Measuring age-specific frequencies of an allele that regulates the expression of heat
shock protein 26 in populations of Drosophila melanogaster
Stephanie Lu
Mentor: Dr. Michael Rose
The aging process is generally associated with the accumulation of protein damage over
time. Heat shock proteins, which act as molecular chaperones, may mitigate this damage
to some extent. Preliminary data suggests that the expression of a particular heat shock
protein, Hsp26, is associated with a longevity phenotype in Drosophila melanogaster.
p26 is an allele for a transposable element insertion into the hsp26 gene promoter region
that interrupts transcription. Populations of flies that have been selected for a longevity
phenotype have low frequencies of this allele, and short-lived populations have very high
frequencies of this allele. To test the idea that the absence of the p26 allele is associated
with longevity, replicate populations were highly inbred through full-sib mating to
establish lines homozygous for the p26 allele and lines homozygous for the wildtype.
Twelve generations of isofemale transfers were carried out in three replicate populations,
starting at 60 lines per population. Molecular genotyping methods revealed that nine of
the 13 populations remaining after this intense inbreeding regime are completely
homozygous at this locus. Three lines are homozygous for the wild-type allele,
suggesting that they express the gene normally; six lines are homozygous for the p26
allele, suggesting that they have decreased expression of the gene. This study provides
the necessary preliminary data to test for the effect of the p26 allele on longevity. Future
experiments will directly compare longevity in the populations homozygous for the wildtype allele to the populations homozygous for the p26 allele.