Differential expression of the MHM region and of sex-determining-related genes during gonadal development in chicken embryos

Caetano, Leony Cristina; Gennaro, F. G. O.; Coelho, Kunie Iabuki Rabello; Araújo, Flávio Marcos Gomes; Vila, Reginaldo Aparecido; Araújo, Aderson S; Bernardo, Ana de Melo; Marcondes, C. R.; Lopes, Susana M. Chuva de Sousa; Ramos, Ester Silveira

doi:10.4238/2014.february.13.2

Cited by 21 publications

(18 citation statements)

References 34 publications

(40 reference statements)

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“…In a recent study of brazilian geneticists that used variant of RT-PCR was shown that the largest transcription of MHM for the analyzed period of incubation (4 -14 days) is detected at 8 and 14. The males in the absence of transcription of this gene show an intense activity of DMRT1 [38]. Results of work once again confirm the participation of RNA MHM in differential regulation of male and female alleles of DMRT1 gene.…”

Section: Sexual Differentiation In Birdssupporting

confidence: 70%

Problems of Birds Sex Determination

Trukhina¹,

Smirnov²

2014

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Sex determination system in birds is characterized by a homo-(Neognatae) and heteromorphic (Paleognatae) sex chromosomes. Heterogametic sex is female (ZZ/ZW system). DMRT1 gene is a gene regarded as a main male sex determining factor in this group of animals. The question remains about the participation of other factors (HEMOGEN, AMH etc.) in appearance of testis, and the role of steroid hormones in formation of ovaries. Complete sex inversion is not typical for species with genotypic sex determination (GSD), although the effect of estrogen metabolites is noted for birds. For birds epigenetic mechanisms of regulation (methylation of DNA and non-coding RNA) have been described for sex controlling genes such as CYP19A1 and DMRT1.

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Section: Sexual Differentiation In Birdssupporting

confidence: 70%

Problems of Birds Sex Determination

Trukhina¹,

Smirnov²

2014

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“…Sharing an overall identity of 67% at the amino acid level and up to 90% identity when specifically considering the HMG DNA‐binding domain, the X‐chromosomal SOX3 ‐encoded protein is most similar to SRY . Consistent with this hypothesis, the expression of SOX3 has been documented in the developing gonads of mice, chicken , fish , and frog . Only the absence of SOX3 expression in the developing marsupial gonad is not consistent with a conserved role in mammalian sex determination .…”

Section: Master Sex‐determining Genes: Case Studies From Sox and Dm Dmentioning

confidence: 95%

Plasticity of gene‐regulatory networks controlling sex determination: of masters, slaves, usual suspects, newcomers, and usurpators

2015

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Sexual dimorphism is one of the most pervasive and diverse features of animal morphology, physiology, and behavior. Despite the generality of the phenomenon itself, the mechanisms controlling how sex is determined differ considerably among various organismic groups, have evolved repeatedly and independently, and the underlying molecular pathways can change quickly during evolution. Even within closely related groups of organisms for which the development of gonads on the morphological, histological, and cell biological level is undistinguishable, the molecular control and the regulation of the factors involved in sex determination and gonad differentiation can be substantially different. The biological meaning of the high molecular plasticity of an otherwise common developmental program is unknown. While comparative studies suggest that the downstream effectors of sexdetermining pathways tend to be more stable than the triggering mechanisms at the top, it is still unclear how conserved the downstream networks are and how all components work together. After many years of stasis, when the molecular basis of sex determination was amenable only in the few classical model organisms (fly, worm, mouse), recently, sex-determining genes from several animal species have been identified and new studies have elucidated some novel regulatory interactions and biological functions of the downstream network, particularly in vertebrates. These data have considerably changed our classical perception of a simple linear developmental cascade that makes the decision for the embryo to develop as male or female, and how it evolves.

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“…Given that it is situated within the oldest portion of the avian sex chromosomes (Zhou et al 2014), it may be that selection for dosage compensation has simply had longer to act on this region, in a similar way to the more complete dosage compensation on the older regions of the therian X chromosome (Carrel and Willard 2005). In contrast, on the basis of coexpression patterns, others have suggested that the MHM locus is a regulator of DMRT1 (Yang et al 2010b;Caetano et al 2014), the major avian sex-determining gene (Smith et al 2009), which is located nearby on the Z chromosome. Therefore, the distinct sex-specific regulatory pattern of genes in this region instead may reflect an important role in sex-specific fitness and sexual differentiation.…”

mentioning

confidence: 93%

Conservation of Regional Variation in Sex-Specific Sex Chromosome Regulation

Wright

Zimmer²,

Harrison³

et al. 2015

Genetics

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Regional variation in sex-specific gene regulation has been observed across sex chromosomes in a range of animals and is often a function of sex chromosome age. The avian Z chromosome exhibits substantial regional variation in sex-specific regulation, where older regions show elevated levels of male-biased expression. Distinct sex-specific regulation also has been observed across the male hypermethylated (MHM) region, which has been suggested to be a region of nascent dosage compensation. Intriguingly, MHM region regulatory features have not been observed in distantly related avian species despite the hypothesis that it is situated within the oldest region of the avian Z chromosome and is therefore orthologous across most birds. This situation contrasts with the conservation of other aspects of regional variation in gene expression observed on the avian sex chromosomes but could be the result of sampling bias. We sampled taxa across the Galloanserae, an avian clade spanning 90 million years, to test whether regional variation in sexspecific gene regulation across the Z chromosome is conserved. We show that the MHM region is conserved across a large portion of the avian phylogeny, together with other sex-specific regulatory features of the avian Z chromosome. Our results from multiple lines of evidence suggest that the sex-specific expression pattern of the MHM region is not consistent with nascent dosage compensation.KEYWORDS sex-biased gene expression; male hypermethylated region S EX chromosomes exhibit extensive sex-specific gene regulation in many animals, largely resulting from two independent forces. First, the reduced gene content on the sex-limited Y or W chromosome observed in many species (Bachtrog 2013) leads to a reduction in gene dose in the heterogametic sex for X-or Z-linked genes. Because gene expression is often a function of gene dose, this dosage effect (Zhang et al. 2013) means that many X-or Z-linked loci show differences in gene expression between males and females. Variation in gene dose is often thought to be detrimental, and different mechanisms of dosage compensation have evolved to address the differences in sex chromosome dose in some organisms (Mank 2013). Dosage compensation mechanisms in several organisms show extensive regional variation, with some regions exhibiting less complete compensation than other regions on the therian (Carrel and Willard 2005) and stickleback (Schultheiß et al. 2015) X chromosomes.Second, independent of gene dose differences, sex chromosomes are also inherited unequally between the sexes, leading to distinct evolutionary forces relative to the autosomes (Rice 1984;Charlesworth et al. 1987). In particular, conflicting selection on males and females results in unequal sex-specific selection pressures acting on the sex chromosomes. This, in turn, influences rates of sequence and expression evolution (Vicoso and Charlesworth 2009;Meisel and Connallon 2013). Older sex chromosome regions, where recombination between the Z-W orthologs was halted earlier...

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Differential expression of the MHM region and of sex-determining-related genes during gonadal development in chicken embryos

Cited by 21 publications

References 34 publications

Problems of Birds Sex Determination

Problems of Birds Sex Determination

Plasticity of gene‐regulatory networks controlling sex determination: of masters, slaves, usual suspects, newcomers, and usurpators

Conservation of Regional Variation in Sex-Specific Sex Chromosome Regulation

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