School of Molecular Biosciences Graduate Student Seminars

About the event

PRESENTER: Brianne Jones, Advisor: Dr. Cynthia Haseltine

TITLE: Development of an In Vivo Break Double-Strand Break Repair System in the Hyperthermophilic Acidophile Saccharolobus solfataricus to Elucidate DNA Damage Repair in Archaea

ABSTRACT: Homologous recombination (HR) is an essential mechanism for repair of DNA double-strand breaks in all organisms. This process is necessary for recovery from a variety of environmental insults including UV and ionizing radiation, chemical exposure, and oxidative processes as well as damage that arises from general cellular activities including replication and transcription. While significant progress has been made toward understanding the biochemical function of HR proteins in vitro, to fully understand the roles these proteins play during repair an in vivo approach is critical. Evolutionarily, archaea are considered to be reminiscent of some of the most ancient forms of life on Earth and they share attributes with both bacteria and eukaryotes. The relationship between archaea and eukaryotes is especially close when considering mechanisms involving nucleic acid metabolism, including approaches for HR. To better understand the activities of HR-related proteins in archaea, we have used the crenarchaeon Saccharolobus solfataricus as a model. Here we describe the design of a novel in vivo inducible site-directed double-strand break assay system which incorporates the recognition site of a homing endonuclease at a specific genomic location. A double-strand break can be induced by a simple change in carbon source within the growth medium, producing a mapped, controlled break that can be directly monitored. Using antibodies specific for two HR-related proteins and chromatin immunoprecipitation techniques, we have determined the presence (and absence) of these proteins in vivo at a double-strand break for the first time. Further application of this system will expand to determine protein arrival and persistence at the break site as well as evaluation of consequences for double-strand breaks in a transcriptionally active region. These studies will increase our understanding of genomic stability mechanisms in archaea and contribute not only to archaeal research but also provide insight into the intersection of double-strand break repair mechanisms and transcription.

PRESENTER:  Jimena Ruiz, Advisor: Dr. Jennifer Watts

TITLE: Investigating the Influences of Mitochondrial Stress and Lipids on DGLA-Induced Ferroptosis in C. elegans

ABSTRACT: Ferroptosis is an iron-dependent form of regulated cell death that is characterized by a toxic buildup of lipid peroxides. Ferroptosis has been shown to have antitumor properties and is linked to several diseases including neurodegenerative, cardiovascular, and hepatic diseases. A better understanding of the mechanisms and cell biology behind ferroptosis will allow for the development of new therapeutics. The Watts lab previously discovered that the ω-6 fatty acid, dihomo-g-linolenic acid (DGLA) causes germ cell death and sterility via ferroptosis in C. elegans. Since the C. elegans germline contains a vast number of mitochondria, which are a major source of reactive oxygen species (ROS), we predict that mitochondria influence DGLA-induced ferroptosis in C. elegans germ cells. To investigate this, we will use mutant strains lacking specific mitochondrial function and perform various lipidomic analyses, such as gas chromatography/mass spectrometry and thin layer chromatography, RNA sequencing, and confocal microscopy. In this proposal, we aim to analyze the relationship between mitochondrial stress and dietary-induced ferroptosis by looking at the transcription factor ATFS-1, which is responsible for maintaining mitochondrial homeostasis in C. elegans. Secondly, we will determine if mitochondrial-generated ROS, specifically derived from the electron transport chain, contributes to DGLA-induced ferroptosis. Lastly, using the auxin-inducible degradation 2 system, we will see how the mitochondrial phospholipoid, cardiolipin, affects DGLA-induced ferroptosis in our nematode model. In conclusion, these studies will give us better insight into the influences of mitochondria on DGLA-induced ferroptosis.

The School of Molecular Biosciences prepares students for careers in science, health, and medicine.

Offering undergraduate, graduate, and postdoctoral training in biochemistry, genetics and cell biology, and microbiology.