Tag: Poster 56

The Role of the BAF Chromatin Remodeling Complex during Heart Valve Development

Presenter : Maithri Sarangam

Mentor : Kryn Stankunas

Major : Biology

Poster 56

Human heart valves are remarkable structures that open and close billions of time during a lifetime. Like any structure under constant mechanical strain, their shape and molecular composition are finely tuned to maximize efficiency and longevity. The development of these valves must also be finely tuned to produce proper the shape and composition, or dangerous health consequences may arise. We are studying the developmental processes of valve formation. Particularly, we are interested in the role of the BAF chromatin remodel- ing complex. Chromatin refers to the complex of DNA and histone proteins. Cell nuclei contain a series of cylindrical histone com- plexes, around which DNA is wrapped. The structure resembles a single thread wrapped around a series of spools with approximately
2 loops per spool. The BAF complex regulates gene expression by altering nucleosome positioning. We believe the BAF complex is required for the proper development of the aortic and pulmonic valves. We used mouse models and complex mouse genetic techniques to study the role of the BAF complex on mammalian heart valve development. Using a crelox system, we caused a loss of function of the BAF complex by knocking out Brg1, the key ATP-ase required for the complex to function. We then used various staining methods to study the resulting phenotype at different time points during the later stages of development. The results suggest that the BAF complex is required for proper organization of the valve shape and molecular composition.

Paleoecology of the Enigmatic Rhinoceros Chilotherium in Central Asia

Presenter: Selina Robson

Mentors: Samantha Hopkins and Edward Davis, Geology

Poster: 56

Majors: Geology and Psychology 

We report a new occurrence of the rhinocerotid Chilotherium in the Kochkor basin in Kyrgyzstan. While some geologic reports refer to Chilotherium in Kyrgyzstan, no described material exists from the country and all published material has gone missing. Therefore, our new material is important for not only recognizing the occurrence of the genus, but also understanding the evolution, ecology, and dispersion of various fossil taxa including Chilotherium. Few studies have examined the global distribution of Chilotherium. While the taxon is not uncommon, we found that 84% of Chilotherium specimens were found in China. Thus, the Kyrgyz specimens represent an important geographic extension of the taxon, and may clarify the relationship between ecology and species diversity. Our database of Chilotherium occurrences only reports localities above 2,000m elevation. While paleoaltitudes may be different than modern altitudes, recent studies support the construction of both the Himalayan and Tien Shan ranges prior to the late Mio/Pliocene. This indicates that Chilotherium occupied an ecological niche that is different from other rhinos. Of the collected fossils from Kyrgyzstan, Chilotherium is the most abundant taxon. A species level diagnosis of Chilotherium is difficult because the taxonomy is poorly constrained. There are three valid species but close to 20 published species. By mapping occurrences globally, we hope to clarify taxonomic relationships as well as to assign the new Kyrgyz material to a species level.

The Hepatopancreatic Duct: A Conduit for Bacterial Factors from the Gut to Reach Peripheral Organs?

Presenter: Daniel Derrick

Co-Presenters: Jennifer Hampton, Karen Guillemin

Faculty Mentor: Karen Guillemin, Jennifer Hampton

Presentation Type: Poster 56

Primary Research Area: Science

Major: Biology

Funding Source: NIH: National Institute of General Medical Sciences grant, award number P50GM098911, $162,152

Host-microbe interactions are important for normal development of the host, and often, secreted bacterial products play essential roles in these interactions. In zebrafish, the protein BefA is secreted by a subset of resident bacterial species in the gut. Interestingly, BefA is sufficient to induce expansion of pancreatic beta cells during early larval development. Previously, BefA has also been shown to have effects on cultured murine beta cells, suggesting that it may have a direct mechanism of action. This raises an intriguing question: how can a protein secreted by bacteria in the lumen of the gut exert effects on an entirely separate organ? For BefA to act directly on beta cells in vivo, it must somehow travel from the gut to the pancreas. Here, we examined whether a functional hepatopancreatic duct, which connects the pancreas to the gastrointestinal tract, is necessary for BefA-mediated expansion of beta cells. To do so, immunofluorescence labeling and confocal microscopy were used to count pancreatic beta cells in zebrafish that lack an intact hepatopancreatic duct due to a loss-of-function mutation in the sox9b gene. Despite the lack of this duct, sox9b mutants still exhibited a robust response to BefA treatment, which suggests that BefA promotes beta cell expansion independent of the hepatopancreatic duct.

Monitoring Squirrel Populations at LCC Campus Using Ink Tunnels and Hair Tubes

Presenter(s): Mallory Roberts − Biology

Faculty Mentor(s): Stacey Kiser

Poster 56

Research Area: Biology

Student researchers at Lane Community College have studied and monitored a vast array of species on campus over the past several years. While the presence of squirrels may seem ubiquitous in this area, we don’t have much data regarding species distribution and population on campus. Easy access to such information allows for further student research and may encourage interest in squirrels and squirrel-related activities on college campuses (survey). Over the course of two terms, squirrel populations were monitored in different areas of LCC Campus using two different methods. The first method captured tracks of small mammals by using an ink tunnel. Ink was placed on the outside of the tunnel with paper inside, allowing the animals to walk through and track the ink onto paper. Peanut butter and birdseed were used inside the tunnel as bait. One tunnel was placed at each of three locations throughout campus, and a game camera was placed outside of each tunnel. I was able to confirm tracks of both mice and squirrels with this method. I observed squirrels at locations closer to the wooded area near the south parking lot and chose to explore this area further. During the second term, I selected a different method using hair tubes which were constructed with PVC pipes measuring approximately two feet in length (61 cm) and three inches diameter (8 cm). I placed three wood pieces (shims) approximately two feet in length inside the pipe and secured them using a drill and screw, and double-sided tape was placed on the wood at each entrance to the pipe. The tape captured hairs from animals that entered the tubes, allowing for another method of identification. Peanut butter and bird seed were again used as bait. I selected two locations within the south woods and placed three hair tubes near each other in both locations. Each tube was secured vertically on a tree trunk, approximately five feet from the ground. A game camera monitored each location. Using photographs along with identification of tracks and hairs, I was able to affirm the presence of several different species at LCC main campus. Townsend’s chipmunks (Tamias townsendii) visited the south woods sites most frequently and appeared during both fall and winter terms. I also confirmed sight of a fox squirrel (Sciurus niger) and a western grey squirrel (Sciurius griseus) in the south woods. I captured images of other species throughout this project, including a gray fox (Urocyon cinereoargenteus), crows (Corvus brachyrhynchos), and turkeys (Meleagris gallopavo). Data collected regarding squirrel species and population will be entered into a national database used for research on college campuses.

References: Peplinski, J. and Brown, J. “Campus Squirrels”. Survey.

Connexins are not responsible for specification of the electrical synapse

Presenter(s): Elisa Trujillo

Faculty Mentor(s): Adam Miller & Abagael Lasseigne

Poster 56

 Session: Sciences

In order to initiate synaptogenesis two cells must come together and undergo intracellular communication; both can be done through a protein with cell adhesive properties. At chemical synapses, extracellular cell adhesion molecules allow two neurons to communicate in order to recruit compatible pre- and postsynaptic machinery. By contrast little is known about electrical synapses, where gap junction channels physically couple neurons. Transmembrane gap junction proteins at the electrical synapse, Connexins, have adhesive properties. We hypothesized that Connexins are required to initiate electrical synapse formation. To investigate this we created Connexin mutant animals and assessed whether or not a highly stereotyped electrical circuit containing Mauthner neurons was still morphologically normal. We used the localization of the required scaffolding protein, Tjp1b, as an indicator for electrical synapse specification. Connexin proteins are co-dependent; without one Connexin the other is unable to localize to the synapse. I tested the requirement of the pre- and postsynaptically required Connexin proteins for normal neuron morphology and Tjp1b localization by selecting fish with green fluorescent protein (GFP) positive Mauthner neurons and immunostaining zebrafish larvae for Tjp1b, and GFP in animals with non-functional Connexin proteins. Despite the loss of Connexins, Tjp1b still localized at the potential electrical synapse site and the morphology of the Mauthner neuron remained normal. Thus, Connexins do not appear to be the proteins responsible for electrical synapse initiation. My future work will aim to identify the protein with cell adhesion properties necessary for electrical synaptogenesis.