The Behavior of the XY Pair in Mammals

Solari, Alberto J.

doi:10.1016/s0074-7696(08)60928-6

Cited by 302 publications

(217 citation statements)

References 114 publications

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“…Although it is not known which factors promote the association of SYCP1 with these unsynapsed regions, it is likely that, in the thickened AEs of sex chromosomes, SYCP2 and SYCP3 form a structural framework for the deposition of SYCP1. This could be the case of the regions where AEs split into several filaments, a feature described for both sex and autosomal chromosomes (Solari 1974;del Mazo and Gil-Alberdi 1986;Dietrich et al 1992). Thus, sex chromosomal AEs show particular structure and peculiar protein composition.…”

Section: Sex Chromosomal Aes Are Highly Modified In Eutherian Mammalsmentioning

confidence: 96%

“…In this sense, it is important to take into account the special behavior of sex chromosomes as regards their chromatin condensation and inactivation, which gives rise to sex chromosomes as a compacted chromatin domain, i.e., the sex body (Solari 1974;McKee and Handel 1993). Perhaps some of the many proteins that associate to the sex chromosomes during the first meiotic prophase (review by Hoyer-Fender 2003;Handel 2004) may induce a specific and differential conformation of the sex chromatin, which could have an influence on the axial organization of these chromosomes.…”

Section: The Overcrowded Axes Of Eutherian Sex Chromosomes and Sex Chmentioning

confidence: 99%

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Sex chromosomes, synapsis, and cohesins: a complex affair

et al. 2006

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During first meiotic prophase, homologous chromosomes are held together by the synaptonemal complex, a tripartite proteinaceous structure that extends along the entire length of meiotic bivalents. While this feature is applicable for autosomes, sex chromosomes often escape from this rule. Many species present sex chromosomes that differ between them in their morphology, length, and gene content. Moreover, in some species, sex chromosomes appear in a single dose in one of the sexes. In all of these cases, the behavior of sex chromosomes during meiosis is conspicuously affected, and this includes the assembly and dynamics of the synaptonemal complex. We review in this study the structure of the synaptonemal complex in the sex chromosomes of three groups of organisms, namely: mammals, orthopterans, and hemipterans, which present different patterns of sex chromosome structure and behavior. Of special interest is the analysis of the organization of the axial/lateral elements of the synaptonemal complex in relation to other axial structures organized along meiotic chromosomes, mainly the cohesin axis. The differences found in the behavior of both axial structures reveal that while the organization of a cohesin axis along sex chromosomes is a conserved feature in most organisms and it shows very little morphological variations, the axial/lateral elements of the synaptonemal complex present a wide range of structural modifications on these chromosomes.

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Section: Sex Chromosomal Aes Are Highly Modified In Eutherian Mammalsmentioning

confidence: 96%

Section: The Overcrowded Axes Of Eutherian Sex Chromosomes and Sex Chmentioning

confidence: 99%

Sex chromosomes, synapsis, and cohesins: a complex affair

et al. 2006

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“…The accumulation of both male-and female-biased genes on the X chromosome is consistent with the predictions of W. Rice 3 and previous reports on mice and humans [6][7][8] . We believe that the paucity of testis-enriched genes on the mouse X is mainly attributable to the effects of MSCI 19,20 . The under-representation of male-biased genes on the mouse X chromosome is similar to that reported for male-specific genes in Drosophila melanogaster and Caenorhabditis elegans 9,10 , where (in C. elegans, at least) MSCI is present 25,26 .…”

mentioning

confidence: 96%

“…3a) 17,18 . Sex chromosomes are condensed and transcriptionally repressed at the onset of male meiosis (meiotic sex chromosome inactivation, MSCI) [19][20][21] . To elucidate the effect of MSCI on the genomic distribution of male-biased genes, we analyzed the transcripts of testes from Spo11 -/-mice which have a genetic ablation of cells past the early stages of spermatogenesis.…”

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confidence: 99%

The mouse X chromosome is enriched for sex-biased genes not subject to selection by meiotic sex chromosome inactivation

et al. 2004

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Sex chromosomes are subject to sex-specific selective evolutionary forces 1,2 . One model predicts that genes with sexbiased expression should be enriched on the X chromosome 2-5 . In agreement with Rice's hypothesis 3 , spermatogonial genes are over-represented on the X chromosome of mice 6 and sex-and reproduction-related genes are over-represented on the human X chromosome 7,8 . Male-biased genes are under-represented on the X chromosome in worms and flies 9-11 , however. Here we show that mouse spermatogenesis genes are relatively underrepresented on the X chromosome and female-biased genes are enriched on it. We used Spo11 -/-mice blocked in spermatogenesis early in meiosis 12 to evaluate the temporal pattern of gene expression in sperm development. Genes expressed before the Spo11 block are enriched on the X chromosome, whereas those expressed later in spermatogenesis are depleted. Inactivation of the X chromosome in male meiosis may be a universal driving force for X-chromosome demasculinization.To investigate the genomic distribution of mouse genes with patterns of sex-biased expression, we analyzed the chromosomal distribution of genes expressed in sexually dimorphic tissues. We consider genes that are preferentially expressed in such tissues as testis, ovary and placenta to be sex-biased genes. We used two approaches to define the tissue specificity of genes expressed in mice: analysis of large-scale microarray-based gene expression data and analysis of the distribution of expressed-sequence tags (ESTs) in different cDNA libraries. Instead of focusing on transcripts restricted to a single tissue, our analysis targeted the identification of tissue-enriched transcripts using a 'preferential expression measure' (PEM) 13 . As an uniform source of expression data, we used publicly available data sets of mouse RNA samples representing 49 tissues hybridized to Affymetrix mouse U74A microarrays (GNF data set) 14 and 20 tissues analyzed with RIKEN cDNA microarrays (RIKEN data set) 15 .In the GNF data set 14 , expression of 624 genes (∼7% of all analyzed) in testis was three times greater than the median expression in other tissues, and expression of 361 genes in testis was five times greater (PEM values >1.58 and >2.32, respectively). These genes are considered testis-enriched genes. The chromosomal distribution of testisenriched genes was significantly different from uniform (χ 2 = 30.8, P = 0.05; Fig. 1a and Supplementary Table 1 online). The most significant deviation from the average gene density was on the X chromosome, where testis-enriched genes were 2.5 times less dense (the ratio of the density of testis-enriched genes on the X chromosome to the average density on all chromosomes, ρ X , was 0.40; χ 2 = 7.7, P = 0.006). The depletion of testis-enriched genes on the X chromosome was independent of the cut-off (three or five times greater expression) used in the selection process (Table 1). In addition, genes that were expressed most highly in testis and all the genes detected in testis were underrepresen...

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“…In particular, during meiosis of mammalian spermatogenesis, the sex chromosomes undergo meiotic sex chromosome inactivation (MSCI), while autosomes remain transcriptionally active (Solari 1974, Handel et al 1994). MSCI appears to be part of a common process that silences unsynapsed chromatin during the pachytene stage of meiosis I, a phenomenon termed MSUC (meiotic silencing of unsynapsed chromatin) (Baarends et al 2005, Turner et al 2005.…”

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confidence: 99%

The role of spermatogonially expressed germ cell-specific genes in mammalian meiosis

Wang

Pan

2007

Chromosome Res

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Meiosis, a hallmark of sexual reproduction, reduces the chromatin complement by half to cope with genome doubling at fertilization and permits exchange of genetic material between parental genomes. Recent functional studies of novel proteins have greatly enhanced our understanding of the regulation of meiosis. The unique status of sex chromosomes in the male germ line may have shaped their content of germ line-intrinsic genes during evolution. Previously, a unique set of 36 spermatogonially expressed, mouse germ cell-specific genes was identified in one genomic screen. Thirteen of these genes have been disrupted in mice and two-thirds of these mouse mutants exhibit meiotic defects. Therefore, we hypothesize that the majority of uncharacterized germ cellspecific genes identified in the same screen, including 11 X-linked genes, might also play important roles in meiosis. In particular, we cite previously unpublished studies demonstrating that the NXF2 protein, an X-encoded factor, is present in early spermatocytes.

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The Behavior of the XY Pair in Mammals

Cited by 302 publications

References 114 publications

Sex chromosomes, synapsis, and cohesins: a complex affair

Sex chromosomes, synapsis, and cohesins: a complex affair

The mouse X chromosome is enriched for sex-biased genes not subject to selection by meiotic sex chromosome inactivation

The role of spermatogonially expressed germ cell-specific genes in mammalian meiosis

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