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181.
Responses of soil microbial communities to prescribed burning in two paired vegetation sites in southern China 总被引:4,自引:0,他引:4
Sun Yuxin Wu Jianping Shao Yuanhu Zhou Lixia Mai Bixian Lin Yongbiao Fu Shenglei 《Ecological Research》2011,26(3):669-677
Prescribed burning is a common site preparation practice for forest plantation in southern China. However, the effects of
prescribed burning on soil microbial communities are poorly understood. This study examined changes in microbial community
structure, measured by phospholipid fatty acids (PLFAs), after a single prescribed burning in two paired vegetation sites
in southern China. The results showed that the total amount of PLFA (totPLFA) was similar under two vegetation types in the
wet season but differed among vegetation type in the dry season, and was affected significantly by burning treatment only
in the wet season. Bacterial PLFA (bactPLFA) and fungal PLFA (fungPLFA) in burned plots all decreased compared to the unburned
plots in both seasons (P = 0.059). Fungi appeared more sensitive to prescribed burning than bacteria. Both G+ bacterial PLFA and G− bacterial PLFA were decreased by the burning treatment in both dry and wet seasons. Principal component analysis of PLFAs
showed that the burning treatment induced a shift in soil microbial community structure. The variation in soil microbial community
structure was correlated significantly to soil organic carbon, total nitrogen, available phosphorus and exchangeable potassium.
Our results suggest that prescribed burning results in short-term changes in soil microbial communities but the long-term
effects of prescribed burning on soil microbial community remain unknown and merit further investigation. 相似文献
182.
Sherif Louis Katalin Benedek Michael Mowat George Klein Sabine Mai 《Cytotechnology》2004,44(3):143-149
Characterization of genetic disorders in humans and animal models requires identification of chromosomal aberrations. However, identifying fine deletions or insertion in metaphase chromosomes has been always a challenge due to limitations of resolution. In this study we developed a rapid method for chromosome elongation using two different intercalating agents: ethidium bromide and 5-bromo-2′-deoxyuridine (BrdU), together with a short-term mitotic block using colcemid. About 70% of the chromosomes from cells that underwent this elongation procedure reached three times longer than those prepared from control cells. FISH experiments using elongated chromosomes revealed a duplicated region of chromosome 11 that was not visible in cells prepared with conventional methods. 相似文献
183.
The present study was to test the hypothesis that anti-arrhythmic properties of verapamil may be accompanied by preserving connexin43 (Cx43) protein via calcium influx inhibition. In an in vivo study, myocardial ischemic arrhythmia was induced by occlusion of the left anterior descending (LAD) coronary artery for 45 min in Sprague-Dawley rats. Verapamil, a calcium channel antagonist, was injected i.v. into a femoral vein prior to ischemia. Effects of verapamil on arrhythmias induced by Bay K8644 (a calcium channel agonist) were also determined. In an ex vivo study, the isolated heart underwent an initial 10 min of baseline normal perfusion and was subjected to high calcium perfusion in the absence or presence of verapamil. Cardiac arrhythmia was measured by electrocardiogram (ECG) and Cx43 protein was determined by immunohistochemistry and western blotting. Administration of verapamil prior to myocardial ischemia significantly reduced the incidence of ventricular arrhythmias and total arrhythmia scores, with the reductions in heat rate, mean arterial pressure and left ventricular systolic pressure. Verapamil also inhibited arrhythmias induced by Bay K8644 and high calcium perfusion. Effect of verapamil on ischemic arrhythmia scores was abolished by heptanol, a Cx43 protein uncoupler and Gap 26, a Cx43 channels inhibitor. Immunohistochemistry data showed that ischemia-induced redistribution and reduced immunostaining of Cx43 were prevented by verapamil. In addition, diminished expression of Cx43 protein determined by western blotting was observed following myocardial ischemia in vivo or following high calcium perfusion ex vivo and was preserved after verapamil administration. Our data suggest that verapamil may confer an anti-arrhythmic effect via calcium influx inhibition, inhibition of oxygen consumption and accompanied by preservation of Cx43 protein. 相似文献
184.
While the practical application of electrode materials depends intensively on the Li+ ion storage mechanisms correlating ultimately with the coulombic efficiency, reversible capacity, and morphology variation of electrode material upon cycling, only intercalation‐type electrode materials have proven viable for commercialization up to now. This paper reviews the promising anode materials of metal vanadates (MxVyOz, M = Co, Cu, Mn, Fe, Zn, Ni, Li) that have high capacity, low cost, and abundant resource, and also discusses the related Li+ ion storage mechanism. It is concluded that most of these (MxVyOz, M = Co, Cu, Mn, Fe, Zn, Ni) exhibit irreversible redox reactions upon lithiation/delithiation accompanied by large volume expansion, which is not favorable for industrial applications. In particular, Li3VO4 with specific intercalation Li+ ion storage mechanism and compatible merits of safety and energy density exhibits great potential for practical application. This review systematically summarizes the latest progress in Li3VO4 research, including the representative fabrication approaches for advanced morphology and state‐of‐the‐art technologies to boost performance and the morphology variation associated with Li+ ion storage mechanisms. Furthermore, an outlook on where breakthroughs for Li3VO4 may be most likely achieved will be provided. 相似文献
185.
Park SM Yan BC Park JH Choi JH Yoo KY Lee CH Baek YY Kim YM Kang IJ Won MH 《Cellular and molecular neurobiology》2012,32(3):423-434
Tetanus toxin (TeT), an exotoxin, has been studied to cause tetanus in mammalian brains, and it can block the release of some
neurotransmitters and affect seizure propagation. In the present study, we investigated neuronal damage/death and glial changes
in the mouse hippocampus after systemic administration (intraperitoneal injection) of TeT 10 and 100 ng/kg. In both the 10
and 100 ng/kg TeT-treated groups, no neuronal death occurred in any subregions of the mouse hippocampus until 24 h post-treatment;
however, there were changes in glia in the hippocampus depending on time course and dosage. The morphology of GFAP-immunoreactive
astrocytes and Iba-1-immunoreactive microglia was apparently changed in the 100 ng/kg TeT treated-group compared to the 10 ng/kg
TeT treated-group. In the 100 ng/kg TeT treated-group, they were increased in size and their immunoreactivity was distinctively
increased from 12 h post-treatment. We also found that their protein levels were increased in the hippocampus at 12 h post-treatment
of 100 ng/kg TeT. In conclusion, these results indicate that the systemic administration of 100 ng/kg TeT induced a distinctive
microglia changes in the mouse hippocampus without any neuronal death/damage. 相似文献
186.
Ho Joong Sung Mee Kyung Jung Yong-Bin Eom Jong-Eun Lee Jae Woong Sull Sun Ha Jee 《Genes & genomics.》2012,34(1):103-106
Fasting glucose level is the most basic and widely used indicator of diabetes. Several genome wide association studies have reported that the gene encoding melatonin receptor 1B (MTNR1B) exerts a major effect on serum fasting glucose levels. We tested for the association between single nucleotide polymorphisms (SNPs) in the MTNR1B gene and fasting glucose levels in a Korean population consisting of 8,229 subjects taken from two community-based cohorts. The mean age of the subjects in the study population was 51.9 years. For this study, we selected 363 SNPs located in the MTNR1B gene, which is located on chromosome 11. Multivariate linear regression models were used to test for genotypic effects on fasting glucose levels while adjusting for age and sex under an additive model. The MTNR1B SNP most highly associated with fasting glucose levels was rs10830962 (p=1.95×10?5), followed by rs3847554 (p=3.16×10?4). Replication of these initial findings is important to better understand the correlation between MTNR1B variations and their effects, especially in Asian populations. 相似文献
187.
Background: Helicobacter pylori infection is difficult to diagnose in children, especially in developing countries where noninvasive methods such as urea breath test are often not available. We evaluate the sensitivity and specificity of a new monoclonal antibody-based antigen-in-stool enzyme immunoassay (Premier Platinum HpSA PLUS) for diagnosis of H. pylori infection in Vietnamese children.
Materials and Methods: Sensitivity of the antigen-in-stool test was evaluated in 232 children, 3–15 years of age, who were positive for H. pylori infection by culture from biopsies. For evaluation of the specificity 98 children of similar age with nongastrointestinal conditions and who were negative for H. pylori infection by serologic assays were included with blood and stool samples.
Results: Of the 232 culture-positive children, 224 were also positive by Premier Platinum HpSA PLUS. Of the 98 control children, 93 were H. pylori negative also in the stool test. The sensitivity of Premier Platinum HpSA PLUS was thus 96.6% (95% CI 93.3–98.5) and the specificity was 94.9% (95% CI 88.5–98.3).
Conclusions: The findings have demonstrated Premium Platinum HpSA PLUS to be a reliable method for detection of H. pylori infection also in children in our area. 相似文献
Materials and Methods: Sensitivity of the antigen-in-stool test was evaluated in 232 children, 3–15 years of age, who were positive for H. pylori infection by culture from biopsies. For evaluation of the specificity 98 children of similar age with nongastrointestinal conditions and who were negative for H. pylori infection by serologic assays were included with blood and stool samples.
Results: Of the 232 culture-positive children, 224 were also positive by Premier Platinum HpSA PLUS. Of the 98 control children, 93 were H. pylori negative also in the stool test. The sensitivity of Premier Platinum HpSA PLUS was thus 96.6% (95% CI 93.3–98.5) and the specificity was 94.9% (95% CI 88.5–98.3).
Conclusions: The findings have demonstrated Premium Platinum HpSA PLUS to be a reliable method for detection of H. pylori infection also in children in our area. 相似文献
188.
Van VQ Darwiche J Raymond M Lesage S Bouguermouh S Rubio M Sarfati M 《Journal of immunology (Baltimore, Md. : 1950)》2008,181(8):5204-5208
Peripheral CD103(+)Foxp3(+) regulatory T cells (Tregs) can develop both from conventional naive T cells upon cognate Ag delivery under tolerogenic conditions and from thymic-derived, expanded/differentiated natural Tregs. We here show that CD47 expression, a marker of self on hematopoietic cells, selectively regulated CD103(+)Foxp3(+) Treg homeostasis at the steady state. First, the proportion of effector/memory-like (CD44(high)CD62L(low)) CD103(+)Foxp3(+) Tregs rapidly augmented with age in CD47-deficient mice (CD47(-/-)) as compared with age-matched control littermates. Yet, the percentage of quiescent (CD44(low)CD62L(high)) CD103(-)Foxp3(+) Tregs remained stable. Second, the increased proliferation rate (BrdU incorporation) observed within the CD47(-/-)Foxp3(+) Treg subpopulation was restricted to those Tregs expressing CD103. Third, CD47(-/-) Tregs maintained a normal suppressive function in vitro and in vivo and their increased proportion in old mice led to a decline of Ag-specific T cell responses. Thus, sustained CD47 expression throughout life is critical to avoid an excessive expansion of CD103(+) Tregs that may overwhelmingly inhibit Ag-specific T cell responses. 相似文献
189.
The vertical distribution of a bloom-forming Microcystis population was studied based on the relevant limnological parameters obtained from the lower Nakdong River (Mulgum) during
the summer of 1994. Over three months (late June to late September), a high abundance of Microcystis population (mean ± SD, 2.9 ± 8.4 × 105 cells ml−1, n = 40) and algal biomass (mean ± SD, chlorophyll a, 131 ± 346 μg l−1, n = 31) was persistent throughout the entire water column (0–5 m, n = 11). The vertical distribution of carbon content was uneven, with a high concentration near the surface zone (mean ± SD,
total, 7.9 ± 7.8; Microcystis, 5.2 ± 8.3 μg C ml−1, n = 15). Incorporating limnological and meteorological factors, a diel study of the vertical distribution of Microcystis showed that the chlorophyll a concentration was highest near the surface zone on a calm night (wind velocity, <2 m s−1, 2300–700) but was evenly distributed on a windy day (>4 m s−1, 1100–1900). Among many possible factors, wind velocity may have played an important role in controlling the vertical distribution
of Microcystis in the lower Nakdong River.
Received: July 12, 1999 / Accepted: November 15, 1999 相似文献
190.
S Le Vu A Velter L Meyer G Peytavin J Guinard J Pillonel F Barin C Semaille 《PloS one》2012,7(6):e39872
BACKGROUND: Population-based estimates of HIV incidence in France have revealed that men who have sex with men (MSM) are the most affected population and contribute to nearly half of new infections each year. We sought to estimate HIV incidence among sexually active MSM in Paris gay community social venues. METHODOLOGY/ PRINCIPAL FINDINGS: A cross-sectional survey was conducted in 2009 in a sample of commercial venues such as bars, saunas and backrooms. We collected a behavioural questionnaire and blood sample. Specimens were tested for HIV infection and positive specimens then tested for recent infection by the enzyme immunoassay for recent HIV-1 infection (EIA-RI). We assessed the presence of antiretroviral therapy among infected individuals to rule out treated patients in the algorithm that determined recent infection. Biomarker-based cross-sectional incidence estimates were calculated. We enrolled 886 MSM participants among which 157 (18%) tested HIV positive. In positive individuals who knew they were infected, 75% of EIA-RI positive results were due to ART. Of 157 HIV positive specimens, 15 were deemed to be recently infected. The overall HIV incidence was estimated at 3.8% person-years (py) [95%CI: 1.5-6.2]. Although differences were not significant, incidence was estimated to be 3.5% py [0.1-6.1] in men having had a negative HIV test in previous year and 4.8% py [0.1-10.6] in men having had their last HIV test more than one year before the survey, or never tested. Incidence was estimated at 4.1% py [0-8.3] in men under 35 years and 2.5% py [0-5.4] in older men. CONCLUSIONS/ SIGNIFICANCE: This is the first community-based survey to estimate HIV incidence among MSM in France. It includes ART detection and reveals a high level of HIV transmission in sexually active individuals, despite a high uptake of HIV testing. These data call for effective prevention programs targeting MSM engaged in high-risk behaviours. 相似文献