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991.
A matter of scale: apparent niche differentiation of diploid and tetraploid plants may depend on extent and grain of analysis 下载免费PDF全文
Bernhard Kirchheimer Christoph C. F. Schinkel Agnes S. Dellinger Simone Klatt Dietmar Moser Manuela Winkler Jonathan Lenoir Marco Caccianiga Antoine Guisan Diego Nieto‐Lugilde Jens‐Christian Svenning Wilfried Thuiller Pascal Vittoz Wolfgang Willner Niklaus E. Zimmermann Elvira Hrandl Stefan Dullinger 《Journal of Biogeography》2016,43(4):716-726
992.
Swarna Mohan Debamitra Das Robert J. Bauer Annie Heroux Jenna K. Zalewski Simone Heber Atinuke M. Dosunmu-Ogunbi Michael A. Trakselis Jeffrey D. Hildebrand Andrew P. VanDemark 《PloS one》2013,8(12)
Rho-associated coiled coil containing protein kinase (Rho-kinase or Rock) is a well-defined determinant of actin organization and dynamics in most animal cells characterized to date. One of the primary effectors of Rock is non-muscle myosin II. Activation of Rock results in increased contractility of myosin II and subsequent changes in actin architecture and cell morphology. The regulation of Rock is thought to occur via autoinhibition of the kinase domain via intramolecular interactions between the N-terminus and the C-terminus of the kinase. This autoinhibited state can be relieved via proteolytic cleavage, binding of lipids to a Pleckstrin Homology domain near the C-terminus, or binding of GTP-bound RhoA to the central coiled-coil region of Rock. Recent work has identified the Shroom family of proteins as an additional regulator of Rock either at the level of cellular distribution or catalytic activity or both. The Shroom-Rock complex is conserved in most animals and is essential for the formation of the neural tube, eye, and gut in vertebrates. To address the mechanism by which Shroom and Rock interact, we have solved the structure of the coiled-coil region of Rock that binds to Shroom proteins. Consistent with other observations, the Shroom binding domain is a parallel coiled-coil dimer. Using biochemical approaches, we have identified a large patch of residues that contribute to Shrm binding. Their orientation suggests that there may be two independent Shrm binding sites on opposing faces of the coiled-coil region of Rock. Finally, we show that the binding surface is essential for Rock colocalization with Shroom and for Shroom-mediated changes in cell morphology. 相似文献
993.
Current climatic models predict increasing frequency and magnitude of extreme climatic events (ECEs). Ecological studies recognize the importance of these extremes as drivers of plant growth and mortality, as well as drivers of ecological and evolutionary processes. Here we review observational and experimental studies on ECEs on herbaceous plants and shrubs. Extreme events considered were heat waves, drought, advanced or delayed snowmelt, heavy rainfalls, frosts, pulsed watering and flooding. We analysed 39 studies dealing with direct response of plant to ECEs in different ecosystems, with a particular focus on cold ecosystems (alpine and arctic). Although the number of studies increases every year, the understanding of ecological consequences of ECEs is fragmentary. In general, ECEs affected negatively on physiological processes (efficiency of photosystem II, stomatal conductance and leaf water potential), productivity and reproduction, and had consequences on population demography and recruitment several years after ECE. Indeed, the plant responses to ECEs were species specific and depended on the plant life stage and the timing of ECE. In fact, the magnitude of the effect of ECEs decreased over the growing season. Drought had the most severe effect on plants, while heat waves had minor effect if water was available. The overlap of different ECEs had an additive effect (e.g. drought associated to heat-waves). In general, both neutral or positive plant responses were found and acclimation is possible. In some cases, ECEs exert a strong selective pressure on plant species. 相似文献
994.
Trophic cascades initiated by fungal plant endosymbionts impair reproductive performance of parasitoids in the second generation 总被引:1,自引:0,他引:1
Variation in plant quality can transmit up the food chain and may affect herbivores and their antagonists in the same direction. Fungal endosymbionts of grasses change the resource quality by producing toxins. We used an aphid-parasitoid model system to explore how endophyte effects cascade up the food chain and influence individual parasitoid performance. We show that the presence of an endophyte in the grass Lolium perenne has a much stronger negative impact on the performance of the parasitoid Aphidius ervi than on its aphid host Metopolophium festucae. Although the presence of endophytes did not influence the parasitism rate of endophyte-naïve parasitoids or their offspring’s survival to adulthood, most parasitoids developing within aphids from endophyte-infected plants did not reproduce at all. This indicates a delayed but very strong effect of endophytes on parasitoid performance, which should ultimately affect plant performance negatively by releasing endophyte-tolerant herbivores from top-down limitations. 相似文献
995.
Studies on cognitive effort have shown that pupil dilation is a reliable indicator of memory load. However, it is conceivable that there are other sources of effort involved in memory that also affect pupil dilation. One of these is the ease with which an item can be retrieved from memory. Here, we present the results of an experiment in which we studied the way in which pupil dilation acts as an online marker for memory processing during the retrieval of paired associates while reducing confounds associated with motor responses. Paired associates were categorized into sets containing either 4 or 7 items. After learning the paired associates once, pupil dilation was measured during the presentation of the retrieval cue during four repetitions of each set. Memory strength was operationalized as the number of repetitions (frequency) and set-size, since having more items per set results in a lower average recency. Dilation decreased with increased memory strength, supporting the hypothesis that the amplitude of the evoked pupillary response correlates positively with retrieval effort. Thus, while many studies have shown that “memory load” influences pupil dilation, our results indicate that the task-evoked pupillary response is also sensitive to the experimentally manipulated memory strength of individual items. As these effects were observed well before the response had been given, this study also suggests that pupil dilation can be used to assess an item’s memory strength without requiring an overt response. 相似文献
996.
Helicobacter pylori infection contributes to placental impairment in preeclampsia: basic and clinical evidences 下载免费PDF全文
997.
Per O. Widlund Marija Podolski Simone Reber Joshua Alper Marko Storch Anthony A. Hyman Jonathon Howard David N. Drechsel 《Molecular biology of the cell》2012,23(22):4393-4401
We have developed a protocol that allows rapid and efficient purification of native, active tubulin from a variety of species and tissue sources by affinity chromatography. The affinity matrix comprises a bacterially expressed, recombinant protein, the TOG1/2 domains from Saccharomyces cerevisiae Stu2, covalently coupled to a Sepharose support. The resin has a high capacity to specifically bind tubulin from clarified crude cell extracts, and, after washing, highly purified tubulin can be eluted under mild conditions. The eluted tubulin is fully functional and can be efficiently assembled into microtubules. The method eliminates the need to use heterologous systems for the study of microtubule-associated proteins and motor proteins, which has been a major issue in microtubule-related research. 相似文献
998.
999.
Gláubia Sartori Ana Paula Pesarico Simone Pinton Fernando Dobrachinski Silvane Souza Roman Fernanda Pauletto Luiz Carlos Rodrigues Junior Marina Prigol 《Cell biochemistry and function》2012,30(1):1-10
Propolis has been highlighted for its antioxidant, anti‐inflammatory and antiviral properties. The purpose of this study was to investigate if brown Brazilian hydroalcoholic propolis extract (HPE) protects against vaginal lesions caused by herpes simplex virus type 2 (HSV‐2) in female BALB/c mice. The treatment was divided in 5 days of pre‐treatment with HPE [50 mg·kg–1, once a day, intragastric (i.g.)], HSV‐2 infection [10 µl of a solution 1 × 102 plaque‐forming unit (PFU·ml–1 HSV‐2), intravaginal inoculation at day 6] and post‐treatment with HPE (50 mg·kg–1) for 5 days more. At day 11, the animals were killed, and the in vivo analysis (score of lesions) and ex vivo analysis [haematological and histological evaluation; superoxide dismutase (SOD), catalase (CAT) and myeloperoxidase (MPO) activities; reactive species (RS), tyrosine nitration levels, non‐protein thiols (NPSH) and ascorbic acid (AA) levels] were carried out. HPE treatment reduced extravaginal lesions and the histological damage caused by HSV‐2 infection in vaginal tissues of animals. HPE was able to decrease RS, tyrosine nitration, AA levels and MPO activity. Also, it protected against the inhibition of CAT activity in vaginal tissues of mice. HPE promoted protective effect on HSV‐2 infected animals by acting on inflammatory and oxidative processes, and this effect probably is caused by its antioxidant and anti‐inflammatory properties. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
1000.