The Naked Scientists

The Naked Scientists Forum

Author Topic: lyonisation, quick Question  (Read 8707 times)

Offline alastair84

  • Jr. Member
  • **
  • Posts: 22
    • View Profile
lyonisation, quick Question
« on: 12/05/2004 18:41:02 »
i understand lyonisation is the process of random X chromosome inactivation in a famale, which involves methylation of certian parts of one of the X chromosomes.
Just a quick question:
Does lyonisation affect ALL the cells in the female?
e.g. do some cells escape lyonisation and have both X chromosomes active?


 

Offline Rokitansky

  • Sr. Member
  • ****
  • Posts: 108
    • View Profile
Re: lyonisation, quick Question
« Reply #1 on: 12/05/2004 18:54:11 »
Sincerly, i don`t know. But, what i do know, is that there are parts of X chromosome which are not inactivated. These genes have their own locuses on the short part of Y chromosome also (in males), and these are called pseudoautosomic genes.
 

Offline alastair84

  • Jr. Member
  • **
  • Posts: 22
    • View Profile
Re: lyonisation, quick Question
« Reply #2 on: 12/05/2004 19:00:58 »
yes, of course. Logical thinking would determine this, because if ALL of the genes of one of the X Xsomes were inactivated, then the female would effectively have Turners Syndrome, which results from genotype of 45, X0
 

Offline alastair84

  • Jr. Member
  • **
  • Posts: 22
    • View Profile
Re: lyonisation, quick Question
« Reply #3 on: 12/05/2004 19:02:59 »
actually from the above reasoning, one could assume that ALL cells in the female DO undergo lyonisation, otherwise the female may have symptoms of 47, XXX??? this is some dodgy reasoning from me, lol.
« Last Edit: 12/05/2004 19:04:18 by alastair84 »
 

Offline Rokitansky

  • Sr. Member
  • ****
  • Posts: 108
    • View Profile
Re: lyonisation, quick Question
« Reply #4 on: 12/05/2004 22:17:32 »
quote:
Originally posted by alastair84

actually from the above reasoning, one could assume that ALL cells in the female DO undergo lyonisation, otherwise the female may have symptoms of 47, XXX??? this is some dodgy reasoning from me, lol.



well, no. Symptoms in 47,XXX are due to genes in those pseudoautosomic loci are in excess. In this female, both X chromosomes are inactivated.
I was thinking through this and it could have been a reactivation of second X chromosome before mejotic division in gonads take place, but functional significance of this is unclear to me.
 

Offline alastair84

  • Jr. Member
  • **
  • Posts: 22
    • View Profile
Re: lyonisation, quick Question
« Reply #5 on: 12/05/2004 22:46:18 »
thanks. I have researched a little more and think the answer to the original question is yes, all cells undergo lyonisation, well that's what i'm going to put down in my exams coming up anyway.
 

Offline Rokitansky

  • Sr. Member
  • ****
  • Posts: 108
    • View Profile
Re: lyonisation, quick Question
« Reply #6 on: 12/05/2004 23:21:16 »
good luck !
« Last Edit: 12/05/2004 23:22:15 by Rokitansky »
 

Offline chris

  • Neilep Level Member
  • ******
  • Posts: 5339
  • Thanked: 65 times
  • The Naked Scientist
    • View Profile
    • The Naked Scientists
Re: lyonisation, quick Question
« Reply #7 on: 13/05/2004 03:16:12 »
The question of Lyonisation was discussed in a previous topic, here's the link :

http://nakedscientists.com/forum/topic.asp?TOPIC_ID=793&whichpage=1

Chris

"I never forget a face, but in your case I'll make an exception"
 - Groucho Marx
 

Offline MayoFlyFarmer

  • Hero Member
  • *****
  • Posts: 863
    • View Profile
    • http://www.myspace.com/wiguyinmn
Re: lyonisation, quick Question
« Reply #8 on: 13/05/2004 07:07:51 »
quick answer = yes

That's no moon.... its a GRAPEFRUIT!!!!
 

Offline MayoFlyFarmer

  • Hero Member
  • *****
  • Posts: 863
    • View Profile
    • http://www.myspace.com/wiguyinmn
Re: lyonisation, quick Question
« Reply #9 on: 13/05/2004 07:08:23 »
well i guess there are exceptions to every rule, but i can't think of any and I assume you just meant in general

That's no moon.... its a GRAPEFRUIT!!!!
 

The Naked Scientists Forum

Re: lyonisation, quick Question
« Reply #9 on: 13/05/2004 07:08:23 »

 

SMF 2.0.10 | SMF © 2015, Simple Machines
SMFAds for Free Forums