Involvement of X-chromosome Reactivation in Augmenting Cancer Testis Antigens Expression:A Hypothesis

Cancer testis antigens（CTAs） are attractive targets for tumor immunotherapy because of their tumor-specific expression.Since more than half of confirmed CTAs are located on the X-chromosome,we asked whether there is a link between CTA expression and X-chromosomes.Recent reports have shown that reactivation of the inactive X-chromosome,known as X-chromosome reactivation（XCR）,a unique phenomenon that exists in many high-risk tumors in women,can transform the expression of many X-linked genes from monoallelic to biallelic.In this review,we discuss the link between CTA and XCR with the hopes of providing some novel insights into tumor biology.

Fine-scale evolutionary genetic insights into Anopheles gambiae X-chromosome

Understanding the genetic architecture of indi-vidual taxa of medical importance is the first step for designing disease preventive strategies. To understand the genetic details and evolu-tionary perspective of the model malaria vector, Anopheles gambiae and to use the information in other species of local importance, we scanned the published X-chromosome se-quence for detail characterization and obtain evolutionary status of different genes. The te-locentric X-chromosome contains 106 genes of known functions and 982 novel genes. Majori-ties of both the known and novel genes are with introns. The known genes are strictly biased towards less number of introns;about half of the total known genes have only one or two in-trons. The extreme sized (either long or short) genes were found to be most prevalent (58% short and 23% large). Statistically significant positive correlations between gene length and intron length as well as with intron number and intron length were obtained signifying the role of introns in contributing to the overall size of the known genes of X-chromosome in An. gam-biae. We compared each individual gene of An. gambiae with 33 other taxa having whole ge-nome sequence information. In general, the mosquito Aedes aegypti was found to be ge-netically closest and the yeast Saccharomyces cerevisiae as most distant taxa to An. gambiae. Further, only about a quarter of the known genes of X-chromosome were unique to An. gambiae and majorities have orthologs in dif-ferent taxa. A phylogenetic tree was constructed based on a single gene found to be highly orthologous across all the 34 taxa. Evolutionary relationships among 13 different taxa were in-ferred which corroborate the previous and pre-sent findings on genetic relationships across various taxa.

Sex-biased autophagy as a potential mechanism mediating sex differences in ischemic stroke outcome

Stroke is the second leading cause of death and a major cause of disability worldwide,and biological sex is an important determining factor in stroke incidence and pathology.From childhood through adulthood,men have a higher incidence of stroke compared with women.Abundant research has confirmed the beneficial effects of estrogen in experimental ischemic stroke but genetic factors such as the X-chromosome complement can also play an important role in determining sex differences in stroke.Autophagy is a self-degrading cellular process orchestrated by multiple core proteins,which leads to the engulfment of cytoplasmic material and degradation of cargo after autophagy vesicles fuse with lysosomes or endosomes.The levels and the activity of components of these signaling pathways and of autophagy-related proteins can be altered during ischemic insults.Ischemic stroke activates autophagy,however,whether inhibiting autophagy after stroke is beneficial in the brain is still under a debate.Autophagy is a potential mechanism that may contribute to differences in stroke progression between the sexes.Furthermore,the effects of manipulating autophagy may also differ between the sexes.Mechanisms that regulate autophagy in a sex-dependent manner in ischemic stroke remain unexplored.In this review,we summarize clinical and pre-clinical evidence for sex differences in stroke.We briefly introduce the autophagy process and summarize the effects of gonadal hormones in autophagy in the brain and discuss X-linked genes that could potentially regulate brain autophagy.Finally,we review pre-clinical studies that address the mechanisms that could mediate sex differences in brain autophagy after stroke.

Analysis of Linkage for Ten X-STR Markers in a Rio de Janeiro(Brazil)Three-Generation Family Sample

Recently, typing of polymorphisms on the X chromosome has become a standard technique in forensic genetics and a growing number of short tandem repeats (STR) has been established in this chromosome related to genetic population studies. Knowledge of marker recombination is very important especially when the X chromosome typing is used in forensic kinship analysis. It is known that the meiotic recombination is not a simple function of the physical distance between segments of the DNA but the recombination events between them tend to be clustered at special regions of the chromosome. Information on the rate of recombination among markers can be gathered by studying families through several generations. In this work we have typed DNA samples of pedigree consisting of nineteen families in Rio de Janeiro, constituted of grandfather, mother and grandson, and in some cases grandmother and aunt, and reported the recombination of 10 STR markers of the X chromosome. The study of the linkage analysis using the LOD score has shown that the marker pairs DXS8378-DXS7423, DXS7132-DXS9898, DXS7132-GATA172D05 DXS9898-DXS7133 and DXS6809-DXS7133 are not transmitted in a random way, during a recombination event.