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«Strengthening the Nation through Diversity, Innovation & Leadership in STEM San Antonio,Texas · October 3-6, 2013 Get Connected! Connect with the ...»

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Obesity has become a rising problem affecting one-third of the US population. It is connected to conditions such as diabetes, high blood pressure, and cancer. Males and females gain weight differently with males gaining more visceral fat and females gaining more subcutaneous fat. Sex differences in body weight and adiposity have been studied from the viewpoint of sex chromosomes and gonadal hormones. Previous work using the four core genotypes (FCG) model shows that the number of X chromosomes in particular affects weight gain when gonadal hormones are absent. The FCG model is composed of XX and XY mice with testes (gonadal male) and XX and XY mice with ovaries (gonadal female). The XX gonadectomized mice show higher levels of weight gain and adiposity than the XY gonadectomized mice and also show more food intake during their inactive phase than the XY mice. Here the hypothesis was that weight gain and adiposity are a result of a higher intake of food during the inactive phase. To test the hypothesis, mice were prevented from eating during the inactive phase. Two groups were compared, one group of XX mice eating ad libitum and another group of XX mice eating only during the active phase. If the XX and XY mice show no difference in weight gain and adiposity when there is no inactive-phase eating, it can be concluded that the number of X chromosomes influences feeding rhythms that might contribute to the accumulation of body fat.




Jamie Garcia, Xin Li, Jinxiu Lu, Yin Tintut.

University of California, Los Angeles, Los Angeles, CA.

A high fat diet over an extended period of time can cause hyperlipidemia. Hyperlipidemia, the consistently high concentration of low-density lipoprotein (LDL), or lipids, in the blood, causes an accumulation of lipid oxidation products in the subendothelial spaces of arteries and bone. Prolonged accumulation of these lipids leads to oxidative modifications and elicits an inflammatory reaction. This project is investigating the possibility that oxidant stress is mediating the pathway from oxidized lipid to parathyroid hormone receptor (PTH1R) expression. This pathway is important because if PTH1R expression is reduced, downstream processes such as osteoblastic differentiation will be affected. Evidence suggests that the presence of hyperlipidemia reduces PTH1R expression. The inflammatory lipids inhibit osteoblastic differentiation and decrease response to intermittent parathyroid hormone treatment (iPTH).

The hypothesis is that oxidant stress mediates the effects of inflammatory lipids on PTH1R expression in osteoblasts.

Calvarial preosteoblasts (MC3T3-E1) were plated to determine PTH1R gene expression at 2, 4, 6, 8, 10, and 12 days


by real-time RT-qPCR. This PTH1R time-course experiment showed that expression of the PTH1R gene peaked after 4 days. MC3T3-E1 cells were also plated and treated with the enzyme xanthine oxidase (5 mu/mL, 10 mu/mL, and 25 mu/mL), and the substrate xanthine (25 uM). Xanthine and xanthine oxidase (XXO) are known to produce oxidant stress. Results showed that PTH1R expression was inhibited in a dose-dependent manner by XXO. Pretreatment of MC3T3-E1 cells with XXO reduces PTH-induced expression of Nurr1 and PTH1R. Our preliminary experiments showed that oxidant stress might be mediating osteoblastic differentiation and PTH1R levels.



Celeste Passement1, Thomas Macrini1, Cossandra Bauer2, Shayna Levine3, Lorena Havill3.

St. Mary’s University, San Antonio, TX, 2Southwest National Primate Research Center, San Antonio, TX, 3Texas 1 Biomedical Research Institute, San Antonio, TX.

Osteoarthritis (OA) is a degenerative disorder of synovial joints with several known risk factors in humans. Disease etiology is not well understood, and the disease cannot be reliably diagnosed until late stages. Baboons have skeletons that resemble those of humans in many ways, including development of musculoskeletal disorders such as naturally occurring OA. Our purpose was to develop a radiographic grading system so that OA can be noninvasively imaged in live baboons to track the progression of the disease. Knee radiographs of 47 baboons were analyzed, and a grading system for OA severity was developed based on the grading systems of other model animals and humans.

Our grading scale ranges from 0 (unaffected) to 3 (advanced) OA based on the presence or absence of osteophytes, intrajoint calcifications, subchondral bone erosion, and femoral-tibial contact. A blind interobserver analysis yielded a substantial agreement of 74% (n = 94 knees) between two radiograph scorers with a coefficient mean of 0.61.

We found slight agreement between our radiographic OA grades and visually assessed severity scores of articular cartilage of the knees of the same animals with a coefficient mean of 0.18. Radiography is currently the standard for diagnosing OA in humans and, because of this, we are applying the imaging technique to baboons as part of the broader research program to establish baboons as model animals for human OA.




Piedad Alcala1, Rodney Cooper2.

Heritage University, Toppenish, WA, 2US Department of Agriculture-Agricultural Research Service, Wapato, Wapato, 1 WA.

Zebra chip is a new disease affecting potatoes in Central America, North America, and New Zealand. Zebra-chip disease is responsible for millions of dollars in losses to the potato industry. The disease is caused by the phloemlimited bacterium Liberibacter, “Candidatus Liberibacter solanacearum” and is vectored by the potato/tomato psyllid Bactericera cockerelli. To date, little is known about how Liberibacter moves through plant tissues from acquisition sites. Studies have shown transport of minerals, hormones, photosynthates, organic compounds, and other signal molecules in phloem tissues is controlled by vascular architecture. We assessed whether vascular architecture influences translocation of Liberibacter from the initial site of infection to distant, noninfected plant tissues. Potato and tomato plants were grown under normal greenhouse conditions until plants had 5 fully-expanded leaves. Plant vascular architecture was mapped by excising the terminal leaflet of the second fully expanded leaf and inserting the petiole into a microfuge tube containing 0.25% rhodamine-B tracer dye, and observing the translocation of the dye from the cut petiole. For examination of Liberibacter translocation, 5 Liberibacter-infected potato psyllids were confined to the terminal leaflet of the second fully expanded leaf for 24 hours. After 2 weeks, all leaves were tested for Liberibacter infection using PCR. Results obtained will facilitate the development of effective risk assessments, prevention, and diagnostic strategies for zebra chip disease.



Aaron Clarke, Janet Fitzakerley, George Trachte.

University of Minnesota Medical School, Duluth, Duluth, MN.

Atrial natriuretic peptide (ANP) is a critical regulator of fluid balance that has an important role in hearing. ANP acts via the guanylyl cyclase NPR-A to raise intracellular cyclic guanosine monophosphate (cGMP) concentrations. Decreased cochlear cGMP have been correlated with hearing loss. In the current study, the hypothesis was tested that raising


Biological Sciences plasma ANP concentrations increases cochlear cGMP and improves hearing. Adult CBA/J mice with normal hearing were given 10 minutes of intra-arterial saline infusion as a control, followed by an ANP infusion (0.25 ng/g/hr) for a maximum of 30 minutes or an infusion of cyclic ANP (cANP; 60 ng/g/hr) for a maximum of 70 minutes to prevent ANP degradation. Hearing was assessed at 2 to 3 minute intervals using auditory brainstem response (ABR) techniques.

Plasma ANP and cochlear cGMP were determined following the infusion. Infusions which increased plasma concentrations 0.1 ng/mL resulted in hearing improvements of 5 to 20 dB. Hearing improvements reached their peak at approximately 10 minutes after the ANP infusion started and returned to control values after 20 to 30 minutes.

In mice infused with cANP, peak improvements were observed approximately 30 minutes after the infusion began and returned to baseline about 60 minutes later. Determination of the effect of increased plasma ANP on cochlear cGMP is the goal of this summer project. The data obtained thus far support the hypothesis that circulating ANP modulates cochlear function via a mechanism mediated by cGMP. [Supported by a grant from the American Otological Society and funding from the Pathways to Advanced Degrees in Life Sciences (NIH/NIGMS R25GM086669)].



Tracylyn Yellowhair, Nikki Jernigan.

University of New Mexico Health Sciences Center, Albuquerque, NM.

Pulmonary arterial remodeling associated with chronic hypoxia (CH)-induced pulmonary hypertension is attributed to the medial hypertrophy and hyperplasia of pulmonary arterial smooth muscle cells (PASMC) which leads to increased wall thickness and neomuscularization of small pulmonary arteries. This response is largely dependent on elevated intracellular free Ca2+ ([Ca2+]i) in PASMC. Recently, our laboratory has demonstrated an important role for the voltage-insensitive, Ca2+-permeable ion channel, acid-sensing ion channel 1 (ASIC1), in mediating enhanced Ca2+ influx in PASMC from CH animals. In addition, ASICs have been shown to contribute to migration, proliferation, and apoptosis in many different cell types. Therefore, we hypothesize that ASIC1 contributes to the pulmonary arterial remodeling associated with CH-induced pulmonary hypertension. To test this hypothesis, we assessed indices of CH (4 wk, PB = 380 mmHg)-induced pulmonary arterial remodeling in wild-type (ASIC1+/+) and ASIC1 knockout (ASIC1mice. Immunofluorescence was performed for antismooth-muscle alpha actin in paraffin-embedded lung tissue /sections to determine the number of fully muscularized arteries and the degree of muscularization. CH increased the number of fully muscularized arteries in ASIC+/+ but not ASIC-/- mice. Furthermore, the degree of muscularization was greater in small pulmonary arteries from CH versus control ASIC1+/+ mice. However, such medial hypertrophy was absent in arteries from ASIC1-/- mice. These data suggest that ASIC1 contributes to pulmonary arterial remodeling in CH-induced pulmonary hypertension. To further our investigation, we plan to examine the specific role of ASIC1 in proliferation, migration, and apoptosis associated with this response.



Alejandra Cabrera, Tyrone Hayes, Brian Tian, Rupali Sood, Flor Gowans, Michelle Vy, Sherrie Gallipeau, Xuan (Susan) Luong.

University of California, Berkeley, Berkeley, CA.

Previous studies showed that the herbicide atrazine inhibited male reproductive behavior in exposed African clawed frogs (Xenopus laevis). Atrazine both reduces androgens and induces estradiol (E2) production. The current studies were designed to determine whether the decrease in androgen or the increase in estrogen is directly responsible for the loss of male mating behavior. Initial studies treated male X. laevis with E2 by immersion. E2 had no effect on behavior, but it was revealed that frogs rapidly metabolized E2. We therefore examined 17α-ethinyl estradiol (EE2) as an alternative to E2. EE2 is a synthetic compound used extensively in oral contraceptives and can affect endocrine pathways that affect reproductive functions. EE2 is degraded and metabolized less easily than E2 because of the ethinyl group in C17; therefore it serves as a better alternative to test the effects of estrogen on the male X. laevis.

We hypothesize that EE2 will decrease reproductive behavior and male fertility. Clasping behavior, fertility, and testosterone will be measured to assess reproductive success.

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BEND Victoria Congdon1, Kelly Darnell2, Ken Dunton2.

University of Texas at Austin, Austin, TX, 2University of Texas Marine Science Institute, Port Aransas, TX.

1 Seagrasses are submerged marine plants found along most coastlines worldwide. They form vast underwater meadows whose leaf canopies extend into the water column and provide essential food and habitat for commercially and ecologically important species. The influence of seagrass leaf canopy on water flow is complex and depends on several factors, including seagrass leaf length, shoot density, water velocity, and water depth. We investigated the effects of seagrass canopy and water depth on flow velocity at three locations along the Texas Coastal Bend that experience different flow regimes. Water speed and direction were characterized within and adjacent to natural turtle grass (Thalassia testudinum) and shoal grass (Halodule wrightii) beds using SeaHorse HOBO-ware current tilt meters. Results indicate that presence of the seagrass canopy, species morphology, and water depth influenced water flow at each of the three sites. These results have implications for flow-mediated processes in seagrass meadows such as seed and larval dispersal, nutrient cycling, and sedimentation.





Jennifer Delgado1, Thomas Unruh2.

Heritage University, Toppenish, WA, 2Yakima Agricultural Research Laboratory, USDA-Agricultural Research Service, 1 Wapato, WA.

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