Of light and mouse embryos: Less is more

摘要

Although light is essential for life on this planet, Hamlet's sun pun, "Not so, my lord, Ⅰ am too much in the sun" (Hamlet, Act I, Scene 2, line 68), points to the detrimental effects of light on cells by means of light's ability to generate DNA damage by promoting thymidine-dimer formation as well as reactive oxygen species (ROS) that can damage DNA, proteins, and lipids. Such damage can lead to premature cell death or cancer. The small number of cells of the early developing embryo makes it particularly vulnerable to light-induced damage. In lower species, such as marine organisms that develop at or near the water's surface, mechanisms have evolved to protect the developing embryo from light, in particular high-energy UV radiation. These mechanisms typically entail the egg's producing UV-absorbing compounds (1). The work reported by Takenaka et al. (2) in a recent issue of PNAS describes the effect of light on mouse zygotes.