Developmental asynchrony and antagonism of sex determination pathways in a lizard with temperature-induced sex reversal

Abstract Rising global temperatures threaten to disrupt population sex ratios, which can in turn cause mate shortages, reduce population growth and adaptive potential, and increase extinction risk, particularly when ratios are male biased. Sex ratio distortion can then have cascading effects across other species and even ecosystems. Our understanding of the problem is limited by how often studies measure temperature effects in both sexes. To address this, the current review surveyed 194 published studies of heat tolerance, finding that the majority did not even mention the sex of the individuals used, with <10% reporting results for males and females separately. Although the data are incomplete, this review assessed phylogenetic patterns of thermally induced sex ratio bias for 3 different mechanisms: sex-biased heat tolerance, temperature-dependent sex determination (TSD), and temperature-induced sex reversal. For sex-biased heat tolerance, documented examples span a large taxonomic range including arthropods, chordates, protists, and plants. Here, superior heat tolerance is more common in females than males, but the direction of tolerance appears to be phylogenetically fluid, perhaps due to the large number of contributing factors. For TSD, well-documented examples are limited to reptiles, where high temperature usually favors females, and fishes, where high temperature consistently favors males. For temperature-induced sex reversal, unambiguous cases are again limited to vertebrates, and high temperature usually favors males in fishes and amphibians, with mixed effects in reptiles. There is urgent need for further work on the full taxonomic extent of temperature-induced sex ratio distortion, including joint effects of the multiple contributing mechanisms.

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Roles of Anti-Müllerian hormone (Amh) and its duplicates in sex determination and germ cell proliferation of Nile tilapia

Genetics ◽

10.1093/genetics/iyab237 ◽

2021 ◽

Author(s):

Xingyong Liu ◽

Shengfei Dai ◽

Jiahong Wu ◽

Xueyan Wei ◽

Xin Zhou ◽

...

Keyword(s):

Cell Proliferation ◽

Sex Determination ◽

Germ Cell ◽

Y Chromosome ◽

X Chromosome ◽

Nile Tilapia ◽

Critical Period ◽

Sex Reversal ◽

Homozygous Mutation ◽

Germ Cell Proliferation

Abstract Duplicates of amh are crucial for fish sex determination and differentiation. In Nile tilapia, unlike in other teleosts, amh is located on X chromosome. The Y chromosome amh (amh△-y) is mutated with 5 bp insertion and 233 bp deletion in the coding sequence, and tandem duplicate of amh on Y chromosome (amhy) has been identified as the sex determiner. However, the expression of amh, amh△-y and amhy, their roles in germ cell proliferation and the molecular mechanism of how amhy determines sex is still unclear. In this study, expression and functions of each duplicate were analyzed. Sex reversal occurred only when amhy was mutated as revealed by single, double and triple mutation of the three duplicates in XY fish. Homozygous mutation of amhy in YY fish also resulted in sex reversal. Earlier and higher expression of amhy/Amhy was observed in XY gonads compared with amh/Amh during sex determination. Amhy could inhibit the transcription of cyp19a1a through Amhr2/Smads signaling. Loss of cyp19a1a rescued the sex reversal phenotype in XY fish with amhy mutation. Interestingly, mutation of both amh and amhy in XY fish or homozygous mutation of amhy in YY fish resulted in infertile females with significantly increased germ cell proliferation. Taken together, these results indicated that up-regulation of amhy during the critical period of sex determination makes it the sex-determining gene, and it functions through repressing cyp19a1a expression via Amhr2/Smads signaling pathway. Amh retained its function in controlling germ cell proliferation as reported in other teleosts, while amh△-y was nonfunctionalized.

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Role of mammalian Y chromosome in sex determination

Philosophical Transactions of the Royal Society of London Series B Biological Sciences ◽

10.1098/rstb.1988.0114 ◽

1988 ◽

Vol 322 (1208) ◽

pp. 63-72 ◽

Cited By ~ 34

Keyword(s):

Cell Differentiation ◽

Sex Determination ◽

Y Chromosome ◽

Sertoli Cell ◽

Sertoli Cells ◽

Sex Reversal ◽

Testicular Development ◽

Chimeric Mouse ◽

Embryonic Gonad

It has long been assumed that the mammalian Y chromosome either encodes, or controls the production of, a diffusible testis-determining molecule, exposure of the embryonic gonad to this molecule being all that is required to divert it along the testicular pathway. My recent finding that Sertoli cells in XX ↔ XY chimeric mouse testes are exclusively XY has led me to propose a new model in which the Y acts cell-autonomously to bring about Sertoli-cell differentiation. I have suggested that all other aspects of foetal testicular development are triggered by the Sertoli cells without further Y-chromosome involvement. This model thus equates mammalian sex determination with Sertoli-cell determination. Examples of natural and experimentally induced sex reversal are discussed in the context of this model.

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Development of Gonads, Sex Determination, and Sex Reversal inXenopus

Xenopus Development ◽

10.1002/9781118492833.ch11 ◽

2014 ◽

pp. 199-214 ◽

Cited By ~ 1

Author(s):

Rafał P. Piprek ◽

Jacek Z. Kubiak

Keyword(s):

Sex Determination ◽

Sex Reversal

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005.Efficiency of nuclear import of the chromatin-remodelling factor SRY is critical for sex determination

Reproduction Fertility and Development ◽

10.1071/srb05abs005 ◽

2005 ◽

Vol 17 (9) ◽

pp. 64

Author(s):

D. A. Jans ◽

G. Kaur ◽

I. K. H. Poon ◽

A. Delluc-Clavieries ◽

K. M. Wagstaff

Keyword(s):

Sex Determination ◽

Nuclear Localization ◽

Nuclear Import ◽

Sex Reversal ◽

Nuclear Accumulation ◽

Missense Mutations ◽

Nuclear Localization Signals ◽

Testicular Cells ◽

Xy Sex Reversal

15% of cases of human XY sex reversal are due to mutations in SRY (sex determining region on the Y chromosome), many of which map to one of SRY’s two independently acting nuclear localization signals (NLSs) flanking its DNA binding domain. The C-terminal NLS (C-NLS) targets SRY to the nucleus through a ‘conventional’ pathway dependent on the nuclear import receptor importin-β (Imp-β). No importin has been shown to bind the N-terminal NLS (N-NLS), but it is known to interact with the Ca2+-binding protein calmodulin (CaM). We examined seven distinct missense mutations in the SRY NLSs from XY sex-reversed human females for effects on nuclear import and ability to interact with CaM/Imp-β1. All mutations were found to result in reduced nuclear localization in transfected testicular cells compared to wild type. The CaM antagonist, calmidazolium chloride (CDZ), was found to significantly reduce SRY nuclear accumulation, indicating a dependence of SRY nuclear import on CaM. Intriguingly, N-NLS mutants were resistant to CDZ’s effects, implying a loss of interaction with CaM; this was confirmed directly by in vitro binding experiments using recombinantly expressed protein. Either impaired CaM or Imp-β1 binding can thus be the basis of sex-reversal in human patients. Our results implicate a CaM-dependent nuclear import pathway for SRY mediated by the N-NLS that, together with the C-NLS, is required to achieve threshold levels of SRY in the nucleus for male sex determination.

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Sex Reversal In Individual Oysters

Journal of the Fisheries Research Board of Canada ◽

10.1139/f40-038 ◽

1941 ◽

Vol 5b (4) ◽

pp. 361-364 ◽

Cited By ~ 2

Author(s):

Alfreda Berkeley Needler

Keyword(s):

Sex Determination ◽

Sex Reversal

Among 57 individual oysters (Ostrea virginica) followed from 1932 to 1936, almost every variation occurs from no change in sex to change almost every year. High proportion of unchanging males suggests these as genetically males and the others with apparently random sex determination as hermaphrodites.

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