Victoria Williams, Elizabeth Young
Faculty Sponsor: Dr. Karen Hales
During sperm formation in Drosophila melanogaster, mitochondria undergo dramatic shape changes. Mitochondria harness energy to power cellular processes and problems with mitochondrial shaping have been implicated in human neurodegenerative disorders such as Parkinson’s. Peroxisomes help break down molecules such as very long chain fatty acids or hydrogen peroxide. Growing evidence suggests that certain gene products link these two cellular organelles. Males homozygous for mutations in either nmd or the similar protein CG4701 exhibit mitochondrial phenotypes. nmd is expressed ubiquitously in the fly whereas CG4701 is a testis-specific gene expressed only during later stages of spermatogenesis. Flies lacking functional nmd in germline cells cannot properly form peroxisomes during spermatogenesis. We aimed to define the role of CG4701 in mitochondria and peroxisome shaping by generating new mutant alleles for CG4701. To do so, we used CRISPR/Cas9 to perform targeted mutagenesis in the protein-coding region of the gene. The CG4701 mutant strains commonly exhibit misshapen mitochondria with large vacuoles beginning in onion stage and remaining throughout leaf blade and elongation. We also examined the function of CG4701 and peroxisome shaping in flies with reduced expression of nmd and mutated CG4701 by using Bam-Gal4 to drive the expression of UAS-SKL-GFP, a protein that targets the peroxisome matrix. CG4701 mutants with fluorescent membrane protein PMP-34 Cerulean appears to vary, generally showing some more mislocalization of this protein to mitochondria and/or less localization to smaller fluorescent punctae, suggesting an inability of PMP-34 Cerulean to localize to peroxisomes.
