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The Journal of Experimental Zoology Aug 1998Most amphibians lack morphologically distinguishable sex chromosomes, but a number of experimental techniques have shown that amphibian sex determination is controlled... (Review)
Review
Most amphibians lack morphologically distinguishable sex chromosomes, but a number of experimental techniques have shown that amphibian sex determination is controlled genetically. The few studies suggesting that environment influences sex determination in amphibians have all been conducted at temperatures outside of the range normally experienced by the species under study, and these effects probably do not occur under natural conditions. No sex-determining genes have been described in amphibians, and sex differentiation can be altered by treatment with exogenous steroid hormones. The effects of sex steroids vary extensively between species, and a variety of steroids can alter the sex ratios of treated larvae. The role of endogenous sex steroids in gonadal differentiation has not been fully explored; thus the natural role of steroids in amphibian gonadal differentiation is unknown. Sex steroid receptors have not been examined in amphibian gonads, and the mechanism of steroid action on the gonad is unclear. In addition to steroids, the thyroid hormones may play a role in gonadal differentiation. Pituitary gonadotrop(h)ins affect gonadal growth, but not differentiation or maturation of gonads. In addition to the issue of resolving the mechanisms underlying hormone action in gonadal differentiation, other debates concerning interactions between the developing gonads and the invading germ cells, and even the origin of the medullary and cortical portions of the developing gonads, remain unresolved. Studies examining links between sex determination and gonadal differentiation are needed. In addition, examinations of variation in steroidal effects on gonadal development in a phylogenetic context are lacking.
Topics: Amphibians; Animals; Female; Male; Ovary; Sex Determination Processes; Sex Differentiation; Testis
PubMed: 9662826
DOI: No ID Found -
General and Comparative Endocrinology Jul 2010Protandrous black porgy fish, Acanthopagrus schlegeli, have a striking life cycle with a male sex differentiation at the juvenile stage and male-to-female sex change at... (Review)
Review
Protandrous black porgy fish, Acanthopagrus schlegeli, have a striking life cycle with a male sex differentiation at the juvenile stage and male-to-female sex change at 3 years of age. We had characterized the sex differentiation and sex change in this species by the integrative approaches of histology, endocrine and molecular genetics. The fish differentiated in gonad at the age around 4-months and the gonad further developed with a bisexual gonad for almost for 3 years and sex change at 3 year of age. An antagonistic relationship in the testicular and ovarian tissues was found during the development of the gonadal tissue. Male- (such as sf-1, dmrt1, dax-1 and amh) and female- (such as wnt4, foxl2 and cyp19a1a) promoting genes were associated with testicular and ovarian development, respectively. During gonadal sex differentiation, steroidogenic pathway and estrogen signaling were also highly expressed in the brain. The increased expression of sf-1 and wnt4, cyp19a1a in ovarian tissue and decreased expression of dax-1 in the ovarian tissue may play important roles in sex change from a male-to-female. Endocrine factors such as estradiol and luteinizing hormone may also involve in the natural sex change. Estradiol induced the expression of female-promoting genes and resulted in the precocious sex change in black porgy. Our series of studies shed light on the sex differentiation and sex change in protandrous black porgy and other animals.
Topics: Animals; Brain; Female; Gene Expression Profiling; Gene Expression Regulation, Developmental; Gonads; Hermaphroditic Organisms; Male; Neuronal Plasticity; Perciformes; Sex Determination Processes; Sex Differentiation
PubMed: 19917286
DOI: 10.1016/j.ygcen.2009.11.003 -
Best Practice & Research. Clinical... Feb 2003The purpose of this chapter is to review the presentation and management of patients affected by conditions of abnormal sex differentiation. First, the processes of... (Review)
Review
The purpose of this chapter is to review the presentation and management of patients affected by conditions of abnormal sex differentiation. First, the processes of normal sex differentiation are covered, followed by an overview of the various syndromes of abnormal sex differentiation, or intersex conditions, that can occur. These disorders are presented according to the following categories: patients who possess a 46,XX chromosome complement, those who possess a 46,XY chromosome complement, and individuals who present with an atypical sex chromosome complement (i.e. 45,XO or 45,X0/46,XY mosaicism). A description of the medical, surgical and psychological treatment options for people affected by various intersex conditions and reared as females are included. Practice points, based on research studies when available, are dispersed throughout the chapter. Additionally, information pertaining to relevant Internet websites and patient support groups are provided, so that medical staff can educate their patients about the availability of these resources.
Topics: Disorders of Sex Development; Female; Genitalia; Humans; Male; Sex Characteristics; Sex Chromosome Aberrations; Sex Differentiation
PubMed: 12758223
DOI: 10.1053/ybeog.2003.0354 -
Journal of Neuroendocrinology Jan 2020Sex differences among neurones in the ventrolateral region of the ventromedial hypothalamic nucleus (VMHvl) allow for the display of a diversity of sex-typical... (Review)
Review
Sex differences among neurones in the ventrolateral region of the ventromedial hypothalamic nucleus (VMHvl) allow for the display of a diversity of sex-typical behaviours and physiological responses, ranging from mating behaviour to metabolism. Here, we review recent studies that interrogate the relationship between sex-typical responses and changes in cellular phenotypes. We discuss technologies that increase the resolution of molecular profiling or targeting of cell populations, including single-cell transcriptional profiling and conditional viral genetic approaches to manipulate neurone survival or activity. Overall, emerging studies indicate that sex-typical functions of the VMH may be mediated by phenotypically distinct and sexually differentiated neurone populations within the VMHvl. Future studies in this and other brain regions could exploit cell-type-specific tools to reveal the cell populations and molecular mediators that modulate sex-typical responses. Furthermore, cell-type-specific analyses of the effects of sexually differentiating factors, including sex hormones, can test the hypothesis that distinct cell types within a single brain region vary with respect to sexual differentiation.
Topics: Animals; Female; Humans; Male; Neurons; Sex Characteristics; Sex Differentiation; Sexual Behavior, Animal; Ventromedial Hypothalamic Nucleus
PubMed: 31605642
DOI: 10.1111/jne.12801 -
Genetics, Selection, Evolution : GSE Apr 2014The molecular mechanisms that underlie sex determination and differentiation are conserved and diversified. In fish species, temperature-dependent sex determination and... (Review)
Review
The molecular mechanisms that underlie sex determination and differentiation are conserved and diversified. In fish species, temperature-dependent sex determination and differentiation seem to be ubiquitous and molecular players involved in these mechanisms may be conserved. Although how the ambient temperature transduces signals to the undifferentiated gonads remains to be elucidated, the genes downstream in the sex differentiation pathway are shared between sex-determining mechanisms. In this paper, we review recent advances on the molecular players that participate in the sex determination and differentiation in fish species, by putting emphasis on temperature-dependent sex determination and differentiation, which include temperature-dependent sex determination and genetic sex determination plus temperature effects. Application of temperature-dependent sex differentiation in farmed fish and the consequences of temperature-induced sex reversal are discussed.
Topics: Animals; Female; Fishes; Gene-Environment Interaction; Male; Ovary; Sex Differentiation; Temperature; Testis
PubMed: 24735220
DOI: 10.1186/1297-9686-46-26 -
Biology of Sex Differences Jun 2022In this systematic review, we highlight the differences between the male and female zebrafish brains to understand their differentiation and their use in studying... (Review)
Review
In this systematic review, we highlight the differences between the male and female zebrafish brains to understand their differentiation and their use in studying sex-specific neurological diseases. Male and female brains display subtle differences at the cellular level which may be important in driving sex-specific signaling. Sex differences in the brain have been observed in humans as well as in non-human species. However, the molecular mechanisms of brain sex differentiation remain unclear. The classical model of brain sex differentiation suggests that the steroid hormones derived from the gonads are the primary determinants in establishing male and female neural networks. Recent studies indicate that the developing brain shows sex-specific differences in gene expression prior to gonadal hormone action. Hence, genetic differences may also be responsible for differentiating the brain into male and female types. Understanding the signaling mechanisms involved in brain sex differentiation could help further elucidate the sex-specific incidences of certain neurological diseases. The zebrafish model could be appropriate for enhancing our understanding of brain sex differentiation and the signaling involved in neurological diseases. Zebrafish brains show sex-specific differences at the hormonal level, and recent advances in RNA sequencing have highlighted critical sex-specific differences at the transcript level. The differences are also evident at the cellular and metabolite levels, which could be important in organizing sex-specific neuronal signaling. Furthermore, in addition to having one ortholog for 70% of the human gene, zebrafish also shares brain structural similarities with other higher eukaryotes, including mammals. Hence, deciphering brain sex differentiation in zebrafish will help further enhance the diagnostic and pharmacological intervention of neurological diseases.
Topics: Animals; Brain; Female; Gonads; Male; Mammals; Sex Characteristics; Sex Differentiation; Zebrafish
PubMed: 35715828
DOI: 10.1186/s13293-022-00442-2 -
Sexual Development : Genetics,... 2009Environmental factors affect the sex ratio of many gonochoristic fish species. They can either determine sex or influence sex differentiation. Temperature is the most... (Review)
Review
Environmental factors affect the sex ratio of many gonochoristic fish species. They can either determine sex or influence sex differentiation. Temperature is the most common environmental cue affecting sex but density, pH and hypoxia have also been shown to influence the sex ratio of fish species from very divergent orders. Differential growth or developmental rate is suggested to influence sex differentiation in sea bass. Studies in most fish species used domestic strains reared under controlled conditions. In tilapia and sea bass, domestic stocks and field-collected populations showed similar patterns of thermosensitivity under controlled conditions. Genetic variability of thermosensitivity is seen between populations but also between families within the same population. Furthermore, in the Nile tilapia progeny testing of wild male breeders has strongly suggested the existence of XX males in 2 different natural populations. Tilapia and Atlantic silverside studies have shown that temperature sensitivity is a heritable trait which can respond to directional (tilapia) or frequency dependent selection. In tilapia, transitional forms within a genetic sex determination (GSD) and environmental sex determination (ESD) continuum seem to exist. Temperature regulates the expression of the ovarian-aromatase cyp19a1 which is consistently inhibited in temperature masculinized gonads. Foxl2 is suppressed before cyp19a1. Recent in vitro studies have shown that foxl2 activates cyp19a1, suggesting that temperature acts directly on foxl2 or further upstream. Dmrt1 up-regulation is correlated with temperature-induced male phenotypes. Temperature through apoptosis or germ cell proliferation could be a critical threshold for male or female sex differentiation.
Topics: Animals; Environment; Fishes; Genetic Variation; Sex Determination Processes; Sex Differentiation; Temperature
PubMed: 19684457
DOI: 10.1159/000223077 -
PeerJ 2024Sex determination in chickens at an early embryonic stage has been a longstanding challenge in poultry production due to the unique ZZ:ZW sex chromosome system and... (Review)
Review
Sex determination in chickens at an early embryonic stage has been a longstanding challenge in poultry production due to the unique ZZ:ZW sex chromosome system and various influencing factors. This review has summarized the genes related to the sex differentiation of chicken early embryos (mainly , , , , , , , , , , , , , , and in this article), and has found that these contributions enhance our understanding of the genetic basis of sex determination in chickens, while identifying potential gene targets for future research. This knowledge may inform and guide the development of sex screening technologies for hatching eggs and support advancements in gene-editing approaches for chicken embryos. Moreover, these insights offer hope for enhancing animal welfare and promoting conservation efforts in poultry production.
Topics: Chick Embryo; Animals; Chickens; Sex Differentiation; Sex Determination Processes; Sex Chromosomes
PubMed: 38525278
DOI: 10.7717/peerj.17072 -
Ecotoxicology and Environmental Safety Nov 2023Human activities have been exerting widespread stress and environmental risks in aquatic ecosystems. Environmental stress, including temperature rise, acidification,... (Review)
Review
Human activities have been exerting widespread stress and environmental risks in aquatic ecosystems. Environmental stress, including temperature rise, acidification, hypoxia, light pollution, and crowding, had a considerable negative impact on the life histology of aquatic animals, especially on sex differentiation (SDi) and the resulting sex ratios. Understanding how the sex of fish responds to stressful environments is of great importance for understanding the origin and maintenance of sex, the dynamics of the natural population in the changing world, and the precise application of sex control in aquaculture. This review conducted an exhaustive search of the available literature on the influence of environmental stress (ES) on SDi. Evidence has shown that all types of ES can affect SDi and universally result in an increase in males or masculinization, which has been reported in 100 fish species and 121 cases. Then, this comprehensive review aimed to summarize the molecular biology, physiology, cytology, and epigenetic mechanisms through which ES contributes to male development or masculinization. The relationship between ES and fish SDi from multiple aspects was analyzed, and it was found that environmental sex differentiation (ESDi) is the result of the combined effects of genetic and epigenetic factors, self-physiological regulation, and response to environmental signals, which involves a sophisticated network of various hormones and numerous genes at multiple levels and multiple gradations in bipotential gonads. In both normal male differentiation and ES-induced masculinization, the stress pathway and epigenetic regulation play important roles; however, how they co-regulate SDi is unclear. Evidence suggests that the universal emergence or increase in males in aquatic animals is an adaptation to moderate ES. ES-induced sex reversal should be fully investigated in more fish species and extensively in the wild. The potential aquaculture applications and difficulties associated with ESDi have also been addressed. Finally, the knowledge gaps in the ESDi are presented, which will guide the priorities of future research.
Topics: Animals; Humans; Male; Ecosystem; Epigenesis, Genetic; Sex Differentiation; Aquaculture; Gonads
PubMed: 37918334
DOI: 10.1016/j.ecoenv.2023.115654 -
Sexual Development : Genetics,... 2014As temperature-dependent sex determination (TSD) and homozygote or heterozygote genetic sex determination (GSD) exist in multiple reptilian taxa, they represent sex... (Review)
Review
As temperature-dependent sex determination (TSD) and homozygote or heterozygote genetic sex determination (GSD) exist in multiple reptilian taxa, they represent sex determination systems that have emerged de novo. Current investigations have revealed that the genetic mechanisms used by various reptilian species are similar to those used by other vertebrates. However, the recent completion or near completion of various reptilian genome projects suggests that new studies examining related species with and without TSD could begin to provide additional insight into the evolution of TSD and GSD in vertebrate ancestors. Major questions still remain concerning germ cell migration and specification, the differentiation of gonadal accessory cells, such as the Sertoli cells and granulosa cells of the developing testis and ovary, respectively, and the mechanisms by which gene expression is regulated during TSD events. Further, reptilian sentinels and their mechanisms of gonadogenesis will likely remain important indicator species for environmental health. Thus, ongoing and new investigations need to tie molecular information to gonadal morphogenesis and function in reptiles. Such data will not only provide important information for an understanding of the evolution of these phenomena in vertebrates, but could also provide an important understanding of the health of the environment around us.
Topics: Animals; Female; Gonads; Male; Reptiles; Sex Differentiation
PubMed: 24642710
DOI: 10.1159/000358892