Molecular Mechanisms of Sexual Development

Parma, P.; Radi, Orietta

doi:10.1159/000332209

Cited by 22 publications

(14 citation statements)

References 217 publications

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“…1 in Valenzuela et al [2003]). Nor does it negate the extensive similarities in the composition of the developmental networks underlying vertebrate sexual development [Parma and Radi, 2012;Valenzuela et al, 2013]. However, the existence of a common network of genes underlying sexual development does not disprove the fundamental difference between GSD and ESD manifested by the presence/ absence of sex chromosomes.…”

Section: Resultsmentioning

confidence: 96%

Molecular Cytogenetic Search for Cryptic Sex Chromosomes in Painted Turtles Chrysemys picta

Valenzuela

Badenhorst

Montiel

et al. 2014

Cytogenet Genome Res

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Sex determination is triggered by factors ranging from genotypic (GSD) to environmental (ESD), or both GSD + EE (GSD susceptible to environmental effects), and its evolution remains enigmatic. The presence/absence of sex chromosomes purportedly separates species at the ESD end of the continuum from the rest (GSD and GSD + EE) because the evolutionary dynamics of sex chromosomes and autosomes differ. However, studies suggest that turtles with temperature-dependent sex determination (TSD) are cryptically GSD and possess sex chromosomes. Here, we test this hypothesis in painted turtles Chrysemys picta (TSD), using comparative-genome-hybridization (CGH), a technique known to detect morphologically indistinguishable sex chromosomes in other turtles and reptiles. Our results show no evidence for the existence of sex chromosomes in painted turtles. While it remains plausible that cryptic sex chromosomes may exist in TSD turtles that are characterized by minor genetic differences that cannot be detected at the resolution of CGH, previous attempts have failed to identify sex-specific markers. Genomic sequencing should prove useful in providing conclusive evidence in this regard. If such efforts uncover sex chromosomes in TSD turtles, it may reveal the existence of a fundamental constraint for the evolution of a full spectrum of sex determination (from pure GSD to pure TSD) that is predicted theoretically. Finding sex chromosomes in ESD organisms would question whether pure ESD mechanisms exist at all in nature, or whether those systems currently considered pure ESD simply await the characterization of an underlying GSD architecture.

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Section: Resultsmentioning

confidence: 96%

Molecular Cytogenetic Search for Cryptic Sex Chromosomes in Painted Turtles Chrysemys picta

Valenzuela

Badenhorst

Montiel

et al. 2014

Cytogenet Genome Res

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“…The presence of the SRY gene induces the switch for male/female differentiation by activating the SOX9 gene, which is responsible for Sertoli cell differentiation and the development of normal testis architecture (Parma and Radi ). In the absence of SRY , the equivalent gene responsible for XX, testicular DSD has not been found in dogs or several other species.…”

Section: Discussionmentioning

confidence: 99%

First Description of Scrotal Testicles in a Dog Affected by 78, XX Testicular Disorder of Sex Development

Carro

Rosset

Josson-Schramme

et al. 2014

Reprod Domestic Animals

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An eight-month-old female dog presented with ambiguous external genitalia. A thorough clinical examination together with various imaging techniques and a histology examination showed the presence of two testicles linked to both the Mullerian and Wolffian ducts. The discovery of the 78,XX SRY-negative karyotype led to the diagnosis of incoherence between the chromosomal and gonadal sex, which is typical for a 78,XX testicular disorder of sex development. Our case was unique because the testicles were still located in their normal scrotal position, whereas the literature contains reports of the presence of cryptorchid testicles in this karyotype setting. To our knowledge, this is the first case that describes an SRY-negative 78,XX testicular disorder of sex development with bilateral scrotal testicles.

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“…Vertebrate primary sexual development is controlled by a gene network that regulates sex determination (the commitment to the male or female gonadal fate) and sex differentiation (the development of sex-specific cellular and other phenotypes) (Parma and Radi, 2012). Most elements of this gene regulatory network are common to all vertebrates (Morrish and Sinclair, 2002;Place and Lance, 2004;Rhen and Schroeder, 2010).…”

Section: Introductionmentioning

confidence: 99%

Transcriptional evolution underlying vertebrate sexual development

Valenzuela

Neuwald

Literman

2012

Developmental Dynamics

107

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Explaining the diversity of vertebrate sex-determining mechanisms ranging from genotypic (GSD) to temperature-dependent (TSD) remains a developmental and evolutionary conundrum. Using a phylogenetic framework, we explore the transcriptional evolution during gonadogenesis of several genes involved in sexual development, combining novel data from Chrysemys picta turtles (TSD) and published data from other TSD and GSD vertebrates. Our novel C. picta dataset underscores Sf1 and Wt1 as potential activators of the thermosensitive period and uncovered the first evidence of Dax1 involvement in male development in a TSD vertebrate. Contrasting transcriptional profiles revealed male-biased Wt1 expression in fish while monomorphic expression is found in tetrapods but absent in turtles. Sf1 expression appears highly labile with transitions among testicular, ovarian, and non-sex-specific gonadal formation patterns among and within lineages. Dax1's dual role in ovarian and testicular formation is found in fish and mammals but is dosage-sensitive exclusively in eutherian mammals due to its X-linkage in this group. Contrastingly, Sox9 male-biased and Aromatase female-biased expression appear ancestral and virtually conserved throughout vertebrates despite significant heterochronic changes in expression as other elements likely replaced their function in early gonadogenesis. Finally, research avenues are highlighted to further study the evolution of the regulatory network of sexual development. Developmental Dynamics 242:307-319,

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Molecular Mechanisms of Sexual Development

Cited by 22 publications

References 217 publications

Molecular Cytogenetic Search for Cryptic Sex Chromosomes in Painted Turtles <b><i>Chrysemys picta</i></b>

Molecular Cytogenetic Search for Cryptic Sex Chromosomes in Painted Turtles <b><i>Chrysemys picta</i></b>

First Description of Scrotal Testicles in a Dog Affected by 78, XX Testicular Disorder of Sex Development

Transcriptional evolution underlying vertebrate sexual development

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