Traditionally, the study of essential and pleiotropic genes have posed unique challenges in the domain of reverse genetics. Knockout of essential genes can result in death or sterility, thus complicating phenotypic analysis. The complete inactivation of pleiotropic genes permits superficial investigation but may shroud the significance of independent expression events. Easily toggled between states, temperature sensitive mutations can abate some of these obstacles in gene function studies. The
spe-6 gene of C. elegans is required for spermatid activation, major sperm protein assembly, and the proper execution of meiosis I. Two intronic mutations in
spe-6 (
zq18,and
hc190) independently and in a temperature-dependent manner reduce the of function of this gene. At 25oC, a majority of
spe-6(
zq18) precursor mRNA is aberrantly spliced, subsequently invoking a reduction of fertility. At 15oC, fewer
spe-6(
zq18) transcripts are incorrectly spliced, and affected worms maintain normal fertility.
spe-6(
hc190) follows this same pattern of conditional fecundity. However, aberrant splicing of this allele has not been detected, possibly due to nonsense-mediated mRNA decay. The
zq18 and
hc190 alleles are characterized by guanine-to-adenine substitutions on the 5th and 1st bases, respectively, immediately flanking the 3' end of the exon. Furthermore, the 5' intronic sequence encompassing these two mutations is highly conserved amongst Eukaryotic genes and implicated in exon-intron junction recognition. Here, we report the effects of
zq18- and
hc190-like point mutations in other genes without a native restrictive temperature. MosSCI and the CRISPR/Cas9 system were used to recreate the aforementioned substitutions in
Cbr-unc-119 and
spe-44. It was found that
Cbr-unc-119(
zq18-like) does not have a restrictive temperature and is phenotypically comparable to the wild type allele. Similarly,
zq18- and
hc190-like substitutions in
spe-44 do not result in substantial phenotypic variance from wild type worms. From this, we conclude that
zq18- and
hc190-like mutations do not universally elicit a temperature-sensitive 'toggle' in the gene that they reside. With further investigation, we hope to elucidate the relationship between highly-conserved intronic positions and temperature-sensitive gene expression.