排序方式: 共有35条查询结果,搜索用时 15 毫秒
1.
Diego Sustaita Patty Finfrock Quickert Laura Patterson Laureen Barthman-Thompson Sarah Estrella 《The Journal of wildlife management》2011,75(6):1498-1507
We undertook a 2-year (2002–2004) mark–recapture study to investigate demographic performance and habitat use of salt marsh harvest mice (Reithrodontomys raviventris halicoetes) in the Suisun Marsh. We examined the effects of different wetland types and microhabitats on 3 demographic variables: density, reproductive potential, and persistence. Our results indicate that microhabitats dominated by mixed vegetation or pickleweed (Salicornia spp.) supported similar salt marsh harvest mouse densities, reproductive potential, and persistence throughout much of the year, whereas few salt marsh harvest mice inhabited upland grass-dominated microhabitats. We found that densities were higher in diked wetlands, whereas post-winter persistence was higher in tidal wetlands, and reproductive potential did not differ statistically between wetland types. Our results emphasize the importance of mixed vegetation for providing adequate salt marsh harvest mouse habitat and suggest that, despite their physiognomic and hydrological differences, both diked and tidal wetlands support salt marsh harvest mouse populations by promoting different demographic attributes. We recommend that habitat management, restoration, and enhancement efforts include areas containing mixed vegetation in addition to pickleweed in both diked and tidal wetlands. © 2011 The Wildlife Society. 相似文献
2.
3.
Xiang Y. Zhang Yannick R. Brunet Laureen Logger Badreddine Douzi Christian Cambillau Laure Journet Eric Cascales 《PloS one》2013,8(11)
The Type VI secretion system (T6SS) is a versatile machine that delivers toxins into either eukaryotic or bacterial cells. At a molecular level, the T6SS is composed of a membrane complex that anchors a long cytoplasmic tubular structure to the cell envelope. This structure is thought to resemble the tail of contractile bacteriophages. It is composed of the Hcp protein that assembles into hexameric rings stacked onto each other to form a tube similar to the phage tail tube. This tube is proposed to be wrapped by a structure called the sheath, composed of two proteins, TssB and TssC. It has been shown using fluorescence microscopy that the TssB and TssC proteins assemble into a tubular structure that cycles between long and short conformations suggesting that, similarly to the bacteriophage sheath, the T6SS sheath undergoes elongation and contraction events. The TssB and TssC proteins have been shown to interact and a specific α-helix of TssB is required for this interaction. Here, we confirm that the TssB and TssC proteins interact in enteroaggregative E. coli. We further show that this interaction requires the N-terminal region of TssC and the conserved α-helix of TssB. Using site-directed mutagenesis coupled to phenotypic analyses, we demonstrate that an hydrophobic motif located in the N-terminal region of this helix is required for interaction with TssC, sheath assembly and T6SS function. 相似文献
4.
Beryl Royer-Bertrand Matteo Torsello Donata Rimoldi Ikram El Zaoui Katarina Cisarova Rosanna Pescini-Gobert Franck Raynaud Leonidas Zografos Ann Schalenbourg Daniel Speiser Michael Nicolas Laureen Vallat Robert Klein Serge Leyvraz Giovanni Ciriello Nicolò Riggi Alexandre P. Moulin Carlo Rivolta 《American journal of human genetics》2016,99(5):1190-1198
5.
6.
7.
Weingärtner O Lütjohann D Vanmierlo T Müller S Günther L Herrmann W Böhm M Laufs U Herrmann M 《Chemistry and physics of lipids》2011,(6):451-456
Objective
Hypercholesterolemia is a major risk factor for cardiovascular disease (CVD), and diabetes mellitus and statin treatment affect cholesterol metabolism. The aim of the present study was to evaluate markers of cholesterol metabolism and determine their relationship with CVD in patients without diabetes mellitus who were not receiving statin treatment.Methods
In addition to conventional CVD risk factors, plasma levels of campesterol and sitosterol (indicators of cholesterol absorption) and lathosterol (an indicator of cholesterol synthesis) were determined in 835 consecutive patients referred for coronary angiography. Coronary artery disease was evaluated by coronary angiograms, carotid atherosclerosis and peripheral vascular disease were assessed by Doppler ultrasound, and cerebrovascular accidents and transient ischemic attacks were identified by medical history.Results
After excluding patients with known diabetes mellitus and those receiving statin treatment, 177 patients were included in the analysis. Compared to patients without CVDs (n = 111), patients with concomitant CVDs (n = 66) had a reduced lathosterol-to-cholesterol ratio (1.25 ± 0.61 vs. 1.38 ± 0.63, P < 0.05) and an increased campesterol-to-cholesterol ratio (1.81 ± 1.04 vs. 1.50 ± 0.69, P < 0.05), indicating that enhanced absorption and reduced synthesis of cholesterol is associated with CVD development. Logistic regression analysis including all established cardiovascular risk factors (age, sex, total cholesterol, arterial hypertension, body mass index and smoking) revealed that campesterol and the campesterol-to-cholesterol ratio were significant predictors of concomitant CVD in this patient population.Conclusion
In patients without diabetes mellitus, markers of enhanced cholesterol absorption were a strong predictor for concomitant CVD. 相似文献8.
Laureen C. Colis Debasis Chakraborti Pablo Hilario Christopher McCarty Ashis K. Basu 《Nucleosides, nucleotides & nucleic acids》2013,32(2):67-77
Two different approaches to synthesize oligonucleotides containing the 2 ′-deoxyguanosine adducts formed by nitropyrenes are described. A direct reaction of an unmodified oligonucleotide with an activated nitropyrene derivative is a convenient biomimetic approach for generating the major adducts in DNA. A total synthetic approach, by contrast, involves several synthetic steps, including Buchwald-Hartwig Pd-catalyzed coupling, but can be used for incorporating both the major and minor adducts in DNA in high yield. 相似文献
9.
10.
Maria-Grazia Ascenzi Andre Lutz Xia Du Laureen Klimecky Neal Kawas Talia Hourany Joelle Jahng Jesse Chin Yin Tintut Udo Nackenhors Joyce Keyak 《Journal of biomechanics》2014
To improve bone strength prediction beyond limitations of assessment founded solely on the bone mineral component, we investigated the effect of hyperlipidemia, present in more than 40% of osteoporotic patients, on multiscale structure of murine bone. Our overarching purpose is to estimate bone strength accurately, to facilitate mitigating fracture morbidity and mortality in patients. Because (i) orientation of collagen type I affects, independently of degree of mineralization, cortical bone?s micro-structural strength; and, (ii) hyperlipidemia affects collagen orientation and μCT volumetric tissue mineral density (vTMD) in murine cortical bone, we have constructed the first multiscale finite element (mFE), mouse-specific femoral model to study the effect of collagen orientation and vTMD on strength in Ldlr−/−, a mouse model of hyperlipidemia, and its control wild type, on either high fat diet or normal diet. Each µCT scan-based mFE model included either element-specific elastic orthotropic properties calculated from collagen orientation and vTMD (collagen-density model) by experimentally validated formulation, or usual element-specific elastic isotropic material properties dependent on vTMD-only (density-only model). We found that collagen orientation, assessed by circularly polarized light and confocal microscopies, and vTMD, differed among groups and that microindentation results strongly correlate with elastic modulus of collagen-density models (r2=0.85, p=10−5). Collagen-density models yielded (1) larger strains, and therefore lower strength, in simulations of 3-point bending and physiological loading; and (2) higher correlation between mFE-predicted strength and 3-point bending experimental strength, than density-only models. This novel method supports ongoing translational research to achieve the as yet elusive goal of accurate bone strength prediction. 相似文献