 2004;Ezaz et al, 2004;Karayucel et al, 2004]. Two recent studies mapped the location of 13 genes known to be involved in the sex determination pathway of other vertebrates in tilapia.…”

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confidence: 99%

Genetics of Sex Determination in Tilapiine Species

Cnaani

Lee

Zilberman

et al. 2008

Sex Dev

217

210

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We identified DNA markers linked to sex determining genes in six closely related species of tilapiine fishes. The mode of sex determination differed among species. In Oreochromis karongae and Tilapia mariae the sex-determining locus is on linkage group (LG) 3 and the female is heterogametic (WZ-ZZ system). In O. niloticus and T. zillii the sex-determining locus is on LG1 and the male is heterogametic (XX-XY system). A more complex pattern was observed in O. aureus and O. mossambicus, in which markers on both LG1 and LG3 were associated with sex. We found evidence for sex-linked lethal effects on LG1, as well as interactions between loci in the two linkage groups. Comparison of genetic and physical maps demonstrated a broad region of recombination suppression harboring the sex-determining locus on LG3. Sex-specific recombination suppression was found in the female heterogametic sex. Sequence analysis showed the accumulation of repetitive elements in this region. Phylogenetic analysis suggests that at least two transitions in the mode of sex determination have occurred in this clade. This variation in sex determination mechanisms among closely related species makes tilapias an excellent model system for studying the evolution of sex chromosomes in vertebrates.

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“…Because this phenomenon was observed in meiotic gynogens (EP and EH groups), a proportion of these alleles must be located close to centromeres, where chiasma interference will cause homozygosity (Moens, ; Streisinger et al ., ). Recessive male‐determining mutations have been previously found in three fish species with female homogamety: C. carpio (Komen et al ., ), O. niloticus (Karayucel et al ., ; Sarder et al ., ) and rainbow trout Oncorhynchus mykiss (Walbaum 1792) (Quillet et al ., ), but to our knowledge have not been reported in species with female heterogamety or polygenic sex determination.…”

Section: Discussionmentioning

confidence: 99%

Effects of homozygosity on sex determination in zebrafish Danio rerio

Delomas

Dąbrowski

2018

Journal of Fish Biology

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Gynogenetic zebrafish Danio rerio were obtained by activating D. rerio oocytes with UV irradiated common carp Cyprinus carpio sperm and then applying one of four different shocks [two (early) meiotic and two (late) mitotic shocks]. Gynogens produced by three of the shocks survived to maturity. All adult gynogens (n = 52) except one were found to be male. There was no difference in growth rate between the biparental controls and gynogens produced through the most effective shock, thereby eliminating growth rate as a possible cause of the skewed sex ratio. Gynogen males had reduced fertility compared to biparental controls, with about half of gynogens being unable to reproduce through natural spawning (all controls reproduced successfully). Gynogen males that did reproduce gave lower fertilization rates compared with controls. This demonstrates the negative effects of increased homozygosity on male reproductive function. Families sired by meiotic gynogen males were more likely to be female biased (33% of families) compared with families sired by biparental control males (11%). In addition to confirming the polygenic nature of sex determination in D. rerio, these observations suggest that recessive or over‐dominant male‐determining alleles are present in domesticated D. rerio populations.

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Evidence for two unlinked “sex reversal” loci in the Nile tilapia, Oreochromis niloticus, and for linkage of one of these to the red body colour gene

Cited by 23 publications

References 24 publications

Mapping and Validation of the Major Sex-Determining Region in Nile Tilapia (Oreochromis niloticus L.) Using RAD Sequencing

Mapping and Validation of the Major Sex-Determining Region in Nile Tilapia (Oreochromis niloticus L.) Using RAD Sequencing

Genetics of Sex Determination in Tilapiine Species

Effects of homozygosity on sex determination in zebrafish Danio rerio

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