Tag: Poster 78

A Diversity of Endophytic Fungi Can Transfer from Host-Leaf Tissue Directly into Woody Substrates

Presenter: Aaron Nelson

Faculty Mentor: Roo Vandergrift, Bitty Roy

Presentation Type: Poster 78

Primary Research Area: Science

Major: Biology

Funding Source: UROP mini-grant $1000; UnderGrEBES award, GrEBES (Graduate Evolutionary Biology and Ecology Students) $500

Endophytes are defined as fungi that grow within plant tissues without causing disease symptoms. Virtually all terrestrial plants on earth possess endophytic fungi, and while some benefits for the plant hosts have been observed, the benefits for many of the fungal partners are still unknown. One hypothesis is that endophytic fungi within leaves gain enhanced dispersal abilities to other substrates when the leaves fall. This would require that endophytes have the ability to transfer from leaf-tissues into other substrates such as woody litter. We set out to test the presence of this ability and to gain an initial glimpse of how widespread this ability may be among fungal endophytes. We accomplished this by surface-sterilizing leaves from an evergreen tree (Nectandra lineatifolia) and placing leaf fragments onto pieces of sterilized birch wood, giving endophytes an opportunity to colonize the wood. Fungal cultures were then grown out of the wood onto agar plates and isolated, resulting in 477 fungal isolates, 64 of which we determined to be morphologically distinct from one another. The DNA from each morphotype was extracted and amplified and is currently being analyzed. Our finding that a multitude of fungal endophytes can readily transfer to a woody substrates suggests that endophytism may play a major roles both in the dispersal of fungi and in the ecology of decomposition in forests in general.

Abundance & Composition of Sponges, Algae, and Oysters on Mangrove Prop Roots: Effects of Location in Bocas Del Toro, Panama

Presenter(s): Ellie Jones − Marine Biology

Co Presenter(s): Emily Bork

Faculty Mentor(s): Richard Emlet

Poster 78

Research Area: Marine Biology

Funding: Global Education Oregon Mills Scholarship

Mangrove forests create an important community at the interface of land and sea. Since 1980, 20-35% of global mangrove area has been lost due to deforestation, aquaculture, and pollution. Degradation or loss also impacts the marine communities living on the prop roots. In this research, we studied mangrove communities near the Bocas Research Station of the Smithsonian Tropical Research Institute (BRS-STRI) in Panama to determine if the abundance and composition of prop root epibionts vary with proximity to human development. We hypothesized that sponge, algal, and oyster abundance will increase with proximity to human development due to higher nutrient content, but sponge species richness will decrease due to conditions that can only be tolerated by one or a few dominant species. We took water quality and biological measurements from a village site, adjacent to a human-occupied shoreline, and a reserve site, in the vicinity of BRS-STRI. Water quality measurements included temperature, salinity, pH, water clarity, and organic matter. Biological measurements included sponge, algae, and oyster abundance, as well as sponge color and morphotype. There were a greater number of sponge species at the reserve than the village site. Temperature was higher at the reserve site, but no other abiotic factors differed. Turf algae was more abundant at the village site, but no other epibionts differed. Our work is significant because mangrove communities are particularly vulnerable to environmental stressors. It is important to identify potential bioindicators of environmental stress in these ecosystems to be able to adequately monitor further change.

Understanding the mechanisms of gp32 filament assembly and sliding on ssDNA templates of known length and polarity

Presenter(s): Megan Barney

Faculty Mentor(s): Andrew Marcus

Poster 78

Session: Sciences

DNA replication is a core biological process that rapidly occurs in both eukaryotic and prokaryotic cells with extreme precision. Gene product 32 (gp32) is a ssDNA binding protein that is important in theT4 bacteriophage DNA replication complex. gp32 is known to bind cooperatively spanning 7 nucleotides of ssDNA. Not only is it known to bind, but it has the ability to unbind from regions of exposed ssDNA during DNA synthesis. This thesis reports microsecond single-molecule FRET (smFRET) measurements on Cy3/Cy5-labeled primer- template (p/t) DNA constructs with and without an addition of 0.5uM gp32. The measurements obtained report the distance between the chromophores that are used to label the ends of 14 and 15 nucleotide segments of ssDNA attached to a p/t DNA construct. These distance measurements can track the conformational changes seen between protein bound vs. unbound states on the microsecond time scale. To analyze the data, a multipoint time correlation function analysis is utilized in order to compare the revealed kinetics of the possible conformational adaptation experienced by the ssDNA of interest. The results of our analysis demonstrate that both length and polarity of the ssDNA influence the way in which gp32 interacts with the ssDNA. Therefore, this SSB is likely to play a critical role at the replication fork during DNA synthesis.