Abstract
In this experiment, we are using Caenorhabditis elegans (C. elegans) and conducting a
forward genetic screen. A forward genetic screen is a method that allows for the
identification of genes that are responsible for a particular phenotype of an organism, and to
isolate mutations. When the mutation or phenotype of interest has been isolated, the
student is able to analyze the processes that regulate that gene’s function. The forward
genetic screen conducted in this experiment aims at, the gene classification of C. elegans,
him; which is a high incidence of males in a population. The mutant gene allele is also known
as him-8 (el1489) IV. Since C. elegans develop rapidly the expected duration of this
experiment is about 7 days. The C. elegans used in this experiment were mutagenized by
Ethyl methanesulfonate (EMS). EMS alters the base pairing of guanine with thymine. Ten
adult worms were transferred onto ten separate plates (which contain lawns of Escherichia
coli for them to feed on) and were allowed to lay eggs. After the adult worms have laid their
eggs they are removed and flames to prevent overpopulation on the plates. The eggs are
given time to develop into adult phase and then about five worms from each plate are
transferred onto clean plates to observe for mutants and isolate any mutants so they can lay
eggs and produce offspring. At least one mutant worm is expected so it can provide offspring
which can be analyzed for the carried phenotype.