X-linked gene expression and sex determination in Caenorhabditis elegans

✍ Scribed by Philip M. Meneely

• Book ID: 102758531
• Publisher: John Wiley and Sons
• Year: 1990
• Tongue: English
• Weight: 716 KB
• Volume: 12
• Category: Article
• ISSN: 0265-9247
• DOI: 10.1002/bies.950121102

✦ Synopsis

The signal for 'sex determination in the nematode Caenorhabditis elegans is the ratio between the number of X chromosomes and the number of sets of autosomes (the X/A ratio). Animals with an X/A ratio of 0.67 (a triploid with two X chromosomes) or less are males. Animals with an X/A ratio of 0.75 or more are hermaphrodites. Thus, diploid males have one X chromosome and diploid hermaphrodites have two X chromosomes.

However, the difference in X-chromosome number between the sexes is not reflected in general levels of X-linked gene expression because of the phenomenon of dosage compensation. In dosage compensation, X-linked gene expression appears to be 'turned down' in 2X animals to the 1X level of expression. An intriguing and unexplained finding is that mutations and X-chromosome duplications that elevate X-linked gene expression also feminize triploid males. One way that this relationship between sex determination and X-linked gene expression may be operating is discussed.