Inter-generational Consequences for Growing C.elegans in Liquid

Abstract

In recent years, studies in Caenorhabditis elegans nematodes have shown that different stresses can generate multigenerational changes. Here we show that worms that grow in liquid media, and also their plate-grown progeny, are different from worms whose ancestors were grown on plates. It has been suggested that C.elegans might encounter liquid environments in nature, although actual observations in the wild are few and far between. In contrast, in the lab, growing worms in liquid is commonplace, and often used as an alternative to growing worms on agar plates, to control the composition of the worms' diet, to starve (and synchronize) worms, or to grow large populations for biochemical assays. We found that plate-grown descendants of M9 liquid media-grown worms were longer than control worms, and the heritable effects were apparent already very early in development. We tested for the involvement of different known epigenetic inheritance mechanisms, but could not find a single mutant in which these intergenerational effects are canceled. While we found that growing in liquid always leads to inter-generational changes in the worms' size, trans-generational effects were found to be variable, and in some cases the effects were gone after 1-2 generations. These results demonstrate that standard cultivation conditions in early life can dramatically change the worms' physiology in adulthood, and can also affect the next generations.

H3K9me3 is required for inheritance of small RNAs that target a unique subset of newly evolved genes

“…RNA interference (RNAi) responses are inherited in Caenorhabditis elegans nematodes across generations via heritable small RNAs (Alcazar et al, 2008; Buckley et al, 2012; Vastenhouw et al, 2006). In worms, exposure to a number of environmental challenges, such as viral infection (Gammon et al, 2017; Rechavi et al, 2011), starvation (Rechavi et al, 2014), heat (Klosin et al, 2017), and growth in liquid (Lev et al, 2018) induces heritable physiological responses that persist for multiple generations. Inheritance of such transmitted information was linked to inheritance of small RNAs and chromatin modifications, and hypothesized to protect and prepare the progeny for the environmental challenges that the ancestors met.…”