Tag: Poster 68

The Effect of a Patent Foramen Ovale on Thermoregulatory and Ventilatory Responses During Passive Heating and Cooling

Presenter: Madeline Hay

Faculty Mentor: Andrew Lovering, Louise Bishop

Presentation Type: Poster 68

Primary Research Area: Science

Major: Human Physiology

A patent foramen ovale (PFO) is an intracardiac shunt present in ~1/3 of the population that allows blood flow to bypass pulmonary circulation which may reduce respiratory cooling. During passive heating, ventilation increases to dissipate heat from the lungs. Because individuals with a PFO (PFO+) have a higher core temperature (Tcore), it was hypothesized that PFO+ subjects would increase ventilation at a higher Tcore than subjects without a PFO (PFO-) during passive heating and would shiver at a higher Tcore during passive cooling. 22 males (11 PFO+, 11 PFO-) completed a passive heating and passive cooling trial. For passive heating, individuals were immersed in a 40°C water bath until 1) 30 minutes elapsed, 2) Tcore reached 39.5°C, 3) they felt lightheaded or 4) they requested to exit. For passive cooling, individuals were immersed in a 20°C water bath until 1) 60 minutes elapsed, 2) Tcore reached 35.5°C, 3) sustained shivering occurred or 4) they requested to exit. In both trials, PFO+ had a higher Tcore. During passive heating, PFO+ had a lower ventilation than PFO-. Additionally, PFO+ shivered at a higher Tcore than the PFO-subjects during passive cooling. The results suggest that PFO+ have a higher Tcore and that this greater temperature is defended in both hot and cold environments. A PFO may be beneficial by preventing hypothermia but detrimental by facilitating heat stroke.

Petrographic and Geochemical Correlation between Central Oregon Dikes and Flows to the Columbia River Flood Basalts.

Presenter(s): Olivia Andersen – Geological Sciences

Faculty Mentor(s): Ray Weldon

Poster 68

Research Area: Natural Science

Funding: Presidential Undergraduate Research Scholars Program (PURS Program)

Central Oregon is made up of numerous basalt flows and dikes, having been produced from multiple volcanic events. While much of the basalt in the region has been mapped Picture Gorge Basalt of the Columbia River Flood Basalts, the local dikes may have a different source than the type area Picture Gorge Basalt. To further correlate or distinguish the local dikes from the basalt flows in the Central Oregon region, we used petrographic features observed from thin sections and compared the geochemistry of two dike samples to the geochemistry of various local basalt samples.

From the X-Ray Fluorescence (XRF) data of each sample, we produced plots that showed relationships and trends between our samples. There are three clusters in our plots. One cluster contains the dike samples and one of the PGB samples. These samples are abundant in TiO2, P2O5, SiO2 and K2O while having low percentages of MgO, Al2O3, and CaO. The second cluster consists of five PGB samples, with low measures of TiO2, P2O5, SiO2 and K2O while containing higher traces of MgO, Al2O3 and CaO. The last two basalt samples makes a third cluster of data points, which generally falls in the middle of the trend line created by the two clusters mentioned earlier.

The Petrographic features observed further explain the geochemistry. The dike and NR1 samples are a mixture of glass, albite, and few orthoclase grains, resulting in higher oxide content of SiO2, K2O and Na2O were as the cluster of five PGB samples have higher percentages of large pyroxene grains and fewer plagioclase grains and glass, resulting in higher traces of MgO, Al2O3 and CaO.

All samples plot within Grande Ronde Basalt boundaries, which have high silica content and MgO contents ranging from 2.5- 6.5 wt% and TiO2 ranging from 1.6-2.8 wt% (Reidel 2013). Plotting TiO2, P2O5, MgO and K2O offer the most reliable indicators used to identify and distinguish flows (Reidel 2016, Hooper 2000). To further our study, we compared the geochemistry of the PGB to other flow events of the CRFB, such as the Steens and Imnaha basalts. Both the Steens and Imnaha basalts plot below the Grande Ronde Basalt on an alkali vs. silica plot (Camp 2013), indicating that the dikes in Central Oregon are indeed Picture Gorge Basalt.

Mechanisms of sister chromatid repair during meiotic double-strand DNA break repair

Presenter(s): Anna Horacek

Faculty Mentor(s): Diana Libuda & Erik Toraason

Oral Session 3 M 

Poster 68

Session: Sciences

Most sexually reproducing organisms utilize meiosis, a specialized form of cell division, to generate haploid gametes such as eggs and sperm. Meiotic cells utilize recombination to repair double-strand DNA breaks (DSBs) with either the sister chromatid or homologous chromosome as a repair template. Although recombination with the homologous chromosome has been extensively studied, little is known about engagement of the sister chromatid during meiotic DSB repair. To characterize sister chromatid recombination, we have developed a sister chromatid repair (SCR) assay in Caenorhabditis elegans. The SCR assay contains engineered nucleotide polymorphisms enabling the detection of gene conversions between sister chromatids, which arise from the nonreciprocal exchange of sequences between chromosome templates and indicate recombination intermediates. Analysis of these conversions tracts indicate that throughout meiotic prophase I: 1) sister chromatid repair intermediates remain central to the site of DSB induction; and, 2) sister chromatid repair is highly processive, as template switching is not observed. Interestingly, the length of conversion tracts, indicating the extent of DSB resectioning, changes in the presence of a homolog repair template. In the absence of a homolog repair template, the conversion tract size is uniform throughout prophase I. When a homolog repair template is present, large conversion tracts (>210bp) are observed only in late prophase I, suggesting the presence of the homolog repair template may affect the extent of DSB resectioning in late prophase I. Taken together, our work presents a comprehensive analysis of meiotic sister chromatid recombination and defines mechanisms fundamental to the preservation of genomic integrity.