Mitochondrial dysfunction and oxidative stress have been proposed to contribute to organismal aging. In the nematode C. elegans, reduction of mitochondrial function through knockdown of genes encoding components of the electron transport chain (ETC) is sufficient to increase life span. The increased longevity is not solely the by-product of decreased oxidative damage generated by the ETC, but also involves induction of the mitochondrial unfolded protein response (UPR^mt), as evidenced by the observation that life span extension requires an intact UPR^mt. The cytoplasm, endoplasmic reticulum, and mitochondria have each evolved compartment-specific signal transduction pathways to alter nuclear gene expression in response to perturbations in protein homeostasis. However, little is known about the UPR^mt and the mechanism by which unfolded proteins are recognized in the mitochondria and signal changes in gene expression. Previous studies demonstrate that knockdown of ETC components and a subset of mitochondrial proteins induce the GFP reporters for mitochondrial chaperones hsp-6 and hsp-60. To identify novel genes involved in the UPR^mt, we are performing a forward genome-wide RNAi screen using the hsp-6::GFP reporter and measuring UPR^mt activity by fluorescent microscopy. Upon completion of the screen, we expect positive hits to include mitochondrial proteins, signaling molecules, and transcription factors that regulate the UPR^mt. Consistent with previous studies, gene knockdowns that have robustly induced the UPR^mt thus far in our screen are largely components of the ETC. In addition, the screen has yielded many novel hits including genes outside of the mitochondria and of unknown function. After the screen is complete, we will validate the RNAi clones that induce the UPR^mt and perform lifespan experiments to understand how the UPR^mt is involved in the aging process. Our screen will further understanding of how the mitochondria and nucleus communicate with one another in order to maintain mitochondrial proteostasis and illuminate how mitochondrial stress contributes to aging.

Over the past few decades the budding yeast Saccharomyces cerevisiae has emerged as a prominent model for aging research. One method for measuring aging in yeast is to determine the replicative life span (RLS) of mother cells, defined as the number of daughter cells produced prior to irreversible cell cycle arrest. The Kaeberlein Lab Dissection Team has measured RLS for hundreds of thousands of yeast mother cells over the past few years. In addition to RLS, we have also recently began recording the budding pattern at end of life as an additional phenotype of interest since these mutations have been known to lead to irregular cell cycle regulation. 4 different categories are used to define the terminal morphology of yeast cells: unbudded (U), small bud (S), long bud (L), and clumped (C). From the data gathered thus far, a positive correlation has been made between the terminal budding pattern of cells with reduced RLS compared to their unbudded counterparts. Meaning contructs that stop replicating mid cell cycle (S, L, or C) live shorter lives. We speculate that genomic instability contributes to terminal arrest in the budded state, but further research needs to be conducted to confirm this theory. It will also be of interest to determine how specific genetic defects lead to altered frequencies of the 4 different terminal morphologies and their relationship to replicative life span.

Shrimp waste-water (SWW) is rich in nutrients that include both phosphorus and nitrogen. A significant amount of money is spent by aqua culturists to eliminate these macronutrients before the water is released into the environment. In this study, we determined whether algae, which need phosphorus and nitrogen to grow, of commercial value (e.g., for biofuel, aqua feeds or neutraceutical production) can be maintained in this waste-water stream. Experiments tested for the ability of SWW to support algal growth when these organisms were grown in: (1) COREs media (control) as well as (2) SWW media (experimental) that contain: (a) no phosphate, (b) no nitrate, or (c) no nitrate or phosphate addition(s). Three algae that grow in marine waters were tested: B. chromulina, UWC 695, and Isochrysis galbana (UWC635) in each of the medium types listed above. Cell counts were taken regularly throughout the course of algal culture growth using a BD Flow cytometer. Neutral lipids and lipid profiles were measured using BODIPY 505/515 dye and Gas chromatography–mass spectrometry (GC/MS) analysis respectively.