X chromosome dosage compensation does occur in germ cells. A study published today in the open access journal Journal of Biology reveals that expression of the genes on the X chromosome is doubled in Drosophila germ cells to compensate for the missing second X chromosome. The study shows that this also occurs in C. elegans and mice somatic cells. In human female somatic cells, one of the two X chromosomes is inactivated to equilibrate expression between the sexes, but this unbalances the expression of the X compared to the other chromosomes. This study is the first demonstration that the X chromosome is upregulated in germs cells, which brings the X chromosome and the other chromosomes back into balance. The study is also the first demonstration that upregulation of the X chromosome in somatic tissue is conserved across species.
Vaijayanti Gupta from the National Institute of Diabetes and Digestive and Kidney Disease at the National Institutes of Health (NIH), Bethesda, USA collaborated with colleagues from the Center for Information Technology at the NIH and colleagues from Incyte Genomics, Palo Alto, USA. Gupta et al. carried out microarray analyses of 2,245 genes present on the X chromosome of Drosophila germ cells and somatic cells. Drosophila males have one X chromosome and two autosomes (X;AA) while Drosophila females have two X chromosomes and two autosomes (XX;AA).
The results of the microarray analyses show that the single male X chromosome is expressed at the same level as the two female X chromosomes put together in both somatic cells and germ cells. By creating sex-transformed flies, Gupta et al. were able to show a two-fold X-chromosome mRNA level difference compared with the autosomes in both male and female germ cells with a single X chromosome. This indicates that the X chromosome is hypertranscribed compared to the autosomes in germ cells. Gupta et al.'s results suggest that the two X chromosomes in female germ cells are repressed Page: 1 2 Related biology news :1
Contact: Juliette Savin
. Biologists at Tufts University discover 1 reason why chromosomes break, often leading to cancer2
. Double identities lie behind chromosome disorders3
. St. Jude study yields secrets of chromosome movement4
. Physicist cracks womens random but always lucky choice of X chromosome5
. Researchers shed light on shrinking of chromosomes6
. Researchers attach genes to minichromosomes in maize7
. Baumann Lab defines proteins that distinguish chromosome ends from DNA double-strand breaks8
. New technique will produce a better chromosome map9
. Short chromosomes put cancer cells in forced rest10
. Shortening chromosomes cause for earlier cancer onset in families with rare syndrome11
. The pull of bacterial chromosome segregation