Semiquantitative analysis of X-linked gene expression during spermatogenesis in the mouse: Ethidium-bromide staining of RT-PCR products

McCarrey, John R.; Dilworth, Donald D.; Sharp, R. Mark

doi:10.1016/1050-3862(92)90051-6

Cited by 50 publications

(34 citation statements)

References 18 publications

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“…Silencing of the sex chromosomes during male meiosis (MSCI) has been recognized for a long time (Monesi 1965;Lifschytz and Lindsley 1972;McCarrey et al 1992). However, recent studies have uncovered significant differences between MSCI and somatic X inactivation established in the embryo.…”

Section: Sex Chromosome Inactivation In Spermatogenesismentioning

confidence: 99%

See 1 more Smart Citation

Dosage compensation in mammals: fine-tuning the expression of the X chromosome

Heard¹,

Distèche²

2006

Genes Dev.

459

390

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Mammalian females have two X chromosomes and males have only one. This has led to the evolution of special mechanisms of dosage compensation. The inactivation of one X chromosome in females equalizes gene expression between the sexes. This process of X-chromosome inactivation (XCI) is a remarkable example of longrange, monoallelic gene silencing and facultative heterochromatin formation, and the questions surrounding it have fascinated biologists for decades. How does the inactivation of more than a thousand genes on one X chromosome take place while the other X chromosome, present in the same nucleus, remains genetically active? What are the underlying mechanisms that trigger the initial differential treatment of the two X chromosomes? How is this differential treatment maintained once it has been established, and how are some genes able to escape the process? Does the mechanism of X inactivation vary between species and even between lineages? In this review, X inactivation is considered in evolutionary terms, and we discuss recent insights into the epigenetic changes and developmental timing of this process. We also review the discovery and possible implications of a second form of dosage compensation in mammals that deals with the unique, potentially haploinsufficient, status of the X chromosome with respect to autosomal gene expression.In mammals, dosage compensation for X-linked gene products between XX and XY individuals is achieved by silencing one of the two X chromosomes in female cells (Lyon 1961). A second form of dosage compensation maintains a balanced expression between X-linked and autosomal genes by doubling the transcriptional output of the active X. These distinctive regulatory processes derive from the unique evolution of the sex chromosomes. In eutherians, X-chromosome inactivation (XCI) affects the paternal or maternal X chromosome randomly during early development, and the inactive state is then stably inherited, giving rise to adults that are mosaics for two cell types, expressing one or the other X chromosome. The initiation of X inactivation is controlled by the X-inactivation center (Xic), which produces the noncoding Xist transcript responsible for triggering silencing in cis. In marsupials and in the extraembryonic tissues of some placental mammals such as rodents, XCI is imprinted, with the paternal X chromosome (Xp) being inactivated. Imprinted XCI has been proposed to represent the ancestral form of X inactivation. Furthermore, it has been proposed that imprinted XCI may have arisen as a carryover effect from meiotic sex chromosome inactivation (MSCI) in the male germline, a process found in several species that results in silencing of the X and Y chromosomes. We discuss data suggesting that in mice, MSCI may not be essential for imprinted Xp inactivation, raising the possibility that imprinted XCI may have arisen more than once during evolution. We also discuss new insights into the phenomenon of escape from XCI. Although XCI affects most of the X chromosome, several X-linked gene...

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Section: Sex Chromosome Inactivation In Spermatogenesismentioning

confidence: 99%

“…Unpaired autosomes are subject to the same chromatin modifications. (McCarrey et al 1992;Khalil et al 2004). However, recent studies suggest that the X and Y chromosomes do retain some heterochromatic marks acquired during meiotic inactivation (Namekawa et al 2006;Turner et al 2006).…”

Section: Sex Chromosome Inactivation In Spermatogenesismentioning

confidence: 99%

Dosage compensation in mammals: fine-tuning the expression of the X chromosome

Heard¹,

Distèche²

2006

Genes Dev.

459

390

View full text Add to dashboard Cite

show abstract

“…During meiotic sex chromosome inactivation (MSCI) in the paternal germ line, the synapsed X and Y chromosomes become transcriptionally silenced at the pachytene stage of prophase I (Lifschytz and Lindsley 1972). Analyses of a limited number of X-linked genes have shown that Pgk1, Pdha1, Hprt, Zfx, Phka1, and G6pd all remain silent in the postmeiotic sperm (Singer-Sam et al 1990;McCarrey et al 1992aMcCarrey et al , 2000Hendriksen et al 1997). Nonetheless, some genes are clearly reexpressed in postmeiotic sperm (Hendriksen et al 1995), a fact that has been used as a counterargument to the preinactivation hypothesis (Heard 2004).…”

Section: Preinactivation Versus De Novo X-inactivationmentioning

confidence: 99%

A Continuity of X-Chromosome Silence from Gamete to Zygote

Huynh¹,

Lee²

2004

Cold Spring Harbor Symposia on Quantitative Biology

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“…Early cytological studies found that the X and Y chromosomes are heterochromatic from as early as meiotic S-phase (Odartchenko and Pavillard 1970) and semiquantitative RTPCR experiments concluded that repression of specific X-linked genes initiated in leptotene and/or zygotene (Singer-Sam et al 1990;McCarrey et al 1992). Analyzing gene expression during these very early meiotic stages is inherently difficult because transcription levels throughout the genome, as assayed by tritiated uridine uptake (Monesi 1965) and Cot1 RNA FISH ) are very low.…”

Section: Function Of the Sex Chromosomes In Mammalian Fertilitymentioning

confidence: 99%

Function of the Sex Chromosomes in Mammalian Fertility

Heard

Turner²

2011

Cold Spring Harbor Perspectives in Biology

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The sex chromosomes play a highly specialized role in germ cell development in mammals, being enriched in genes expressed in the testis and ovary. Sex chromosome abnormalities (e.g., Klinefelter [XXY] and Turner [XO] syndrome) constitute the largest class of chromosome abnormalities and the commonest genetic cause of infertility in humans. Understanding how sex-gene expression is regulated is therefore critical to our understanding of human reproduction. Here, we describe how the expression of sex-linked genes varies during germ cell development; in females, the inactive X chromosome is reactivated before meiosis, whereas in males the X and Y chromosomes are inactivated at this stage. We discuss the epigenetics of sex chromosome inactivation and how this process has influenced the gene content of the mammalian X and Y chromosomes. We also present working models for how perturbations in sex chromosome inactivation or reactivation result in subfertility in the major classes of sex chromosome abnormalities.T he evolution of sex chromosomes from a pair of autosomes is clearly advantageous to species in enabling sexual reproduction and the genetic fitness that results, but also necessitates the coevolution of strategies to deal with unique situations that arise. These include the lack of homology between the X and Y chromosomes in the male germline in which autosomal homologs must pair and the imbalance in Xlinked gene dosage between males and females. In mammals, this sex chromosome imbalance is dealt with by inactivating one of the two X chromosomes during early female development. In the female germline, the inactive X chromosome is reactivated before meiosis. In the male germline, the X and Y chromosomes undergo meiotic inactivation that is linked to their unique unpaired status. This is a conserved process and has important implications for the evolution of sex chromosome gene content. In this article, we will cover these different aspects of sex chromosome behavior and function in mammals, including the role of sex chromosomes in sex determination and the behavior of the sex chromosomes during gametogenetesis, particularly in the male germline.

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Semiquantitative analysis of X-linked gene expression during spermatogenesis in the mouse: Ethidium-bromide staining of RT-PCR products

Cited by 50 publications

References 18 publications

Dosage compensation in mammals: fine-tuning the expression of the X chromosome

Dosage compensation in mammals: fine-tuning the expression of the X chromosome

A Continuity of X-Chromosome Silence from Gamete to Zygote

Function of the Sex Chromosomes in Mammalian Fertility

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