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1.
A wide variety of eukaryotic membrane proteins are anchored to the outside of cells by covalent linkage to glycosyl phosphatidylinositol (GPI). One of the best characterized examples is the variant surface glycoprotein (VSG) of the protozoan parasite, Trypanosoma brucei. The structure of the GPI precursor is ethanolamine-PO4-Man alpha 1-2Man alpha 1-6Man alpha 1-4GlcNH2-PI; the phosphoethanolamine moiety forms an amide linkage to the VSG polypeptide alpha-COOH group during its attachment to protein. Here we report that the serine esterase inhibitor, phenylmethanesulphonyl fluoride (PMSF), inhibits phosphoethanolamine incorporation into the GPI precursor resulting in the accumulation of a Man3GlcNH2-PI intermediate. PMSF exerts this effect both in living trypanosomes and in a trypanosome-derived cell-free system. This is the first report of an inhibitor which affects GPI biosynthesis but not N-glycosylation. A model of the mechanism of phosphoethanolamine incorporation into the GPI precursor, based on the known properties of PMSF, is presented.  相似文献   
2.
Scientific progress depends upon the accumulation of empirical knowledge via reproducible methodology. Although reproducibility is a main tenet of the scientific method, recent studies have highlighted widespread failures in adherence to this ideal. The goal of this study was to gauge the level of computational reproducibility, or the ability to obtain the same results using the same data and analytic methods as in the original publication, in the field of wildlife science. We randomly selected 80 papers published in the Journal of Wildlife Management and Wildlife Society Bulletin between 1 June 2016 and 1 June 2018. Of those that were suitable for reproducibility review (n = 74), we attempted to obtain study data from online repositories or directly from authors. Forty-two authors did not respond to our requests, and we were further unable to obtain data from authors of 13 other studies. Of the 19 studies for which we were able to obtain data and complete our analysis, we judged that 13 were mostly or fully reproducible. We conclude that the studies with publicly available data or data shared upon request were largely reproducible, but we remain concerned about the difficulty in obtaining data from recently published papers. We recommend increased data-sharing, data organization and documentation, communication, and training to advance computational reproducibility in the wildlife sciences. © 2020 The Authors. The Journal of Wildlife Management published by Wiley Periodicals, Inc. on behalf of The Wildlife Society.  相似文献   
3.
The Pyk2 tyrosine kinase can be activated by both calcium-dependent and calcium-independent mechanisms. Exposure to moderate hypoxia (5% O(2)) induced a rapid and persistent tyrosine phosphorylation of Pyk2 in pheochromocytoma (PC12) cells. Hypoxia and KCl-depolarization increased the phosphotyrosine content of Pyk2 by twofold and fourfold, respectively. Both of these effects were abolished in the absence of extracellular calcium. There was a modest activation of MAPK in parallel with the onset of Pyk2 phosphorylation. However, there was no detectable activation of either JNK or c-src, two other known downstream targets of Pyk2. Thus, exposure to hypoxia may selectively target specific subsets of Pyk2 signalling pathways.  相似文献   
4.
Yin XR  Shi YN  Min T  Luo ZR  Yao YC  Xu Q  Ferguson I  Chen KS 《Planta》2012,235(5):895-906
Thirteen ethylene signaling related genes were isolated and studied during ripening of non-astringent ‘Yangfeng’ and astringent ‘Mopan’ persimmon fruit. Some of these genes were characterized as ethylene responsive. Treatments, including ethylene and CO2, had different effects on persimmon ripening, but overlapping roles in astringency removal, such as increasing the reduction in levels of soluble tannins. DkERS1, DkETR2, and DkERF8, may participate in persimmon fruit ripening and softening. The expression patterns of DkETR2, DkERF4, and DkERF5 had significant correlations with decreases in soluble tannins in ‘Mopan’ persimmon fruit, suggesting that these genes might be key components in persimmon fruit astringency removal and be the linkage between different treatments, while DkERF1 and DkERF6 may be specifically involved in CO2 induced astringency removal. The possible roles of ethylene signaling genes in persimmon fruit astringency removal are discussed.  相似文献   
5.
Discomfort during load carriage is a major issue for activities using backpacks (e.g. infantry maneuvers, children carrying school supplies, or outdoor sports). It is currently unclear which mechanical parameters are responsible for subjectively perceived discomfort. The aim of this study was to identify objectively measured mechanical predictors of discomfort during load carriage. We compared twelve different configurations of a typical load carriage system, a commercially available backpack with a hip belt. The pressure distribution under the hip belt and the shoulder strap, as well as the tensile force in the strap and the relative motion of the backpack were measured. Multiple linear regression analyses were conducted to investigate possible predictors of discomfort. The results demonstrate that static peak pressure, or alternatively, static strap force is a significant (p<0.001) predictor of discomfort during load carriage in the shoulder and hip region, accounting for 85% or more of the variation in discomfort. As an additional finding, we discovered that the regression coefficients of these predictors are significantly smaller for the hip than for the shoulder region. As static peak pressure is measured directly on the body, it is less dependent on the type of load carriage system than static strap force. Therefore, static peak pressure is well suited as a generally applicable, objective mechanical parameter for the optimization of load carriage system design. Alternatively, when limited to load carriage systems of the type backpack with hip belt, static strap force is the most valuable predictor of discomfort. The regionally differing regression coefficients of both predictors imply that the hip region is significantly more tolerant than the shoulder region. In order to minimize discomfort, users should be encouraged to shift load from the shoulders to the hip region wherever possible, at the same time likely decreasing the risk of low back pain or injury.  相似文献   
6.
We propose a novel hybrid single-electron device for reprogrammable low-power logic operations, the magnetic single-electron transistor (MSET). The device consists of an aluminium single-electron transistor with a GaMnAs magnetic back-gate. Changing between different logic gate functions is realized by reorienting the magnetic moments of the magnetic layer, which induces a voltage shift on the Coulomb blockade oscillations of the MSET. We show that we can arbitrarily reprogram the function of the device from an n-type SET for in-plane magnetization of the GaMnAs layer to p-type SET for out-of-plane magnetization orientation. Moreover, we demonstrate a set of reprogrammable Boolean gates and its logical complement at the single device level. Finally, we propose two sets of reconfigurable binary gates using combinations of two MSETs in a pull-down network.  相似文献   
7.
Hatchling Sceloporus undulatus elongatus from Washington Co., Utah and S. u. garmani from Woods Co., Oklahoma were raised to maturity and reproduction under identical laboratory conditions with ad libitum food availability. Growth, allometry, age and size of maturity, clutch size and egg mass were compared among lab-raised cohorts from the two populations, among lab-raised and field-caught animals (including their field-caught mothers) and, for growth, with values obtained by previously published field studies on the same or nearby populations. For all traits population differences observed in previous field studies and current field samples resulted from both a plastic response to proximate environmental conditions and intrinsic (possibly genetic) difference. The most plastic traits were growth and age of maturity. Cohorts from both populations expressed the ability to mature in less than 6 months in the laboratory but only the S.u. garmani express early maturity in the field. Allometric differences generated during growth in the lab were not observed in field samples but may reflect an adaptive physiological difference. The least plastic trait was egg mass. The only trait for which the rank order of the difference in the field was reversed in the lab was growth rate. S.u. elongatus grew significantly faster than S.u. garmani in the lab but much slower in the field. The tendency of S.u. garmani females to breed at minimum size of maturity may be greater than that of S.u. elongatus.  相似文献   
8.
A fluidized-bed reactor (FBR) was used to enrich an aerobic chlorophenol-degrading microbial culture. Long-term continuous-flow operation with low effluent concentrations selected oligotrophic microorganisms producing good-quality effluent for pentachlorophenol(PCP)-contaminated water. PCP biodegradation kinetics was studied using this FBR enrichment culture. The results from FBR batch experiments were modeled using a modified Haldane equation, which resulted in the following kinetic constants: q max = 0.41 mg PCP mg protein−1 day−1, K S = 16 μg l−1, K i = 5.3 mg l−1, and n = 3.5. These results show that the culture has a high affinity for PCP but is also inhibited by relatively low PCP concentrations (above 1.1 mg PCP l−1). This enrichment culture was maintained over 1 year of continuous-flow operation with PCP as the sole source of carbon and energy. During continuous-flow operation, effluent concentrations below 2 μg l−1 were achieved at 268 min hydraulic retention time (t HR) and 2.5 mg PCP l−1 feed concentration. An increase in loading rate by decreasing t HR did not significantly deteriorate the effluent quality until a t HR decrease from 30 min to 21 min resulted in process failure. Recovery from process failure was slow. Decreasing the feed PCP concentration and increasing t HR resulted in an improved process recovery. Received: 10 October 1996 / Received revision: 21 January 1997 / Accepted: 24 January 1997  相似文献   
9.
Opportunistic viruses are a major problem for immunosuppressed individuals, particularly following organ or stem cell transplantation. Current treatments are non-existent or suffer from problems such as high toxicity or development of resistant strains. We previously published that a trafficking inhibitor that targets a host protein greatly reduces the replication of human cytomegalovirus. This inhibitor was also shown to be moderately effective against polyomaviruses, another family of opportunistic viruses. We have developed a panel of analogues for this inhibitor and have shown that these analogues maintain their high efficacy against HCMV, while substantially lowering the concentration required to inhibit polyomavirus replication. By targeting a host protein these compounds are able to inhibit the replication of two very different viruses. These observations open up the possibility of pan-viral inhibitors for immunosuppressed individuals that are effective against multiple, diverse opportunistic viruses.  相似文献   
10.
The 480 species of leafy spurges, Euphorbia subgenus Esula, represent the main temperate radiation in the large genus Euphorbia. This group is distributed primarily in temperate Eurasia, but with smaller, disjunct centres of diversity in the mountains of the Old World tropics, in temperate southern Africa and in the New World. The majority of New World diversity (32 species) occurs in a single section, section Tithymalus. We analysed sequences of the nrITS and plastid ndhF, trnH‐psbA, trnS‐trnG and trnD‐trnT regions to reconstruct the phylogeny of section Tithymalus and to examine the origins and diversification of the species native to the New World. Our results indicate that the New World species of section Tithymalus form a clade that is sister to the widespread, weedy E. peplus. The New World species fall into two primary groups: a ‘northern annual clade’ from eastern North America and a diverse clade of both annual and perennial species that is divided into three subgroups. Within the second group, there is a small ‘southern annual clade’ from Texas and northern Mexico, a perennial ‘Brachycera clade’ from the western United States and northern Mexico, and a perennial ‘Esuliformis clade’ from montane areas of Mexico, Guatemala, Honduras and the Caribbean island of Hispaniola. Ancestral state reconstructions indicate that the annual habit probably evolved in the ancestor of E. peplus and the New World clade, with a subsequent reversal to the perennial habit. In conjunction with this phylogenetic framework, the New World species of section Tithymalus are comprehensively reviewed. © 2014 The Linnean Society of London, Botanical Journal of the Linnean Society, 2014, 175 , 191–228.  相似文献   
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