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Biology Projects

Biology

Do bacteria found on the skin of the Pacific tree frog (Pseudacris regilla) play a role in protecting the frogs from fungal disease?

Dr. Kathy Szick

Chytridiomycosis, a disease caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd), is causing a major decline in amphibian populations worldwide. Interestingly, some species will survive and co-exist in the presence of Bd. Our previous research reveals that bacteria associated with the skin of the North American Bull frog (Rana catesbeiana) and the California toad (Bufo boreas halophilus) secrete antifungal compounds, which may play a role in protecting their host. We have also observed that in the Southern San Joaquin Valley, the Pacific tree frog (Pseudacris regilla) is thriving despite the presence of this invasive pathogen. The success of the Pacific tree frog may be attributed to the commensal bacteria living on their skin. Given that for humans and other animals, skin acts as the first barrier of defense, we hypothesize that the bacteria found on the skin of the Pacific tree frog will inhibit the growth of Bd. Furthermore, we believe that the cutaneous bacteria may inhibit the growth of known amphibian and human pathogens. This project aims to identify each bacterial isolate that demonstrates antifungal properties by using DNA sequence analysis, and examining the diversity of cutaneous antifungal microbes. Antifungal bacterial isolates detected in this project may have the potential to widely impact global amphibian conservation and but more importantly their metabolites might be useful for novel chemotherapeutics to combat human diseases.

Genetic Diversity of Wolbachia in phorid flies

Dr. Paul Smith

Wolbachia is a genus of bacteria which infects arthropod species, including a high proportion of insects, as well as some nematodes. It is one of the world's most common parasitic microbes and is possibly the most common reproductive parasite. Its interactions with its hosts are often complex, and in some cases have evolved to be mutualistic rather than parasitic. Some host insect species cannot reproduce, or even survive, without Wolbachia infection. This project will examine Wolbachia genetic diversity within the host fly genus Anevrina. The goal is to compare host and parasite phylogenies and examine any coevolutionary patterns that exist between the two lineages.

Water transport and wood structures in campus trees.

Dr. Anna Jacobsen

Water is transported in plants through vascular tissue called xylem. Within the xylem water moves through special water conducting tubes composed of vessel element cells. The structure of these cells is an important determinant of tree water use and also impacts the biomechanics of the wood of trees. This summer we will be conducting measures of the structure and anatomy of vessel elements within several species of trees growing on the California State University, Bakersfield campus. We will also be measuring the length of the water transport vessels and the biomechanics (strength and rigidity) of wood samples. These data will be combined with ongoing measures of tree drought tolerance and water transport efficiency. This research is part of a multi-year funded grant project designed to examine xylem vessel structural traits as they relate to the xylem's ability to efficiently and safely transport water. Although knowledge of xylem vessel structure and function is important in understanding plant water use and water transport, the structure of vessel networks remains little studied. The overarching hypothesis to be tested is that vessel structure determines xylem hydraulic function.