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51.
Summary The fluctuations of ODR, moisture content in the crust and the soil beneath the crust and crust strength during emergence
period have been presented. The limiting factors of the seed environment under crusted soil conditions have been described
and identified. In the early part of the emergence period ODR and in the later part crust strength were the limiting factors.
The emergence characteristics of the 12 soybean varieties of varying seed sizes were analysed in detail. The small seeded
varieties (Type-1 and Type-49) were less susceptible to the effects of increasing crust strength and maintained distinct emergence
advantage over the large seeded varieties. Since the large seeded varieties confronted the hard crust barriers for a longer
period of time, their seedling mortality was more than 50 per cent as compared to around 30 per cent in case of small seeded
ones. 相似文献
52.
53.
54.
Ghosh S Sachan A Sen SK Mitra A 《Journal of industrial microbiology & biotechnology》2007,34(2):131-138
Streptomyces sannanensis MTCC 6637 was examined for its potentiality to transform ferulic acid into its corresponding hydroxybenzoate-derivatives.
Cultures of S. sannanensis when grown on minimal medium containing ferulic acid as sole carbon source, vanillic acid accumulation was observed in the
medium as the major biotransformed product along with transient formation of vanillin. A maximum amount of 400 mg/l vanillic
acid accumulation was observed, when cultures were grown on 5 mM ferulic acid at 28°C. This accumulation of vanillic acid
was found to be stable in the culture media for a long period of time, thus facilitating its recovery. Purification of vanillic
acid was achieved by gel filtration chromatography using Sephadex™ LH-20 matrix. Catabolic route of ferulic acid biotransformation
by S. sannanensis has also been demonstrated. The metabolic inhibitor experiment [by supplementation of 3,4 methylenedioxy-cinnamic acid (MDCA),
a metabolic inhibitor of phenylpropanoid enzyme 4-hydroxycinnamoyl-CoA ligase (4-CL) along with ferulic acid] suggested that
biotransformation of ferulic acid into vanillic acid mainly proceeds via CoA-dependent route. In vitro conversions of ferulic
acid to vanillin, vanillic acid and vanillin to vanillic acid were also demonstrated with cell extract of S. sannanensis. Further degradation of vanillic acid to other intermediates such as, protocatechuic acid and guaiacol was not observed,
which was also confirmed in vitro with cell extract. 相似文献
55.
56.
The present study was carried out in vitro to determine the efficacy of indigenous fungi isolated from egg masses of root-knot nematode, Meloidogyne incognita on egg parasitism, egg hatching, mobility and mortality against root-knot nematode, M. incognita. The tested fungi were Acremonium strictum, Aspergillus terreus, A. nidulans, A. niger, Chetomium aubense, Chladosporium oxysporum, Fusarium chlamydosporium, F. dimarum, F. oxysporum, F. solani, Paecilomyces lilacinus, Pochonia chlamydosporia, Trichoderma viride and T. harzianum. All tested fungi showed varied effects against the nematodes. Culture filtrates of A. strictum was very effective against the nematode in regards to egg parasitism (53%), egg hatching inhibition (86%) and mortality (68%) compared to controls. A. strictum was found to have an advantage over P. lilacinus, P. chlamydosporia, T. viride and T. harzianum in that it caused greater mortality of the second stage juveniles (J2). A. terreus did not show egg parasitism but was found to be highly toxic against second stage juveniles (J2) causing high mortality (around 68%). Thus, A. strictum and A. terreus showed good biocontrol potential against root-knot nematode, M. incognita under in vitro conditions. 相似文献
57.
Matthew J. Ferrari Ali Djibo Rebecca F. Grais Nita Bharti Bryan T. Grenfell Ottar N. Bjornstad 《Proceedings. Biological sciences / The Royal Society》2010,277(1695):2775-2782
Seasonally driven cycles of incidence have been consistently observed for a range of directly transmitted pathogens. Though frequently observed, the mechanism of seasonality for directly transmitted human pathogens is rarely well understood. Despite significant annual variation in magnitude, measles outbreaks in Niger consistently begin in the dry season and decline at the onset of the seasonal rains. We estimate the seasonal fluctuation in measles transmission rates for the 38 districts and urban centres of Niger, from 11 years of weekly incidence reports. We show that transmission rates are consistently in anti-phase to the rainfall patterns across the country. The strength of the seasonal forcing of transmission is not correlated with the latitudinal rainfall gradient, as would be expected if transmission rates were determined purely by environmental conditions. Rather, seasonal forcing is correlated with the population size, with larger seasonal fluctuation in more populous, urban areas. This pattern is consistent with seasonal variation in human density and contact rates due to agricultural cycles. The stronger seasonality in large cities drives deep inter-epidemic troughs and results in frequent local extinction of measles, which contrasts starkly to the conventional observation that large cities, by virtue of their size, act as reservoirs of measles. 相似文献
58.
Michael S. Watt Darren J. Kriticos Karina J. B. Potter Lucy K. Manning Nita Tallent-Halsell Graeme W. Bourdôt 《Biological invasions》2010,12(11):3711-3725
The expansion of the global area planted in fast-growing forest species seems likely as a means of offsetting carbon dioxide
emissions and developing a sustainable bio-energy resource. Selecting appropriate sites for these plantations will require
consideration of the effect of climate change on plantation growth and risks from abiotic and biotic factors. Buddleja davidii has been identified as a weed that has a major impact on plantation forest production in New Zealand. While it is at present
restricted mainly to the North Island, a large proportion of the area identified for forest expansion is in eastern and southern
regions of the South Island where the weed is presently relatively scarce. In this study we use a process-oriented climatic
niche model (CLIMEX) to identify climatically suitable areas for B. davidii under current climate and future climate during the 2080s. This analysis indicates areas most at risk from invasion by B. davidii are in eastern and southern regions of the South Island. As B. davidii predominantly colonises disturbed areas, the likely increases in plantation forest area within this region can be expected
to promote the spread of B. davidii. Strategies that could be implemented to manage B. davidii in this region are discussed. This study highlights the general utility of process-oriented niche models in identifying possible
threats to planned primary production activities from invasive weed species. This type of knowledge is invaluable in planning
and allocation of often scarce resources to most effectively control high impact weeds. Without the synoptic view of the invasion
and the assets at risk, there is a strong potential for regional pest management to be parochial, and consequently less effective
at all scales. 相似文献
59.
Gkrania-Klotsas E Ye Z Cooper AJ Sharp SJ Luben R Biggs ML Chen LK Gokulakrishnan K Hanefeld M Ingelsson E Lai WA Lin SY Lind L Lohsoonthorn V Mohan V Muscari A Nilsson G Ohrvik J Chao Qiang J Jenny NS Tamakoshi K Temelkova-Kurktschiev T Wang YY Yajnik CS Zoli M Khaw KT Forouhi NG Wareham NJ Langenberg C 《PloS one》2010,5(10):e13405
Objective
Biological evidence suggests that inflammation might induce type 2 diabetes (T2D), and epidemiological studies have shown an association between higher white blood cell count (WBC) and T2D. However, the association has not been systematically investigated.Research Design and Methods
Studies were identified through computer-based and manual searches. Previously unreported studies were sought through correspondence. 20 studies were identified (8,647 T2D cases and 85,040 non-cases). Estimates of the association of WBC with T2D were combined using random effects meta-analysis; sources of heterogeneity as well as presence of publication bias were explored.Results
The combined relative risk (RR) comparing the top to bottom tertile of the WBC count was 1.61 (95% CI: 1.45; 1.79, p = 1.5*10−18). Substantial heterogeneity was present (I2 = 83%). For granulocytes the RR was 1.38 (95% CI: 1.17; 1.64, p = 1.5*10−4), for lymphocytes 1.26 (95% CI: 1.02; 1.56, p = 0.029), and for monocytes 0.93 (95% CI: 0.68; 1.28, p = 0.67) comparing top to bottom tertile. In cross-sectional studies, RR was 1.74 (95% CI: 1.49; 2.02, p = 7.7*10−13), while in cohort studies it was 1.48 (95% CI: 1.22; 1.79, p = 7.7*10−5). We assessed the impact of confounding in EPIC-Norfolk study and found that the age and sex adjusted HR of 2.19 (95% CI: 1.74; 2.75) was attenuated to 1.82 (95% CI: 1.45; 2.29) after further accounting for smoking, T2D family history, physical activity, education, BMI and waist circumference.Conclusions
A raised WBC is associated with higher risk of T2D. The presence of publication bias and failure to control for all potential confounders in all studies means the observed association is likely an overestimate. 相似文献60.