Muscimol acts in dorsomedial but not paraventricular hypothalamic nucleus to suppress cardiovascular effects of stress

Both the dorsomedial hypothalamic nucleus (DMH) and the paraventricular hypothalamic nucleus (PVN) have been implicated in the neural control of the cardiovascular response to stress. We used the GABAA agonist muscimol to inhibit neuronal activation and attempted to identify hypothalamic nuclei required for the cardiovascular response to air stress. Chronically instrumented rats received bilateral injections of either 80 pmol of muscimol or 100 nl of saline vehicle into the DMH, the PVN, or an intermediate area (including the rostral edge of the DMH and the region between the two nuclei) and were placed immediately in a restraining tube and subjected to 20 min of air stress. In all rats, air stress after vehicle injections caused marked increases in heart rate (137 +/- 6 beats/min) and blood pressure (26 +/- 2 mmHg). Microinjection of muscimol into the DMH suppressed the heart rate and blood pressure response by 85 and 68%, respectively. Identical microinjection of muscimol into the intermediate area between the DMH and the PVN attenuated the increases in heart rate by only 46% and in blood pressure by 52%. In contrast, similar injections into the vicinity of the PVN failed to alter the cardiovascular response to air stress. These findings demonstrate that muscimol-induced inhibition of neuronal activity in the region of the DMH blocks air stress-induced increases in heart rate and arterial pressure, whereas similar treatment in the area of the PVN has no effect

The Experiences of American Indian Participants and Site Coordinators in a Gestational Diabetes Risk Reduction Trial

Gestational diabetes mellitus is the most common complication of pregnancy and contributes to increased risk for type 2 diabetes in both the mother and offspring. We developed and evaluated a gestational diabetes risk reduction and preconception counseling program, Stopping GDM (SGDM), for American Indian females. The purpose of this study is to examine the experiences of American Indian mother-daughter dyad participants and the site coordinators who facilitated the SGDM randomized controlled trial to inform program revisions. We engaged mother-daughter dyads (n = 22 dyads) and site coordinators (n = 6) in focus group interviews. Four themes emerged: (1) SGDM sparked valuable quality conversation for dyads; (2) gestational diabetes risk factors and risk reduction was new information for most dyads; (3) all trial sites experienced challenges to recruitment and engagement; and (4) study-improvement recommendations. These findings will be used to enhance SGDM to decrease adverse intergenerational health impacts of gestational diabetes in American Indian communities

Improved understanding of novel sources of resistance against the light leaf spot pathogen, Pyrenopeziza brassicae

Chinthani Shanika Karandeni Dewage, Kavithra Jayani Wijerathna, Henrik U. Stotz, and Bruce D. L. Fitt, 'Improved understanding of novel sources of resistance against the light leaf spot pathogen, Pyrenopeziza brassicae', paper presented at the Association of Applied Biologists Conference Crop Production in Southern Britain 2017, 15 - 16 February 2017, Peterborough, UK. Proceedings available online at: http://www.aab.org.uk/contentok.php?id=501.In this work, the endophytic growth phase of the light leaf spot pathogen Pyrenopeziza brassicae in selected lines from a doubled haploid (DH) population of oilseed rape, which is known to segregate for resistance against P. brassicae, was characterised using controlled environment (CE) experiments. Fungal staining techniques and pathogen-specific quantitative polymerase chain reactions (qPCR) were used to observe and quantify the pathogen biomass, respectively. The qPCR results showed that the resistant lines contained little P. brassicae DNA and there seemed to be little to no change in the amount of DNA over time. In contrast, there was a considerable increase in pathogen DNA in susceptible lines from 0 to 24 days post inoculation (dpi). These results were also reflected in observations made by a fungal staining method. In addition, leaf samples of these DH lines, collected at three different times from winter oilseed rape field experiments, were analysed using qPCR. The resistant lines had a considerably smaller amount of P. brassicae DNA in leaf samples collected later in the cropping season than that in susceptible lines

Genes in the postgenomic era

We outline three very different concepts of the gene - 'instrumental', 'nominal', and 'postgenomic'. The instrumental gene has a critical role in the construction and interpretation of experiments in which the relationship between genotype and phenotype is explored via hybridization between organisms or directly between nucleic acid molecules. It also plays an important theoretical role in the foundations of disciplines such as quantitative genetics and population genetics. The nominal gene is a critical practical tool, allowing stable communication between bioscientists in a wide range of fields grounded in well-defined sequences of nucleotides, but this concept does not embody major theoretical insights into genome structure or function. The post-genomic gene embodies the continuing project of understanding how genome structure supports genome function, but with a deflationary picture of the gene as a structural unit. This final concept of the gene poses a significant challenge to conventional assumptions about the relationship between genome structure and function, and between genotype and phenotype

Rapid South Atlantic spreading changes and coeval vertical motion in surrounding continents: Evidence for temporal changes of pressure-driven upper mantle flow

International audienceThe South Atlantic region displays (1) a topographic gradient across the basin, with Africa elevated relative to South America, (2) a bimodal spreading history with fast spreading rates in Late Cretaceous and Eo-Oligocene, and (3) episodic regional uplift events in the adjacent continents concentrated in Late Cretaceous and Oligocene. Here we show that these observations can be linked by dynamic processes within Earth's mantle, through temporal changes in asthenosphere flow beneath the region. The topographic gradient implies westward, pressure-driven mantle flow beneath the basin, while the rapid spreading rate changes, on order 10 million years, require significant decoupling of regional plate motion from the large-scale mantle buoyancy distribution through a mechanically weak asthenosphere. Andean topographic growth in late Miocene can explain the most recent South Atlantic spreading velocity reduction, arising from increased plate boundary forcing associated with the newly elevated topography. But this mechanism is unlikely to explain the Late Cretaceous/Tertiary spreading variations, as changes in Andean paleoelevation at the time are small. We propose an unsteady pressure-driven flow component in the asthenosphere beneath the South Atlantic region to explain the Late Cretaceous/Tertiary spreading rate variations. Temporal changes in mantle flow due to temporal changes in regional mantle pressure gradients imply a correlation of horizontal and vertical motions: we find that this prediction from our models agrees with geologic and geophysical observations of the South Atlantic region, including episodes of passive margin uplift, regional basin reactivation, and magmatic activity

Pressure-Driven Poiseuille Flow: A Major Component of the Torque-Balance Governing Pacific Plate Motion

The Pacific Plate is thought to be driven mainly by slab pull, associated with subduction along the Aleutians-Japan, Marianas-Izu-Bonin, and Tonga-Kermadec trenches. This implies that viscous flow within the sub-Pacific asthenosphere is mainly generated by overlying plate motion (i.e., Couette flow) and that the associated shear stresses at the lithosphere's base are resisting such motion. Recent studies on glacial isostatic adjustment and lithosphere dynamics provide tighter constraints on the viscosity and thickness of Earth's asthenosphere and, therefore, on the amount of shear stress that asthenosphere and lithosphere mutually exchange, by virtue of Newton's third law of motion. In light of these constraints, the notion that subduction is the main driver of present-day Pacific Plate motion becomes somewhat unviable, as the pulling force that would be required by slabs exceeds the maximum available from their negative buoyancy. Here we use coupled global models of mantle and lithosphere dynamics to show that the sub-Pacific asthenosphere features a significant component of pressure-driven (i.e., Poiseuille) flow and that this has driven at least 50% of the Pacific Plate motion since, at least, 15 Ma. A corollary of our models is that a sublithospheric pressure difference as high as ±50 MPa is required across the Pacific domain.I. L. S. acknowledges support from CONICYT Becas-Chile scholarship and from IGN at the University of Copenhagen. D. R. D. acknowledges funding from the Australian Research Council, via grants FT140101262 and DP170100058

Graphene-Capped Liquid Thin Films for Electrochemical Operando X-ray Spectroscopy and Scanning Electron Microscopy

Electrochemistry is a promising building block for the global transition to a sustainable energy market. Particularly the electroreduction of CO2 and the electrolysis of water might be strategic elements for chemical energy conversion. The reactions of interest are inner-sphere reactions, which occur on the surface of the electrode, and the biased interface between the electrode surface and the electrolyte is of central importance to the reactivity of an electrode. However, a potential-dependent observation of this buried interface is challenging, which slows the development of catalyst materials. Here we describe a sample architecture using a graphene blanket that allows surface sensitive studies of biased electrochemical interfaces. At the examples of near ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) and environmental scanning electron microscopy (ESEM), we show that the combination of a graphene blanket and a permeable membrane leads to the formation of a liquid thin film between them. This liquid thin film is stable against a water partial pressure below 1 mbar. These properties of the sample assembly extend the study of solid–liquid interfaces to highly surface sensitive techniques, such as electron spectroscopy/microscopy. In fact, photoelectrons with an effective attenuation length of only 10 Å can be detected, which is close to the absolute minimum possible in aqueous solutions. The in-situ cells and the sample preparation necessary to employ our method are comparatively simple. Transferring this approach to other surface sensitive measurement techniques should therefore be straightforward. We see our approach as a starting point for more studies on electrochemical interfaces and surface processes under applied potential. Such studies would be of high value for the rational design of electrocatalysts