Dosage compensation

About: Dosage compensation is a research topic. Over the lifetime, 1920 publications have been published within this topic receiving 124589 citations.

Guy1, a Y-linked embryonic signal, regulates dosage compensation in Anopheles stephensi by increasing X gene expression.

Abstract: We previously showed that Guy1, a primary signal expressed from the Y chromosome, is a strong candidate for a male-determining factor that confers female-specific lethality in Anopheles stephensi (Criscione et al., 2016). Here, we present evidence that Guy1 increases X gene expression in Guy1-transgenic females from two independent lines, providing a mechanism underlying the Guy1-conferred female lethality. The median level gene expression (MGE) of X-linked genes is significantly higher than autosomal genes in Guy1-transgenic females while there is no significant difference in MGE between X and autosomal genes in wild-type females. Furthermore, Guy1 significantly upregulates at least 40% of the 996 genes across the X chromosome in transgenic females. Guy1-conferred female-specific lethality is remarkably stable and completely penetrant. These findings indicate that Guy1 regulates dosage compensation in An. stephensi and components of dosage compensation may be explored to develop novel strategies to control mosquito-borne diseases.

Sex-linked isozymes and sex chromosome evolution and inactivation in kangaroos

Abstract: The structural genes for the enzymes glucose-6-phosphate dehydrogenase (G6PD) and phosphoglycerate kinase (PGK A ) are sex-linked in marsupials. This accords with Ohno's thesis of the conservative nature of the X-linkage group in mammals, since those two genes are also sex-linked in Man. The data on the inheritance of isozymic forms of these enzymes and the phenotypes of females heterozygous for them suggest that the cells and tissues of kangaroos may be divided into at least two kinds. One kind, represented by the blood, has dosage compensation achieved by paternal X-inactivation . The other kind, represented by primary uncloned cultures of fibroblasts, may have both chromosomes active though whether within the same cell is not known. The G6PD patterns of heterozygotes seemingly have interaction products, a result which is compatible either with activity of both alleles within the same cell or transfer of gene product between cells within a mixture of cells with contrasting types active. PGK A patterns of lysates of primary uncloned cultures of fibroblasts and also muscle homogenates, both derived from heterozygotes, show expression of both isozymes with the maternally derived one always predominant.

Prenatal diagnosis of a small supernumerary, XIST-negative, mosaic ring X chromosome identified by fluorescence in situ hybridization in an abnormal male fetus

Abstract: Marker or ring X [r(X)] chromosomes of varying size are often found in patients with Turner syndrome. Patients with very small r(X) chromosomes that did not include the X-inactivation locus (XIST) have been described with a more severe phenotype. Small r(X) chromosomes are rare in males and there are only five previous reports of such cases. We report the identification of a small supernumerary X chromosome in an abnormal male fetus. Cytogenetic analysis from chorionic villus sampling was performed because of fetal nuchal translucency thickness and it showed mosaicism 46,XY/47,XY,+r(X)/48,XY,+r(X),+r(X). Fluorescence in situ hybridizations (FISH) showed the marker to be of X-chromosome origin and not to contain the XIST locus. Additional specific probes showed that the r(X) included a euchromatic region in proximal Xq. At 20 weeks gestation, a second ultrasound examination revealed cerebral abnormalities. After genetic counselling, the pregnancy was terminated. The fetus we describe is the first male with a mosaic XIST-negative r(X) chromosome identified at prenatal diagnosis. The phenotype we observed was probably the result of functional disomy of the genes in the r(X) chromosome, secondary to loss of the XIST locus.