3,010 research outputs found

    Effects of 2G on Gene Expression of Stress-Related Hormones in Rat Placenta

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    Understanding the effects of spaceflight on mammalian reproductive and developmental physiology is important to future human space exploration and permanent settlement beyond Earth orbit. Fetal developmental programming, including modulation of the HPA axis, is thought to originate at the placental-uterine interface, where both transfer of maternal hormones to the fetus and synthesis of endogenous hormones occurs. In healthy rats, fetal corticosterone levels are kept significantly lower by 11BetaHSD-2, which inactivates corticosterone by conversion into cortisone. Placental tissues express endogenous HPA axis-associated hormones including corticotropin-releasing hormone (CRH), pre-opiomelanocortin (POMC), and vasopressin, which may contribute to fetal programming alongside maternal hormones. DNA methylase 3A, 11BetaHSD-2, and 11BetaHSD-1, which are involved in the regulation of maternal cortisol transfer and modulation of the HPA axis, are also expressed in placental tissues along with glucocorticoid receptor and may be affected by differential gravity exposure during pregnancy. Fetuses may respond differently to maternal glucocorticoid exposure during gestation through sexually dimorphic expression of corticosterone-modulating hormones. To elucidate effects of altered gravity on placental gene expression, here we present a ground-based analogue study involving continuous centrifugation to produce 2g hypergravity. We hypothesized that exposure to 2g would induce a decrease in 11BetaHSD-2 expression through the downregulation of DNA methylase 3a and GC receptor, along with concurrent upregulation in endogenous CRH, POMC, and vasopressin expression. Timed pregnant female rats were exposed to 2G from Gestational day 6 to Gestational day 20, and comparisons made with Stationary Control (SC) and Vivarium Control (VC) dams at 1G. Dams were euthanized and placentas harvested on G20. We homogenized placental tissues, extracted and purified RNA, synthesized cDNA, and quantified the expression levels of the genes of interest relative to the GAPDH housekeeping gene, using RT-qPCR and gene-specific cDNA probes. Elucidation of glucocorticoid transfer and synthesis in the placenta can provide new insights into the unique dynamics of mammalian development in microgravity and guide future multi-generational studies in space

    The effect of the motion of the Sun on the light-time in interplanetary relativistic experiments

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    In 2002 a measurement of the effect of solar gravity upon the phase of coherent microwave beams passing near the Sun has been carried out with the Cassini mission, allowing a very accurate measurement of the PPN parameter γ\gamma. The data have been analyzed with NASA's Orbit Determination Program (ODP) in the Barycentric Celestial Reference System, in which the Sun moves around the centre of mass of the solar system with a velocity v⊙v_\odot of about 10 m/sec; the question arises, what correction this implies for the predicted phase shift. After a review of the way the ODP works, we set the problem in the framework of Lorentz (and Galilean) transformations and evaluate the correction; it is several orders of magnitude below our experimental accuracy. We also discuss a recent paper \cite{kopeikin07}, which claims wrong and much larger corrections, and clarify the reasons for the discrepancy.Comment: Final version accepted by Classical and Quantum Gravity (8 Jan. 2008

    Rodent Habitat On ISS: Spaceflight Effects On Mouse Behavior

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    The NASA Decadal Survey (2011), Recapturing a Future for Space Exploration: Life and Physical Sciences Research for a New Era, emphasized the importance of expanding NASA life sciences research to long duration, rodent experiments on the International Space Station (ISS). To accomplish this objective, flight hardware, operations, and science capabilities supporting mouse studies in space were developed at NASA Ames Research Center. The first flight experiment carrying mice, Rodent Research Hardware and Operations Validation (Rodent Research-1), was launched on Sept 21, 2014 in an unmanned Dragon Capsule, SpaceX4, exposing the mice to a total of 37 days in space. Ground control groups were maintained in environmental chambers at Kennedy Space Center. Mouse health and behavior were monitored for the duration of the experiment via video streaming. Here we present behavioral analysis of two groups of five C57BL/6 female adult mice viewed via fixed camera views compared with identically housed Ground Controls. Flight (Flt) and Ground Control (GC) mice exhibited the same range of behaviors, including eating, drinking, exploratory behavior, self- and allo-grooming, and social interactions at similar or greater levels of occurrence. Mice propelled themselves freely and actively throughout the Habitat using their forelimbs to push off or by floating from one cage area to another, and they quickly learned to anchor themselves using tails and/or paws. Overall activity was greater in Flt as compared to GC mice, with spontaneous ambulatory behavior including the development of organized circling or race-tracking behavior that emerged within the first few days of flight and encompassed the primary dark cycle activity for the remainder of the experiment. We quantified the bout frequency, duration and rate of circling with respect to characteristic behaviors observed in the varying stages of the progressive development of circling: flipping utilizing two sides of the habitat, circling, multi-lap circling and group-circling. Once begun, mice did not regress to flipping behavior or other previous behavioral milestones for the remainder of flight. An overall upward trend in circling frequency, rate, duration, participation, and organization was observed over the course of the 37-day spaceflight experiment. In this presentation, we will summarize qualitative observations and quantitative comparisons of mice in microgravity and 1g conditions. Behavioral analyses provide important insights into the overall health and adaptation of mice to the space environment, and identify unique behaviors and social interactions to guide future habitat development and research on rodents in space

    Estrous Cyclicity in Mice During Simulated Weightlessness

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    Hindlimb unloading (HU) is a rodent model system used to simulate weightlessness experienced in space. However, some effects of this approach on rodent physiology are under-studied, specifically the effects on ovarian estrogen production which drives the estrous cycle. To resolve this deficiency, we conducted a ground-based validation study using the HU model, while monitoring estrous cycles in 16-weeks-old female C57BL6 mice. Animals were exposed to HU for 12 days following a 3 day HU cage acclimation period, and estrous cycling was analyzed in HU animals (n=22), normally loaded HU Cage Pair-Fed controls (CPF; n=22), and Vivarium controls fed ad libitum (VIV; n=10). Pair feeding was used to control for potential nutritional deficits on ovarian function. Vaginal cells were sampled daily in all mice via saline lavage. Cells were dried and stained with crystal violet, and the smears evaluated using established vaginal cytology techniques by two individuals blinded to the animal treatment group. Estrous cyclicity was disrupted in nearly all HU and CPF mice, while those maintained in VIV had an average normal cycle length of 4.8+/- 0.5 days, with all stages in the cycle visibly observed. CPF and HU animals arrested in the diestrous phase, which precedes the pre-ovulatory estrogen surge. Additionally, infection-like symptoms characterized by vaginal discharge and swelling arose in several HU animals, which we suspect was due to an inability of these mice to properly groom themselves, and/or due to the change in the gravity vector relative to the vaginal opening, which prevented drainage of the lavage solution. Pair-feeding resulted in similar weight gains of HU and CPF (1.5% vs 3.0%, respectively). The current results indicate that pair-feeding controlled weight gain and that the HU cage alone influenced estrous cyclicity. Thus, longer acclimation needs to be tested to determine if and when normal estrous cycling resumes in non-loaded mice in HU cages prior to HU testing. Future studies might also examine whether modifications to the vaginal lavage procedure might prevent the onset of the infection-like symptoms, and allow estrous cyclicity to be measured in this model system. Research supported by NNX15AB48G to JST

    Predictors of Achievement When Virtual Manipulatives are Used for Mathematics Instruction

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    The purpose of this study was to determine variables that predict performance when virtual manipulatives are used for mathematics instruction. This study included the following quasi-experimental design features: 1) a large number of students (N=350); 2) within-class random-assignment to treatment groups; 3) retention effects measured by post-test and delayed post-test; 4) fidelity of instructional treatments documented through observations; and, 5) instrument development for the unit of study. This design was used to determine variables that predict student performance on tests of fraction knowledge for third- and fourth-grade students in two treatment groups: classroom instruction using texts and physical manipulatives (CI), and computer lab instruction using virtual fraction applets (VM). The Pre-test, Post-test 1, and Post-test 2 measured learning and retention of fraction concepts. Observation ethograms documented representation use. The results revealed that fewer demographic predictors of student performance (e.g., socio-economic status, English language learner status, and gender) exist during fraction instruction when virtual manipulatives were used. When instructors used virtual manipulatives, there was an equalizing effect on achievement in third and fourth grade classrooms, in that fewer demographic factors were influential for VM groups compared to CI groups

    Forage Report 2016

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    In 2016 summer annual forage variety trials were conducted across Kansas near Garden City, Hays, Hutchinson, Mound Valley, and Scandia. All sites evaluated hay and silage entries. Companies were able to enter varieties into any possible combinations of research sites, so not all sites had all varieties. Across the sites, a total of 99 hay varieties and 99 silage varieties were evaluated

    Suicide and Homicide More Common with Limited Urban Tree Canopy Cover

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    Distribution of urban tree canopies is generally not uniform. Multiple variables have been shown to be associated with tree canopy cover, including violence, health, and general well-being. Herein we examine the relationship of tree cover with intentional deaths. Suicide, homicide, and tree cover data were examined by ZIP code for Louisville, a mid-sized city in Kentucky. Relationship between intentional death (suicide and homicide) and tree cover was examined with Poisson regression analysis. In both univariate and multivariate models, suicides (P \u3c 0.0001 and P = 0.0005), homicides (P \u3c 0.0001 and P = 0.03), and combination (P = 0.0541) were negatively associated with tree cover. In this exploratory study we have found that sparse canopy cover is associated with higher rates of intentional human death (both suicides and homicides). Given that suicides and homicides are relatively rare occurrences, these data suggest that larger samples be examined to confirm the relationship between intentional death and canopy cover

    Forage Report 2015

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    In 2015 summer annual forage variety trials were conducted across Kansas near Garden City, Hays, Hutchinson, Mound Valley, and Scandia. All sites evaluated hay and silage entries, except Hutchinson, which only evaluated hay entries. Companies were able to enter varieties into any possible combinations of research sites, so not all sites had all varieties. Across the sites, a total of 30 hay varieties and 22 silage varieties were evaluated
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