气候变暖对中国西北地区农作物种植的影响

采用对农作物生长有指标意义的≥10℃积温和<0℃负积温与农作物适宜种植面积、生长发育速度及产量进行对比统计分析研究,指出气候变暖对中国西北地区农作物种植结构发生了较大改变,冬小麦种植区西伸北扩,棉花面积迅速扩大,多熟制向北和高海拔地区推移.农作物生长发育速度发生了明显变化,春播作物提早播种,喜温作物生育期延长,越冬作物推迟播种,生育期缩短.棉花气候产量明显增加.     

Identification of essential genes in Streptococcus pneumoniae by allelic replacement mutagenesis

To find potential targets of novel antimicrobial agents, we identified essential genes of Streptococcus pneumoniae using comparative genomics and allelic replacement mutagenesis. We compared the genome of S. pneumoniae R6 with those of Bacillus subtilis, Enterococcus faecalis, Escherichia coli, and Staphylococcus aureus, and selected 693 candidate target genes with > 40% amino acid sequence identity to the corresponding genes in at least two of the other species. The 693 genes were disrupted and 133 were found to be essential for growth. Of these, 32 encoded proteins of unknown function, and we were able to identify orthologues of 22 of these genes by genomic comparisons. The experimental method used in this study is easy to perform, rapid and efficient for identifying essential genes of bacterial pathogens.     

The effect of transformation on the virulence of Streptococcus pneumoniae

Although pneumococcus is one of the most frequently encountered opportunistic pathogen in the world, the mechanisms responsible for its infectiveness have not yet been fully understood. In this paper, we have attempted to characterize the effects of pneumococcal transformation on the pathogenesis of the organism. We constructed three transformation-deficient pneumococcal strains, which were designated as Nos. 1d, 2d, and 22d. The construction of these altered strains was achieved via the insertion of the inactivated gene, comE, to strains 1, 2 and 22. We then conducted a comparison between the virulence of the transformation-deficient strains and that of the wild-type strains, via an evaluation of the ability of each strain to adhere to endothelial cells, and also assessed psaA mRNA expression, and the survival of hosts after bacterial challenge. Compared to what was observed with the wild-type strains, our results indicated that the ability of all of the transformation-deficient strains to adhere to the ECV304 cells had been significantly reduced (p < 0.05), the expression of psaA mRNA was reduced significantly (p < 0.05) in strains 2d and 22d, and the median survival time of mice infected with strains 1d and 2d was increased significantly after intraperitoneal bacterial challenge (p < 0.05). The results of our study also clearly indicated that transformation exerts significant effects on the virulence characteristics of S. pneumoniae, although the degree to which this effect is noted appears to depend primarily on the genetic background of the bacteria.     

Heartwood extract of Rhus verniciflua Stokes and its active constituent fisetin attenuate vasoconstriction through calcium-dependent mechanism in rat aorta

Rhus verniciflua Stokes (RVS) exert cardiovascular protective activity by promoting blood circulation, but its active ingredients and underlying mechanism have yet to be identified. This study investigated the vascular effects of RVS, focusing on vasoconstriction and smooth muscle Ca²⁺ signaling. RVS heartwood extract attenuated contraction of aortic rings induced by the vasoconstrictors serotonin and phenylephrine, and inhibited the Ca²⁺ signaling evoked by serotonin in vascular smooth muscle cells. Subsequent activity-guided fractionation identified fisetin as an active constituent exerting a Ca²⁺ inhibitory effect. Fisetin could inhibit major Ca²⁺ mobilization pathways including extracellular Ca²⁺ influx mediated by the L-type voltage-gated Ca²⁺ channel, Ca²⁺ release from the intracellular store and store-operated Ca²⁺ entry. In accordance with Ca²⁺ inhibitory effect, fisetin attenuated vasoconstriction by serotonin and phenylephrine. These results suggest that the anticontractile effect, which is presumably mediated by inhibition of Ca²⁺ signaling, may contribute to the improvement of blood circulation by RVS.     

Acute toxicity of copper to <Emphasis Type="Italic">Daphnia galeata</Emphasis> under different magnesium and calcium conditions

A number of risk assessments of the adverse effects of Cu and its compounds have been conducted since it is one of the leading substances responsible for water contamination. However, with the exception of standard organisms, ecotoxicological knowledge is still scarce. Here, we examined the influence of Ca²⁺ and Mg²⁺ concentrations on acute toxicity of Cu toward a cladoceran, Daphnia galeata Sars. We found that the protective effects of Ca²⁺ against copper toxicity were larger than those of Mg²⁺. BLM parameters (log Ks) for Ca and Mg estimated based on our 48-h LC₅₀ (50 % lethal concentration), respectively, were 3.14 and 2.29. The log K of Ca was similar to that reported in previous studies using Daphnia magna; however, the log K of Mg was lower by one order of magnitude. Our results suggest that there is some mechanistic difference related to the Mg uptake between D. magna and D. galeata. The results obtained from the present study will contribute to the water quality criteria of copper in soft water because D. galeata is a widespread (distributed in Eurasia and North America) and common species, even in soft water lakes.     

孤儿核受体SHP敲减抑制BMP9诱导C3H10T1/2细胞的成骨分化

孤儿核受体SHP(small heterodimer partner)是核受体超家族中的一员,具有LXXLL模体及配体结合域,但无经典的DNA结合域.它可与多种转录因子结合,调节细胞的增殖、分化和代谢等生物学过程.但目前关于SHP在BMP9诱导成骨分化中的确切作用却尚不清楚.本研究证明,SHP参与BMP9诱导的C3H10T1/2细胞成骨分化. RT-PCR结合Western印迹方法检测蛋白揭示,异位表达BMP9上调了SHP在C3H10T1/2细胞中的表达. 小干扰RNA敲减SHP基因在C3H10T1/2细胞的表达下调了成骨相关基因Runx2、Id1、Id2及CTGF的表达,而过表达BMP9则可上调这些基因的表达.碱性磷酸酶(ALP)活性测定/染色及茜素红染色显示,敲减核受体SHP基因可抑制BMP9的成骨分化作用,而过表达BMP9可部分消除SHP 敲减导致的成骨抑制作用.上述结果提示,核受体SHP为BMP9诱导的C3H10T1/2细胞成骨分化所必需. 究竟BMP9如何上调SHP基因表达,以及SHP究竟通过何种机制上调BMP9下游成骨分化相关基因的表达尚待进一步研究.     

A NEW SPECIES OF SARGUS (DIPTERA, STRATIOMYIDAE,SARGIINAE) EROM ANHUI, CHINA

记述了安徽黄山风景名胜区瘦腹水虻属Sargus Fabricius,1798 1新种,黄山瘦腹水虻Sargus huangshanensis sp.nov..详细描述了其形态特征,并绘制了其主要鉴别特征图,所有标本均保存在贵州大学昆虫研究所.     

Genome shuffling and ribosome engineering of Streptomyces virginiae for improved virginiamycin production

Bioprocess and Biosystems Engineering - The production of virginiamycin (VGM) from Streptomyces virginiae was improved by genome shuffling and ribosome engineering companied with a high-throughput...     

眼蕈蚊属害虫危害金线莲的首次报道(英文)

兰科Orchidaceae植物金线莲Anoectochilus roxburghii(Wall.)Lindl是一种在中国广泛使用的中草药.本文首次报道两种迟眼蕈蚊属害虫危害金线莲,即Bradysia impatiens(Johannsen,1912)和Bradysia ocellaris(Comstock,1882).这一发现提醒昆虫学家和农民应当注意金线莲和其他兰科植物上的潜在害虫,具有重要的经济意义.