植物根负向光性反应

本文介绍植物根的负向光性反应研究现状和进展。     

鄂东大别山国家重点保护野生植物优先保护定量研究

在野外调查的基础上,运用濒危系数、遗传价值系数和物种价值系数对鄂东大别山18种国家重点保护野生植物的优先保护顺序进行定量分析。结果表明属一级保护的有银杏、南方红豆杉、大别山五针松、金钱松、巴山榧树、连香树和楠木共7种,占38.9%;属二级保护的有秤锤树、喜树、香果树、鹅掌楸和川黄檗共5种,占27.8%;属三级保护的有厚朴、凹叶厚朴和榉树3种,占16.7%;属四级保护的有樟树、野大豆和金荞麦共3种,占16.7%。并提出了加强国家重点保护野生植物的保护措施。     

Monogenea from the middle Yangtze Valley: Sinomazocraes changjiangensis n. g., n. sp. (Family Mazocraeidae Price, 1936) on a clupeiform fish from Hubei Province,China

Sinomazocraes changjiangensis n. g., n. sp. (Monogenea: Mazocraeidae) is described from the gills of the shortjaw tapertail anchovy Coilia brachygnathus collected from Jiayu and Huanggang Counties (Hubei Province), which are located in the middle reaches of the Yangtze River. The structure of the clamps and copulatory organ are similar to those of Heteromazocraes Mamaev, 1981. However, although Sinomazocraes also has four pairs of clamps, it is distinguished from other genera in the family by the fact that the three anterior clamps on one side of the body are significantly larger than the others. Variations in the form of the clamps in different species of the Mazocraeidae are discussed.     

Impact of extreme drought on tree-ring width and vessel anatomical features of Chukrasia tabularis

Multiple sources of evidence suggest an increasing frequency of extreme climatic events during the past century. In Bangladesh, a country strongly influenced by the South Asian monsoon climate, the years 1999 and 2006 were the most severe droughts among the ten drought events identified over the last four decades. We investigated the impact of these two drought events on radial growth and xylem anatomical features of the brevi-deciduous tree species Chukrasia tabularis in a moist tropical forest in Bangladesh. Tree radial growth declined by 54% during the 1999 and 48.7% during the 2006 droughts, respectively. Among the wood anatomical features, the number of vessels (NV) showed the highest sensitivity to drought, with a 45% decrease in the 1999 drought year, followed by total vessel area (TVA) and mean vessel area (MVA). On the other hand, Vessel density (VD) increased by 13% during the 1999 drought but the increase in VD was very low in the drought year 2006. The decreasing vessel area and increasing vessel density indicate xylem hydraulic adaptation of C. tabularis to minimize drought induced cavitation risk and to avoid hydraulic failure. The significant correlations between the Standardized Precipitation Evapotranspiration Index (SPEI) and time series of tree-ring width and vessel variables imply that decline in radial growth and changes in vessel features in C. tabularis are likely to be caused by drought induced water stress. Our analyses suggest that radial growth and wood anatomical features of C. tabularis are highly sensitive to extreme drought events in South Asian moist tropical forests and can be used to reconstruct past droughts and to model tree response to drought stress under future climate conditions.     

Comparison of interactions between human serum albumin and silver nanoparticles of different sizes using spectroscopic methods

Three different sizes (15.9 ± 2.1 nm, 26.4 ± 3.2 nm and 39.8 ± 4.0 nm, respectively) of citrate‐coated silver nanoparticles (SNPs) have been synthesized and characterized. The interactions of the synthesized SNPs with human serum albumin (HSA) at physiological pH have been systematically studied by UV‐vis absorption spectroscopy, fluorescence spectroscopy, synchronous fluorescence spectroscopy, three‐dimensional fluorescence spectroscopy and circular dichroism (CD) spectroscopy. The results indicate that the SNPs can bind to HSA with high affinity and quench the intrinsic fluorescence of HSA. The binding constants and quenching rate constants were calculated. The apparent association constants (K_app) values are 2.14 × 10⁴ M^–1 for 15.9 nm SNP, 1.65 × 10⁴ M^–1 for 26.4 nm SNP and 1.37 × 10⁴ M^–1 for 39.8 nm SNP, respectively. The values of binding constant obtained from the fluorescence quenching data match well with that determined from the absorption spectral changes. These results suggest that the smaller SNPs have stronger interactions to HSA than the larger ones at the same concentrations. Synchronous fluorescence, three‐dimensional fluorescence and CD spectroscopy studies show that the synthesized SNPs can induce slight conformational changes in HSA. Copyright © 2014 John Wiley & Sons, Ltd.     

中国隐斑谷蛾属一新种(鳞翅目:谷蛾科)

隐斑谷蛾属Crypsithyris全世界已知38种,其中5种分布于中国。本文记述了采自湖南、贵州和江西的1新种:锯隐斑谷蛾Crypsithyris serrata Xiao et Li,sp.nov.(Figs.1～3)。新种与分布日本的Crypsithyris japonica Petersen et Gaedike和Crypsithyris saigusai Gaedike相似,主要区别如下:新种前翅暗褐色,具1大的椭圆形透明斑以及沿后缘具1赭白色纵带;抱器瓣近矩形,末端斜直;抱器背基突大,W形;阳茎约与囊形突等长,两侧具数个锯齿。后2种前翅乳白色,具1模糊的透明斑,在透明斑外侧有1暗斑;抱器瓣基半部宽于端半部,末端尖或钝圆;抱器背基突窄并相连成桥;阳茎明显长于囊形突且两侧无锯齿。模式标本保存在南开大学生命科学学院昆虫标本室。     

Translational suppression by hammerhead ribozymes and inactive variants in S. cerevisiae

The activity of hammerhead ribozymes in S. cerevisiae was assessed using two ribozymes that were designed to intramolecularly attack the hepatitis B viral X mRNA. The ribozymes effectively suppressed the expression of the X-lacZ fusion gene, when they were inserted at the 5′ end of the X mRNA. The ribozymes cleaved the target RNA efficiently at the targeted phosphodiester bond, but the inactive mutants carrying G5-to-A substitution in the core did not, as the total RNA preparations of yeast extracts was assayed by primer extension. These G5A mutants, however, exerted the suppression as effectively as the wild-type ribozymes. The results, with several mutations introduced to a ribozyme, suggested that either mere formation of hammerhead-like structures with the three stems, or the formation of any two stems, could inhibit translation. Thus, the hammerhead-like structures, leading to cleavage or not, could effectively suppress translation, especially when formed around the initiation codon. The G5-to-A and U7-to-G mutations and replacement of the stem-II hairpin tetraloop did not appear to affect the formation of the inhibitory structure(s). The inhibition that was observed when stems I and III were directly connected without a loop or with a stem II hairpin was completely relieved when they were connected with only the loop of stem II (not containing the stem portion).     

鄂东大别山区国家重点保护野生植物及保护对策

据调查统计,鄂东大别山区共有国家保护植物18种,其中I级保护植物2种,它们是银杏和南方红豆杉;II级保护植物16种,它们是大别山五针松、金钱松、巴山榧树、榉树、金荞麦、连香树、厚朴、凹叶厚朴、鹅掌楸、樟树、桢楠、野大豆、秤锤树、喜树、香果树和黄皮树.分别占湖北省分布的39.1%,25%和44.4%.该区的这些国家保护植物具有分布集中、居群规模小、片段化严重、垂直分布明显的特点.建议建立以天堂寨为核心的湖北大别山自然保护区,并提出了相应的保护对策.