Studying the African turquoise killifish, which enters into a suspended state called "diapause" during dry and unfavorable growing seasons, researchers uncovered mechanisms that allow the arrested fish to be maintained for long periods while being protected from the normal consequences of aging. Their results are potentially relevant to understanding human aging and aging-associated disease. To survive extreme environments, many species throughout the animal kingdom have evolved the ability to enter one of several unique types of suspended life. One of the most common types, diapause, suspends embryonic development during harsh conditions and enables organisms to hold out for favorable conditions before resuming development. Remarkably, the time spent in diapause doesn't affect the longevity, nor the overall aging of the organism once it "wakes up" and continues to grow. However, the physiological mechanisms by which diapause protects organisms from aging remain unknown. Chi-Kuo Hu and colleagues investigated diapause and its effects on subsequent life in the African turquoise killifish, an emergent model for studying aging in vertebrates. This killifish lives in temporary ponds that dry to dust for long periods of the year. To survive drought, killifish embryos enter diapause - sometimes spending a lifetime in the state - until the rains refill their shallow homes. The authors found that diapause protects the fish embryos against the ravages of time without consequences for the total lifespan or fitness of the adults. Genes involved in muscle development and function appear to play an especially important role in diapause. Also during diapause, chromatin remodeling factors are critical in regulating gene expression, specifically members of the Polycomb family of transcriptional repressors. The study "provides some of the first insight into the anti-aging mechanisms of vertebrate diapause," writes Marc Van Gilst in a related Perspective.
