氮源对紫云英根瘤菌nod基因表达的作用

高浓度的硫酸铵阻碍了紫云英根瘤菌诱导紫云英根毛发生典型的根毛变形并明显抑制了紫云英结瘤能力。通过对融合子的β-半乳精苷酶活性的测定进一步表明高浓度的硫酸铵对紫云英的结瘤调节基因nodDZ、共同结瘤基因nodA及nodBC的表达有抑制作用而对结瘤调节基因nodD1的表达无抑制作用。     

Molecular dynamics of synthetic leucine-serine ion channels in a phospholipid membrane

Molecular dynamics calculations were carried out on models of two synthetic leucine-serine ion channels: a tetrameric bundle with sequence (LSLLLSL)(3)NH(2) and a hexameric bundle with sequence (LSSLLSL)(3)NH(2). Each protein bundle is inserted in a palmitoyloleoylphosphatidylcholine bilayer membrane and solvated by simple point charge water molecules inside the pore and at both mouths. Both systems appear to be stable in the absence of an electric field during the 4 ns of molecular dynamics simulation. The water motion in the narrow pore of the four-helix bundle is highly restricted and may provide suitable conditions for proton transfer via a water wire mechanism. In the wider hexameric pore, the water diffuses much more slowly than in bulk but is still mobile. This, along with the dimensions of the pore, supports the observation that this peptide is selective for monovalent cations. Reasonable agreement of predicted conductances with experimentally determined values lends support to the validity of the simulations.     

一株石油降解菌培养基的优化

目的：有效降低石油降解菌株CT-6在工业生产中的培养成本,提高培养速度。方法：利用Minitab软件,采用中心组合设计、响应面分析,以葡萄糖、蔗糖、可溶性淀粉为碳源,以硝酸铵、尿素、氯化铵为氮源,对高效降解石油菌株CT-6的培养基进行了优化。结果：当碳源葡萄糖为5.6818g/L、氮源氯化铵为3.8030g/L时,菌株CT-6培养17h,OD600达到0.615。结论：优化前后,菌体CT-6的OD600分别为0.289和0.615,提高了112.8%,说明该培养基更有利于菌株CT-6的生长。     

Total fertilization failure and idiopathic subfertility

Background  

To gain more insight in whether failure of intrauterine insemination (IUI) treatment in patients with idiopathic subfertility could be related to diminished fertilization, the aim of this study is to compare the fertilization of an initial IVF procedure after six cycles of IUI and the fertilization of an initial IVF procedure without preceding IUI cycles in couples with idiopathic subfertility.     

三种抗癫痫药对癫痫患者脑电图的背景影响比较研究

目的：研究对比三种抗癫痫药（苯妥因钠、丙戊酸钠、卡马西平）对癫痫患者脑电图的背景影响。方法：选取我院于2009年3月至2011年2月收治的60例癫痫患者,随机分为苯妥因钠（PHT）、卡马西平（CBZ）和丙戊酸钠（SVP）组各20例,动态观察各组患者于治疗期间痫样波放电的频度和EEG背景的变化。结果：EEG痫样波放电的抑制率以SVP最为明显,而CBZ在EEG背景活动影响方面均比其他两组显著。结论：三种药物对癫痫波放电的抑制顺序是SVP〉PHT〉CBZ,SVP组明显优于其他两组。     

Dispersal ability in codling moth: mark–release–recapture experiments and kinship analysis

• 1 The present study focused on the dispersal patterns in the codling moth because such information is fundamental for determining the dynamics and genetics of the pest populations and for developing efficient management programmes.
• 2 We implemented mark–release–recapture experiments (MRR) with both male and female codling moths of two laboratory and one wild population using a sex pheromone and pear ester as attractants in delta traps. The experiments were conducted in apple orchards in central Greece over two consecutive years (2007–2008). In addition, kinship assignment tests were applied on 303 genotyped individuals (11 microsatellite loci) from two contiguous apple orchards in central Greece aiming to estimate the dispersal of fertilized females.
• 3 Both MRR and kinship analysis revealed that most male and female adults dispersed within 80 m, whereas some individuals moved at longer distances (maximum distance of approximately 200 m). A Bayesian analysis on microsatellite data revealed that exchange rates of codling moths between neighbouring orchards ranged among generations from 17.6 to 32.7%. The exchange rate between these orchards estimated by kinship analysis was 25.6% over all generations.
• 4 The collected data confirm the view of the sedentary nature of coding moth and indicate that genotypes able to migrate at long distances are not present in the studied area. The availability of food resources within orchards during the growing season is one possible factor that could favour this sedentary behaviour.

     

A widespread plant-fungal-bacterial symbiosis promotes plant biodiversity,plant nutrition and seedling recruitment

Highly diverse microbial assemblages colonize plant roots. It is still poorly understood whether different members of this root microbiome act synergistically by supplying different services (for example, different limiting nutrients) to plants and plant communities. In order to test this, we manipulated the presence of two widespread plant root symbionts, arbuscular mycorrhizal fungi and nitrogen-fixing rhizobia bacteria in model grassland communities established in axenic microcosms. Here, we demonstrate that both symbionts complement each other resulting in increased plant diversity, enhanced seedling recruitment and improved nutrient acquisition compared with a single symbiont situation. Legume seedlings obtained up to 15-fold higher productivity if they formed an association with both symbionts, opposed to productivity they reached with only one symbiont. Our results reveal the importance of functional diversity of symbionts and demonstrate that different members of the root microbiome can complement each other in acquiring different limiting nutrients and in driving important ecosystem functions.     

Uncertainty in ensemble forecasting of species distribution

Species distribution modelling has been widely applied in order to assess the potential impacts of climate change on biodiversity. Many methodological decisions, taken during the modelling process and forecasts, may, however, lead to a large variability in the assessment of future impacts. Using measures of species range change and turnover, the potential impacts of climate change on French stream fish species and assemblages were evaluated. Our main focus was to quantify the uncertainty in the projections of these impacts arising from four sources of uncertainty: initial datasets (Data), statistical methods [species distribution models (SDM)], general circulation models (GCM), and gas emission scenarios (GES). Several modalities of the aforementioned uncertainty sources were combined in an ensemble forecasting framework resulting in 8400 different projections. The variance explained by each source was then extracted from this whole ensemble of projections. Overall, SDM contributed to the largest variation in projections, followed by GCM, whose contribution increased over time equalling almost the proportion of variance explained by SDM in 2080. Data and GES had little influence on the variability in projections. Future projections of range change were more consistent for species with a large geographical extent (i.e., distribution along latitudinal or stream gradients) or with restricted environmental requirements (i.e., small thermal or elevation ranges). Variability in projections of turnover was spatially structured at the scale of France, indicating that certain particular geographical areas should be considered with care when projecting the potential impacts of climate change. The results of this study, therefore, emphasized that particular attention should be paid to the use of predictions ensembles resulting from the application of several statistical methods and climate models. Moreover, forecasted impacts of climate change should always be provided with an assessment of their uncertainty, so that management and conservation decisions can be taken in the full knowledge of their reliability.