A complex of Pdi1p and the mannosidase Htm1p initiates clearance of unfolded glycoproteins from the endoplasmic reticulum

Endoplasmic reticulum (ER)-resident mannosidases generate asparagine-linked oligosaccharide signals that trigger ER-associated protein degradation (ERAD) of unfolded glycoproteins. In this study, we provide in vitro evidence that a complex of the yeast protein disulfide isomerase Pdi1p and the mannosidase Htm1p processes Man(8)GlcNAc(2) carbohydrates bound to unfolded proteins, yielding Man(7)GlcNAc(2). This glycan serves as a signal for HRD ligase-mediated glycoprotein disposal. We identified a point mutation in PDI1 that prevents complex formation of the oxidoreductase with Htm1p, diminishes mannosidase activity, and delays degradation of unfolded glycoproteins in vivo. Our results show that Pdi1p is engaged in both recognition and glycan signal processing of ERAD substrates and suggest that protein folding and breakdown are not separated but interconnected processes. We propose a stochastic model for how a given glycoprotein is partitioned into folding or degradation pathways and how the flux through these pathways is adjusted to stress conditions.     

Early response of the platypus to climate warming

Combining a climatic envelope modelling technique with more than two centuries (1800–2009) of distribution records has revealed the effects of a changing climate on the egg‐laying monotreme, the platypus, Ornithorhynchus anatinus. We show that the main factor associated with platypus occurrence switched from aquatic habitat availability (estimated by rainfall) to thermal tolerances (estimated by annual maximum temperature) in the 1960s. This correlates directly with the change in the annual maximum temperature anomaly from cooler to warmer conditions in southeastern Australia. Modelling of platypus habitat under emission scenarios (A1B, A2, B1 and B2) revealed large decreases (>30%) in thermally suitable habitat by 2070. This reduction, compounded by increasing demands for water for agriculture and potable use, suggests that there is real cause for concern over the future status of this species, and highlights the need for restoration of thermal refugia within the platypus’ modelled range.     

Crossmodal session rating of perceived exertion response at low and moderate intensities

Session rating of perceived exertion (SRPE) permits global effort estimations after an exercise bout and has shown promise for evaluating training load. However, factors mediating SRPE are not well understood. The purpose of this study was to compare SRPE between cycling and treadmill exercise at low and moderate intensities. In a counterbalanced order, male subjects (n = 7) completed a VO2max trial on a cycle ergometer and a motor-driven treadmill. Then, participants completed trials at 50 and 75% mode-specific VO2max on a cycle ergometer (BK75, BK50) and a treadmill (TM75, TM50) to achieve ～ 400-kcal energy expenditure per trial. Acute RPE (i.e., during exercise) at 5 minutes, midway, and test termination were recorded with SRPE (20-minutes postexercise) expressed as overall (SRPEO), legs (SRPEL), and breathing also recorded were heart rate (HR) and change in rectal temperature (ΔTrec). Significance was accepted at p ≤ 0.05. Repeated-measures analysis of variance revealed significantly greater SRPE for higher intensities within each mode. Crossmodal comparisons also show a higher SRPE at moderate (75% VO2max) intensities [SRPEO] = BK75: 7.6 ± 1.0, TM75: 6.9 ± 1.3) vs. lower (50% VO2max) intensities (BK50: 4.6 ± 1.4, TM50: 4.6 ± 1.1). Within modes, SRPE corresponded well with ΔTrec and HR. Acute RPE was linked with intensity and drifted upward across time. Results indicated that overall and differentiated SRPEs are magnified with exercise intensity with the corresponding disruption in internal environment potentially mediating subjective responses. From a practical application standpoint, SRPE provides a subjective assessment for immediate evaluation of daily training. Results indicate that, when using SRPE to monitor training, consideration should be given to responses across differing exercise modes.     

Biology and systematics of the New World Phyllocnistis Zeller leafminers of the avocado genus Persea (Lepidoptera, Gracillariidae)

Four New World species of Phyllocnistis Zeller are described from serpentine mines in Persea (Family Lauraceae). Phyllocnistis hyperpersea,new species, mines the upper leaf surfaces of avocado, Persea americana Mill., and red bay, Persea borbonia (L.) Spreng. and ranges over much of the southeastern United States into Central America. Phyllocnistis subpersea,new species, mines the underside and occasionally upper sides of new leaves of Persea borbonia in southeastern United States. Phyllocnistis longipalpa, new species, known only from southern Florida also mines the undersides of new leaves of Persea borbonia. Phyllocnistis perseafolia,new species, mines both leaf surfaces and possibly fruits of Persea americana in Colombia, South America. As in all known species of Phyllocnistis, the early instars are subepidermal sapfeeders in young (not fully hardened) foliage, and the final instar is an extremely specialized, nonfeeding larval form, whose primary function is to spin the silken cocoon, at the mine terminus, prior to pupation. Early stages are illustrated and described for three of the species. The unusual morphology of the pupae, particularly the frontal process of the head, is shown to be one of the most useful morphological sources of diagnostic characters for species identification of Phyllocnistis. COI barcode sequence distances are provided for the four proposed species and a fifth, undescribed species from Costa Rica.     

Imaging and characterisation of the surface of live cells

Determining the organisation of key molecules on the surface of live cells in two dimensions and how this changes during biological processes, such as signaling, is a major challenge in cell biology and requires methods with nanoscale resolution. Recent advances in fluorescence imaging both at the diffraction limit tracking single molecules and exploiting super resolution imaging have now reached a stage where they can provide fundamentally new insights. Complementary developments in scanning ion conductance microscopy also allow the cell surface to be imaged with nanoscale resolution. The challenge now is to combine the information obtained using these different methods and on different cells to obtain a coherent view of the cell surface. In the future this needs to be driven by interdisciplinary research between physical scientists and biologists.     

Militarised natural history: tales of the avocet's return to postwar Britain

Absent as a breeding bird from Britain for at least a century, avocets (Recurvirostra avosetta) began nesting on the east coast of Britain, in Suffolk, shortly after the end of the Second World War, having honed in on two spots on Britain's coast that had been flooded for war-related reasons. The avocets' presence was surrounded in secrecy, while a dedicated few kept up a protective watch over them. As the Royal Society for the Protection of Birds (RSPB) took over responsibility for the flourishing colony, they claimed the episode as a symbol of success for British protection, later making the bird their logo. Counter to the RSPB's story of protecting a British bird, I read the narratives of events in terms of making a bird British. I show how, as postwar Britain slumped economically and spiritually and tried to rebuild itself, the birds became a vehicle for formulating national identity: of Britain as a home to which to return and belong. Exploring the themes of returning servicemen and closed territories, the paper also examines the episode in terms of the naturalisation of the military and the militarisation of nature.     

Mapping Fusarium wilt race 1 resistance genes in cotton by inheritance,QTL and sequencing composition

Knowledge of the inheritance of disease resistance and genomic regions housing resistance (R) genes is essential to prevent expanding pathogen threats such as Fusarium wilt [Fusarium oxysporum f.sp. vasinfectum (FOV) Atk. Sny & Hans] in cotton (Gossypium spp.). We conducted a comprehensive study combining conventional inheritance, genetic and quantitative trait loci (QTL) mapping, QTL marker-sequence composition, and genome sequencing to examine the distribution, structure and organization of disease R genes to race 1 of FOV in the cotton genome. Molecular markers were applied to F₂ and recombinant inbred line (RIL) interspecific mapping populations from the crosses Pima-S7 (G. barbadense L.) × ‘Acala NemX’ (G. hirsutum L.) and Upland TM-1 (G. hirsutum) × Pima 3-79 (G. barbadense), respectively. Three greenhouse tests and one field test were used to obtain sequential estimates of severity index (DSI) of leaves, and vascular stem and root staining (VRS). A single resistance gene model was observed for the F₂ population based on inheritance of phenotypes. However, additional inheritance analyses and QTL mapping indicated gene interactions and inheritance from nine cotton chromosomes, with major QTLs detected on five chromosomes [Fov1-C06, Fov1-C08, (Fov1-C11 ₁ and Fov1-C11 ₂₎ , Fov1-C16 and Fov1-C19 loci], explaining 8–31% of the DSI or VRS variation. The Fov1-C16 QTL locus identified in the F₂ and in the RIL populations had a significant role in conferring FOV race 1 resistance in different cotton backgrounds. Identified molecular markers may have important potential for breeding effective FOV race 1 resistance into elite cultivars by marker-assisted selection. Reconciliation between genetic and physical mapping of gene annotations from marker-DNA and new DNA sequences of BAC clones tagged with the resistance-associated QTLs revealed defenses genes induced upon pathogen infection and gene regions rich in disease-response elements, respectively. These offer candidate gene targets for Fusarium wilt resistance response in cotton and other host plants.