scholarly journals Temperature-Dependent Sex Determination in Gekko japonicus (Gekkonidae, Reptilia). (temperature-dependent sex determination/Gekko japonicus/sex differentiation/Reptilia)

1985 ◽  
Vol 27 (2) ◽  
pp. 117-120 ◽  
Author(s):  
SHOJI TOKUNAGA
Keyword(s):  
Sex Determination ◽  
Sex Differentiation ◽  
Temperature Dependent ◽  
Gekko Japonicus

scholarly journals Thyroid hormone modulates offspring sex ratio in a turtle with temperature-dependent sex determination

2016 ◽  
Vol 283 (1841) ◽  
pp. 20161206 ◽  
Author(s):  
Bao-Jun Sun ◽  
Teng Li ◽  
Yi Mu ◽  
Jessica K. McGlashan ◽  
Arthur Georges ◽  
...  
Keyword(s):  
Thyroid Hormone ◽  
Sex Ratio ◽  
Sex Determination ◽  
Sex Differentiation ◽  
Developmental Rate ◽  
Temperature Dependent ◽  
Gene Encoding ◽  
Offspring Sex Ratio ◽  
Offspring Sex ◽  
Underlying Mechanisms

The adaptive significance of temperature-dependent sex determination (TSD) has attracted a great deal of research, but the underlying mechanisms by which temperature determines the sex of a developing embryo remain poorly understood. Here, we manipulated the level of a thyroid hormone (TH), triiodothyronine (T 3 ), during embryonic development (by adding excess T 3 to the eggs of the red-eared slider turtle Trachemys scripta , a reptile with TSD), to test two competing hypotheses on the proximate basis for TSD: the developmental rate hypothesis versus the hormone hypothesis . Exogenous TH accelerated embryonic heart rate (and hence metabolic rate), developmental rate, and rates of early post-hatching growth. More importantly, hyperthyroid conditions depressed expression of Cyp19a1 (the gene encoding for aromatase) and levels of oestradiol, and induced more male offspring. This result is contrary to the direction of sex-ratio shift predicted by the developmental rate hypothesis , but consistent with that predicted by the hormone hypothesis . Our results suggest an important role for THs in regulating sex steroid hormones, and therefore, in affecting gonadal sex differentiation in TSD reptiles. Our study has implications for the conservation of TSD reptiles in the context of global change because environmental contaminants may disrupt the activity of THs, and thereby affect offspring sex in TSD reptiles.

scholarly journals Molecular evolution of Dmrt1 accompanies change of sex-determining mechanisms in reptilia

2014 ◽  
Vol 10 (12) ◽  
pp. 20140809 ◽  
Author(s):  
Daniel E. Janes ◽  
Christopher L. Organ ◽  
Rami Stiglec ◽  
Denis O'Meally ◽  
Stephen D. Sarre ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Molecular Evolution ◽  
Sex Determination ◽  
Sex Differentiation ◽  
Evolution Of Sex ◽  
Temperature Dependent ◽  
Exon 2 ◽  
Ancestral Condition ◽  
Genotypic Sex Determination

In reptiles, sex-determining mechanisms have evolved repeatedly and reversibly between genotypic and temperature-dependent sex determination. The gene Dmrt1 directs male determination in chicken (and presumably other birds), and regulates sex differentiation in animals as distantly related as fruit flies, nematodes and humans. Here, we show a consistent molecular difference in Dmrt1 between reptiles with genotypic and temperature-dependent sex determination. Among 34 non-avian reptiles, a convergently evolved pair of amino acids encoded by sequence within exon 2 near the DM-binding domain of Dmrt1 distinguishes species with either type of sex determination. We suggest that this amino acid shift accompanied the evolution of genotypic sex determination from an ancestral condition of temperature-dependent sex determination at least three times among reptiles, as evident in turtles, birds and squamates. This novel hypothesis describes the evolution of sex-determining mechanisms as turnover events accompanied by one or two small mutations.

scholarly journals The role of Cyp19a1 in female pathway of a freshwater turtle (Mauremys reevesii) with temperature-dependent sex determination

2021 ◽  
Author(s):  
Pengfei Wu ◽  
Xifeng Wang ◽  
Fei Gao ◽  
Weiguo Du
Keyword(s):  
Sex Determination ◽  
Sex Differentiation ◽  
Critical Role ◽  
Temperature Shift ◽  
Vital Role ◽  
Freshwater Turtle ◽  
Temperature Dependent ◽  
Female Sex ◽  
Determination Process ◽  
Sexually Dimorphic Expression

The molecular mechanism of temperature-dependent sex determination (TSD) in reptiles has been drawn great interest from biologists for several decades. However, which genetic factors are essential for TSD remain elusive, especially for the female sex determination process. Cyp19a1, encodes an enzyme of aromatase catalyzing the conversion of testosterone to estrogen, has been confirmed to modulate steroid hormones involved in the sexual differentiation of many species, but whether it has a critical role in determining the gonadal sexual fate in TSD is still to be elucidated. Here, we identified that Cyp19a1 expression exhibited a temperature-dependent, sexually dimorphic expression pattern, preceding gonadal sex differentiation in a TSD turtle Mauremys reevesii. Cyp19a1 expression in gonads increased dramatically when embryos developed at high female-producing temperatures (FPT), but were extremely low throughout embryogenesis at low male-producing temperatures (MPT). Cyp19a1 expression increased rapidly in response to the temperature shift from MPT to FPT in developing gonads. The sexual phenotype of turtles was successfully reversed by aromatase inhibitor treatment at FPT, and by estrogen treatment at MPT, accompanied with the rapid upregulation of Cyp19a1. These results demonstrate that Cyp19a1 is essential for the female sex determination process in M. reevesii, indicating its vital role in the female pathway of TSD.

scholarly journals Cortisol Is Involved in Temperature-Dependent Sex Determination in the Japanese Flounder

Endocrinology ◽  
2010 ◽  
Vol 151 (8) ◽  
pp. 3900-3908 ◽  
Author(s):  
Toshiya Yamaguchi ◽  
Norifumi Yoshinaga ◽  
Takashi Yazawa ◽  
Koichiro Gen ◽  
Takeshi Kitano
Keyword(s):  
Sex Determination ◽  
Water Temperature ◽  
Mrna Expression ◽  
Molecular Mechanisms ◽  
Sex Differentiation ◽  
Paralichthys Olivaceus ◽  
High Water ◽  
Japanese Flounder ◽  
High Water Temperature ◽  
Temperature Dependent

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.

scholarly journals Sex determination in mythology and history

2005 ◽  
Vol 49 (1) ◽  
pp. 7-13 ◽  
Author(s):  
Ursula Mittwoch
Keyword(s):  
Sex Determination ◽  
Sex Chromosome ◽  
Environmental Control ◽  
Sex Differentiation ◽  
Unexpected Finding ◽  
Temperature Dependent ◽  
Sex Chromosome Abnormalities ◽  
History Of ◽  
Male Sex ◽  
And Function

The history of ideas on how the sexes became divided spans at least three thousand years. The biblical account of the origin of Eve, and the opinions of the philosophers of classical Greece, have unexpected bearings on present-day ideas. The scientific study of sex determination can be said to have begun in the 17th century with the discovery of spermatozoa, but the origin and function of the "spermatic animalcules" eluded investigators until 1841. The mammalian egg was discovered in 1827, and in the last quarter of the century fertilization was observed. The view current at that time, that sex determination was under environmental control, gave way to the idea of chromosomal determination in the first quarter of the 20th century. The study of human and other mammalian chromosomes during the third quarter of the century, and the discovery of sex-chromosome abnormalities, emphasized the importance of the Y chromosome for male sex determination. The last quarter of the century witnessed a hunt for the "testis-determining" gene, thought to be responsible for the differentiation of Sertoli cells, and culminating in the isolation of SRY (Sry in the mouse). However, an increasing number of additional genes and growth factors were found to be required for the establishment of male sex. During the same period evidence emerged that male development was accompanied by enhanced growth, both of gonads and whole embryos. An unexpected finding was the demonstration of temperature-dependent sex determination in reptiles. With the advent of the 21st century, it was shown that Sry induces cell proliferation in fetal mouse gonads, and it has been suggested that male sex differentiation in mammals requires a higher metabolic rate. These insights could lead to a better understanding and improved treatment of abnormalities of sexual development.

scholarly journals Transcriptome sequencing and comparative analysis of adult ovary and testis identify potential gonadal maintenance-related genes in Mauremys reevesii with temperature-dependent sex determination

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e6557 ◽  
Author(s):  
Lei Xiong ◽  
Jinxiu Dong ◽  
Hui Jiang ◽  
Jiawei Zan ◽  
Jiucui Tong ◽  
...  
Keyword(s):  
Sex Determination ◽  
Signaling Pathway ◽  
Hedgehog Signaling ◽  
Sex Differentiation ◽  
Wnt Signaling Pathway ◽  
Gonad Development ◽  
Hippo Signaling ◽  
Rna Seq ◽  
Temperature Dependent ◽  
Type 3

Mauremys reevesii is a classical organism with temperature-dependent sex determination (TSD). Gonad development in early life has recently received considerable attention but gonadal maintenance after sex differentiation in turtles with TSD remains a mystery. In this study, we sequenced the transcriptomes for the adult testis and ovary using RNA-seq, and 36,221 transcripts were identified. In total, 1,594 differentially expressed genes (DEGs) were identified where 756 DEGs were upregulated in the testis and 838 DEGs were upregulated in the ovary. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analysis suggested that the TGF-beta signaling pathway and Hedgehog signaling pathway have important roles in testis maintenance and spermatogenesis, whereas the Hippo signaling pathway and Wnt signaling pathway are likely to participate in ovary maintenance. We determined the existence of antagonistic networks containing significant specific-expressed genes and pathways related to gonadal maintenance and gametogenesis in the adult gonads of M. reevesii. The candidate gene Fibronectin type 3 and ankyrin repeat domains 1 (FANK1) might be involved with the regulation of testis spermatogenesis.

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