Late-onset vanishing testis-like syndrome in a 38,XX/38,XY agonadic pig (Sus scrofa)

Here we describe the case of a pig with intersex traits including ambiguous external genitalia, sex chromosome abnormalities and a late-onset vanishing testis-like syndrome. It was identified shortly after birth by presenting a predominantly female phenotype with two large scrotal masses resembling testes. The karyotype is 38,XX (53%)/38,XY (47%). Sex steroid levels were undetectable at 1 and 7 months old, whereas circulating cortisol levels were typical. DNA studies excluded gene alterations in sex-determining region Y (SRY), dosage-sensitive sex reversal-congenital adrenal hypoplasia critical region on the X chromosome protein 1 (DAX1), SRY-related high mobility group-box gene 9 (SOX9), nuclear receptor subfamily 5, group a, member 1 (NR5A1), nuclear receptor subfamily 3, group c, member 4 (NR3C4) and steroid 5-alpha-reductase 2 (SRD5A2). At 8 months of age the XX/XY pig evinced delayed growth; however, the most striking phenotypic change was that the testes-like structures completely vanished in a 2–3-week period. The internal genitalia were found to consist of a portion of a vagina and urethra. No fallopian tubes, uterus or remnants of Wolffian derivatives were observed. More importantly, no testes, ovaries, ovotestis or gonadal streaks could be identified. The XX/XY sex chromosome dosage and/or overexpression of the DAX1 gene on the X chromosome in the presence of a wild-type SRY gene may have caused this predominantly female phenotype. This specimen represents an atypical case of 38,XX/38,XY chimeric, ovotesticular disorder of sex development associated with agonadism.

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Nuclear Receptor Subfamily 0 Group B Member 2

10.32388/ta2n9p ◽

2020 ◽

Author(s):

Keyword(s):

Nuclear Receptor ◽

Group B ◽

Nuclear Receptor Subfamily

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Bisection of the X chromosome disrupts the initiation of chromosome silencing during meiosis in Caenorhabditis elegans

Nature Communications ◽

10.1038/s41467-021-24815-0 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Yisrael Rappaport ◽

Hanna Achache ◽

Roni Falk ◽

Omer Murik ◽

Oren Ram ◽

...

Keyword(s):

Caenorhabditis Elegans ◽

Rna Polymerase Ii ◽

X Chromosome ◽

Sex Chromosomes ◽

Sex Chromosome ◽

Transcription Analysis ◽

X Chromosomes ◽

Unique Character ◽

Active Transcription ◽

Heterogametic Sex

AbstractDuring meiosis, gene expression is silenced in aberrantly unsynapsed chromatin and in heterogametic sex chromosomes. Initiation of sex chromosome silencing is disrupted in meiocytes with sex chromosome-autosome translocations. To determine whether this is due to aberrant synapsis or loss of continuity of sex chromosomes, we engineered Caenorhabditis elegans nematodes with non-translocated, bisected X chromosomes. In early meiocytes of mutant males and hermaphrodites, X segments are enriched with euchromatin assembly markers and active RNA polymerase II staining, indicating active transcription. Analysis of RNA-seq data showed that genes from the X chromosome are upregulated in gonads of mutant worms. Contrary to previous models, which predicted that any unsynapsed chromatin is silenced during meiosis, our data indicate that unsynapsed X segments are transcribed. Therefore, our results suggest that sex chromosome chromatin has a unique character that facilitates its meiotic expression when its continuity is lost, regardless of whether or not it is synapsed.

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Deficit of Mitonuclear Genes on the Human X Chromosome Predates Sex Chromosome Formation

Genome Biology and Evolution ◽

10.1093/gbe/evv017 ◽

2015 ◽

Vol 7 (2) ◽

pp. 636-641 ◽

Cited By ~ 4

Author(s):

Rebecca Dean ◽

Fabian Zimmer ◽

Judith E. Mank

Keyword(s):

X Chromosome ◽

Sex Chromosome ◽

Chromosome Formation

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Absence of X-chromosome dosage compensation in the primordial germ cells of Drosophila embryos

Scientific Reports ◽

10.1038/s41598-021-84402-7 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Ryoma Ota ◽

Makoto Hayashi ◽

Shumpei Morita ◽

Hiroki Miura ◽

Satoru Kobayashi

Keyword(s):

X Chromosome ◽

Germ Cells ◽

Dosage Compensation ◽

Sex Chromosome ◽

Primordial Germ Cells ◽

Histone H4 ◽

X Chromosomes ◽

Essential Components ◽

Msl Complex ◽

Male Specific

AbstractDosage compensation is a mechanism that equalizes sex chromosome gene expression between the sexes. In Drosophila, individuals with two X chromosomes (XX) become female, whereas males have one X chromosome (XY). In males, dosage compensation of the X chromosome in the soma is achieved by five proteins and two non-coding RNAs, which assemble into the male-specific lethal (MSL) complex to upregulate X-linked genes twofold. By contrast, it remains unclear whether dosage compensation occurs in the germline. To address this issue, we performed transcriptome analysis of male and female primordial germ cells (PGCs). We found that the expression levels of X-linked genes were approximately twofold higher in female PGCs than in male PGCs. Acetylation of lysine residue 16 on histone H4 (H4K16ac), which is catalyzed by the MSL complex, was undetectable in these cells. In male PGCs, hyperactivation of X-linked genes and H4K16ac were induced by overexpression of the essential components of the MSL complex, which were expressed at very low levels in PGCs. Together, these findings indicate that failure of MSL complex formation results in the absence of X-chromosome dosage compensation in male PGCs.

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X-Linked Signature of Reproductive Isolation in Humans is Mirrored in a Howler Monkey Hybrid Zone

Journal of Heredity ◽

10.1093/jhered/esaa021 ◽

2020 ◽

Vol 111 (5) ◽

pp. 419-428 ◽

Cited By ~ 1

Author(s):

Marcella D Baiz ◽

Priscilla K Tucker ◽

Jacob L Mueller ◽

Liliana Cortés-Ortiz

Keyword(s):

Reproductive Isolation ◽

X Chromosome ◽

Hybrid Zone ◽

Sex Chromosome ◽

Genomic Sequence ◽

Alouatta Palliata ◽

Model Systems ◽

Howler Monkey ◽

Autosomal Snps ◽

Outlier Region

Abstract Reproductive isolation is a fundamental step in speciation. While sex chromosomes have been linked to reproductive isolation in many model systems, including hominids, genetic studies of the contribution of sex chromosome loci to speciation for natural populations are relatively sparse. Natural hybrid zones can help identify genomic regions contributing to reproductive isolation, like hybrid incompatibility loci, since these regions exhibit reduced introgression between parental species. Here, we use a primate hybrid zone (Alouatta palliata × Alouatta pigra) to test for reduced introgression of X-linked SNPs compared to autosomal SNPs. To identify X-linked sequence in A. palliata, we used a sex-biased mapping approach with whole-genome re-sequencing data. We then used genomic cline analysis with reduced-representation sequence data for parental A. palliata and A. pigra individuals and hybrids (n = 88) to identify regions with non-neutral introgression. We identified ~26 Mb of non-repetitive, putatively X-linked genomic sequence in A. palliata, most of which mapped collinearly to the marmoset and human X chromosomes. We found that X-linked SNPs had reduced introgression and an excess of ancestry from A. palliata as compared to autosomal SNPs. One outlier region with reduced introgression overlaps a previously described “desert” of archaic hominin ancestry on the human X chromosome. These results are consistent with a large role for the X chromosome in speciation across animal taxa and further, suggest shared features in the genomic basis of the evolution of reproductive isolation in primates.

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Sperm Competition and the Dynamics of X Chromosome Drive: Stability and Extinction

Genetics ◽

10.1093/genetics/160.4.1721 ◽

2002 ◽

Vol 160 (4) ◽

pp. 1721-1731 ◽

Cited By ~ 1

Author(s):

Jesse E Taylor ◽

John Jaenike

Keyword(s):

Sex Ratio ◽

Sperm Competition ◽

X Chromosome ◽

Sex Chromosome ◽

Basin Of Attraction ◽

Male Mating ◽

Male And Female ◽

Mating Rate ◽

Female Mating ◽

Balanced Polymorphism

AbstractSeveral empirical studies of sperm competition in populations polymorphic for a driving X chromosome have revealed that Sex-ratio males (those carrying a driving X) are at a disadvantage relative to Standard males. Because the frequency of the driving X chromosome determines the population-level sex ratio and thus alters male and female mating rates, the evolutionary consequences of sperm competition for sex chromosome meiotic drive are subtle. As the SR allele increases in frequency, the ratio of females to males also increases, causing an increase in the male mating rate and a decrease in the female mating rate. While the former change may exacerbate the disadvantage of Sex-ratio males during sperm competition, the latter change decreases the incidence of sperm competition within the population. We analyze a model of the effects of sperm competition on a driving X chromosome and show that these opposing trends in male and female mating rates can result in two coexisting locally stable equilibria, one corresponding to a balanced polymorphism of the SR and ST alleles and the second to fixation of the ST allele. Stochastic fluctuations of either the population sex ratio or the SR frequency can then drive the population away from the balanced polymorphism and into the basin of attraction for the second equilibrium, resulting in fixation of the SR allele and extinction of the population.

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