Post reply

Reply to the message by David Turell

Name:

E-mail: (optional, won't be displayed directly)

Leave this field empty:

Homepage: (optional)

Leave this field empty:

Location: (optional)

Remember me (cookie)

Category:

Subject:

Formatting help

skip to input

format text bold: [b]bold text[/b]
format text italic: [i]italic text[/i]
insert hyperlink: [link=http://example.com/]link text[/link] / [link]http://example.com/[/link]
set text color: [color=#rgb]colored text[/color]
font size: [size=small]small text[/size]; [size=large]large text[/size]
insert list: [list][*]list item[/list]
insert image: [img]http://example.com/image.jpg[/img]; left: [img=left]http://example.com/image.jpg[/img]; right: [img=right]http://example.com/image.jpg[/img]; thumbnail: [img=thumbnail]http://example.com/image.jpg[/img]; thumbnail left: [img=thumbnail-left]http://example.com/image.jpg[/img]; thumbnail right: [img=thumbnail-right]http://example.com/image.jpg[/img]

:-)
;-)
:-P
:-D
:-|
:-(

Message:

> In mammals one female chromosome is inactivated for proper genome function:-http://www.sciencedaily.com/releases/2015/08/150810110747.htm-"Nature ensures this does not happen: one of the X chromosomes is completely and permanently inactivated during a female&apos;s early development in the womb. The mechanism responsible for this inactivation is not yet fully understood. However, research into mice has shown that a ribonucleic acid (RNA) molecule called Xist plays a pivotal role in the process. Several hundred copies of this molecule attach themselves to one of the two X chromosomes. Scientists believe that these RNA molecules dock onto other molecules which then inactivate the chromosome.-***-"The scientists were thus able to isolate surviving stem cells and identify seven genes that are central to X inactivation. One of them is called Spen. Scientists were already aware that Spen produces a protein which allows it to bind with RNA and essentially prevents the genes from being read. In other experiments, ETH researchers were able to show that if a mouse cell lacks the Spen gene, the proteins responsible for altering chromosome structure are not able to accumulate as efficiently at the X chromosome.-***-"The genes for Xist and Spen are found in humans as well. Thus, as Wutz points out, this research offers us some insight into the human system -- at least at the theoretical level, as mouse genetics cannot be mapped directly to humans.-"A few years ago, a team of French researchers postulated that, in addition to Xist, humans also have another system which ensures that the single X chromosome in men and one of the two X chromosomes in women remain active. This activating system does not exist in mice. Due to the interplay of activating and inactivating factors, regulation of X chromosomes in humans might therefore be more complicated than originally thought. Geneticists wanting to understand these processes in detail still have plenty of work ahead of them."-Comment: Sexual reproduction allows for more variation in evolution, but created this problem and required this solution. Still looks planned to me.