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11.
Background
The pH is an important parameter controlling many metabolic and signalling pathways in living cells. Recombinant fluorescent pH indicators (pHluorins) have come into vogue for monitoring cellular pH. They are derived from the most popular Aequorea victoria GFP (Av-GFP). Here, we present a novel fluorescent pH reporter protein from the orange seapen Ptilosarcus gurneyi (Pt-GFP) and compare its properties with pHluorins for expression and use in plants. 相似文献12.
The European corn borer (Ostrinia nubilalis) is one of the most important pests of maize (Zea mays). Injuries to the plants caused by the larvae of the European corn borer may represent entrance gates for fungal-spores. The cultivation of Bacillus thuringiensis maize (Bt-maize) is one possibility to reduce infestation by the European corn borer. The aim of the present project was to determine and to compare the number of species and the frequency of Fusarium spp. infestation in Bt-maize (cry1Ab) and conventional maize. In 2003, we analysed the Fusarium spp. infestation of samples of chaffed Bt-maize and its isogenic variety on two experimental fields in the Oderbruch region (Germany), an European corn borer infested area. The conventional variety on the first of the experimental fields (previous crop wheat and forking cultivation) showed a small infestation (16%) of Ostrinia nubilalis while in the conventional variety on the second field (previous crop maize and not forking cultivation) the infestation of the European corn borer was almost three times higher (47%). In the conventional variety on both of the experimental fields we found a high Fusarium spp. infestation (70%). Especially species of the section Liseola dominates, among them: F. subglutinans, F. proliferatum und F. verticillioides. The Fusarium infestation in the samples of Bt-maize from the field with previous crop wheat and forking cultivation was just as high as in the conventional variety (70%). The infestation of Fusarium spp. in the samples of Bt-maize from the field with previous crop maize and forking cultivation was more than 20?% lower. 相似文献
13.
Current silvicultural treatments in beech forests are aimed at achieving thick logs without discoloured hardwood. Therefore
intensive thinning is applied already in younger stands with the objective of large-sized trunks at an age of 100 years. However,
this approach bears the risk that dead wood structures and broken trees are completely removed from the forest. The impact
of three different silvicultural management intensity levels on wood-inhabiting fungi over decades was investigated in a large
beech forest (>10,000 ha) in southern Germany in 69 sampling plots: A Intensive Thinning and Logging with high-value trees,
B Conservation-Oriented Logging with integration of special structures such as dead wood and broken trees and C Strict Forest
Reserves with no logging for 30 years. The analysis of community showed marked differences in the fungus species composition
of the three treatments, independent of stand age. The relative frequencies of species between treatments were statistically
different. Indicator species for naturalness were more abundant at sites with low silvicultural management intensity. Fomes fomentarius, the most common fungus in virgin forests and strict forest reserves, is almost missing in forests with high-management intensity.
The species richness seemed to be lower where intensive thinning was applied (P = 0.051). Species characteristic for coarse woody debris were associated to low management intensity, whereas species with
a significant preference for stumps became more frequent with increasing management intensity. A total amount of dead wood
higher than 60 m3/ha was found to enable significantly higher numbers of species indicators of naturalness (P = 0.013). In conclusion, when applying intensive silvicultural treatment, the role of dead wood needs to be actively considered
in order to maintain the natural biocoenosis of beech forests. 相似文献
14.
The objectives of the study were to investigate mineral soil profiles as a living space for microbial decomposers and the relation of microbial properties to soil acidity. We estimated microbial biomass C on concentration (g g–1 DW) as well as on volume basis (g m–2) and the microbial biomass C to soil organic C ratio along a vertical gradient from L horizon to 20 cm in the mineral soil and along a gradient of increasing acidity at five beech forest stands in Germany. Microbial biomass C concentration ranged from 17,000–34,000 g Cmic g–1 DW in the litter layer and decreased dramatically down the profile to 29–264 g Cmic g–1 DW at 15–20 cm depth in the mineral soil. This represents depth gradients of microbial biomass C concentrations ranging from a factor of 65 in slightly acidic and up to 875 in acidic soils. In contrast, microbial biomass C calculated on a volume basis (g Cmic m–2) showed a different pattern since a considerable part of the microbial biomass C was located in the mineral soils. In the soil profile 22–34% of the microbial biomass C was found in the mineral soil at strictly acidic sites and as much as 64–88% in slightly acidic soils. The microbial biomass C to soil organic carbon ratios decreased in general down from the L horizon in the forest floor to 0–5 cm depth in the mineral soils. In strongly acidic mineral soils however, the C to soil organic carbon ratio increased with depth, suggesting a positive relation to increasing pH. We conclude from depth gradients of soil pH and microbial biomass C to soil organic carbon ratio that pH affects this ratio at acidic sites. The inter-site comparison indicates that acidity restricts microbial biomass C in the mineral soils. 相似文献
15.
Parker M Pollnitz AP Cozzolino D Francis IL Herderich MJ 《Journal of agricultural and food chemistry》2007,55(15):5948-5955
16.
Like marine fish freshwater fish are an important source of essential fatty acids for human nutrition. However, the fatty
acid composition of pond fish can vary considerably and strongly depends on that of the ingested food. Investigations on the
fatty acid composition of common carp (Cyprinus carpio) and tench (Tinca tinca) have shown that different methods of rearing and feeding cause substantial variations in the proportions of the n-6 and
n-3 polyunsaturated fatty acids of these fish species. Carp reared on the basis of natural food in ponds exhibit high contents
of n-6 as well as n-3 fatty acids in their muscle triacylglycerols. On the other hand carp fed supplementary wheat in ponds
resulted in somewhat lower levels of these essential fatty acids. High amounts of n-3 fatty acids can be found in carp fed
high-energy diets containing high levels of fish oil. Analogous results were obtained in experiments with tench reared under
different nutritional conditions. While rearing on the basis of only natural food in ponds as well as feeding supplementary
wheat yielded in similar levels of n-3 and n-6 polyunsaturated fatty acids, higher contents of n-3 fatty acids were recorded
in tench fed pellets. High levels of n-3 polyunsaturated fatty acids in foodstuffs have positive effects on human health.
Experiments with different cultured fish species proved that the fatty acid composition of the edible parts can be influenced
by the diet. Therefore, a finishing diet with a suitable fatty acid profile can be used to improve the nutritional quality
of fish products of farmed origin. 相似文献
17.
Erich Inselsbacher Nina Hinko-Najera Umana Markus Gorfer Katrin Ripka Rebecca Hood-Novotny Wolfgang Wanek 《Soil biology & biochemistry》2010,42(2):360-372
Agricultural systems that receive high amounts of inorganic nitrogen (N) fertilizer in the form of either ammonium (NH4+), nitrate (NO3−) or a combination thereof are expected to differ in soil N transformation rates and fates of NH4+ and NO3−. Using 15N tracer techniques this study examines how crop plants and soil microbes vary in their ability to take up and compete for fertilizer N on a short time scale (hours to days). Single plants of barley (Hordeum vulgare L. cv. Morex) were grown on two agricultural soils in microcosms which received either NH4+, NO3− or NH4NO3. Within each fertilizer treatment traces of 15NH4+ and 15NO3− were added separately. During 8 days of fertilization the fate of fertilizer 15N into plants, microbial biomass and inorganic soil N pools as well as changes in gross N transformation rates were investigated. One week after fertilization 45-80% of initially applied 15N was recovered in crop plants compared to only 1-10% in soil microbes, proving that plants were the strongest competitors for fertilizer N. In terms of N uptake soil microbes out-competed plants only during the first 4 h of N application independent of soil and fertilizer N form. Within one day microbial N uptake declined substantially, probably due to carbon limitation. In both soils, plants and soil microbes took up more NO3− than NH4+ independent of initially applied N form. Surprisingly, no inhibitory effect of NH4+ on the uptake and assimilation of nitrate in both, plants and microbes, was observed, probably because fast nitrification rates led to a swift depletion of the ammonium pool. Compared to plant and microbial NH4+ uptake rates, gross nitrification rates were 3-75-fold higher, indicating that nitrifiers were the strongest competitors for NH4+ in both soils. The rapid conversion of NH4+ to NO3− and preferential use of NO3− by soil microbes suggest that in agricultural systems with high inorganic N fertilizer inputs the soil microbial community could adapt to high concentrations of NO3− and shift towards enhanced reliance on NO3− for their N supply. 相似文献
18.
R A McCarthy W L Steffens C A Brown S A Brown M Ard D R Finco 《Canadian journal of veterinary research》2001,65(2):125-130
The primary objective of this study was to determine the effects of diets containing 18% or 34% protein on glomerular mesangial area (GMA) and basement membrane thickness (GBMT) in uninephrectomized aged dogs. A secondary objective was to determine the combined effects of aging and uninephrectomy on GMA and GBMT in dogs. Ten clinically healthy, pure-bred dogs were unilaterally nephrectomized at about 8 y of age. After 2 mo, 5 dogs were fed an 18% protein diet and 5 dogs were fed a 34% protein diet for 48 mo. At month 48, the dogs were euthanized and the remaining kidney was collected. Samples of kidney from both times of collection were used to measure GMA and GBMT using electron microscopy. The effects of diet on GMA and GBMT were analyzed (student's t-test) using necropsy/nephrectomy score ratios. The effects of time-nephrectomy were determined by comparing nephrectomy values for GMA and GBMT with necropsy values (paired t-test). Dogs fed 34% dietary protein did not have a significant increase in GMA and GBM thickness when compared to dogs fed the 18% protein diet. A significant increase in GMA and GBMT occurred with time-nephrectomy (P = 0.011 and 0.018, respectively). Although dietary protein intake was not a significant factor in causing structural changes to glomeruli in uninephrectomized aged dogs, the power to detect a difference was low. However, significant effects of aging and nephrectomy were detected despite the low power of the study. These results suggest that the increases in GMA and GBMT that occur over time are not markedly influenced by dietary protein intake. However, subtle protein effects cannot be eliminated as a possibility based on this study. 相似文献
19.
Maria Holmberg Anu Akujärvi Saku Anttila Lauri Arvola Irina Bergström Kristin Böttcher Xiaoming Feng Martin Forsius Inese Huttunen Markus Huttunen Yki Laine Heikki Lehtonen Jari Liski Laura Mononen Katri Rankinen Anna Repo Vanamo Piirainen Pekka Vanhala Petteri Vihervaara 《Landscape Ecology》2015,30(3):561-577
20.
Background and Objective Terrestrial ecotoxicity data are required for many research purposes. The data are derived either from the literature or elaborated by own investigations. As the terrestrial toxicity tests are usually time-consuming and labour intensive, the experiments are performed with a limited number of test organisms and soils. In the context of a project sponsored by CEFIC-LRI (European Chemical Industry Council Long-Range Research Initiative), EC50-values were systematically elaborated for eight chemicals with a wide range of logKow-values (CdCl2, Trinitrotoluene, 3,4-dichloroaniline, 2,4-dichlorophenol, Tributyltinchloride, Pentachlorophenol, Benzo(a)pyrene, p,p-dichloro-2,2-diphenyl-1,1,1-trichloroethane). The substances were selected covering a broad range of physico-chemical and ecotoxicological properties. As toxicity endpoints, microbial activities, plant germination and growth as well as reproduction of earthworms and collembola were determined. As such systematic investigations are rarely performed and for some substances no data existed, the data pool is made available to the scientific community.Methods All toxicity tests were conducted on three different soil types (sandy soil, silty soil, loamy soil), according to ISO and OECD guidelines Results, Discussion, Conclusion and Outlook The different toxicities of the chemicals, the influence of soil properties on bioavailability as well as different sensitivities of test organisms and test parameters are reflected by the EC50-values. The results showed that the EC50-values calculated on the basis of nominal concentrations can significantly vary from EC50-values derived from analytical concentrations for some substances. To avoid false conclusions, this has to be considered especially when concentrations determined in the field are compared with toxicity data obtained from the literature or calculated on the basis of nominal concentrations. Moreover, the results indicate that terrestrial ecotoxicological tests should be accompanied by chemical analyses, to be sure to derive sound EC50-values.
As the tests were performed according to international guidelines, the comprehensive data pool relevant for the terrestrial ecotoxicity of eight chemicals is considered to be of great value for further research and discussions dealing with the habitat function of soils. 相似文献