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排序方式: 共有471条查询结果,搜索用时 515 毫秒
71.
Jerri Caldeira Jeremiah Bustos Julianne Peabody Bryce Chackerian David S. Peabody 《PloS one》2015,10(10)
The possibility of a contraceptive vaccine targeting human chorionic gonadotropin has long been recognized, but never fully realized. Here we describe an epitope-specific approach based on immunogenic display of hCG-derived peptides on virus-like particles of RNA bacteriophage. A number of recombinant VLPs were constructed, each displaying a different hCG-derived peptide. Some were taken from the disordered C-terminal tail of the hormone, another came from an internal loop, and yet another was an epitope mimic produced by affinity-selection on an hCG-neutralizing antibody target. Immunization of mice with some VLPs yielded antisera that bound the hormone and neutralized hCG biological activity. 相似文献
72.
Antonio Montagnoli R. Kasten Dumroese Mattia Terzaghi Jeremiah R. Pinto Nicoletta Fulgaro Gabriella Stefania Scippa 《Plant biosystems》2018,152(3):515-523
We found that different spectra, provided by light-emitting diodes or a fluorescent lamp, caused different photomorphological responses depending on tree seedling type (coniferous or broad-leaved), species, seedling development stage, and seedling fraction (shoot or root). For two conifers (Picea abies and Pinus sylvestris) soon after germination (≤40 days), more seedling growth was related to a lower ratio of red-to-far-red (R:FR) light. As growth continued to 120 days, spectra with a greater complement of blue light yielded more growth. Roots showed more plasticity to light spectra than shoots. In general for the evergreen broad-leaved Quercus ilex, spectra with additional R:FR than for conifers yielded more growth in the first 57 days. Subsequently as seedlings grew, shoot growth appeared to be influenced less by light source than roots, with root length showing the greatest responses. Our results suggest that manipulating light spectra to foster desired seedling traits may be another tool for use in the production of high-quality seedlings as defined through the Target Plant Concept. Such seedlings are needed for restoration of the two billion hectares of degraded forestland, especially on harsh sites such as those found in the Mediterranean region, and to sequester carbon to mitigate climate change. 相似文献
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74.
Plass-Johnson Jeremiah G. Heiden Jasmin P. Abu Nur Lukman Muhammad Teichberg Mirta 《Coral reefs (Online)》2016,35(1):229-243
Coral Reefs - The composition of coral reef benthic communities is strongly affected by variation in water quality and consumer abundance and composition. This is particularly evident in highly... 相似文献
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77.
The predominant biosynthetic route to vitamin B6 is catalyzed by a single enzyme. The synthase subunit of this enzyme, Pdx1, operates in concert with the glutaminase subunit, Pdx2, to catalyze the complex condensation of ribose 5-phosphate, glutamine and glyceraldehyde 3-phosphate to form pyridoxal 5'-phosphate, the active form of vitamin B6. In previous studies it became clear that many if not all of the reaction intermediates were covalently bound to the synthase subunit, thus making them difficult to isolate and characterize. Here we show that it is possible to follow a single turnover reaction by heteronuclear NMR using (13)C- and (15)N-labeled substrates as well as (15)N-labeled synthase. By denaturing the enzyme at points along the reaction coordinate, we solved the structures of three covalently bound intermediates. This analysis revealed a new 1,5 migration of the lysine amine linking the intermediate to the enzyme during the conversion of ribose 5-phosphate to pyridoxal 5'-phosphate. 相似文献
78.
Malinda R. Schaefer Elizabeth R. Wonderlich Jeremiah F. Roeth Jolie A. Leonard Kathleen L. Collins 《PLoS pathogens》2008,4(8)
To facilitate viral infection and spread, HIV-1 Nef disrupts the surface
expression of the viral receptor (CD4) and molecules capable of presenting HIV
antigens to the immune system (MHC-I). To accomplish this, Nef binds to the
cytoplasmic tails of both molecules and then, by mechanisms that are not well
understood, disrupts the trafficking of each molecule in different ways.
Specifically, Nef promotes CD4 internalization after it has been transported to
the cell surface, whereas Nef uses the clathrin adaptor, AP-1, to disrupt normal
transport of MHC-I from the TGN to the cell surface. Despite these differences
in initial intracellular trafficking, we demonstrate that MHC-I and CD4 are
ultimately found in the same Rab7+ vesicles and are both
targeted for degradation via the activity of the Nef-interacting protein,
β-COP. Moreover, we demonstrate that Nef contains two separable
β-COP binding sites. One site, an arginine (RXR) motif in the N-terminal
α helical domain of Nef, is necessary for maximal MHC-I degradation. The
second site, composed of a di-acidic motif located in the C-terminal loop domain
of Nef, is needed for efficient CD4 degradation. The requirement for redundant
motifs with distinct roles supports a model in which Nef exists in multiple
conformational states that allow access to different motifs, depending upon
which cellular target is bound by Nef. 相似文献
79.
Jacob N. Barney J. Jeremiah Mann Guy B. Kyser Eduardo Blumwald Allen Van Deynze Joseph M. DiTomaso 《Plant science》2009,177(6):724-732
Switchgrass (Panicum virgatum L.), a native of eastern and central North America, is a leading candidate as a dedicated biofuel feedstock in the US due to its broad adaptability, rapid growth rate, and ability to grow in low production soils. To begin to characterize the important agronomic and ecological traits related to environmental tolerance of switchgrass, we evaluated fitness under stressful growing conditions. We assessed the germination, establishment, performance, and reproductive potential of four common accessions, both upland and lowland ecotypes, at various levels of soil moisture availability (moisture deficit to flooded) in the greenhouse. Seeds emerged and established (55–90% survival) under all soil moisture conditions (−0.3 MPa to flooded). Transplants of lowland ecotypes performed as well in flooded conditions as in field capacity controls, though flooding reduced performance of upland ecotypes. Drought treatments (−4.0 and −11.0 MPa) reduced tiller length and number, leaf area, and biomass production by up to 80%. However, once established, all plants survived at −4.0 MPa and had the same proportion of tillers in flower as at field capacity. The ability of switchgrass to germinate, establish, and flower in low moisture and flooded conditions, particularly lowland ecotypes, may increase the range of environments suitable for biofuel cultivation, and can serve as a baseline for further ecological studies and genetic improvement. 相似文献
80.
Kevin B. Potts Colin A. Chapman Jeremiah S. Lwanga 《The Journal of animal ecology》2009,78(6):1269-1277
1. Despite a long history of research on the influence of fruit availability on the population density of large-bodied vertebrate frugivores, operational understanding of the factors regulating density in these taxa remains elusive. We propose that fruit resources can be distinguished from one another on the basis of their functional role for the animals in question, and that such a classification system can aid in identifying the most influential determinants of frugivore density.
2. We compared the availability of several resource classes between two sites in Kibale National Park, Uganda separated by only 12 km yet differing threefold in density of chimpanzees ( Pan troglodytes ).
3. We categorized plant species used for fruit by chimpanzees according to their availability relative to habitat-wide fruit productivity, and by their tendency towards inter-individual fruiting synchrony. We predicted that the site of high chimpanzee density would support a higher density of food plant species tending to produce crops during periods of high habitat-wide productivity [high fruit abundance (HFA foods)] and of those tending to fruit synchronously among individuals during times of low habitat-wide availability (sLFA foods). The first food class should provide chimpanzees with a high nutrient density (and thus promote population growth), whereas the second should provide stable subsistence during lean periods and thus a temporally consistent resource base.
4. Counter to our prediction, only sLFA resources were more abundant at the site of high chimpanzee density than at the site of low density. We suggest that sLFA resources are most important in influencing density of large-bodied frugivores. 相似文献
2. We compared the availability of several resource classes between two sites in Kibale National Park, Uganda separated by only 12 km yet differing threefold in density of chimpanzees ( Pan troglodytes ).
3. We categorized plant species used for fruit by chimpanzees according to their availability relative to habitat-wide fruit productivity, and by their tendency towards inter-individual fruiting synchrony. We predicted that the site of high chimpanzee density would support a higher density of food plant species tending to produce crops during periods of high habitat-wide productivity [high fruit abundance (HFA foods)] and of those tending to fruit synchronously among individuals during times of low habitat-wide availability (sLFA foods). The first food class should provide chimpanzees with a high nutrient density (and thus promote population growth), whereas the second should provide stable subsistence during lean periods and thus a temporally consistent resource base.
4. Counter to our prediction, only sLFA resources were more abundant at the site of high chimpanzee density than at the site of low density. We suggest that sLFA resources are most important in influencing density of large-bodied frugivores. 相似文献