Evidence for feasibility of fetal trophoblastic cell-based noninvasive prenatal testing.

Objective: The goal was to develop methods for detection of chromosomal and subchromosomal abnormalities in fetal cells in the mother's circulation at 10-16 weeks' gestation using analysis by array comparative genomic hybridization (CGH) and/or next-generation sequencing (NGS).

Method: Nucleated cells from 30 mL of blood collected at 10-16 weeks' gestation were separated from red cells by density fractionation and then immunostained to identify cytokeratin positive and CD45 negative trophoblasts. Individual cells were picked and subjected to whole genome amplification, genotyping, and analysis by array CGH and NGS.

US Military Child and Adolescent Psychiatry Training Programs and Careers of Military Child Psychiatrists.

Military child and adolescent psychiatry (CAP) fellowship programs offer educational experiences universal to all civilian training programs in the USA. They also offer unique training opportunities not found in civilian CAP fellowships in order to prepare graduates to serve the needs of military families. Military-specific curricula and exposures prepare trainees to address various issues faced by military families, in contending with frequent military moves, parental deployments, and disrupted social ties.

Unusual chromatin status and organization of the inactive X chromosome in murine trophoblast giant cells.

Mammalian X-chromosome inactivation (XCI) enables dosage compensation between XX females and XY males. It is an essential process and its absence in XX individuals results in early lethality due primarily to extra-embryonic defects. This sensitivity to X-linked gene dosage in extra-embryonic tissues is difficult to reconcile with the reported tendency of escape from XCI in these tissues.

Nuclear organization and dosage compensation.

Dosage compensation is a strategy to deal with the imbalance of sex chromosomal gene products relative to autosomes and also between the sexes. The mechanisms that ensure dosage compensation for X-chromosome activity have been extensively studied in mammals, worms, and flies. Although each entails very different mechanisms to equalize the dose of X-linked genes between the sexes, they all involve the co-ordinate regulation of hundreds of genes specifically on the sex chromosomes and not the autosomes.

LINE-1 activity in facultative heterochromatin formation during X chromosome inactivation.

During X chromosome inactivation (XCI), Xist RNA coats and silences one of the two X chromosomes in female cells. Little is known about how XCI spreads across the chromosome, although LINE-1 elements have been proposed to play a role. Here we show that LINEs participate in creating a silent nuclear compartment into which genes become recruited.

High-resolution analysis of epigenetic changes associated with X inactivation.

Differentiation of female murine ES cells triggers silencing of one X chromosome through X-chromosome inactivation (XCI). Immunofluorescence studies showed that soon after Xist RNA coating the inactive X (Xi) undergoes many heterochromatic changes, including the acquisition of H3K27me3. However, the mechanisms that lead to the establishment of heterochromatin remain unclear.

Combined immunofluorescence, RNA fluorescent in situ hybridization, and DNA fluorescent in situ hybridization to study chromatin changes, transcriptional activity, nuclear organization, and X-chromosome inactivation.

Epigenetic mechanisms lead to the stable regulation of gene expression without alteration of DNA and trigger initiation and/or maintenance of cell-type-specific transcriptional profiles. Indeed, modulation of chromatin structure and the global 3D organization of the genome and nuclear architecture participate in the precise control of transcription. Thus, dissection of these epigenetic mechanisms is essential for our understanding of gene regulation.

A phosphorylated subpopulation of the histone variant macroH2A1 is excluded from the inactive X chromosome and enriched during mitosis.

Histone variants play an important role in numerous biological processes through changes in nucleosome structure and stability and possibly through mechanisms influenced by posttranslational modifications unique to a histone variant. The family of histone H2A variants includes members such as H2A.Z, the DNA damage-associated H2A.

Inducible XIST-dependent X-chromosome inactivation in human somatic cells is reversible.

During embryogenesis, the XIST RNA is expressed from and localizes to one X chromosome in females and induces chromosome-wide silencing. Although many changes to inactive X heterochromatin are known, the functional relationships between different modifications are not well understood, and studies of the initiation of X-inactivation have been largely confined to mouse. We now present a model system for human XIST RNA function in which induction of an XIST cDNA in somatic cells results in localized XIST RNA and transcriptional silencing.

Silencing of the mammalian X chromosome.

Mammalian X chromosome inactivation is one of the most striking examples of epigenetic gene regulation. Early in development one of the pair of approximately 160-Mb X chromosomes is chosen to be silenced, and this silencing is then stably inherited through subsequent somatic cell divisions. Recent advances have revealed many of the chromatin changes that underlie this stable silencing of an entire chromosome.

Beyond sense: the role of antisense RNA in controlling Xist expression.

The Xist RNA is a critical component of X inactivation, and Tsix is a non-coding antisense RNA to the Xist gene. We review the data from mouse that demonstrates that Tsix serves to regulate Xist expression. TSIX antisense transcripts have also been detected in humans, but without a manipulatable system to study the inactivation process in humans it remains unknown whether these antisense transcripts are functional in regulating human XIST.

Characterization of expression at the human XIST locus in somatic, embryonal carcinoma, and transgenic cell lines.

X inactivation requires XIST, a functional RNA that is expressed exclusively from, and localizes to, the inactive X in female somatic cells. In mouse, low-level unstable transcription of Xist is observed prior to the time of inactivation, and an antisense transcript, Tsix, is a critical regulator of early Xist expression. To examine the presence and impact of an antisense transcript in humans we have characterized the extent of sense and antisense transcription in human somatic, transgenic, and embryonal carcinoma (EC) cell lines.