CAREER: Genetic Dissection of Mitochondrial Morphogenesis During Drosophila Spermatogenesis

Davidson College, Davidson NC

Investigators

Abstract

Mitochondria are the organelles in which the energy from food is harnessed into ATP. In many cell types, mitochondria undergo dynamic shape changes and regulated movement, events which are thought to coordinate delivery of ATP to subcellular regions with highest energy demand. Mechanisms by which mitochondria are moved and shaped have been partially characterized in single-celled eukaryotes, but not all of these mechanisms are conserved in more complex organisms. The scientific goal of this project is to elucidate molecular mechanisms of mitochondrial dynamics during spermatogenesis in Drosophila melanogaster. An undergraduate research program will be established, and students will identify and characterize genes associated with mitochondrial morphogenesis. The educational goal is to incorporate experimental questions from the research into a genetics laboratory course taught annually at Davidson College. Spermatogenesis in Drosophila is an ideal metazoan model system for genetic analysis of mitochondrial morphogenesis, since 1) mitochondria normally aggregate, fuse, and elongate beside the flagellar axoneme in spermatids, and 2) genetic defects in mitochondrial morphogenesis can lead to sterility, a phenotype for which many genetic screens have been performed. Students will take both forward and reverse genetic approaches to characterize gene products that are required for mitochondrial movement and shaping in Drosophila spermatids. These approaches interweave many classical and molecular genetic techniques, such as recombination mapping, transposon mobilization, complementation, polymerase chain reaction, DNA subcloning, blotting and hybridization, and immunolocalization. Sequence analysis using online tools and computer databases will be an essential component of the research. Students will benefit from the connections they observe between classroom learning and laboratory discoveries, especially as they see the integration of classical and molecular genetics. Undergraduates in independent projects and in the genetics laboratory course will be particularly motivated by the prospect of contributing original findings to the scientific literature. Sperm cells require a great deal of energy; the structures within each cell that generate and provide usable "fuel" are mitochondria. During sperm cell formation, mitochondria undergo shape changes essential for sperm cell motility. In this project, undergraduates will perform studies of sterile mutant fruit fly strains that show mitochondrial defects. Students will identify and characterize genes which control the movement and shaping of mitochondria. This project will expand knowledge of mechanisms of mitochondrial dynamics.