Enriching for Males: Maintaining a Stock of Male C. elegans

Abstract

Source: Singaravelu, G., et al. Isolation and In vitro Activation of Caenorhabditis elegans Sperm. J. Vis. Exp. (2011).

Nematodes can be propagated easily in the lab–in part because hermaphrodites can reproduce by self-fertilization.  However, genetic crosses and other experiments may require a large number of males.  This video describes a method to enrich for male C. elegans.

Protocol

This protocol is an excerpt from Singaravelu et al, Isolation and In vitro Activation of Caenorhabditis elegans Sperm, J. Vis. Exp. (2011).

1. Enrichment of male population

1. Depending on the experimental need, large numbers of males can be obtained by employing one of the following strategies:
   1. large population of wild type males can be obtained by crossing 5 wild type males and 1 hermaphrodite on a small lawn of OP50 seeded at the center of NGM plate. Roughly 50% of the succeeding generation will be wild type males.
   2. him-5(e1490) or him-8(e1489) hermaphrodites throw large number of males. him-5 and him-8 males are fertile and there is no obvious defect in sperm morphology and function. So, him-5 or him-8 males can be used in lieu of wild type males for many experiments.

2. Identification and isolation of males

1. Examine the tail morphology of worms; the male worm's tail is rounded.
2. Pick L4 stage males and transfer them to a NGM plate seeded with E. coli OP50 and let them grow for a day or two. Growing celibate males in the absence of hermaphrodites prevent the loss of sperm and thus large number of spermatids would be available during experimental procedure.