Title: Visualizing the evolution of Hox gene expression in the Drosophila abdomenisualizing the evolution of Hox gene expression in the Drosophila abdomen
Abstract:
Hox genes are deeply conserved genes that provide segmental identity to the developing animal body. However, Hox genes have also been shown to control the evolution of other rapidly evolving traits such as abdominal pigmentation in Drosophila. In Drosophila melanogaster, the Hox gene Abd-B is expressed within the developing male abdomen which directly results in a dark pigmentation pattern. In contrast, some species within the melanogaster subgroup have evolved a reduction in Abd-B expression producing a lighter pattern. Given this result and the variety of pigmentation patterns across the entire Drosophila phylogeny, I hypothesize that Abd-B expression has evolved in other more distantly related species to produce unique pigmentation patterns. To explore this possibility, I will utilize hybridization chain reaction (HCR) to understand the endogenous expression pattern of Abd-B mRNA within multiple species. Previous methods have failed to do this, but my results show that Abd-B mRNA expression can be visualized in multiple tissues–including the developing abdomen–and across species. My results also demonstrate that certain limitations of HCR can be overcome using HCR probes designed in house.
Title: HtrA: the serine protease is also a post-translocation chaperone
Abstract:
Streptococcus pneumoniae is a Gram-positive bacterium that typically inhabits the human nasopharynx. While asymptomatic carriage is common, the bacterium can transition into invasive infection, where the most vulnerable populations are children, the elderly, and immunocompromised, making S. pneumoniae a significant health threat. An important aspect of S. pneumoniae pathogenesis and function is the secretion of proteins across its cell membrane. However, this environment between the cell membrane and the cell wall, presents several challenges for protein folding. HtrA is a multifunctional secreted protein that has both chaperone and protease activity and is thought to take part in protein quality control in this outer membrane space. In S. pneumoniae, HtrA consists of a transmembrane domain, a serine protease domain, and a PDZ domain. I will conduct phenotypic assays with several S. pneumoniae HtrA mutant bacterial strains, including strains that lack HtrA protease activity, lack a PDZ domain, or have mutations in the PDZ domain predicted to be important for substrate binding. I will compare these mutants to the wildtype S. pneumoniae strain, the HtrA deletion mutant, and HtrA complement strain. I will focus on phenotypic assays that require HtrA activity, such as secreted hemolytic activity, host cell adherence, susceptibility to cell wall-active antimicrobials, survival under osmotic stress and mouse infection models to determine the specific requirements for the HtrA serine protease domain and PDZ domain in bacterial physiology and virulence.
Rebeiz and Cahoon Lab
Friday, September 20th, 2024
12:00PM
Langley A219B