Oral Presentations - Session 2B: UC 327
|Friday, April 11th|
Layer Specific Distribution of Cholinergic Interneurons in the Hippocampus
Elizabeth L. Catudio-Garrett
1:40 PM - 2:00 PM
Release of the neurotransmitter acetylcholine (ACh) into the hippocampus is essential for learning and memory. Lack of hippocampal acetylcholine is associated with cognitive deficits in Alzheimer’s disease. The major source of acetylcholine in the hippocampus is extrinsic and supplied by the medial septum-diagonal band of Broca (MS-DBB). However, hippocampal cholinergic interneurons may be an intrinsic source of ACh. Originally discovered using antibodies to the ACh synthesizing enzyme choline acetyltransferase (ChAT), little is known about these intrinsic cholinergic interneurons. With advances in technology, a ChATxRosa26-YFP mouse was developed that enabled the visualization of yellow fluorescent protein (YFP) in hippocampal cholinergic interneurons. The experiments were designed to investigate the localization of hippocampal cholinergic interneurons across five dimensions, spanning layers, subregions, hemispheres, ages, and gender. By identifying locations where the cholinergic interneurons are most densely populated, and identifying any differences in cell populations, one can begin to infer the physiological significance of these specialized cells. In four ChATxRosa-YFP mice, YFP+ cell counts and distributions (mean ± SEM) were recorded in serial sections in CA3, CA1 and dentate gyrus (DG) regions. We found layer specificity within CA3, CA1, and DG regions (p
The Origin of Novel Morphologies: A Case Study of a Rhinoceros Beetle
2:20 PM - 2:40 PM
The origin of novel morphological structures has mystified biologists for centuries. These often-impressive structures appear to spring into existence, without passing through any intermediate forms. An exciting recent discovery in evolutionary biology is that some novel morphologies evolve via co-option of existing gene networks. When these ancient networks are deployed in new locations novel structures can result.
Rhinoceros beetle horns are impressive novel morphologies; some horns are longer than their bearer’s body. There is evidence that dung beetles, another group of horn-bearing beetles, have co-opted the insect appendage patterning pathway (APP) for horn development. Dung beetles diverged from rhinoceros beetles roughly 150 MYA, and horns arose independently in these groups. I propose to investigate whether the APP is also responsible for horn development in the rhinoceros beetle Trypoxylus dichotomus.
RNA interference involves injecting RNA into an organism at a precise time in development. The animal’s enzyme Dicer matches this injected RNA with its own messenger RNA strands and destroys them. Destruction turns off the targeted gene during development, allowing insight into the function of that gene. I will use this technique to silence three candidate genes from the APP in larvae of T. dichotomus. The larvae will then be allowed to continue metamorphosis into adults and I will measure differences in horn characteristics.
If these genes are involved in horn development, I expect to see dramatic differences between the horns of treatment and control beetles. This would suggest that rhinoceros beetles have co-opted the insect APP. Finding no difference in horn morphology, however, would implicate a fundamentally different mechanism for horn evolution. Either way, my studies will provide critical first insights to the origins of these novel traits, and will allow a better understanding of the relative ease of co-opting existing gene pathways for various, and often novel, functions.
Mercury Contamination in the Local Osprey Population
Harrison Cooper, The University of Montana
2:40 PM - 3:00 PM
Osprey are birds of prey that feed exclusively on a diet of fish, and are therefore extremely susceptible to contamination in the aquatic systems. In particular, methyl mercury is known to be a very dangerous neurotoxin. This is part of a long-term study of osprey biology and demography, in which the current study focuses on ecotoxicology of methyl mercury in ospreys. The purpose of this study is twofold: to determine the extent of Mercury contamination in the Clark Fork River as well as to understand the effect it is having on osprey’s reproductive success. In order to accomplish this, we surveyed many osprey nests throughout the area, in both high-mercury and low-mercury watersheds. We took small blood and feather samples as well as counting the number of eggs and chicks in each nest. We also used remote control helicopters as a relatively non-invasive method for counting eggs in the nest. I also developed an interactive map to serve both for a convenient database as well as a part of public outreach. Mercury concentration in osprey blood has a significant and disturbing effect on the survivorship of osprey chicks; over half of the eggs in some nest fail to hatch. Ospreys are a useful indicator of overall river health, and this shockingly high contamination level may have severe implications for the ecosystem and human life.
Comparing the Effects of Ultrasound and Stretching on Hip Flexor Flexibility and Postural Control
3:40 PM - 4:00 PM
Context: Stretching has become a universally accepted practice used to increase flexibility, reduce muscle injury, and improve performance. In addition to stretching, modalities, such as ultrasound have been used to increase collagen extensibility, therefore increasing range of motion through deep heating. The premise for this study was to see if combining a stretching routine with ultrasound would improve range of motion (ROM) and postural control. Purpose: The purpose of this three trial study was to assess the effectiveness of both ultrasound and static stretching on hip flexor range of motion and postural control. Participant: Three males and three females between the ages of 18 and 30 were studied. All of the participants were moderately active and had not sustained an injury to their dominant leg six months prior to the study. Methods: Each participant completed all three trials (ultrasound alone, stretching alone, ultrasound and stretching combined) within one week, with a 24-hour period placed between each trial. Active hip extension and star excursion balance measurements were taken before and after each trial. Results: The 2 X 3 repeated measures ANOVA revealed no statistical significance for hip extension and SEBT (p=0.79 and p=0.13 respectively). The combo and US trials both showed a decrease in hip ROM, whereas static stretching improved hip ROM slightly (not significant). Conclusion: This research intended to determine ultrasound’s outcomes on increasing ROM and postural control in the hip flexors and how these effects could be enhanced by a stretching routine. However, the results of this study were found to be inconclusive for all three trials performed.
Novel CYP26 Inhibitors as a Treatment for Alzheimer’s Disease
4:00 PM - 4:20 PM
More than 5 million Americans are living with Alzheimer’s Disease (AD) and an American develops AD every 68 seconds. With no cures or significantly effective treatments available the number of Americans with AD is estimated to reach 7.1 million in 2025. AD is characterized by the increase in beta-amyloid plaques located in the extracellular space between the brain’s nerve cells. The endogenous chemical, retinoic acid (RA), plays a role in learning and memory and has been shown to reduce amyloid-beta plaques and rescue learning deficits associated with AD. However, the rapid metabolism of RA by hydrolase CYP26 results in a short half-life. We propose CYP26 inhibition to cause an increase in endogenous RA. Increased concentrations of RA in the brain increase the retinoic acid receptor (RAR) and retinoic x receptor (RXR) signaling pathways which contribute to learning and memory. RAR/RXR signaling plays a critical role in learning, memory and long-term potentiation by mediating synaptic transmission and potentiation in the hippocampus. With the use of a mouse model, a novel CYP26 inhibitor can be tested using pharmacokinetic and behavioral studies, such as the Morris water maze and Y maze, as a basis to measure its effectiveness as a treatment method of AD.
The role of RNase Y in rpoS transcript processing in B. burgdorferi
Richard LeCoultre, University of Montana - Missoula
4:20 PM - 4:40 PM
Lyme disease affects an estimated 300,000 Americans yearly, and, if untreated, can be deadly. Borrelia burgdorferi, the bacterium that causes Lyme disease, is likely transmitted to hosts in a process involving rpoS messenger RNA (mRNA) processing via ribonucleases (RNases). RNases are enzymes that degrade the nucleic acid RNA and are involved in many molecular processes in cells. B. burgdorferi requires a change in gene expression to transmit from its tick vector to a mammalian host. Transmission depends on a complicated cascade of regulatory factors, including the alternative sigma factor, RpoS. Sigma factors are a component of RNA polymerase, the enzyme that transcribes genes. RpoS production requires the translation of a processed rpoS mRNA; however, the mechanism by which this rpoS mRNA is processed is unknown. I am investigating whether the rpoS mRNA is cleaved by RNase Y in B. burgdorferi. Previous research in Bacillus subtilis shows that this enzyme appears to be responsible for both global mRNA stability and degradation. To this end, I am attempting to obtain RNase Y by overexpression of recombinant RNase Y with a truncated transmembrane domain and subsequent purification using the IMPACT system. I am using this purified protein to characterize the potential processing site of the rpoS mRNA by using various artificial rpoS mRNA substrates through an in vitro cleavage assay. This research will contribute to a better understanding of the transmission mechanism of B. burgdorferi and of the function of RNase Y. Additionally, this project has the potential to provide the basis for developing new antimicrobial therapies against Lyme disease. If identified as crucial to transmission of Lyme disease to hosts, the thorough characterization of RNase Y activity in processing mRNA will reveal specific targets for drug and therapy development.
Experimental Evolution of Multicellularity in Chlamydomonas reinhardtii
Jacob Boswell, University of Montana - Missoula
4:40 PM - 5:00 PM
In Life’s nearly four billion year history, organizational transitions have occurred that fundamentally altered the course of evolution. One of these, multicellularity, arose independently in at least two-dozen lineages, giving rise to a remarkable variety of complex forms. In the volvocine algal family, many transitional structures are retained in extant lineages, ranging from the unicellular, flagellated Chlamydomonas reinhardtii to the extravagant Volvox carterii, which contains as many as 50,000 differentiated cells. Many hypotheses have been suggested for the selective pressure that drove the evolution of multicellularity in this group, but none have been explicitly tested. Here, we tested the hypothesis that multicellular Chalmydomonas reinhardtii can evolve due to predatory selective pressure. By maintaining a continuous co-culture of the unicellular algae C. reinhardtii with the predatory ciliate Paramecium, we were able to select for multicellular phenotypes, due to the increased fitness of algal individuals whose size exceeds the maximum particle size of the predators. After 50 weeks of co-culture, a range of multicellular C. reinhardtii individuals were isolated from the experimental populations. As our research continues, we are implementing a number of genetic and genomic techniques to map these multicellular phenotypes on to specific coding and regulatory changes in the genome of the evolved isolates.