Chemical synchronization using household bleach can affect development, behavior and lifespan in <i>Caenorhabditis elegans</i>.

<i>Caenorhabditis elegans</i>, a nematode genetic model, is often synchronized in experiments to accurately observe its unbiased phenotypes. Chemical synchronization, simple bleaching of gravid worms, has been widely used to obtain eggs in bulk because the eggshell is extremely resistant to harsh conditions. While those eggs are considered to preserve their natural properties and are allowed to hatch to obtain synchronized worms, it has not been fully investigated whether chemical synchronization influences embryonic and post-embryonic traits. In this study, we compared some phenotypes observed in worms collected by picking laid eggs and by chemical synchronization. Chemical synchronization decreased hatching and developmental rates and, in some conditions, affected morphological traits, such as body length and head size, and brood size. In contrast, chemical synchronization did not affect the developmental potential of early- or later-stage eggs, or chemosensory behaviors. While the lifespan of wild-type worms did not change, the <i>daf-16 loss-of-function</i> mutant with an extremely short lifespan showed much variation when chemically synchronized. This study clarifies the impacts of chemical synchronization of worms and provides some critical considerations for its use.