tailieunhanh - Báo cáo y học: " Is canalization more than just a beautiful idea"

Tuyển tập các báo cáo nghiên cứu về y học được đăng trên tạp chí y học Wertheim cung cấp cho các bạn kiến thức về ngành y đề tài: Is canalization more than just a beautiful idea? | Sato and Siomi Genome Biology 2010 11 109 http 2010 11 3 109 w Genome Biology RESEARCH HIGHLIGHT L__ Is canalization more than just a beautiful idea Kaoru Sato and Haruhiko Siomi Abstract The heat-shock protein 90 Hsp90 is currently thought to buffer eukaryotic cells against perturbations caused by pre-existing cryptic genetic variation. A new study suggests that the buffering function of Hsp90 could instead be due to its repression of de novo transposon-mediated mutagenesis. In the 1940s the developmental biologist and geneticist CH Waddington coined the concept of developmental stability or the robustness of the phenotype against genetic and environmental perturbations 1 2 . It has been claimed that this robustness termed canalization has evolved under natural selection to stabilize phenotypes and decrease their variability. This is achieved by buffering the expression of traits holding them near their optimal states despite genetic and environmental perturbations. Canalization also allows the accumulation of cryptic genetic variation caused by mutations that do not affect the phenotype. Canalized traits are pheno-typically expressed only in particular environments or genetic backgrounds and become available for natural selection a mechanism that can lead to the assimilation of novel traits. It was found some years ago that reduction in the function of the Hsp90 protein in Drosophila whether by mutation or by specific inhibitors apparently uncovered previously silent genetic variation which led to an increase in morphological variation 3 . Hsp90 is a chaperone and heat-shock protein which in Drosophila is encoded by the Hsp83 gene. The morphological changes could become fixed and stably transmitted even if wild-type Hsp90 function were restored in subsequent generations. These findings implied that functional Hsp90 is a capacitor that accumulates cryptic genetic variation and releases it under certain circumstances that masks .