Membrane Protein Production and Purification from Escherichia coli and Sf9 Insect Cells

A major obstacle to studying membrane proteins by biophysical techniques is the difficulty in producing sufficient amounts of materials for functional and structural studies. To overexpress the target membrane protein heterologously, especially an eukaryotic protein, a key step is to find the optimal host expression system and perform subsequent expression optimization. In this chapter, we describe protocols for screening membrane protein production using bacterial and insect cells, solubilization screening, large-scale production, and commonly used affinity chromatography purification methods. We discuss general optimization conditions, such as promoters and tags, and describe current techniques that can be used in any laboratory without specialized expensive equipment. Especially for insect cells, GFP fusions are particularly useful for localization and in-gel fluorescence detection of the proteins on SDS-PAGE. We give detailed protocols that can be used to screen the best expression and purification conditions for membrane protein study.Peer reviewe

Multifaceted value profiles of forest owner categories in South Sweden: The river helge å catchment as a case study

Forest landscapes provide benefits from a wide range of goods, function and intangible values. But what are different forest owner categories\u27 profiles of economic use and non-use values? This study focuses on the complex forest ownership pattern of the River Helge å catchment including the Kristianstad Vattenrike Biosphere Reserve in southern Sweden. We made 89 telephone interviews with informants representing the four main forest owner categories. Our mapping included consumptive and non-consumptive direct use values, indirect use values, and non-use values such as natural and cultural heritage. While the value profiles of non-industrial forest land owners and municipalities included all value categories, the forest companies focused on wood production, and the Swedish Environmental Protection Agency on nature protection. We discuss the challenges of communicating different forest owners\u27 economic value profiles among stakeholders, the need for a broader suite of forest management systems, and fora for collaborative planning. © 2013 The Author(s)

Women and ARVâ based prevention: opportunities and challenges

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/138349/1/jia29419.pd

Molecular identification of a retinal cell type that responds to upward motion

The retina contains complex circuits of neurons that extract salient information from visual inputs. Signals from photoreceptors are processed by retinal interneurons, integrated by retinal ganglion cells (RGCs) and sent to the brain by RGC axons. Distinct types of RGC respond to different visual features, such as increases or decreases in light intensity (ON and OFF cells, respectively), colour or moving objects1, 2, 3, 4, 5. Thus, RGCs comprise a set of parallel pathways from the eye to the brain. The identification of molecular markers for RGC subsets will facilitate attempts to correlate their structure with their function, assess their synaptic inputs and targets, and study their diversification. Here we show, by means of a transgenic marking method, that junctional adhesion molecule B (JAM-B) marks a previously unrecognized class of OFF RGCs in mice. These cells have asymmetric dendritic arbors aligned in a dorsal-to-ventral direction across the retina. Their receptive fields are also asymmetric and respond selectively to stimuli moving in a soma-to-dendrite direction; because the lens reverses the image of the world on the retina, these cells detect upward motion in the visual field. Thus, JAM-B identifies a unique population of RGCs in which structure corresponds remarkably to function

Gale crater and impact processes – Curiosity’s first 364 Sols on Mars

Impact processes at all scales have been involved in the formation and subsequent evolution of Gale crater. Small impact craters in the vicinity of the Curiosity MSL landing site and rover traverse during the 364 Sols after landing have been studied both from orbit and the surface. Evidence for the effect of impacts on basement outcrops may include loose blocks of sandstone and conglomerate, and disrupted (fractured) sedimentary layers, which are not obviously displaced by erosion. Impact ejecta blankets are likely to be present, but in the absence of distinct glass or impact melt phases are difficult to distinguish from sedimentary/volcaniclastic breccia and conglomerate deposits. The occurrence of individual blocks with diverse petrological characteristics, including igneous textures, have been identified across the surface of Bradbury Rise, and some of these blocks may represent distal ejecta from larger craters in the vicinity of Gale. Distal ejecta may also occur in the form of impact spherules identified in the sediments and drift material. Possible examples of impactites in the form of shatter cones, shocked rocks, and ropy textured fragments of materials that may have been molten have been observed, but cannot be uniquely confirmed. Modification by aeolian processes of craters smaller than 40 m in diameter observed in this study, are indicated by erosion of crater rims, and infill of craters with aeolian and airfall dust deposits. Estimates for resurfacing suggest that craters less than 15 m in diameter may represent steady state between production and destruction. The smallest candidate impact crater observed is ~0.6 m in diameter. The observed crater record and other data are consistent with a resurfacing rate of the order of 10 mm/Myr; considerably greater than the rate from impact cratering alone, but remarkably lower than terrestrial erosion rates

Fourteen Recommendations to Create a More Inclusive Environment for LGBTQ+ Individuals in Academic Biology

Individuals who identify as lesbian, gay, bisexual, transgender, queer, and otherwise nonstraight and/or non-cisgender (LGBTQ+) have often not felt welcome or represented in the biology community. Additionally, biology can present unique challenges for LGBTQ+ students because of the relationship between certain biology topics and their LGBTQ+ identities. Currently, there is no centralized set of guidelines to make biology learning environments more inclusive for LGBTQ+ individuals. Rooted in prior literature and the collective expertise of the authors who identify as members and allies of the LGBTQ+ community, we present a set of actionable recommendations to help biologists, biology educators, and biology education researchers be more inclusive of individuals with LGBTQ+ identities. These recommendations are intended to increase awareness of LGBTQ+ identities and spark conversations about transforming biology learning spaces and the broader academic biology community to become more inclusive of LGBTQ+ individuals

Links between climate, erosion, uplift, and topography during intracontinental mountain building of the Hangay Dome, Mongolia

The Hangay mountain range, a dome in central Mongolia, provides a window into understanding how climate influences the erosion and resulting geomorphic and sedimentary signatures of continental topography. Specifically, asymmetric erosion of the Hangay, associated with a distinct orographic precipitation gradient, offers a natural experiment for exploring uplift, erosion, and the isostatic response to erosional unloading. The flat-topped Hangay peaks preserve low-relief remnant surfaces that provide markers of rock uplift. This makes it possible to map the deformation of a former planar surface during doming and hence to estimate the total extent of erosion by the difference from present day topography. Erosion into the Hangay surface has been significant but incomplete; the morphology of the range indicates a nonequilibrium landscape that may have persisted for millions to tens of millions of years, implying a long response time in this semiarid climate. The extent of erosion across the range correlates with mean annual precipitation. Variability in present-day peak heights across the north-south climatic and erosional gradient provides empirical support for the generally accepted theory that climate-driven erosion will increase the height of mountain peaks by generating greater surface uplift through isostasy. Correction for this isostatic response makes it possible to reconstruct primary surface uplift of the Hangay. Results highlight the importance of considering the interplay between climate, erosion, and uplift in shaping intracontinental topography and thus when interpreting the geomorphic, sedimentary, and geodynamic signatures associated with such topography