Maintaining the integrity of genomic DNA is crucial to cellular function and survival. Proteins such as
Bloom (BLM) DNA helicase function to protect the genome from the deleterious effects of both
exogenous and endogenous sources of DNA damage. Loss of BLM activity in humans leads to the
rare autosomal recessive disorder Bloom Syndrome, which is characterized by developmental
abnormalities, premature aging, and cancer susceptibility. The goal of this proposed research is to
investigate the role that BLM plays in preventing DNA damage associated with repetitive DNA
sequences. Due to the functional conservation between human BLM and Drosophila melanogaster
Blm proteins, we propose to use Drosophila as a model for studying the Blm-dependent replication
challenges posed by repetitive DNA sequences. The cellular consequences of repeat-dependent
replication challenges to Blm remain unknown, but the Drosophila embryo provides us with a useful
model for studying these aspects of Blm function. Our previous data suggest that Blm facilitates
replication of repetitive DNA sequences, particularly the highly repetitive Y chromosome, during early
embryo development. We propose to identify the repetitive sequences on the Y chromosome that
pose Blm-dependent replication challenges and to investigate long-term effects of Blm-deficiency
during early development. We will address these questions in Aim 1 by exploiting natural variation in
Y-linked repetitive DNA sequences in Drosophila to define specific Blm-dependent sequence motifs
on Y chromosomes. To accomplish this, we will screen for lines displaying Y-linked, Blm-dependent
variation and then analyze whole genome sequences of these lines for differences in Y chromosome
repetitive DNA content. Long-term biological effects of Blm-deficiency during embryogenesis will be
investigated in Aim 2 by comparing Blm heterozygous flies that developed with or without maternal
Blm for a variety of phenotypes that might be affected by sub-lethal amounts of DNA damage. Those
phenotypes will include lifespan, fertility, body composition, and locomotor activity. Lastly, in alignment
with the goals of the SuRE program, Aim 3 of this grant will provide high-impact intensive
undergraduate research training of undergraduate students who are underrepresented in biomedical
research. This proposal will provide students with direct participation in the execution, analysis, and
reporting of this research and will support the growing reputation of LC State as a vibrant institution for
future biomedical scientists and healthcare professionals that come from diverse backgrounds.