Triplo-X hermaphrodite of Caenorhabditis elegans: pachytene karyotype analysis, synaptonemal complexes, and pairing mechanisms

1984 ◽  
Vol 26 (1) ◽  
pp. 13-17 ◽  
Author(s):  
Paul Goldstein
Keyword(s):  
Caenorhabditis Elegans ◽  
Karyotype Analysis ◽  
Real Difference ◽  
X Chromosomes ◽  
Synaptonemal Complexes ◽  
Chromosomal Complement ◽  
Male Line ◽  
Pachytene Karyotype

Pairing of the three X chromosomes in the triplo-X strain of Caenorhabditis elegans occurs at pachytene in a two-by-two fashion such that one bivalent and one univalent are formed. The XX bivalent pairs synchronously with the autosomes and the univalent X remains in a similar chromatic state as the rest of the chromosomal complement. Normal tripartite synaptonemal complexes (SC) are formed between all bivalents. The univalent X lacks a SC and an axial core is not observed. The condensation of the univalent X in the triplo-X is different than in the male where the univalent X is heterochromatic. This real difference in condensation states of the chromatin may explain the fact that the univalent X is maintained in the male line yet it is easily lost in the triplo-X strain.

The synaptonemal complexes of Caenorhabditis elegans: pachytene karyotype analysis of hermaphrodites from the recessive him-5 and him-7 mutants

1986 ◽  
Vol 82 (1) ◽  
pp. 119-127
Author(s):  
P. Goldstein
Keyword(s):  
Caenorhabditis Elegans ◽  
X Chromosome ◽  
High Frequency ◽  
Karyotype Analysis ◽  
Nuclear Morphology ◽  
Group V ◽  
Haploid Chromosome Number ◽  
High Incidence ◽  
Physical Position ◽  
Pachytene Karyotype

The him-5 and him-7 mutants (high incidence of males) of Caenorhabditis elegans both showed increased rates of X chromosome non-disjunction (16% and 3%, respectively) but him-7 also had a high frequency of autosomal non-disjunction (34%). Synaptonemal complex (SC) karyotype analysis revealed a haploid chromosome number of six in each strain. Alterations in him-7 nuclear morphology were observed but there were no aberrations in SC structure that could account for the increased frequency of autosomal non-disjunction. However, the frequency of X-chromosome non-disjunction occurred at predicted rates on the basis of the number of disjunction regulator regions (DRRs) present on the SCs. The observation that the levels of X-chromosome non-disjunction were not influenced by the increase in the frequency of autosomal non-disjunction supports the notion that the X chromosome is subject to separate controls during meiosis. The him-7 mutant is nested within the rad-4 map region on linkage group V, however, SC analysis did not reveal the physical position on the chromosome because of synaptic adjustment.

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

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.

Major sex-determining genes and the control of sexual dimorphism in Caenorhabditis elegans

Genome ◽  
1989 ◽  
Vol 31 (2) ◽  
pp. 625-637 ◽  
Author(s):  
Jonathan Hodgkin ◽  
Andrew D. Chisholm ◽  
Michael M. Shen
Keyword(s):  
Caenorhabditis Elegans ◽  
Sex Determination ◽  
X Chromosome ◽  
Germ Line ◽  
Cell Lineage ◽  
Regulatory Genes ◽  
Nematode Caenorhabditis Elegans ◽  
X Chromosomes ◽  
The Many ◽  
Lineage Analysis

Sex determination in Caenorhabditis elegans involves a cascade of major regulatory genes connecting the primary sex determining signal, X chromosome dosage, to key switch genes, which in turn direct development along either male or female pathways. Animals with one X chromosome (XO) are male, while animals with two X chromosomes (XX) are hermaphrodite: hermaphrodite development occurs because the action of the regulatory genes is modified in the germ line so that both sperm and oocytes are made inside a completely female soma. The regulatory genes are being examined by both genetic and molecular means. We discuss how these major genes, in particular the last switch gene in the cascade, tra-1, might regulate the many different sex-specific events that occur during the development of the hermaphrodite and of the male.Key words: nematode, Caenorhabditis elegans, sex determination, sexual differentiation, cell lineage analysis.

scholarly journals Sex-specific regulation of neuronal functions in Caenorhabditis elegans: the sex-determining protein TRA-1 represses goa-1/Gα(i/o)

2019 ◽  
Vol 295 (2) ◽  
pp. 357-371 ◽  
Author(s):  
Vera Kutnyánszky ◽  
Balázs Hargitai ◽  
Bernadette Hotzi ◽  
Mónika Kosztelnik ◽  
Csaba Ortutay ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Molecular Mechanisms ◽  
Neuronal Development ◽  
Fundamental Problem ◽  
Male Mating ◽  
Coding Region ◽  
X Chromosomes ◽  
Sensory Stimuli ◽  
Specific Regulation ◽  
Neuronal Functions

AbstractFemales and males differ substantially in various neuronal functions in divergent, sexually dimorphic animal species, including humans. Despite its developmental, physiological and medical significance, understanding the molecular mechanisms by which sex-specific differences in the anatomy and operation of the nervous system are established remains a fundamental problem in biology. Here, we show that in Caenorhabditis elegans (nematodes), the global sex-determining factor TRA-1 regulates food leaving (mate searching), male mating and adaptation to odorants in a sex-specific manner by repressing the expression of goa-1 gene, which encodes the Gα(i/o) subunit of heterotrimeric G (guanine–nucleotide binding) proteins triggering physiological responses elicited by diverse neurotransmitters and sensory stimuli. Mutations in tra-1 and goa-1 decouple behavioural patterns from the number of X chromosomes. TRA-1 binds to a conserved binding site located in the goa-1 coding region, and downregulates goa-1 expression in hermaphrodites, particularly during embryogenesis when neuronal development largely occurs. These data suggest that the sex-determination machinery is an important modulator of heterotrimeric G protein-mediated signalling and thereby various neuronal functions in this organism and perhaps in other animal phyla.

scholarly journals The DM Domain Transcription Factor MAB-3 Regulates Male Hypersensitivity to Oxidative Stress in Caenorhabditis elegans

2010 ◽  
Vol 30 (14) ◽  
pp. 3453-3459 ◽  
Author(s):  
Hideki Inoue ◽  
Eisuke Nishida
Keyword(s):  
Oxidative Stress ◽  
Transcription Factor ◽  
Caenorhabditis Elegans ◽  
Sex Determination ◽  
Target Genes ◽  
Stress Sensitivity ◽  
Gata Factor ◽  
X Chromosomes ◽  
C Elegans ◽  
Dm Domain

ABSTRACT Sex differences occur in most species and involve a variety of biological characteristics. The nematode Caenorhabditis elegans consists of two sexes, self-fertile hermaphrodites (XX) and males (XO). Males differ from hermaphrodites in morphology, behavior, and life span. Here, we find that male C. elegans worms are much more sensitive than hermaphrodites to oxidative stress and show that the DM domain transcription factor MAB-3 plays a pivotal role in determining this male hypersensitivity. The hypersensitivity to oxidative stress does not depend on the dosage of X chromosomes but is determined by the somatic sex determination pathway. Our analyses show that the male hypersensitivity is controlled by MAB-3, one of the downstream effectors of the master terminal switch TRA-1 in the sex determination pathway. Moreover, we find that MAB-3 suppresses expression of several transcriptional target genes of the ELT-2 GATA factor, which is a global regulator of transcription in the C. elegans intestine, and show that RNA interference (RNAi) against elt-2 increases sensitivity to oxidative stress. These results strongly suggest that the DM domain protein MAB-3 regulates oxidative stress sensitivity by repressing transcription of ELT-2 target genes in the intestine.

scholarly journals Caenorhabditis elegans Dosage Compensation Regulates Histone H4 Chromatin State on X Chromosomes

2012 ◽  
Vol 32 (9) ◽  
pp. 1710-1719 ◽  
Author(s):  
M. B. Wells ◽  
M. J. Snyder ◽  
L. M. Custer ◽  
G. Csankovszki
Keyword(s):  
Caenorhabditis Elegans ◽  
Dosage Compensation ◽  
Chromatin State ◽  
Histone H4 ◽  
X Chromosomes
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