Species-specific distribution of two sympatric Maculinea butterflies across different meadow edges

An important consequence of habitat fragmentation is the increase of edge habitats. Environmental factors in the edges are different from those in the interiors, which causes changes in the distribution of plant and animal species. We aimed to study how edges affect the distribution of two butterfly species within meadow fragments. We therefore investigated the effect of distance from edge and edge type (road edge versus tree edge) on two sympatric large blue species (Maculinea teleius and M. nausithous). Our results showed that edge type had contrasting effects on the two species. M. teleius favoured both interiors and road edges, while M. nausithous preferred the tree edges. In the case of the latter species a strong positive edge effect was also found. This kind of within-habitat niche segregation is probably related to the different microenvironmental conditions at the edges. Foodplant density did not seem to limit the distribution of these species. Our results suggest that interiors of meadows are important for M. teleius, while tree edges maintain the habitats of the regionally rarer butterfly, M. nausithous.     

上海地区某三级医院新职工岗前培训效果分析

目的 旨在通过对我院岗前培训8年经验的总结,摸索出一套在医院文化背景下的岗前培训体系。方法 采用问卷方法对2007—2009年新员工岗前培训效果进行匿名调查,并使用Excel进行数据录入和统计。结果 调查对象中76.63%的员工对师资配置情况及课程设置情况表示满意,54.08%的员工对培训时间与进度表示很合适,69.47%的员工对培训保障措施表示满意,69.42%和80.08%的员工分别对授课形式和培训受益情况表示满意。结论 医院文化及人文医学培训是医院人力资源处岗前培训的核心内容,这对每个从医人员树立正确的职业价值观具有指导作用和现实意义。岗前培训中培训师的授课技巧、专业知识及能力有待进一步提高,今后应不断完善内部培训师的培养途径与方法。     

Synergistic temperature and ethanol effect on<Emphasis Type="Italic"> Saccharomyces cerevisiae</Emphasis> dynamic behaviour in ethanol bio-fuel production

The impact of ethanol and temperature on the dynamic behaviour of Saccharomyces cerevisiae in ethanol biofuel production was studied using an isothermal fed-batch process at five different temperatures. Fermentation parameters and kinetics were quantified. The best performances were found at 30 and 33°C around 120 g l^-1 ethanol produced in 30 h with a slight benefit for growth at 30°C and for ethanol production at 33°C. Glycerol formation, enhanced with increasing temperatures, was coupled with growth for all fermentations; whereas, a decoupling phenomenon occurred at 36 and 39°C pointing out a possible role of glycerol in yeast thermal protection.     

Ethanol formation and enzyme activities around glucose-6-phosphate in Kluyveromyces marxianus CBS 6556 exposed to glucose or lactose excess

The aim of this work was to investigate the physiology of Kluyveromyces marxianus CBS 6556 in terms of its low tendency to form ethanol under exposure to sugar excess, and the split of carbon flux which takes place at the level of glucose-6-phosphate. Measurements were performed in batch cultivations, and after a glucose or a lactose pulse applied to chemostat-grown respiring cells (with a dilution rate of 0.1 h(-1)). No ethanol formation was observed in batch cultivations or during pulse experiments, unless the oxygen supply was shut down, indicating that this organism is more strictly Crabtree-negative than its close relative K. lactis and other known Crabtree-negative yeasts. During the pulse experiments, activities of phosphoglucoisomerase, glucose-6-phosphate dehydrogenase and phosphoglucomutase in cell-free extracts remained rather constant, at higher levels than those of Saccharomyces cerevisiae grown at similar conditions. When cells were exposed to glucose concentrations as high as 26 gl(-1), the activity of phosphoglucomutase was higher than that in cells exposed to 14 gl(-1) glucose, whereas the activities of phosphoglucoisomerase and glucose-6-phosphate dehydrogenase did not change. Our results suggest that the low tendency for ethanol formation in K. marxianus might be a consequence of this yeast's capacity of keeping the glycolytic flux constant, due at least in part to the diversion of carbon flux towards the biosynthesis of carbohydrates and towards the pentose phosphate pathway.     

Small-scale disturbances spread along trophic chains: leaf-cutting ant nests, plants, aphids, and tending ants

Small-scale disturbances caused by animals often modify soil resource availability and may also affect plant attributes. Changes in the phenotype of plants growing on disturbed, nutrient-enriched microsites may influence the distribution and abundance of associated insects. We evaluated how the high nutrient availability generated by leaf-cutting ant nests in a Patagonian desert steppe may spread along the trophic chain, affecting the phenotype of two thistle species, the abundance of a specialist aphid and the composition of the associated assemblage of tending ants. Plants of the thistle species Carduus nutans and Onopordum acanthium growing in piles of waste material generated by leaf-cutting ant nests (i.e., refuse dumps) had more leaves, inflorescences and higher foliar nitrogen content than those in non-nest soils. Overall, plants in refuse dumps showed higher abundance of aphids than plants in non-nest soils, and aphid colonies were of greater size on O. acanthium plants than on C. nutans plants. However, only C. nutans plants showed an increase in aphid abundance when growing on refuse dumps. This resulted in a similar aphid load in both thistle species when growing on refuse dumps. Accordingly, only C. nutans showed an increase in the number of ant species attending aphids when growing on refuse dumps. The increase of soil fertility generated by leaf-cutting ant nests can affect aphid abundance and their tending ant assemblage through its effect on plant size and quality. However, the propagation of small-scale soil disturbances through the trophic chain may depend on the identity of the species involved.     

Diverging patterns of mitochondrial and nuclear DNA diversity in subarctic black spruce: imprint of a founder effect associated with postglacial colonization

High-latitude ecotonal populations at the species margins may exhibit altered patterns of genetic diversity, resulting from more or less recent founder events and from bottleneck effects in response to climate oscillations. Patterns of genetic diversity were investigated in nine populations of the conifer black spruce (Picea mariana [Mill.] BSP.) in northwestern Québec, Canada, using seed-dispersed mitochondrial (mt) DNA and nuclear (nc) DNA. mtDNA diversity (mitotypes) was assessed at three loci, and ncDNA diversity was estimated for nine expressed sequence tag polymorphism (ESTP) loci. Sampling included populations from the boreal forest and the southern and northern subzones of the subarctic forest-tundra, a fire-born ecotone. For ncDNA, populations from all three vegetation zones were highly diverse with little population differentiation (thetaN = 0.014); even the northernmost populations showed no loss of rare alleles. Patterns of mitotype diversity were strikingly different: within-population diversity and population differentiation were high for boreal forest populations [expected heterozygosity per locus (HE) = 0.58 and thetaM = 0.529], but all subarctic populations were fixed for a single mitotype (HE = 0). This lack of variation suggests a founder event caused by long-distance seed establishment during postglacial colonization, consistent with palaeoecological data. The estimated movement of seeds alone (effective number of migrants per generation, NmM < 2) was much restricted compared to that estimated from nuclear variants, which including pollen movement (NmN > 17). This could account for the conservation of a founder imprint in the mtDNA of subarctic black spruce. After reduction, presumably in the early Holocene, the diversity in ncDNA would have been replenished rapidly by pollen-mediated gene flow, and maintained subsequently through vegetative layering during the current cooler period covering the last 3000 years.     

Buoyancy effect on forced convection in the leaf boundary layer

Abstract. Mixed convection (forced convection plus free convection) in the leaf boundary layer was examined by air flow visualization and by evaluation of the boundary layer conductance at different leaf-air temperature differences ( T _L- T _A) under low wind velocities. The visualized air flow was found to become more unstable and buoyant at higher T _L- T _A. An ascending longitudinal plume was induced along the upper surface, and the air flow along the lower surface ascended after passing the trailing leaf edge. The air flow modified by buoyancy was considered to result in an increase in boundary layer conductance ( G _A) for mixed convection, which became higher with higher T _L- T _A as compared with the conductance for pure forced convection without buoyancy. This increase in G _A appeared larger at larger Grashof number (Gr) and at smaller Reynolds number (Re). The dependences of buoyancy effect on Gr and Re were related to 'edge-effects'.     

Optimum concentration and pH of phosphate buffer for assay of cytochrome c oxidase in intact plant mitochondria

For measurement of cytochrome c oxidase activity in intact plant mitochondria the optimum concentration of K-Pi buffer and pH in the reaction was found to be 75 mM and 7.4 respectively. The suitable concentration of K-Pi buffer for suspending and storing mitochondria, however, was found to be 20 mM or lower. These requirements applied equally well for mitochondria from wheat (Triticum aestivum L.), barley (Hordeum vulgare L.), maize (Zea mays L.), and snap bean (Phaseolus vulgaris L.).