Biological Sciences Projects

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Track 2A - Oral Presentations

Climate change is an imminent threat to biodiversity, as evidenced by population declines in many climate-vulnerable species. In addition to long-term occupancy studies, an increasingly-popular monitoring method is non-invasively analyzing individual stress via fecal glucocorticoid metabolites (GCM). The American pika (Ochotona princeps) is a small lagomorph that is sensitive to rising temperatures and has experienced declines in parts of its range. However, a unique population exists in the La Sal Mountains of southern Utah; this population is predicted to be vulnerable because of its isolated nature and southern latitude. To determine relative stress levels among pikas in this unique population, we collected pika scat along elevational transects during summer 2019. We then used an information theoretic framework (AICc) to test competing hypotheses related to the effects of climate, biogeography, and habitat area on pika physiological condition (GCM) along elevational gradients. Elevation was the single strongest predictor of fecal GCM, with higher stress at higher elevation. Although seemingly counterintuitive, 2018-2019 saw abnormally high snowpack and avalanche activity, which reduced food availability in the spring and shortened the haying season at high elevation. These results advance the investigation of how climate-sensitive species respond to climate change and its unpredictable nature.

Members of the soil-dwelling bacterial genus Streptomyces are primarily known for their production of secondary metabolites. These filamentous, spore-producing bacteria are widely distributed in soil and cause various diseases in animals and plants. Dictyostelids are soil-dwelling amoebae that obtain energy and nutrients by consuming bacteria, but potential interactions with streptomycetes have not been extensively studied. We have isolated streptomycetes and dictyostelid strains from a variety of local soils and have begun to identify them. At least one dictyostelid grows when spores from the Streptomyces strains with which they were co-isolated are provided as the sole energy source, and we continue to assess potential interactions. These experiments are important for establishing a better understanding of predator-prey interactions within the soil, for understanding biology of the amoebae, and perhaps for understanding virulence in Streptomyces strains that can cause disease.

Photuris fireflies exhibit an evolutionarily novel photic organ for which the underlying genetic regulation remains unknown. The photic organ is a posterior-ventral structure that serves to catalyze and reflect luminescent reactions. An important feature of the photic organ is that it is overlain by a depigmented cuticle that facilitates luminesce transmission during courtship rituals. However, the genes responsible for the depigmentation remain unidentified. In Drosophila melanogaster, the genes black and ebony are known to repress cuticular pigmentation. We hypothesized that these functions are conserved in Photuris fireflies and that one or both genes have been recruited in the depigmentation of the photic organ’s cuticle. We used RNA interference (RNAi) to intentionally inhibit expression of each target during pupal development. Microscopic examination of the adult RNAi individuals suggests that ebony is involved in the depigmentation of the cuticle surrounding the photic organ of female fireflies, while black is suspected to be involved in pigmentation patterning of the ventral thorax and appendages. These results suggest that photic organ pigment repression is complex and sex-specific in Photuris fireflies.

Track 2B - Poster Presentations

Dictyostelium discoideum is a soil dwelling amoeba that is commonly studied due to its unique life cycle in which starving amoeba aggregate to form multicellular reproductive structures, called fruiting bodies. Although the life cycle has been studied extensively in the laboratory, less is known about the biology of these amoebae in soil. I have assessed whether Dictyostelium amoebae consume Streptomyces bacteria to understand the role of these social amoeba in soil. Streptomycetes are filamentous spore-producing bacteria, found in virtually all soils, that are known for their production of secondary metabolites. These metabolites have antibacterial and antifungal activities. My experiments show that Dictyostelium amoebae are capable of growing when spores from one of several Streptomyces species are supplied as the only food source. All strains tested support growth of the amoebae. These experiments suggest that Streptomyces spores may be a major food source of amoebae in soil and that the amoebae may be a good model to understand microbiological predator-prey relationships in soil.

There has been a global decline in amphibian populations and one major contributor is the fungus Batrachochytrium dendrobatidis (Bd), which causes the disease chytridiomycosis. This pathogen infects the skin of amphibians where it can inhibit electrolyte and gas exchange, ultimately leading to death. There are multiple methods of disease management including laboratory treatments and fungicide applications. However, many of these strategies are either ineffective or unsafe. Recent research has shown that the bacteria Bacillus thuringiensis, found in agricultural biopesticides, produces antifungal volatile organic compounds (VOCs). If Bd growth is inhibited by these VOCs, then there should be reduced Bd growth when B. thuringiensis and Bd are grown adjacently. Bd was plated alongside B. thuringiensis in a divided petri dish and incubated for 14 days. Photos of each plate were analyzed using Image J to assess percentage of Bd cover. Results indicated that B. thuringiensis VOCs significantly inhibited growth of Bd when compared to control plates. This suggests that a widely used biopesticide may be helpful in disease prevention for amphibians with overlapping habitat. This research is an important step towards developing effective disease management strategies for amphibians using common agricultural products.

According to the total body score system, decomposition of human remains can be broken up into four stages: fresh, early decomposition, advanced decomposition and skeletonization. The timing and characteristics of these stages vary in different environments (i.e. wet vs. arid environments). At Colorado Mesa University’s Forensic Investigation Research Station (FIRS) the decomposition of human remains is observed with the goal of understanding how the process occurs in an arid, high desert environment. The aim of this study was to identify different fungi growing on human remains at FIRS. Tissue samples were taken from skin and bone and plated for continued growth in culture. Five different fungal species were identified based on morphological characteristics and grown in pure culture. DNA isolation, amplification and sequencing analyses were used to confirm the identity of each fungus based on their genetic sequences. Using the confirmed identity of each fungus, we hope to conduct further research into the role of fungi in the different stages of decomposition, as well as the differences in fungal growth in different environments. Understanding the role of fungi in decomposition can aid in forensic investigations and determination of the post mortem interval in different crime scene environments.

Batrachochytrium dendrobatidis (Bd) is a fungal pathogen that has led to declines in amphibian populations worldwide. Some amphibians are protected from Bd infection by bacteria that they acquire from their environments. Bacillus thuringiensis (Bt) is a common soil bacteria that makes antifungal and antibacterial metabolites. We hypothesized that the presence of these metabolites in the liquid culture would inhibit the growth of Bd. Secondary metabolites were isolated from two Bt subspecies and tested against the Bd fungus in vitro. The secondary metabolites were extracted from broth cultures of Bt and used in a spectrophotometric growth assay against Bd for one week. It was found that when the metabolites were added to the liquid culture of Bd, the fungus grew better than the control group. The mechanisms by which the increased fungal growth is caused are unknown, but a possible explanation may lie in the signaling capabilities of Bd. Perhaps the fungus is capable of sensing the secondary metabolites and activating transcription factors thus, increasing cellular growth. This effect has been observed in other fungal studies utilizing secondary metabolites. Future studies may involve Bd signaling competency for both competition and growth factors.