Tag: Poster 59

The Effect of Different Light Wavelengths on the Dust Microbiome

Presenter: Andy Siemens

Mentors: Jessica Green and Erica Hartmann, Biology

Poster: 59

Major: Biology 

Different light treatments affect the growth of certain bacterial strains in the built environment, however little is known about the effect of light on an entire bacterial community. The goal of this study is to investigate the impact of UV vs. visible light on the viability of the dust microbiome. We developed a method to quantify viable dust by treating samples with the DNA-binding agent propidium monoazide (PMA), which prevents the amplification of DNA from non-viable cells during polymerase chain reaction (PCR). This technique was used to determine the amount of DNA from live vs. dead cells by comparing amplified 16S gene copy numbers with and without PMA treatment using quantitative PCR (qPCR). As a pilot study, dust samples were treated with broad-spectrum light to determine the appropriate dosage for killing dust microbes. The built environment was simulated using light boxes designed by the Energy Studies in Buildings Laboratory. Experiments were performed in triplicate using identical box setups for each trial. In future experiments, the relationship between different wavelengths of light and bacterial viability will be tested by subjecting dust samples to sunlight with UV wavelengths removed, sunlight with visible and infrared wavelengths removed, and dark conditions. The results from these studies will influence the choice of light filtering in windows for buildings such as hospitals where the elimination of pathogens is extremely important.

Do Chiton Larvae Have Kidney Stones? Unidentified Crystal Structures in the Larval Development Of Mopalia Hindsii

Presenter(s): Christina Ellison − Marine Biology

Faculty Mentor(s): Richard Emlet

Poster 59

Research Area: Natural Science

Funding: National Science Fund (REU program)

Chitons are marine molluscs in the class Polyplacophora. Like many marine organisms, chitons have a pelagic, dispersive larval stage which settles and metamorphoses into an adult form that lives on the benthos. During development, chitons must acquire structures that enable them to function in each of these environmental contexts. While many features of development have been well documented, one structure has yet to be reported. Chiton larvae consistently form a pair of birefringent, crystalline structures, best viewed with cross-polarized light. What they are made of and their function in the animal are unknown. The location and timing of these structures appear consistent with the “larval kidneys” as described by Baeumler et. al 2011, so we hypothesized they could be involved in kidney function. The purpose of this study was to establish a developmental timeline for these structures, to determine their chemical composition, and to record morphological data concerning their appearance (size, shape, number, location). This was achieved by raising chiton larvae and monitoring their development through microscopy. Calcein-tagging, fluorescence microscopy, and a murexide test were used to infer chemical composition. Our results suggest the structures form 4 days post-fertilization and persist at least 5 days after metamorphosis. The structures are composed of many small, calcium-containing crystals. They have been observed in 7 species across 2 suborders and may be a universal feature of chiton development. Our findings are consistent with possible kidney involvement, but functional studies must be done to further support this idea.

Reduced success of S. purpuratus fertilization under low pH conditions

Presenter(s): Clara Rehmann

Co Presenter(s): Joe Dahlke

Faculty Mentor(s): Lisa Munger & Caitlin Plowman

Poster 59

Session: Sciences

The oceans serve as an important carbon sink, but rising amounts of dissolved carbon are reducing their pH. Projections anticipate a decrease in mean surface pH from 8.07 to 7.67 by 2100, and some regions are already experiencing pH fluctuations with lows below 7.15 units. Studies have demonstrated Strongylocentrotus purpuratus urchins to be evolving in response to acidifying conditions, but successful spawning amongst this species may be inhibited by more acidic seawater. To determine the effect of reduced pH on fertilization success, we simulated spawning by mixing collected gametes in seawater solutions of decreasing pH and assessed eggs for fertilization using a compound microscope. We found that mean percent fertilization decreased significantly from pH 8.06 (M=98%, SD=1.81) to pH 7.00 (M=84%, SD=12.33) seawater; t(8)=-2.52, p=.026. Natural pH fluctuations combined with ocean acidification could bring pH levels below 7.00 in the near future, possibly inhibiting the success of S. purpuratus reproduction. The resultant decline in urchin populations would have negative consequences for the Pacific kelp forests in which this species lives and could disrupt these fragile ecosystems.