Modifications of the leaf surface structures of Quercus ilex L. in open, naturally CO2-enriched environments

Two Italian CO₂ springs allowed us to study the long-term effect of a 350–2600 μ mol mol^–1 increase in CO₂ concentrations on the surface structures of leaves of Quercus ilex L. Carbon dioxide increased the quantity of cuticular waxes, above an apparent threshold of 750 μ mol mol^–1 CO₂. Leaf wettability was not modified by CO₂ concentrations. Reduction in stomatal frequency was observable up to 750 μ mol mol^–1 CO₂, the slope being almost the same as that estimated for the increase in CO₂ concentration from pre-industrial times to the present. At higher concentrations, CO₂ seemed to exert no more impact on stomatal frequency.     

氟对镍钛拉簧的腐蚀性研究

目的:研究模拟应用氟化物防龋的口腔环境下,不同浓度氟化物对镍钛拉簧的应力衰减的影响。方法:选取两种国内常用品牌0.010 inch镍钛拉簧各40根,随机将每种拉簧平均分入四个浓度组(0.05%、0.10%、0.15%和对照组),将相同浓度组的不同品牌弹簧分别固定于间距为20 mm的四个支架的两端。将四个支架分别放入37℃人工唾液中水浴。将实验组按浓度分组放入不同浓度氟化人工唾液(0.05%、0.10%、0.15%)中处理5 min,每天三次。分别于实验前、实验后1周、2周、3周、4周用拉伸机测量每根弹簧拉伸至20 mm时的应力。对实验结果使用重复测量的方差分析。结果:时间因素对两种镍钛拉簧拉伸应力的衰减的影响有统计学意义,氟化物浓度有辅助效应,二者有交互作用。氟化物作用下不同品牌镍钛拉簧的应力腐蚀变化不同。(P0.05)。结论:1.氟化物的存在可以增加镍钛拉簧的应力衰减。2.在正畸治疗的临床工作中在使用氟化物时应考虑增加镍钛拉簧的更换频率。     

Synchrony in a Wild Turkey Population and its Relationship to Spring Weather

Abstract: Synchrony is an important component of wildlife population dynamics because it describes spatial pattern in temporal population fluctuations. The strength and spatial extent of synchrony can provide information about the extrinsic and intrinsic forces that shape population structure. Wild turkey (Meleagris gallopavo silvestris) populations undergo annual fluctuations, possibly due to variation in weather during the reproductive season. To determine if spring weather plays a role in synchronizing wild turkey populations, we used a modified Mantel-type spatial autocorrelation procedure to measure the synchrony in fall wild turkey harvest data collected in 443 townships from 1990 to 1995 and compared this to the pattern of synchrony in spring weather variables (May rainfall and temp) over the same period. We measured correlation using Spearman correlation coefficients between the total fall harvests from 1990 to 1995 for each pair of townships, and sorted pairs into 6 50-km distance intervals. We calculated a mean correlation coefficient for each interval and estimated its P-value using resampling. We found moderately significant synchrony in the fall harvest (r_s = 0.12-0.34, P < 0.008) among township pairs <150 km apart, but no significant synchrony beyond this distance. In contrast, both May temperature (r = 0.82-0.90, P < 0.001) and rainfall (r = 0.49-0.76, P < 0.001) were strongly synchronized across all 6 distance intervals. Visual inspection of time series in the wild turkey fall harvest suggests that populations may be synchronized in some years when weather promotes high reproductive success (i.e., a synchronized growth peak) and asynchronous in other years. Knowledge of the spatial dynamics of wild turkey populations will aid wildlife managers in estimating population change, setting harvest quotas, and managing habitat.     

Old fronds serve as a vernal carbon source in the wintergreen fern Dryopteris intermedia (Aspleniaceae)

Maintaining green leaves beyond the growing season has been hypothesized to benefit plants by supplying either a nutrient or a carbon source. Understanding such ecophysiological aspects of plants will help us to appreciate how a species functions in its environment and predict how it might be affected by future changes in that environment. The wintergreen fern species Dryopteris intermedia does not retranslocate nitrogen and phosphorus from old fronds in spring, but photosynthesis does take place in the old fronds during this season. To determine if carbon fixed in the old fronds is translocated to other parts of the plant, we labeled old fronds with (13)C via photosynthetic uptake and examined old fronds, new fronds, fine roots, and rhizomes for (13)C content 1 day and 1 month after labeling the old fronds. Vernally fixed carbon was translocated to the new fronds but not significantly to the below ground tissues. Old fronds in this species, therefore, serve as a carbon source for vernal growth of new fronds. This is the first study in which a fern was labeled with (13)C to track vernally fixed carbon from old fronds to the rest of the plant in a wintergreen species. Future research should examine the precise timing of this carbon movement and examine other species for a similar or contrasting strategy.     

微波萃取苦荞壳中总黄酮工艺研究

本文在提取苦荞壳中总黄酮的工艺实验中,优化了提取溶剂的种类,水和乙醇,同时还使用了超声波和微波辅助提取,并分别将不同因素,如溶剂种类及浓度,提取时间,温度,pH,液固比等,对提取结果的影响作了比较,结果表明,当介质为乙醇时的微波萃取效果明显优于其他提取方法。     

Seed treatment with lactic acid bacteria against seed-borne pathogens of spring wheat

Antifungal potential of lactic acid bacteria (LAB) such as Lactobacillus sakei KTU05-6, Pediococcus acidilactici KTU05-7 and Pediococcus pentosaceus KTU05-8, KTU05-9 and KTU05-10 was tested on naturally contaminated wheat seeds. LAB influence on fungal growth on kernels, seedling diseases and seed germination was examined by laboratory and field experiments. KTU05-10 was selected and later used for seed treatment as solitary strain and in two- or three-component mixtures with KTU05-7 and KTU05-6. The occurrence of Fusarium spp. on wheat kernels in agar plate assays was decreased by seed treatment with all LAB cultures, and the efficacy of each strain depended on incubation temperature. Inoculation of wheat kernels with strains of solitary KTU05-10 and in mixtures with KTU05-7 and KTU05-6 significantly reduced the incidence of Fusarium spp., Bipolaris sorokiniana and Alternaria spp. LAB influence on seed germination and seedling diseases was observed in laboratory and field experiments, but in most cases, this influence was insignificant.     

甘肃马鬃山北山羊春季卧息地的选择

2010年4～5月,在甘肃马鬃山采用样线法对北山羊Capra ibex春季卧息地的选择性进行了研究,共测定了63个卧息地样方,63个对照样方.经过分析表明,北山羊卧息地选择偏好利用阳坡、上坡位、膜果麻黄与裸岩(P<0.05),同时具有海拔高、坡度大、远离道路、远离居民点、距水源较近、接近隐蔽物、隐蔽级高等特征(P<0....     

Thermostablility of phycobiliproteins and antioxidant activity from four thermotolerant cyanobacteria

Four cyanobacterial strains including Cyanosarcina sp. SK40, Phormidium sp. PD40‐1, Scytonema sp. TP40 and Leptolyngbya sp. KC45 were selected and investigated for the phycobiliprotein (PBP) content and thermostable antioxidant activity of their cell‐free extracts. The highest content of 181.63 mg/g dry weight phycobiliprotein was found in Leptolyngbya sp. KC45 with phycoerythrin (PE) as the main phycobiliprotein. Among the PBPs of four thermotolerant cyanobacteria, PE from Leptolyngbya sp. KC45 exhibited the highest thermal stability as 80% of the original level remained after being heated at 60°C for 30 min. Antioxidant activities were detected in the cell‐free extracts of all cyanobacteria and that of Leptolyngbya sp. KC45 was also found in the highest value of 7.44 ± 0.14 and 3.89 ± 0.08 mg gallic acid equivalent (GAE) g^?1 dry weights determined by 2,2‐diphenyl‐1‐picrylhydrazyl radical (DPPH) and reducing power assay, respectively. This also corresponded to the phenolic compound content. Based on DPPH and reducing power assay, antioxidant activities of all cyanobacterial extracts showed the high thermostability as approximately 80% remained after being heated at 80°C for 30 min. However, it clearly indicated that the thermostability of antioxidant activity from the hot spring cyanobacterial cell‐free extract was not contributed only by the PE, but also came from phenolic compounds and other oxidative substances.     

Climate change and the phytoplankton spring bloom: warming and overwintering zooplankton have similar effects on phytoplankton

Indoor mesocosms were used to study the combined effect of warming and of different densities of overwintering mesozooplankton (mainly copepods) on the spring development of phytoplankton in shallow, coastal waters. Similar to previous studies, warming accelerated the spring phytoplankton peak by ca. 1 day °C^?1 whereas zooplankton did not significantly influence timing. Phytoplankton biomass during the experimental period decreased with warming and with higher densities of overwintering zooplankton. Similarly, average cell size and average effective particle size (here: colony size) decreased both with zooplankton density and warming. A decrease in phytoplankton particle size is generally considered at typical footprint of copepod grazing. We conclude that warming induced changes in the magnitude and structure of the phytoplankton spring bloom cannot be understood without considering grazing by overwintering zooplankton.