辣椒素积累生理研究的最新进展

辣椒素的积累主要受到遗传、环境、竞争物质、酶的影响.在遗传方面,辣椒的基因型以及决定辣椒素含量的特定基因对辣椒素的积累起着决定作用,环境中的光照、温度、CO2、肥料起辅助作用,竞争物质,如木质素、类黄酮、蛋白质、单宁、生物碱、香豆素等物质与辣椒素的积累相互抑制,辣椒素的合成酶和降解酶同样影响辣椒素的积累.     

微波消解ICP—MS法测定香菇中重金属含量

采用密闭微波消解法消解香菇样品,在优化微波消解条件的基础上,建立微波消解ICP—MS法同时测定千香菇中As、PI）、Cd、Cr、Cu、Zn、Mn、Fe和Mg九种重金属元素的方法,在最佳试验条件下,加标收率为92．0％～104．6％,RSD为2．2％-5．3％。该方法简便、快速、准确：     

Inferring the effects of landscape structure on roe deer (Capreolus capreolus) movements using a step selection function

In this study, we sought to understand how landscape structure affects roe deer movements within their home-range in a heterogeneous and fragmented agricultural system of south-western France. We analysed the movements of 20 roe deer fitted with GPS collars which recorded their locations every 2–6 h over several months (mean = 9 months). Based on empirical observations and previous studies of roe deer habitat use, we hypothesised that roe deer should avoid buildings and roads, move preferentially along valley bottoms and through the more wooded areas of the landscape. To test these hypotheses we paired each observed movement step with 10 random ones. Using conditional logistic regression, we modelled a step selection function, which represents the probability of selecting a given step as a function of these landscape variables. The selected model indicated that movements were influenced by all the tested landscape features, but not always in the predicted direction: our results suggested that roe deer tend to avoid buildings, roads, valley bottoms and possibly the more wooded areas (although the latter result should be interpreted with caution, as it may be influenced by a bias in the rate of GPS fix acquisition in woods). The distances to buildings and to roads were the most influential variables in the model, suggesting that the avoidance of potential sources of disturbance may be a key factor in determining ranging behaviour of roe deer in human dominated landscapes.     

Inoculation of growing media with the rhizobacterium Variovorax paradoxus 5C-2 reduces unwanted stress responses in hardy ornamental species

Inoculation of growing media with plant growth promoting rhizobacteria (PGPR) has a number of potential benefits for the production of ornamental plants. Certain rhizobacteria synthesise the enzyme ACC deaminase, which cleaves ACC, the precursor of the plant hormone ethylene. Bacterial metabolism is now known to lead to a reduction in [ACC] in the plant transpiration stream and bacteria are hypothesised to act on ACC exuded from roots. This in turn reduces the ethylene generated in plants growing in growing media inoculated with these bacteria. Here we tested if applications of the ACC deaminase containing rhizobacteria Variovorax paradoxus⁵C–²could be of benefit to ornamental growers by reducing ethylene generation in stressed plants. Ethylene is produced at levels that are inhibitory to growth and development under a number of abiotic stresses. The propagation and production of hardy ornamentals is deleteriously affected by abiotic stresses that involve ethylene signalling, including drought and physical wounding. Inoculation of growing media with V. paradoxus 5C-2 lowered ethylene emission from mature leaves of Cytisus × praecox experiencing drought stress. In addition, bacterial inoculation of the growing media resulted in significantly reduced abscission of the mature leaves under drought treatment. Beneficial effects of inoculation where also found in the wounding response of Fargesia murielae following divisional propagation and late season senescence in Aquilegia × hybrida in response to drought stress. Together these results demonstrate that V. paradoxus⁵C–²has real potential for use on ornamental nurseries in situations where plant stresses are unavoidable.     

Communities in context: the influences of multiscale environmental variation on local ant community structure

We explored the ways in which environmental variation at multiple spatial scales influences the organization of ant species into local communities. Ground-dwelling ants were sampled in sandhill habitat at 33 locations throughout northern Florida, USA. Variance partitioning of local, landscape, and regional datasets using partial redundancy analysis indicates that ant community composition is significantly influenced by environmental variability across all scales of analysis. Habitat generalists appear to replace habitat specialists at sites with high proportions of matrix habitat in the surrounding landscape. Conversely, habitat specialists appear to replace habitat generalists at sites with more sandhill habitat in the surrounding landscape and greater amounts of bare ground locally. Local niche differentiation leading to species-sorting, combined with the effects of spatially structured dispersal dynamics at landscape scales, may explain this pattern of community structure. Regional influences on local ant communities were correlated with geographical and environmental gradients at distinct regional scales. Therefore, local ant communities appear to be simultaneously structured by different processes that occur at separate spatial scales: local, landscape, and regional scales defined by spatial extent. Our results illustrate the importance of considering multiscale influences on patterns of organization in ecological communities. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Current velocity and spatial scale as determinants of the distribution and abundance of two rheophilic herbivorous insects

Organisms frequently show marked preferences for specific environmental conditions, but these preferences may change with landscape scale. Patterns of distribution or abundance measured at different scales may reveal something about an organism's perception of the environment. To test this hypothesis, we measured densities of two herbivorous aquatic insects that differed in body morphology and mobility in relation to current velocity measured at different scales in the upper Colorado River (Colorado, USA). Streambed densities of the caddisfly larva Agapetus boulderensis (high hydrodynamic profile, low mobility) and mayfly nymph Epeorus sp. (low hydrodynamic profile, high mobility) were assessed at 3 spatial scales: whole riffles, individual cobbles within riffles, and point locations on cobbles. Riffles were several meters in extent, cobbles measured 10–30 cm in size, and the local scale was within a few centimeters of individual larvae (themselves ca. 0.5–1.0 cm in size). We also quantified the abundance of periphytic food for these herbivores at the cobble and riffle scales. Agapetus favored slow current (<30 cm s^–1) across all scales. Epeorus, by contrast, favored fast current (60–80 cm s^–1) at the local and riffle scale, but not at the cobble scale. Only Agapetus showed a significant relationship to current at the cobble scale, with greatest larval densities occurring at velocities near 30 cm s^–1. We had predicted an inverse correlation between grazer density and periphytic abundance; however, this occurred only for Agapetus, and then only at the cobble scale. These data suggest that organisms respond to environmental gradients at different spatial scales and that the processes driving these responses may change with scale, e.g., shifting from individual habitat selection at local and cobble scales to population responses at the riffle scale. This study also highlights the importance of using the appropriate scale of measurement to accurately assess the relationship between organisms and environmental gradients across scale.     

‘凯特’杧果栽培中果实套袋对其采后品质及贮藏性的影响

 以‘凯特’杧果为材料,研究了栽培中果实套袋至采果时、采前除袋和除袋后喷钙3种处理对采后果皮着色、果实品质和耐贮性的影响。结果表明：3种处理的果实采后果皮的花青苷和类黄酮含量显著降低,总酚含量在青熟时显著低于对照,但完熟后显著高于对照;3种处理不仅加速果皮由绿色向黄色转变,显著提高果皮和果肉的钙含量,而且显著降低果实采后软化速率并抑制果实病情发展,其中除袋后喷钙处理效果最佳;3种处理果实在青熟时果肉淀粉含量显著高于对照,而蔗糖和维生素C含量显著低于对照,但完熟后果实蔗糖、还原性糖、可滴定酸和维生素C含量与对照没有显著差异。3种处理均有利于改善果实的外观品质,并提高果实的耐贮性。     

苹果园沙打旺生草栽培试验

比较了苹果园行间种植沙打旺与清耕2种耕作制度。结果表明:持续种植5 a沙打旺以后,苹果产量与含糖量明显增加;苹果树干周长、百叶重、叶绿素含量增加;土壤有机质含量及速效氮、速效磷、速效钾含量明显提高;土壤孔隙度增加;土壤容重下降。     

The effect of homocysteine on airway smooth muscle cells and fibroblasts

AIM: To study the effect of homocysteine (HCY) on proliferation of airway smooth muscle cells and fibroblasts and the effect of HCY on collagen prodution of airway fibroblasts. METHODS: [³H]-TdR incorpora- tion was measured in cultured airway smooth muscle cells. The [³H]-TdR and [³H]-proline incorporation were mea- sured in cultured airway fibroblasts. RESULTS: HCY induced proliferation of airway smooth muscle cells and fibroblasts in a concentration - dependent manner. HCY also induced collagen production of airway fibroblasts in a concentration - dependent manner. The inhibitors of protein kinase C, H7 and polymyxin B, inhibited HCY - induced proliferation of airway smooth muscle cells. CONCLUSIONS: HCY induced proliferation of airway smooth muscle cells and fibroblasts, HCY also induced collagen production of airway fibroblasts. The HCY - induced proliferation of airway smooth muscle cells may be related to the pathway of PKC signal transduction.     

西瓜多倍体研究应用进展

概述了西瓜多倍体的诱导途径、鉴定方法,多倍体西瓜育种的研究、应用以及前景展望。以期为西瓜的种质创新,品质改善提供基础。