WordNet

invest with or as with a body; give body to (同)personify
the external structure of a vehicle; "the body of the car was badly rusted"
the main mass of a thing
a natural object consisting of a dead animal or person; "they found the body in the lake" (同)dead body
the entire structure of an organism (an animal, plant, or human being); "he felt as if his whole body were on fire" (同)organic structure, physical structure
a collection of particulars considered as a system; "a body of law"; "a body of doctrine"; "a body of precedents"
a group of persons associated by some common tie or occupation and regarded as an entity; "the whole body filed out of the auditorium"; "the student body"; "administrative body"
an individual 3-dimensional object that has mass and that is distinguishable from other objects; "heavenly body"
the central message of a communication; "the body of the message was short"

PrepTutorEJDIC

〈C〉『身体』,肉体 / 〈C〉(人・動物の)『胴体』 / 〈C〉)物の)『主要部』,本体《+『of』+『名』》 / 〈C〉(…の)『団体』,群れ:(…のたくさんの)集まり《+『of』+『名』》 / 〈C〉物体,…体 / 〈U〉実質;(酒・味などの)こく / 〈C〉《話》人
bariumの化学記号
《英話》人;(特に)男

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/11/19 23:10:45」(JST)

wiki en

Nucleus of a female amniotic fluid cell. Top: Both X-chromosome territories are detected by FISH. Shown is a single optical section made with a confocal microscope. Bottom: Same nucleus stained with DAPI and recorded with a CCD camera. The Barr body is indicated by the arrow, it identifies the inactive X (Xi).

Left: DAPI stained female human fibroblast with Barr body (arrow). Right: histone macroH2A1 staining. Arrow points to sex chromatin in DAPI-stained cell nucleus, and to the corresponding sex chromatin site in the histone macroH2A1-staining.

A Barr body (named after discoverer Murray Barr)^[1] is the inactive X chromosome in a female somatic cell,^[2] rendered inactive in a process called lyonization, in those species in which sex is determined by the presence of the Y (including humans) or W chromosome rather than the diploidy of the X. The Lyon hypothesis states that in cells with multiple X chromosomes, all but one are inactivated during mammalian embryogenesis.^[3] This happens early in embryonic development at random in mammals,^[4] except in marsupials and in some extra-embryonic tissues of some placental mammals, in which the father's X chromosome is always deactivated.^[5]

In humans with more than one X chromosome, the number of Barr bodies visible at interphase is always one fewer than the total number of X chromosomes. For example, men with Klinefelter syndrome (47,XXY karyotype) have a single Barr body, whereas women with a 47,XXX karyotype have two Barr bodies. Barr bodies can be seen on the nucleus of neutrophils.

Mechanism

A typical human female has only one Barr body per somatic cell, while a typical human male has none.

Mammalian X-chromosome inactivation is initiated from the X inactivation centre or Xic, usually found near the centromere.^[6] The center contains twelve genes, seven of which code for proteins, five for untranslated RNAs, of which only two are known to play an active role in the X inactivation process, Xist and Tsix.^[6] The centre also appears to be important in chromosome counting: ensuring that random inactivation only takes place when two or more X-chromosomes are present. The provision of an extra artificial Xic in early embryogenesis can induce inactivation of the single X found in male cells.^[6]

The roles of Xist and Tsix appear to be antagonistic. The loss of Tsix expression on the future inactive X chromosome results in an increase in levels of Xist around the Xic. Meanwhile, on the future active X Tsix levels are maintained; thus the levels of Xist remain low.^[7] This shift allows Xist to begin coating the future inactive chromosome, spreading out from the Xic.^[8] In non-random inactivation this choice appears to be fixed and current evidence suggests that the maternally inherited gene may be imprinted.^[4]

It is thought that this constitutes the mechanism of choice, and allows downstream processes to establish the compact state of the Barr body. These changes include histone modifications, such as histone H3 methylation^[9] and histone H2A ubiquitination,^[10] as well as direct modification of the DNA itself, via the methylation of CpG sites.^[11] These changes help inactivate gene expression on the inactive X-chromosome and to bring about its compaction to form the Barr body.

References

Links to full text articles are provided where access is free, in other cases only the abstract has been linked.

^ Barr, M. L., Bertram, E. G., (1949), A Morphological Distinction between Neurones of the Male and Female, and the Behaviour of the Nucleolar Satellite during Accelerated Nucleoprotein Synthesis. Nature. 163 (4148): 676-7.
^ Lyon, M. F., (2003), The Lyon and the LINE hypothesis. j.semcdb 14, 313-318. (Abstract)
^ Lyon, M. F. (1961), Gene Action in the X-chromosome of the Mouse (Mus musculus L.) Nature. 190 (4773): 372-3. doi:10.1038/190372a0 PMID 13764598 (Abstract)
^ ^a ^b Brown,C.J., Robinson,W.P., (1997), XIST Expression and X-Chromosome Inactivation in Human Preimplantation Embryos. Am. J. Hum. Genet. 61, 5-8 (Full Text PDF)
^ Lee, J. T., (2003), X-chromosome inactivation: a multi-disciplinary approach. j.semcdb 14, 311-312. (doi:10.1016/j.semcdb.2003.09.025 Abstract)
^ ^a ^b ^c Rougeulle, C., Avner, P. (2003), Controlling X-inactivation in mammals: what does the centre hold?. j.semcdb 14, 331-340. (Abstract)
^ Lee, J. T., Davidow, L. S., Warshawsky, D., (1999), Tisx, a gene antisense to Xist at the X-inactivation centre. Nat. Genet. 21, 400-404. Full Text
^ Lyon, M. F., (2003), The Lyon and the LINE hypothesis. j.semcdb 14, 313-318. (Abstract
^ Heard, E., Rougeulle, C., Arnaud, D., Avner, P., Allis, C. D. (2001), Methylation of Histone H3 at Lys-9 Is an Early Mark on the X Chromosome during X Inactivation. Cell 107, 727-738. (Full Text)
^ de Napoles,M., Mermoud,J.E., Wakao,R., Tang,Y.A., Endoh,M., Appanah,R., Nesterova,T.B., Silva,J., Otte,A.P., Vidal,M., Koseki,H., Brockdorff,N., (2004), Polycomb Group Proteins Ring1A/B Link Ubiquitylation of Histone H2A to Heritable Gene Silencing and X Inactivation. Dev. Cell 7, 663-676 (Abstract)
^ Chadwick,B.P., Willard,H.F., (2003), Barring gene expression after XIST: maintaining faculative heterochromatin on the inactive X. j.semcdb 14, 359-367 (Abstract)

UpToDate Contents

全文を閲覧するには購読必要です。 To read the full text you will need to subscribe.

1. 小児の身体組成測定 measurement of body composition in children
2. エプスタインバーウイルス（EBウイルス）感染の臨床的特徴および治療 clinical manifestations and treatment of epstein barr virus infection
3. Body dysmorphic disorder: Assessment, diagnosis, and differential diagnosis
4. 成人における抗癌剤の投与 dosing of anticancer agents in adults
5. Corneal abrasions and corneal foreign bodies: Management

English Journal

Novel sex-dependent differentially methylated regions are demethylated in adult male mouse livers.

Ito S1, Hirabayashi K1, Moriishi K2, Matsui Y3, Moriya K4, Koike K5, Matsuura Y6, Shiota K7, Yagi S8.
Biochemical and biophysical research communications.Biochem Biophys Res Commun.2015 Jul 10;462(4):332-8. doi: 10.1016/j.bbrc.2015.04.137. Epub 2015 May 8.
In mammalian livers, sexual dimorphisms are observed in tissue-specific functions and diseases such as hepatocellular carcinoma. We identified sex-dependent differentially methylated regions (S-DMRs) which had been previously been characterized as growth hormone- STAT5 dependent. In this study, we p
PMID 25960295

Neighboring Genes Show Correlated Evolution in Gene Expression.

Ghanbarian AT1, Hurst LD2.
Molecular biology and evolution.Mol Biol Evol.2015 Jul;32(7):1748-66. doi: 10.1093/molbev/msv053. Epub 2015 Mar 4.
When considering the evolution of a gene's expression profile, we commonly assume that this is unaffected by its genomic neighborhood. This is, however, in contrast to what we know about the lack of autonomy between neighboring genes in gene expression profiles in extant taxa. Indeed, in all eukaryo
PMID 25743543

Japanese Journal

A Case of Epstein-Barr VirusEBVAssociated Remnant Gastric Cancer Diagnosed 2 Years After the Distal Gastrectomy for Primary EBV-Associated Gastric Cancer Secondary to Polymyositis