scholarly journals Non-canonical Drosophila X chromosome dosage compensation and repressive topologically-associated domains

2018 ◽  
Author(s):  
Hangnoh Lee ◽  
Brian Oliver
Keyword(s):  
Dosage Compensation ◽  
Sex Chromosomes ◽  
Nuclear Lamina ◽  
Dosage Compensation Complex ◽  
Linked Gene ◽  
Chromatin States ◽  
C Elegans ◽  
Repressive Chromatin ◽  
Topologically Associated Domains ◽  
The Impact

AbstractBackgroundIn animals with XY sex chromosomes, X-linked genes from a single X chromosome in males are imbalanced relative to autosomal genes. To minimize the impact of genic imbalance in male Drosophila, there is a dosage compensation complex (MSL), that equilibrates X-linked gene expression with the autosomes. There are other potential contributions to dosage compensation. Hemizygous autosomal genes located in repressive chromatin domains are often de-repressed. If this homolog-dependent repression occurs on the X, which has no pairing partner, then de-repression could contribute to male dosage compensation.ResultsWe asked whether different chromatin states or topological associations correlate with X chromosome dosage compensation, especially in regions with little MSL occupancy. Our analyses demonstrated that male X chromosome genes that are located in repressive chromatin states are depleted of MSL occupancy, however they show dosage compensation. The genes in these repressive regions were also less sensitive to knockdown of MSL components.ConclusionsOur results suggest that this non-canonical dosage compensation is due to the same trans-acting de-repression that occurs on autosomes. This mechanism would facilitate immediate compensation during the evolution of sex chromosomes from autosomes. This mechanism is similar to that of C. elegans, where enhanced recruitment of X chromosomes to the nuclear lamina dampens X chromosome expression as part of the dosage compensation response in XX individuals.

scholarly journals Finding a Balance: How Diverse Dosage Compensation Strategies Modify Histone H4 to Regulate Transcription

2012 ◽  
Vol 2012 ◽  
pp. 1-12
Author(s):  
Michael B. Wells ◽  
Györgyi Csankovszki ◽  
Laura M. Custer
Keyword(s):  
Gene Expression ◽  
Dosage Compensation ◽  
Sex Chromosomes ◽  
Sex Chromosome ◽  
Current Understanding ◽  
Histone H4 ◽  
Linked Gene ◽  
Expression Levels ◽  
Gene Expression Levels

Dosage compensation balances gene expression levels between the sex chromosomes and autosomes and sex-chromosome-linked gene expression levels between the sexes. Different dosage compensation strategies evolved in different lineages, but all involve changes in chromatin. This paper discusses our current understanding of how modifications of the histone H4 tail, particularly changes in levels of H4 lysine 16 acetylation and H4 lysine 20 methylation, can be used in different contexts to either modulate gene expression levels twofold or to completely inhibit transcription.

scholarly journals Sex-linked gene expression and the reversion to hermaphroditism in Carica papaya L. (Caricaceae)

2020 ◽  
Author(s):  
T Chae ◽  
A Harkess ◽  
RC Moore
Keyword(s):  
Gene Expression ◽  
Y Chromosome ◽  
Dosage Compensation ◽  
Sex Chromosomes ◽  
Carica Papaya ◽  
Developmental Stages ◽  
Potential Candidate ◽  
Linked Gene ◽  
Potential Candidate Gene ◽  
Pseudoautosomal Regions

ABSTRACTOne evolutionary path from hermaphroditism to dioecy is via a gynodioecious intermediate. The evolution of dioecy may also coincide with the formation of sex chromosomes that possess sex-determining loci that are physically linked in a region of suppressed recombination. Dioecious papaya (Carica papaya) has an XY chromosome system, where the presence of a Y chromosome determines males. However, in cultivation, papaya is gynodioecious, due to the conversion of the male Y chromosome to a hermaphroditic Yh chromosome during its domestication. We investigated gene expression linked to the X, Y, and Yh chromosomes at different floral developmental stages in order to identify differentially expressed genes (DEGs) that may be involved in the sexual reversion of males to hermaphrodites. We identified 309 sex-biased genes found on the sex chromosomes, most of which are found in the pseudoautosomal regions (PARs). Female (XX) expression in the sex determining region (SDR) was almost double that of X-linked expression in males (XY) and hermaphrodites (XYh), which rules out dosage compensation for most sex-linked gene; although, an analysis of hemizygous X-linked loci found evidence of partial dosage compensation. Furthermore, we identified a potential candidate gene associated with both sex determination and the transition to hermaphroditism, a homolog of the MADS-box protein SHORT VEGETATIVE PHASE (SVG).

scholarly journals Two Classes of Dosage Compensation Complex Binding Elements along Caenorhabditis elegans X Chromosomes

2009 ◽  
Vol 29 (8) ◽  
pp. 2023-2031 ◽  
Author(s):  
Timothy A. Blauwkamp ◽  
Gyorgyi Csankovszki
Keyword(s):  
Caenorhabditis Elegans ◽  
X Chromosome ◽  
Dosage Compensation ◽  
Gene Products ◽  
Dosage Compensation Complex ◽  
X Chromosomes ◽  
Linked Gene ◽  
Unknown Mechanism

ABSTRACT Dosage compensation equalizes X-linked gene products between the sexes. In Caenorhabditis elegans, the dosage compensation complex (DCC) binds both X chromosomes in XX animals and halves the transcription from each. The DCC is recruited to the X chromosomes by a number of loci, rex sites, and is thought to spread from these sites by an unknown mechanism to cover the rest of the chromosome. Here we describe a novel class of DCC-binding elements that we propose serve as “way stations” for DCC binding and spreading. Both rex sites and way stations comprise strong foci of DCC binding on the native X chromosome. However, rex sites maintain their ability to bind large amounts of DCC even on X duplications detached from the native X, while way stations do not. These results suggest that two distinct classes of DCC-binding elements facilitate recruitment and spreading of the DCC along the X chromosome.

scholarly journals The role of sdc-1 in the sex determination and dosage compensation decisions in Caenorhabditis elegans.

Genetics ◽  
1990 ◽  
Vol 124 (1) ◽  
pp. 91-114 ◽  
Author(s):  
A M Villeneuve ◽  
B J Meyer
Keyword(s):  
Caenorhabditis Elegans ◽  
Sex Determination ◽  
Dosage Compensation ◽  
Temperature Shift ◽  
Linked Gene ◽  
C Elegans ◽  
Genetic Mosaic ◽  
Morphological Defects ◽  
Gene Transcripts ◽  
The One

Abstract Our previous work demonstrated that mutations in the X-linked gene sdc-1 disrupt both sex determination and dosage compensation in Caenorhabditis elegans XX animals, suggesting that sdc-1 acts at a step that is shared by the sex determination and dosage compensation pathways prior to their divergence. In this report, we extend our understanding of early events in C. elegans sex determination and dosage compensation and the role played by sdc-1 in these processes. First, our analysis of 14 new sdc-1 alleles suggests that the phenotypes resulting from the lack of sdc-1 function are (1) an incompletely penetrant sexual transformation of XX animals toward the male fate, and (2) increased levels of X-linked gene transcripts in XX animals, correlated with XX-specific morphological defects but not significant XX-specific lethality. Further, all alleles exhibit strong maternal rescue for all phenotypes assayed. Second, temperature-shift experiments suggest that sdc-1 acts during the first half of embryogenesis in determining somatic sexual phenotype, long before sexual differentiation actually takes place, and consistent with our previous proposal that sdc-1 acts at an early step in the regulatory hierarchy controlling the choice of sexual fate. Other temperature-shift experiments suggest that sdc-1 may be involved in establishing but not maintaining the XX mode of dosage compensation. Third, a genetic mosaic analysis of sdc-1 produced an unusual result: the genotypic mosaics failed to display the sdc-1 sexual transformation phenotypes. This result suggests several possible interpretations: (1) sdc-1 is expressed immediately, in the one- or two-celled embryo; (2) sdc-1 acts non-cell-autonomously, such that expression of the gene in either the AB or P1 lineage can supply sdc-1(+) function to cells of the other lineage; (3) the X/A ratio is assessed immediately, in the one- or two-celled embryo; or (4) the X/A signal directs the choice of sexual fate in a non-cell-autonomous fashion. Finally, examination of the classes of sexual phenotypes produced in sdc-1 mutant strains suggests that different cells in the organism may not choose their sexual fates independently.

scholarly journals Dosage compensation in Bombyx mori is achieved by partial repression of both Z chromosomes in males

2021 ◽  
Author(s):  
Leah F. Rosin ◽  
Yang Chen ◽  
Elissa P Lei
Keyword(s):  
Gene Expression ◽  
Bombyx Mori ◽  
Dosage Compensation ◽  
Sex Chromosome ◽  
Linked Gene ◽  
C Elegans ◽  
Males And Females ◽  
Function Relationship ◽  
Relationship Of ◽  
First Time

Interphase chromatin is organized precisely to facilitate accurate gene expression. The structure-function relationship of chromatin is epitomized in sex chromosome dosage compensation (DC), where sex-linked gene expression is balanced between males and females via sex-specific alterations to 3D chromosome structure. Studies in ZW-bearing species suggest that DC is absent or incomplete in most lineages except butterflies and moths, where male (ZZ) chZ expression is reduced by half to equal females (ZW). However, whether one chZ is inactivated (as in mammals) or both are partially repressed (as in C. elegans) is unknown. Using Oligopaints in the silkworm, Bombyx mori, we visualize autosome and chZ organization in somatic cells from both sexes for the first time. We find that B. mori interphase chromosomes are highly compact relative to Drosophila chromosomes. Importantly, we show that in B. mori males, both chZs are similar in size and shape and are more compact than autosomes or the female chZ after DC establishment, suggesting that both male chZs are partially and equally downregulated. We also find that in the early stages of DC, the female chZ repositions toward the nuclear center concomitant with increased Z-linked gene expression, revealing the first non-sequencing-based support for Ohno's hypothesis. These studies represent the first visualization of interphase genome organization and chZ structure in Lepidoptera. We uncover striking similarities between DC in B. mori and C. elegans, despite these lineages harboring evolutionarily distinct sex chromosomes (ZW/XY), suggesting convergent evolution of DC mechanisms and a possible role for holocentricity in DC evolution.

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