Sauromalus hispidus

Number of Pages: 4Integrative BiologyGeological Science

ACQUIRED STRYCHNINE TOLERANCE BY POCKET GOPHERS

Four adult female Botta\u27s pocket gophers (Thomomys bottae) that had survived many normally potentially lethal doses of strychnine alkaloid in another experiment (Lee 1986) were examined further. These individuals freely consumed 0.5% strychnine bait, and 3 of them also 1% strychnine bait, for long periods without dying, whether or not nontoxic alternate bait was present. After 1 gopher (#5) was taken off its 1% strychnine wheat diet for 44 days, it lost its physiological tolerance to strychnine and died the first day when again exposed to a free choice of nontoxic and 1% strychnine wheat. It consumed only 7 mg/kg of strychnine before dying, whereas another gopher (#42) was able to survive on a mean daily consumption of 275.8 mg/kg of strychnine in a no-choice situation over a period of 28 days. This is almost 40 times the lethal dose of the other animal

Polychlorinated biphenyl exposure alters oxytocin receptor gene expression and maternal behavior in rat model

Polychlorinated biphenyl (PCB) is a persistent organic pollutant known to induce diverse molecular and behavioral alterations. Effects of PCB exposure could be transmitted to future generations via changes in behavior and gene expression. Previous work has shown that PCB-exposure can alter social behavior. The present study extends this work by examining a possible molecular mechanism for these changes. Pregnant rats (Sprague-Dawley) were exposed through diet to a combination of non-coplanar (PCB 47 - 2,20,4,40-tetrachlorobiphenyl) and coplanar (PCB 77 - 3,30,4,40- tetrachlorobiphenyl) congeners. Maternal care behaviors were examined by evaluating the rate and quality of nest building on the last 4 d of gestation and dam/pup interactions on postnatal days 1, 2, 4 and 6. On postnatal day 17, dams were euthanized and hypothalamic tissue was removed for expression analyses of the oxytocin receptor (OXTR) and cytochrome P450 1a1 (Cyp1a1). PCB altered nest building and maternal care behaviors. Specifically, there was a significant increase in time spent in low crouch and high crouch nursing posture on PND 4 and PND 6 respectively. Molecular analysis revealed that PCB exposure upregulated OXTR expression in the hypothalamus of dams. These results provide a possible molecular mechanism for PCB-induced changes in social interactions during early development

Sauromalus varius

Number of Pages: 4Integrative BiologyGeological Science

Correlation between microstructure and magnetotransport in organic semiconductor spin valve structures

We have studied magnetotransport in organic-inorganic hybrid multilayer junctions. In these devices, the organic semiconductor (OSC) Alq$_3$ (tris(8-hydroxyquinoline) aluminum) formed a spacer layer between ferromagnetic (FM) Co and Fe layers. The thickness of the Alq$_3$ layer was in the range of 50-150 nm. Positive magnetoresistance (MR) was observed at 4.2 K in a current perpendicular to plane geometry, and these effects persisted up to room temperature. The devices' microstructure was studied by X-ray reflectometry, Auger electron spectroscopy and polarized neutron reflectometry (PNR). The films show well-defined layers with modest average chemical roughness (3-5 nm) at the interface between the Alq$_3$ and the surrounding FM layers. Reflectometry shows that larger MR effects are associated with smaller FM/Alq$_3$ interface width (both chemical and magnetic) and a magnetically dead layer at the Alq$_3$/Fe interface. The PNR data also show that the Co layer, which was deposited on top of the Alq$_3$, adopts a multi-domain magnetic structure at low field and a perfect anti-parallel state is not obtained. The origins of the observed MR are discussed and attributed to spin coherent transport. A lower bound for the spin diffusion length in Alq$_3$ was estimated as $43 \pm 5$ nm at 80 K. However, the subtle correlations between microstructure and magnetotransport indicate the importance of interfacial effects in these systems.Comment: 21 pages, 11 figures and 2 table

Theranostic Imaging of the Kinases and Proteases that Modulate Cell Death and Survival

Several signaling cascades are involved in cell death, with a significant amount of crosstalk between them. Despite the complexity of these cascades several key pro-survival and pro-death players have been identified. These include PI3-kinase, AKT and caspase-3. Here we review the approaches used to date to perform molecular imaging of these important targets. We focus in particular on approaches that include the possibility of modulating the activity of these kinases and proteases in a theranostic approach

K2-231 b: A sub-Neptune exoplanet transiting a solar twin in Ruprecht 147

We identify a sub-Neptune exoplanet ($R_p = 2.5 \pm 0.2$ R$_\oplus$) transiting a solar twin in the Ruprecht 147 star cluster (3 Gyr, 300 pc, [Fe/H] = +0.1 dex). The ~81 day light curve for EPIC 219800881 (V = 12.71) from K2 Campaign 7 shows six transits with a period of 13.84 days, a depth of ~0.06%, and a duration of ~4 hours. Based on our analysis of high-resolution MIKE spectra, broadband optical and NIR photometry, the cluster parallax and interstellar reddening, and isochrone models from PARSEC, Dartmouth, and MIST, we estimate the following properties for the host star: $M_\star = 1.01 \pm 0.03$ M$_\odot$, $R_\star= 0.95 \pm 0.03$ R$_\odot$, and $T_{\rm eff} = 5695 \pm 50$ K. This star appears to be single, based on our modeling of the photometry, the low radial velocity variability measured over nearly ten years, and Keck/NIRC2 adaptive optics imaging and aperture-masking interferometry. Applying a probabilistic mass-radius relation, we estimate that the mass of this planet is $M_p = 7 +5 -3$ M$_\oplus$, which would cause a RV semi-amplitude of $K = 2 \pm 1$ m s$^{-1}$ that may be measurable with existing precise RV facilities. After statistically validating this planet with BLENDER, we now designate it K2-231 b, making it the second sub-stellar object to be discovered in Ruprecht 147 and the first planet; it joins the small but growing ranks of 23 other planets found in open clusters.Comment: 24 pages, 7 figures, light curve included as separate fil

The Reaction-Diffusion Front for A+B→∅A+B \to\emptyset in One Dimension

We study theoretically and numerically the steady state diffusion controlled reaction $A+B\rightarrow\emptyset$, where currents $J$ of $A$ and $B$ particles are applied at opposite boundaries. For a reaction rate $\lambda$, and equal diffusion constants $D$, we find that when $\lambda J^{-1/2} D^{-1/2}\ll 1$ the reaction front is well described by mean field theory. However, for $\lambda J^{-1/2} D^{-1/2}\gg 1$, the front acquires a Gaussian profile - a result of noise induced wandering of the reaction front center. We make a theoretical prediction for this profile which is in good agreement with simulation. Finally, we investigate the intrinsic (non-wandering) front width and find results consistent with scaling and field theoretic predictions.Comment: 11 pages, revtex, 4 separate PostScript figure

Tobacco Use and Cardiovascular Disease among American Indians: The Strong Heart Study

Tobacco use among American Indians has a long and complicated history ranging from its utilization in spiritual ceremonies to its importance as an economic factor for survival. Despite this cultural tradition and long history, there are few studies of the health effects of tobacco in this population. The Strong Heart Study is a prospective observational study of cardiovascular disease (CVD) in 13 American Indian tribes in Arizona, Oklahoma, and North and South Dakota with 4,549 participants. Baseline examinations were followed by two examinations at regular intervals and 16 years of morbidity and mortality follow-up. Hazard ratios (HRs) for non-fatal CVD for current smokers vs. non-smokers after adjusting for other risk factors were significant in women (HR = 1.94, 95% CI 1.54 to 2.45) and men (HR = 1.59, 95% CI 1.16 to 2.18). Hazard ratios for fatal CVD for current smokers vs. non-smokers after adjusting for other risk factors were significant in women (HR = 1.64, 95% CI 1.04 to 2.58), but not in men. Individuals who smoked and who were diagnosed with diabetes mellitus, hypertension or renal insufficiency were more likely to quit smoking than those without these conditions. On average, American Indians smoke fewer cigarettes per day than other racial/ethnic groups; nevertheless, the ill effects of habitual tobacco use are evident in this population