Academic literature on the topic 'Environmental sex determination, aromatase, sex reversal'
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Journal articles on the topic "Environmental sex determination, aromatase, sex reversal"
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Yamaguchi, Toshiya, Norifumi Yoshinaga, Takashi Yazawa, Koichiro Gen, and Takeshi Kitano. "Cortisol Is Involved in Temperature-Dependent Sex Determination in the Japanese Flounder." Endocrinology 151, no. 8 (June 9, 2010): 3900–3908. http://dx.doi.org/10.1210/en.2010-0228.
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In vertebrates, sex is normally determined by genotype. However, in poikilothermal vertebrates, including reptiles, amphibians, and fishes, sex determination is greatly influenced by environmental factors, such as temperature. Little is known about the molecular mechanisms underlying environmental sex determination in these species. The Japanese flounder (Paralichthys olivaceus) is a teleost fish with an XX/XY sex determination system. However, XX flounder can be induced to develop into predominantly either phenotypic females or males, by rearing at 18 or 27 C, respectively, during the sex differentiation period. Therefore, the flounder provides an excellent model to study the molecular mechanisms underlying temperature-dependent sex determination. We previously showed that an aromatase inhibitor, an antiestrogen, and 27 C treatments cause masculinization of XX flounder, as well as suppression of mRNA expression of ovary-type aromatase (cyp19a1), a steroidogenic enzyme responsible for the conversion of androgens to estrogens in the gonads. Furthermore, estrogen administration completely inhibits masculinization by these treatments, suggesting suppression of cyp19a1 mRNA expression, and the resultant estrogen biosynthesis may trigger masculinization of the XX flounder induced by high water temperature. Here, we demonstrated that cortisol causes female-to-male sex reversal by directly suppressing cyp19a1 mRNA expression via interference with cAMP-mediated activation and that metyrapone (an inhibitor of cortisol synthesis) inhibits 27 C-induced masculinization of XX flounder. Moreover, cortisol concentrations in 27 C-reared juveniles were significantly higher than in 18 C-reared fishes during sexual differentiation. These results strongly suggest that masculinization by high water temperature is ascribable to elevation of cortisol concentration during gonadal sex differentiation in the flounder.
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Orlando, Edward F., Yoshinao Katsu, Shinichi Miyagawa, and Taisen Iguchi. "Cloning and differential expression of estrogen receptor and aromatase genes in the self-fertilizing hermaphrodite and male mangrove rivulus, Kryptolebias marmoratus." Journal of Molecular Endocrinology 37, no. 2 (October 2006): 353–65. http://dx.doi.org/10.1677/jme.1.02101.
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The mechanisms underlying sex determination and differentiation in fishes are labile in response to environmental parameters. Sex-specific phenotypes are largely regulated by sex steroids, and the inhibition or the stimulation of aromatase can reverse sex as well as alter secondary sexual characteristics in fishes. Among vertebrates, the mangrove rivulus is the only known self-fertilizing hermaphrodite. Throughout most of its range, rivulus appear to exist as clonally reproducing hermaphrodites. However, outcrossing has been documented in Belize, where up to 25% of rivulus collected are males. The direct development of (primary) males occurs when embryos are incubated at 18 °C and hermaphrodites develop into secondary males when held at 28 °C. Given the importance of sex steroids, their receptors, and aromatase in sex determination and differentiation of fishes, we cloned, sequenced, and quantified the expression of estrogen receptors (ERα, ERβ) and ovarian (AroA) and brain (AroB) aromatase genes. Hermaphrodites had increased ERα, ERβ, AroA, and AroB gene expression in the liver, gonad, gonad, and brain respectively, compared to males. These data are consistent with the gene expression data reported for other species and are reflective of the presence of ovarian tissue in the hermaphrodites. Interestingly, we show the elevated expression of brain aromatase in the hermaphrodite brain. The role of the dimorphic expression of brain aromatase in the regulation of sex-specific characteristics is intriguing and requires further research. Because of the uniqueness of its reproductive biology, rivulus is an excellent model for elucidating the mechanisms regulating vertebrate sex determination and sexual differentiation.
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Belaid, Baya, Noelle Richard-Mercier, Claude Pieau, and Mireille Dorizzi. "Sex reversal and aromatase in the European pond turtle: Treatment with letrozole after the thermosensitive period for sex determination." Journal of Experimental Zoology 290, no. 5 (2001): 490–97. http://dx.doi.org/10.1002/jez.1092.
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Kroon, Frederieke J., Philip L. Munday, David A. Westcott, Jean-Paul A. Hobbs, and N. Robin Liley. "Aromatase pathway mediates sex change in each direction." Proceedings of the Royal Society B: Biological Sciences 272, no. 1570 (June 16, 2005): 1399–405. http://dx.doi.org/10.1098/rspb.2005.3097.
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The enzyme aromatase controls the androgen/oestrogen ratio by catalysing the irreversible conversion of testosterone into oestradiol (E 2 ). Therefore, the regulation of E 2 synthesis by aromatase is thought to be critical in sexual development and differentiation. Here, we demonstrate for the first time that experimental manipulation of E 2 levels via the aromatase pathway induces adult sex change in each direction in a hermaphroditic fish that naturally exhibits bidirectional sex change. Our results demonstrate that a single enzymatic pathway can regulate both female and male sexual differentiation, and that aromatase may be the key enzyme that transduces environmental, including social, cues to functional sex differentiation in species with environmental sex determination.
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Sun, Li-Na, Xiao-Long Jiang, Qing-Ping Xie, Jing Yuan, Bao-Feng Huang, Wen-Jing Tao, Lin-Yan Zhou, Yoshitaka Nagahama, and De-Shou Wang. "Transdifferentiation of Differentiated Ovary into Functional Testis by Long-Term Treatment of Aromatase Inhibitor in Nile Tilapia." Endocrinology 155, no. 4 (April 1, 2014): 1476–88. http://dx.doi.org/10.1210/en.2013-1959.
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Females with differentiated ovary of a gonochoristic fish, Nile tilapia, were masculinized by long-term treatment with an aromatase inhibitor (Fadrozole) in the present study. The reversed gonads developed into functional testes with fertile sperm. The longer the fish experienced sex differentiation, the longer treatment time was needed for successful sex reversal. Furthermore, Fadrozole-induced sex reversal, designated as secondary sex reversal (SSR), was successfully rescued by supplement of exogenous 17β-estradiol. Gonadal histology, immunohistochemistry, transcriptome, and serum steroid level were analyzed during SSR. The results indicated that spermatogonia were transformed from oogonia or germline stem cell-like cells distributed in germinal epithelium, whereas Leydig and Sertoli cells probably came from the interstitial cells and granulosa cells of the ovarian tissue, respectively. The transdifferentiation of somatic cells, as indicated by the appearance of doublesex- and Mab-3-related transcription factor 1 (pre-Sertoli cells) and cytochrome P450, family 11, subfamily B, polypeptide 2 (pre-Leydig cells)-positive cells in the ovary, provided microniche for the transdifferentiation of germ cells. Decrease of serum 17β-estradiol was detected earlier than increase of serum 11-ketotestosterone, indicating that decrease of estrogen was the cause, whereas increase of androgen was the consequence of SSR. The sex-reversed gonad displayed more similarity in morphology and histology with a testis, whereas the global gene expression profiles remained closer to the female control. Detailed analysis indicated that transdifferentiation was driven by suppression of female pathway genes and activation of male pathway genes. In short, SSR provides a good model for study of sex reversal in teleosts and for understanding of sex determination and differentiation in nonmammalian vertebrates.
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Lambert, Max R., Tien Tran, Andrzej Kilian, Tariq Ezaz, and David K. Skelly. "Molecular evidence for sex reversal in wild populations of green frogs (Rana clamitans)." PeerJ 7 (February 8, 2019): e6449. http://dx.doi.org/10.7717/peerj.6449.
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In vertebrates, sex determination occurs along a continuum from strictly genotypic (GSD), where sex is entirely guided by genes, to strictly environmental (ESD), where rearing conditions, like temperature, determine phenotypic sex. Along this continuum are taxa which have combined genetic and environmental contributions to sex determination (GSD + EE), where some individuals experience environmental effects which cause them to sex reverse and develop their phenotypic sex opposite their genotypic sex. Amphibians are often assumed to be strictly GSD with sex reversal typically considered abnormal. Despite calls to understand the relative natural and anthropogenic causes of amphibian sex reversal, sex reversal has not been closely studied across populations of any wild amphibian, particularly in contrasting environmental conditions. Here, we use sex-linked molecular markers to discover sex reversal in wild populations of green frogs (Rana clamitans) inhabiting ponds in either undeveloped, forested landscapes or in suburban neighborhoods. Our work here begins to suggest that sex reversal may be common within and across green frog populations, occurring in 12 of 16 populations and with frequencies of 2–16% of individuals sampled within populations. Additionally, our results also suggest that intersex phenotypic males and sex reversal are not correlated with each other and are also not correlated with suburban land use. While sex reversal and intersex are often considered aberrant responses to human activities and associated pollution, we found no such associations here. Our data perhaps begin to suggest that, relative to what is often suggested, sex reversal may be a relatively natural process in amphibians. Future research should focus on assessing interactions between genes and the environment to understand the molecular and exogenous basis of sex determination in green frogs and in other amphibians.
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Estermann, Martin Andres, and Craig Allen Smith. "Fadrozole-Mediated Sex Reversal Induces PAX2+Undifferentiated Supporting Cells in Female Chicken Gonads." Journal of the Endocrine Society 5, Supplement_1 (May 1, 2021): A765—A766. http://dx.doi.org/10.1210/jendso/bvab048.1557.
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Abstract During early embryogenesis, the undifferentiated gonad is bipotential and subsequently commits to an ovarian or testicular fate. In birds, double dose of the Z-linked gene DMRT1 is required for testicular differentiation in male embryos (genetically ZZ). In female birds, estrogen plays a key role in ovarian differentiation. 17β-estradiol (E2) induces gonadal feminization when applied to male embryos (ZZ). Conversely, inhibition of estrogen synthesis with the drug fadrozole (FAD) results in testicular development in genetically female embryos (ZW). However, activation of male markers in sex-reversed ZW embryos is typically delayed, raising the possibility that FAD-treated embryos may transition through an undifferentiated state before masculinization. Recently, PAX2 was identified as a marker of undifferentiated supporting cells in the chicken embryo, being downregulated in both sexes at the onset of gonadal sex determination. To investigate the supporting cell differentiation process in estrogen-mediated sex reversal, we injected 1 mg of fadrozole in 100µl of PBS or vehicle into embryonic day 3.5 (E3.5) chicken eggs. Eggs were incubated until E9.5, genotypically sexed (ZZ or ZW) and processed for qRT-PCR and immunofluorescence. Quantitative RT-PCR confirmed that sex reversal had occurred in FAD-treated females, showing a reduction of pre-granulosa cell markers aromatase (P<0.005) and FOXL2 (P<0.05), compared to the control. Interestingly, PAX2 mRNA expression was up-regulated (P<0.05) in sex-reversed females, suggesting an increase in undifferentiated supporting cells (n=6). To confirm this observation, immunofluorescence was used to detect aromatase, SOX9 (male marker) and PAX2. In FAD-treated females, both SOX9+ (male) and aromatase+ (female) cells co-existed in the same gonad, but in separated defined regions. Aromatase positive cells were located in the most apical region of the gonad whereas SOX9 positive cells were detected in the basal region. We detected an increase in PAX2 positive cells in the gonadal medulla between the SOX9 and aromatase positive supporting cells. No SOX9 or PAX2 positive cells were detected in control female gonads (n=3). For feminization experiments 100µl of a 1mg/ml solution of E2 or vehicle (Oil) was injected into E3.5 chicken eggs. No significant increase in PAX2 was detected by qRT-PCR (p>0.05, n=6) and no PAX2 positive cells were detected in E2 treated gonads at E9.5. These results suggest that in fadrozole-mediated masculinization (but not in estrogen-induced feminization) there is an increase in undifferentiated supporting cells. The absence of both estrogens (feminizing) and elevated DMRT1 (masculinizing) could explain why the supporting cells remain in an undifferentiated state in ZW (genetically female) embryos. Further research is required to evaluate the fate of these undifferentiated cells in gonadal sex differentiation.
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Voigt, Cornelia. "Neuroendocrine correlates of sex-role reversal in barred buttonquails." Proceedings of the Royal Society B: Biological Sciences 283, no. 1843 (November 30, 2016): 20161969. http://dx.doi.org/10.1098/rspb.2016.1969.
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Sex differences in brain structure and behaviour are well documented among vertebrates. An excellent model exploring the neural mechanisms of sex differences in behaviour is represented by sex-role-reversed species. In the majority of bird species, males compete over access to mates and resources more strongly than do females. It is thought that the responsible brain regions are therefore more developed in males than in females. Because these behaviours and brain regions are activated by androgens, males usually have increased testosterone levels during breeding. Therefore, in species with sex-role reversal, certain areas of the female brain should be more developed or steroid hormone profiles should be sexually reversed. Here, I studied circulating hormone levels and gene expression of steroid hormone receptors and aromatase in a captive population of barred buttonquails ( Turnix suscitator ). While females performed courtship and agonistic behaviours, there was no evidence for sexually reversed hormone profiles. However, I found female-biased sex differences in gene expression of androgen receptors in several hypothalamic and limbic brain regions that were already in place at hatching. Such sex differences are not known from non-sex-role-reversed species. These data suggest that increased neural sensitivity to androgens could be involved in the mechanisms mediating sex-role-reversed behaviours.
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Zhou, Yingjie, Wei Sun, Han Cai, Haisheng Bao, Yu Zhang, Guoying Qian, and Chutian Ge. "The Role of Anti-Müllerian Hormone in Testis Differentiation Reveals the Significance of the TGF-β Pathway in Reptilian Sex Determination." Genetics 213, no. 4 (October 23, 2019): 1317–27. http://dx.doi.org/10.1534/genetics.119.302527.
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Anti-Müllerian hormone (Amh, or Müllerian-inhibiting substance, Mis), a member of TGF-β superfamily, has been well documented in some vertebrates as initiator or key regulator in sexual development, and particularly in fish. However, its functional role has not yet been identified in reptiles. Here, we characterized the Amh gene in the Chinese soft-shelled turtle Pelodiscus sinensis, a typical reptilian species exhibiting ZZ/ZW sex chromosomes. The messenger RNA of Amh was initially expressed in male embryonic gonads by stage 15, preceding gonadal sex differentiation, and exhibited a male-specific expression pattern throughout embryogenesis. Moreover, Amh was rapidly upregulated during female-to-male sex reversal induced by aromatase inhibitor letrozole. Most importantly, Amh loss of function by RNA interference led to complete feminization of genetic male (ZZ) gonads, suppression of the testicular marker Sox9, and upregulation of the ovarian regulator Cyp19a1. Conversely, overexpression of Amh in ZW embryos resulted in female-to-male sex reversal, characterized by the formation of a testis structure, ectopic activation of Sox9, and a remarkable decline in Cyp19a1. Collectively, these findings provide the first solid evidence that Amh is both necessary and sufficient to drive testicular development in a reptilian species, P. sinensis, highlighting the significance of the TGF-β pathway in reptilian sex determination.
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Sakae, Yuta, and Minoru Tanaka. "Metabolism and Sex Differentiation in Animals from a Starvation Perspective." Sexual Development 15, no. 1-3 (2021): 168–78. http://dx.doi.org/10.1159/000515281.
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Animals determine their sex genetically (GSD: genetic sex determination) and/or environmentally (ESD: environmental sex determination). Medaka (<i>Oryzias latipes</i>) employ a XX/XY GSD system, however, they display female-to-male sex reversal in response to various environmental changes such as temperature, hypoxia, and green light. Interestingly, we found that 5 days of starvation during sex differentiation caused female-to-male sex reversal. In this situation, the metabolism of pantothenate and fatty acid synthesis plays an important role in sex reversal. Metabolism is associated with other biological factors such as germ cells, HPG axis, lipids, and epigenetics, and supplys substances and acts as signal transducers. In this review, we discuss the importance of metabolism during sex differentiation and how metabolism contributes to sex differentiation.
Book chapters on the topic "Environmental sex determination, aromatase, sex reversal"
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West-Eberhard, Mary Jane. "Cross-sexual Transfer." In Developmental Plasticity and Evolution. Oxford University Press, 2003. http://dx.doi.org/10.1093/oso/9780195122343.003.0021.
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Distinctive male and female traits are perhaps the most familiar of all divergent specializations within species. In cross-sexual transfer, discrete traits that are expressed exclusively in one sex in an ancestral species appear in the opposite sex of descendants. An example is the expression of brood care by males in a lineage where ancestral females are the exclusive caretakers of the young, as in some voles (Thomas and Birney, 1979). Despite the prominence of sexual dimorphism and sex reversals in nature, and an early explicit treatment by Darwin, discussed in the next section, cross-sexual transfer is not often recognized as a major factor in the evolution of novelty (but see, on animals, Mayr, 1963, pp. 435-439; Mayr, 1970, p. 254; on plants, Iltis, 1983). When more widely investigated, cross-sexual transfer may prove to rival heterochrony and duplication as an important source of novelties in sexually dimorphic lineages. For this reason, I devote more attention here to cross-sexual transfer than to these other, well-established general patterns of change. The male and female of a sexually dimorphic species may be so different that it is easy to forget that each individual carries most or all of the genes necessary to produce the phenotype of the opposite sex. Sex determination, like caste determination and other switches between alternative phenotypes, depends on only a few genetic loci or, in many species, environmental factors (Bull, 1983). There is considerable flexibility in sex determination and facultative reversal in some taxa. Among fish, for example, there is even a species wherein sex is determined by juvenile size at a critical age (Francis and Barlow, 1993). The sex determination mechanism, whatever its nature, leads to a series of sex-limited responses, often coordinated by hormones and not necessarily all occurring at once. A distinguishing aspect of sexually dimorphic traits in adults is that there is often a close homology between the secondary sexual traits that are differently modified in the two sexes.
Conference papers on the topic "Environmental sex determination, aromatase, sex reversal"
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Ataei, Abdol Hossain, and Figen Kırkpınar. "Application of In-Ovo Injection of Some Substances for Manipulation of Sex and Improving Performance in Chicken." In International Students Science Congress. Izmir International Guest Student Association, 2021. http://dx.doi.org/10.52460/issc.2021.006.
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In intensive production, freshly hatched cockerels are culled in the layer hatchery (7 billion males each year), On the other hand, for meat production rearing female birds has not economic benefits because of male broiler chicks have a faster growth rate and better feed efficiency than females. In this regards several methods are being developed for sex determination in the chick embryo during the incubation period. But these methods need to be rapid, cost-efficient, and suitable practical for commercial use. Additionally, sex determination should be done before pain perception has evolved in chick embryos. Biotechnology by in ovo technique to sex determination of between male and female chicks or sex reversal could improve production and eliminate ethical dilemmas for poultry industries. In birds, the differentiation of embryonic gonads is not determined by genetic gender with the certainty that occurs in mammals and can be affected by early treatment with a steroid hormone. During the development of the chick embryo, the genotype of the zygote determines the nature of the gonads, which then caused male or female phenotype. The differentiation of gonads during the period called the "critical period of sexual differentiation" is accompanied by the beginning of secretion of sexual hormones. Namely, any change in the concentration of steroid hormones during the critical period affects the structure of the gonads. Many synthetic anti-aromatases such as federazole and non-synthetic in plants, mushrooms, and fruits containing natural flavonoids have been used in the experiments in ovo injection of anti-aromatase had no negative effect on the growth performance of sexual reversal female chickens. In conclusion, administration of an aromatase inhibitor causes testicular growth in the genetic female gender, and estrogen administration leads to the production of the left ovotestis in the genetic male gender. Therefore, in the early stages of embryonic development, sexual differentiation can be affected by changing the ratio of sexual hormones. In this review, effects of some substances applied by in ovo injection technique on sex reversal and performance in chicks.
Reports on the topic "Environmental sex determination, aromatase, sex reversal"
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Hulata, Gideon, Thomas D. Kocher, Micha Ron, and Eyal Seroussi. Molecular Mechanisms of Sex Determination in Cultured Tilapias. United States Department of Agriculture, October 2010. http://dx.doi.org/10.32747/2010.7697106.bard.
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Tilapias are among the most important aquaculture commodities worldwide. Commercial production of tilapia is based on monosex culture of males. Current methods for producing all-male fingerlings, including hormone treatments and genetic manipulations, are not entirely reliable, in part because of the genetic complexity of sex determination and sexual differentiation in tilapias. The goals of this project are to map QTL and identify genes regulating sex determination in commonly cultured tilapia species, in order to provide a rational basis for designing reliable genetic approaches for producing all-male fingerlings. The original objectives for this research were: 1) to identify the gene underlying the QTL on LG1 through positional cloning and gene expression analysis; 2) to fine map the QTL on LG 3 and 23; and 3) to characterize the patterns of dominance and epistasis among QTL alleles influencing sex determination. The brain aromatase gene Cyp19b, a possible candidate for the genetic or environmental SD, was mapped to LG7 using our F2 mapping population. This region has not been identified before as affecting SD in tilapias. The QTL affecting SD on LG 1 and 23 have been fine-mapped down to 1 and 4 cM, respectively, but the key regulators for SD have not been found yet. Nevertheless, a very strong association with gender was found on LG23 for marker UNH898. Allele 276 was found almost exclusively in males, and we hypothesized that this allele is a male-associated allele (MAA). Mating of males homozygous for MAA with normal females is underway for production of all-male populations. The first progeny reaching size allowing accurate sexing had 43 males and no females. During the course of the project it became apparent that in order to achieve those objectives there is a need to develop genomic infrastructures that were lacking. Efforts have been devoted to the development of genomic resources: a database consisting of nearly 117k ESTs representing 16 tissues from tilapia were obtained; a web tool based on the RepeatMasker software was designed to assist tilapia genomics; collaboration has been established with a sequencing company to sequence the tilapia genome; steps have been taken toward constructing a microarray to enable comparative analysis of the entire transcriptome that is required in order to detect genes that are differentially expressed between genders in early developmental stages. Genomic resources developed will be invaluable for studies of cichlid physiology, evolution and development, and will hopefully lead to identification of the key regulators of SD. Thus, they will have both scientific and agricultural implications in the coming years.