Human X-chromosome sequence
just when you thought the human genome sequence had already been completed twice, comes the announcement of the completion of the human X-chromosome sequence.
Actually such "completion" announcements have more to do with politics, competition and funding than science. I suppose that it is useful to designate a milestone as a completion, or the project risks looking like it is dragging on forever without achievement.
Anyway, the latest completion includes a detailed bioinformatic analysis of X-chromosome structure and evolution. The linked article is a nice summary of what is possible from comparative sequence analysis. Some highlights: One third of the chromosome consists of LINES (long interspersed elements) which serve as sites for the inititiation of X-chromosome condensation which we will discuss in a few weeks. 75% of the genes are silenced (making females effectively haploid, just like males), 15% are never silenced (so females are effectively diploid for those genes unlike males!) and 10% are variable (so may not even be consistently expressed in females!).
Surprises keep happening!
Actually such "completion" announcements have more to do with politics, competition and funding than science. I suppose that it is useful to designate a milestone as a completion, or the project risks looking like it is dragging on forever without achievement.
Anyway, the latest completion includes a detailed bioinformatic analysis of X-chromosome structure and evolution. The linked article is a nice summary of what is possible from comparative sequence analysis. Some highlights: One third of the chromosome consists of LINES (long interspersed elements) which serve as sites for the inititiation of X-chromosome condensation which we will discuss in a few weeks. 75% of the genes are silenced (making females effectively haploid, just like males), 15% are never silenced (so females are effectively diploid for those genes unlike males!) and 10% are variable (so may not even be consistently expressed in females!).
Surprises keep happening!
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