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排序方式: 共有719条查询结果,搜索用时 31 毫秒
61.
62.
Kate E. Atkin Sandy J. MacDonald Andrew S. Brentnall Jennifer R. Potts Gavin H. Thomas 《FEBS letters》2014
Staphylococcus aureus and Staphylococcus epidermidis cause dangerous and difficult to treat medical device-related infections through their ability to form biofilms. Extracellular poly-N-acetylglucosamine (PNAG) facilitates biofilm formation and is a vaccination target, yet details of its biosynthesis by the icaADBC gene products is limited. IcaC is the proposed transporter for PNAG export, however a comparison of the Ica proteins to homologous exo-polysaccharide synthases suggests that the common IcaAD protein components both synthesise and transport the PNAG. The limited distribution of icaC to the Staphylococcaceae and its membership of a family of membrane-bound acyltransferases, leads us to suggest that IcaC is responsible for the known O-succinylation of PNAG that occurs in staphylococci, identifying a potentially new therapeutic target specific for these bacteria. 相似文献
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Brian H. Tracey Darshan Iyer Eugene A. Lesser Frisso J. Potts Shai N. Gozani 《Biomedical signal processing and control》2010,5(2):158-163
In this study, the nerve conduction study (NCS) waveform assignment performance of algorithms used in a commercial electrodiagnostic instrument was compared against three neurophysiology experts for motor, F-wave, and sensory parameters. Assignments were made on a common set of waveforms, thereby eliminating a source of variability present in earlier studies that relied on re-testing patients. The performance of the algorithms was comparable to the experts as quantified by the inter-class correlation coefficient and Bland–Altman analyses. The observed algorithm-expert agreement was higher than previously reported estimates, suggesting that the approach of scoring a common set of waveforms may provide a more accurate measure of algorithm performance. 相似文献
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Patrick L Cable J Potts D Ignace D Barron-Gafford G Griffith A Alpert H Van Gestel N Robertson T Huxman TE Zak J Loik ME Tissue D 《Oecologia》2007,151(4):704-718
Global climate models predict that in the next century precipitation in desert regions of the USA will increase, which is
anticipated to affect biosphere/atmosphere exchanges of both CO2 and H2O. In a sotol grassland ecosystem in the Chihuahuan Desert at Big Bend National Park, we measured the response of leaf-level
fluxes of CO2 and H2O 1 day before and up to 7 days after three supplemental precipitation pulses in the summer (June, July, and August 2004).
In addition, the responses of leaf, soil, and ecosystem fluxes of CO2 and H2O to these precipitation pulses were also evaluated in September, 1 month after the final seasonal supplemental watering event.
We found that plant carbon fixation responded positively to supplemental precipitation throughout the summer. Both shrubs
and grasses in watered plots had increased rates of photosynthesis following pulses in June and July. In September, only grasses
in watered plots had higher rates of photosynthesis than plants in the control plots. Soil respiration decreased in supplementally
watered plots at the end of the summer. Due to these increased rates of photosynthesis in grasses and decreased rates of daytime
soil respiration, watered ecosystems were a sink for carbon in September, assimilating on average 31 mmol CO2 m−2 s−1 ground area day−1. As a result of a 25% increase in summer precipitation, watered plots fixed eightfold more CO2 during a 24-h period than control plots. In June and July, there were greater rates of transpiration for both grasses and
shrubs in the watered plots. In September, similar rates of transpiration and soil water evaporation led to no observed treatment
differences in ecosystem evapotranspiration, even though grasses transpired significantly more than shrubs. In summary, greater
amounts of summer precipitation may lead to short-term increased carbon uptake by this sotol grassland ecosystem. 相似文献
68.
Feeding sodium butyrate (0.25–1 mg/ml) to cultures of Salinispora tropica NPS21184 enhanced the production of salinosporamide B (NPI-0047) by 319% while inhibiting the production of salinosporamide
A (NPI-0052) by 26%. Liquid chromatography mass spectrometry analysis of the crude extract from the strain NPS21184 fed with
0.5 mg/ml sodium [U-13C4]butyrate indicated that butyrate was incorporated as a contiguous four-carbon unit into NPI-0047 but not into NPI-0052. Nuclear
magnetic resonance analysis of NPI-0047 and NPI-0052 purified from the sodium [U-13C4]butyrate-supplemented culture extract confirmed this incorporation pattern. The above finding is the first direct evidence
to demonstrate that the biosynthesis of NPI-0047 is different from NPI-0052, and NPI-0047 is not a precursor of NPI-0052. 相似文献
69.
Tor F. Næsje Amber-Robyn Childs Paul D. Cowley Warren M. Potts Eva B. Thorstad Finn Økland 《Hydrobiologia》2007,582(1):25-34
The purpose of this study was to test the hypothesis that an estuarine species as the spotted grunter Pomadasys commersonnii is evenly distributed within the estuary and uniformly exploited by different groups of fishers. This was done by investigating
the movements and area use of spotted grunter in relation to the fisheries. The position of 20 acoustically tagged fish was
recorded during 36 days in February and March 2003, by manual tracking and automated data logging receivers. Information on
the fisheries in the estuary was collected through visual registration of fishing effort and interviews. The spotted grunter
moved on average 1.0 km (SD ± 0.7) between positional fixes. Most of the fish were positioned in the lower part of the 12
km long estuary, as 70% of the positional fixes were within the first 3 km, and 89% within the first 6 km. Approximately half
(49%) of all the fixes were between 1.0 and 1.5 km from the estuary mouth. The spotted grunter used on average 4.9 km (SD
± 4.9) of the length of the estuary, and there was no significant relationship between the length of the estuary used and
the body length of the fish (26–39 cm TL). Subsistence fishers accounted for 73% of fishing lines in the water, while recreational
fishers accounted for the rest. Ninety-three percent of the lines were recorded within the first 6 km from the estuary mouth,
of which 80% were recorded within the first 3 km. Almost 1/3 of the fishing effort was recorded between 1.0 and 1.5 km from
the mouth. The hypothesis that the estuarine dependent species spotted grunter was evenly distributed within the estuary was
rejected. However, there was a significant relationship between the distribution of the fishing effort of the subsistence
fishers and the fish, indicating that the spotted grunter was uniformly exploited within the estuary by this group of fishers.
In contrast, there was no relationship between the distribution of fish and recreational anglers. 相似文献
70.
Nesbitt TL Patel PA Yost MJ Goodwin RL Potts JD 《In vitro cellular & developmental biology. Animal》2007,43(1):10-16
Coronary vascular disease is one of the leading causes of mortality and morbidity in the United States. Therefore, a mechanistic
understanding of coronary vessel morphogenesis would aid in the innovation of new therapies targeting vascular disorders.
Moreover, a functionally equivalent in vitro model system allows for the delineation of the molecular mechanisms that regulate
coronary vessel development. In this study, we present a novel in vitro model system. This three-dimensional (3-D) model system
consists of a tubular scaffold, which is engineered from type-I collagen and has been optimized to support the growth of embryonic
cardiac tissues. In this report, proepicardial (PE) cells, the developmental precursors of coronary vessels, have been isolated
from several model species and cultured on this scaffold. In this model system, the PE cells were able to recapitulate several
aspects of coronary vessel morphogenesis including epicardial formation, the epicardial to mesenchymal transformation, and
de novo coronary vessel development or vasculogenesis. The differentiation of PE cells was characterized using a variety of
specific protein markers. The potential uses of this novel coronary developmental model are discussed. 相似文献