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Biochemical changes in young birches in the vicinity of a highway. In spring 1975 clonal birchtrees (grafts) were exposed to polluted air at different distances from a highway. After three months’ ex-posure, leaves showed different concentrations of free amino acids, total phenols, chlorophyll a, chloro-phyll b, (3-carotene, reducing sugars and total content of vitamin C depending on distance from the highway. Also the lead concentration in moss filters showed an approximately exponential decrease with distance from the highway. 相似文献
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Root systems of two contiguous grassland sites (fertilized meadow and abandoned grassland). In the course of an investigation on plant succession and soil development on abandoned grassland, we compared root systems in a fertilized meadow (Arrhenatheretum) with those in grassland abandoned 15 years ago (now being covered mainly by Brachypodium pinnatum). Root lengths were determined by the line intercept method developed by Newman (1966) and Evans (1970). In addition, surface areas and volumes of roots were calculated. In the top layer of the soil (0–5 cm) root lengths and root surfaces were nearly equal in the two sites, but the subsequent exponential decreases with depth were more pronounced in the meadow soil. Root volume (including rhizomes of Brachypodium pinnatum) was much larger in the abandoned grassland site. In addition, results are compared to other investigations on root density. 相似文献
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CH Annandale PC Irons VP Bagla UI Osuagwuh EH Venter 《Reproduction in domestic animals》2010,45(2):250-255
The objectives of this work were to determine the site of persistence of lumpy skin disease virus (LSDV) in bulls shedding the virus in semen for a period longer than 28 days, to determine if the virus is present in all fractions of semen and to study lesions that developed in the genital tract. Six serologically negative postpubertal bulls were experimentally infected with a virulent field isolate of LSDV. The polymerase chain reaction (PCR) was performed on sheath washes, vesicular fluid, supernatant and cell‐rich fractions of semen from day 10 to day 26 postinfection (p.i.). Bulls that were positive by PCR on the whole semen sample collected on day 28 p.i. were slaughtered and tissue samples from their genital tracts submitted for histopathological evaluation, immunoperoxidase staining, virus isolation and PCR. Two of the bulls developed severe lumpy skin disease (LSD) and were found to be shedding viral DNA in their semen on day 28 p.i. Viral DNA was identified in all semen fractions from all bulls, but mostly from the cell‐rich fraction and from the severely affected bulls. The PCR assay was positive on postmortem samples of testes and epididymides from the two severely affected bulls. Virus could be recovered from the testes of these two bulls and from the epididymis of one of them. Immunoperoxidase staining was positive for LSDV staining in sections of testes and epididymides exhibiting necrosis. This study suggests that the testis and epididymis are sites of persistence of LSDV in bulls shedding virus in semen for prolonged periods and revealed that viral DNA is present in all fractions of the ejaculate. 相似文献
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S Gür G Türk E Demirci A Yüce M Sönmez Ş Özer EH Aksu 《Reproduction in domestic animals》2011,46(2):289-295
The aim of this study was to determine the changes in diameter of corpus luteum (CL), maternal progesterone (P) concentration, lipid peroxidation and non‐enzymatic antioxidant levels along with enzymatic antioxidant activities in pregnant ewes bearing single and twin foetuses. The ewes were selected from healthy animals that were brought to the abattoir for slaughtering. The ewes were divided into three groups: Group 1 (non‐pregnant, non‐oestrous, n = 30), Group 2 (pregnant bearing a single foetus, n = 30) and Group 3 (pregnant bearing twin foetuses, n = 12) after they were slaughtered. Pregnant ewes were in the first half of the pregnancy. The diameter of CL and P concentration of pregnant ewes bearing a single foetus or twin foetuses were found higher than that found in non‐pregnant ewes. Similarly, the P concentration of pregnant ewes bearing twin foetuses was higher than that found in pregnant ewes bearing a single foetus. Malondialdehyde (MDA) level in pregnant ewes bearing twin foetuses was higher than that found in both non‐pregnant and pregnant ewes bearing a single foetus. The serum glutathione (GSH) level and glutathione‐peroxidase (GSH‐Px) activity of pregnant ewes bearing twin foetuses were found lower than that found in non‐pregnant ewes. Additionally, the GSH‐Px activity of pregnant ewes bearing twin foetuses was found lower than that found in pregnant ewes bearing a single foetus. No significant difference was found between pregnant ewes bearing female and male foetus with respect to diameter of CL, P concentration and oxidative stress parameters. There were significant positive correlations between foetal number (0, 1, 2) and diameter of CL, P concentration, MDA level, and between P concentration and diameter of CL, MDA level. However, significant negative correlations were found between foetal number (0, 1, 2) and GSH level, GSH‐Px activity, and between P concentration and GSH‐Px activity. In conclusion, the diameter of CL enlarges, P production increases and oxidant/antioxidant balance impairs because of the gestation stress in ewes during pregnancy. 相似文献
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The Influence of the Primary Loess Amelioration on the K Fixation, other Chemical Characteristics and the Yield of Parabraunerden The pH-values, carbonate content and the Ca-saturation of the top soil increase by adding calcareous loess to a loessial soil, whereas the H + Al-saturation decreases. During a two years experiment no change occured on the subsoil. It seems that there is no increased decomposition of organic substance, the decrease of the C-content corresponds with the dilution which took place. In the Ap -horizon the calcareous loess causes a decrease of exchangeable K, whereas K-fixation increases considerably. On a soil poorly supplied with nutrients the primary loess amelioration caused a yield decrease on account of the dilution and the additional fixation of K available for plants. On a well supplied soil a yield increase could be stated which probably can still be increases by fertilizing with additional K. 相似文献
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Climate warming is affecting the biodiversity all around the world, resulting in the expansion or contraction of the geographical range of species, and leading to colonisation (winners) and extinction (losers) events in ecosystems. It is crucial for the conservation of biodiversity to identify these potential winners and losers.We focus here on small standing waterbodies in Switzerland and on five taxonomic groups: vascular plants, snails, beetles, dragonflies and amphibians. We first assessed the sensitivity of each species to climate warming through their thermal preferences, using current altitudinal and latitudinal distribution, as a surrogate for temperature. We then evaluated the resilience of species to perturbations through five ecological and biogeographical criteria applicable to the perturbation “warming”: dispersal ability, degree of habitat specialisation, geographical extent in the study area, future trend in geographical extent, and future trend of habitat availability for species.Potential winners and losers of a warming climate could be quantified through their thermal preferences. The proportion of potential losers ranged from zero species for snails to 33% of the regional species pool for dragonflies. The set of potential winners was much larger, ranging from 53% for amphibians to 61% for dragonflies. A multimetric index combining the five resilience criteria enabled the further prioritisation of the species along a gradient of extinction risk.This potential threat from climate warming is not reflected by the current Red Lists of dragonflies and amphibians, suggesting that conservation management could gain from a complementary label indicating the degree of sensitivity to warming. 相似文献
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Measurements of the partitioning of rhenium (Re) between garnet and silicate liquid from 1.5 to 2.0 gigapascals and 1250 degrees to 1350 degreesC show that Re is compatible in garnet. Oceanic island basalts (OIBs) have lower Re contents than mid-ocean ridge basalt, because garnet-bearing residues of deeper OIB melting will retain Re. Deep-mantle garnetite or eclogite may harbor the missing Re identified in crust-mantle mass balance calculations. Oceanic crust recycled into the upper mantle at subduction zones will retain high Re/Os (osmium) ratios and become enriched in radiogenic 187Os. Recycled eclogite in a mantle source should be easily traced using Re abundances and Os isotopes. 相似文献
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J. J. Oertli 《植物养料与土壤学杂志》1986,149(1):60-67
Non-osmotic moisture stress can be simulated by applying to a plant tissue a solute that cannot penetrate the cell wall. The external reduction in water potential caused by such a non-penetrating solute is compensated for by a reduction in pressure within the cell. The pressure is ambient throughout a cell that has been plasmolysed by a penetrating osmoticum. A supplementary non-penetrating osmoticum must also be compensated for by lowering the internal pressure, i.e. a negative turgor pressure must develop. Onion skin cells can withstand a resulting mechanical stress of up to about 10KPa (1/10 Bar) before collapsing. 相似文献