3种进化类型大豆叶片的某些生理特性比较

半野生、半栽培和栽培大豆叶片可溶性糖和可溶性蛋白含量以及过氧化物酶（POD）和超氧化物歧化酶（SOD）活性均表现为随品种的进化而增加的变化趋势。POD活性在生育期中呈上升变化,SOD活性则随着生育进程逐渐下降。栽培大豆的可溶性糖含量和POD活性以上部叶片最高,半栽培大豆与栽培大豆类似,半野生大豆的变化则不明显。     

不同年代大豆品种根系活力的变化及其与植株生物量的关系

为探索不同年代大豆品种根系活力的变化及其与植株各器官生物量和根系伤流液重量的关系。以吉林省1923~2009年间育成的27个大豆品种为材料进行田间试验,在四叶期(V4),盛花期(R2),结荚盛期(R4)和鼓粒盛期(R6)测定根系活力、伤流液重量和植株各器官生物量。结果表明,随生育期的推进,植株器官生物量不断增加,而根系活力和伤流液重量则呈单峰曲线变化,在R4期达到最大。在R4期,植株根系活力、根系伤流液重量和器官生物量与育成年代均呈显著或极显著正相关,但在V4、R2和R6期均未达到显著水平。在R4期,根系活力与根系伤流液重量、植物器官茎、叶和根生物量呈显著或极显著正相关;各品种间地上部器官生物量与根系活力的比值差异不显著。大豆的遗传改良使地上部器官与根系活力协同演进,在根系活力增强的同时植株器官生物量和根系伤流液重量也增加,且在R4期,根系活力与植物器官生物量和根系伤流液重量相关最为密切;可以把R4期的根系活力作为高产育种的指标之一。     

中国贵州懒甲螨属(蜱螨亚纲,甲螨目,懒甲螨科)及一新种记述

记述中国贵州懒甲螨科Nothridae懒甲螨属Nothrus 5种。编制了分种检索表,其中包括1新种贵阳懒甲螨Nothrus guiyangensis sp.nov.。新种与山地懒甲螨N.monticola Hammer,1961和湿地懒甲螨N.meakanensis近似,与山地懒甲螨的区别在于:新种后背板毛c1长度是c2的1.3倍,后背板刚毛h1不着生于瘤突上,梁毛的形状和后背板毛的形状相似,都是叶状。而后者毛c2长度是c1的一半,毛h1着生于瘤突上,叶毛呈刚毛状,而后背板毛呈叶状。与湿地懒甲螨的区别在于,h1不达于后背板的末端,吻毛无透明的角质鞘,且长度只有两吻毛着生基部间距的1/3,而湿地懒甲螨的h1超过后背板的末缘,吻毛具有透明的角质鞘,且长度只比两吻毛着生基部间距略短。所有标本均保存于贵州大学昆虫研究所标本馆。     

Octameric structure of the human bifunctional enzyme PAICS in purine biosynthesis

Phosphoribosylaminoimidazole carboxylase/phosphoribosylaminoimidazole succinocarboxamide synthetase (PAICS) is an important bifunctional enzyme in de novo purine biosynthesis in vertebrate with both 5-aminoimidazole ribonucleotide carboxylase (AIRc) and 4-(N-succinylcarboxamide)-5-aminoimidazole ribonucleotide synthetase (SAICARs) activities. It becomes an attractive target for rational anticancer drug design, since rapidly dividing cancer cells rely heavily on the purine de novo pathway for synthesis of adenine and guanine, whereas normal cells favor the salvage pathway. Here, we report the crystal structure of human PAICS, the first in the entire PAICS family, at 2.8 Å resolution. It revealed that eight PAICS subunits, each composed of distinct AIRc and SAICARs domains, assemble a compact homo-octamer with an octameric-carboxylase core and four symmetric periphery dimers formed by synthetase domains. Based on structural comparison and functional complementation analyses, the active sites of SAICARs and AIRc were identified, including a putative substrate CO₂-binding site. Furthermore, four symmetry-related, separate tunnel systems in the PAICS octamer were found that connect the active sites of AIRc and SAICARs. This study illustrated the octameric nature of the bifunctional enzyme. Each carboxylase active site is formed by structural elements from three AIRc domains, demonstrating that the octamer structure is essential for the carboxylation activity. Furthermore, the existence of the tunnel system implies a mechanism of intermediate channeling and suggests that the quaternary structure arrangement is crucial for effectively executing the sequential reactions. In addition, this study provides essential structural information for designing PAICS-specific inhibitors for use in cancer chemotherapy.     

土壤pH值对烤烟叶片生理生化特性的影响

烟草生长初期,超氧化物歧化酶(SOD)活性及丙二醛(MDA)含量与pH增长呈正相关,而过氧化氢酶(CAT)和过氧化物酶(POD)活性则随着pH的增加而下降,pH值6.5和7.5时叶绿素含量和净光合速率(Pn)较高,旺长期达到高峰;生长后期,各处理的MDA含量和POD活性最高,SOD、CAT活性最低.各pH值处理的叶片中,叶绿素含量、Pn下降,比叶重达到高峰,但pH 8.5下的烟叶中叶绿素含量高,Pn大,比叶重较小.pH 6.5和7.5下的烟叶中蛋白质和可溶性糖总体含量高于其它pH的.烟碱含量在pH 5.5时最高,pH 8.5时最低.     

礼服甲螨科中国新纪录属及一新种记述(蜱螨亚纲,甲螨目,礼服甲螨科)

记述了采自贵州省贵阳市花溪区高坡的礼服甲螨科中国新纪录属拟礼服甲螨属Trhypochthoniellus Willmann,1928,及其1新种黔拟礼服甲螨Trhypochthoniellus qianensis sp.nov..新种与分布于日本的孔拟礼服甲螨Trhypochthoniellus porticus Fujikawa,2000近似.区别为:新种后背板毛c2和c3长度相等,且毛的长度短于c2-c3间的距离,孔拟礼服甲螨c2毛的长度远远长于c3,且c2毛的长度长于c2-c3间的距离;新种e1毛的长度末达到f1的着生点,近似种e1毛的长度超过了f1的着生点;新种生殖毛光滑,而近似种生殖毛粗糙;新种足的毛序是Ⅰ:1-3-3(1)-3(1)-10(3);Ⅱ:1-4-3-3-11(1);Ⅲ:2-2-3-3-11;Ⅳ:1-2-2-2-10,近似种足的毛序是Ⅰ:1-6-3-4-12;Ⅱ:1-5-3-3-11;Ⅲ:2-2-2-2-10;Ⅳ:1-2-2-2-11.     

Comparison of Vegetation Indices and Red-edge Parameters for Estimating Grassland Cover from Canopy Reflectance Data

There has been a great deal of Interests in the estimation of grassland biophysical parameters such as percentage of vegetation cover （PVC）, aboveground biomass, and leaf-area index with remote sensing data at the canopy scale. In this paper, the percentage of vegetation cover was estimated from vegetation indices using Moderate Resolution Imaging Spectroradiometer （MODIS） data and red-edge parameters through the first derivative spectrum from in situ hypserspectral reflectance data. Hyperspectral reflectance measurements were made on grasslands in Inner Mongolia, China, using an Analytical Spectral Devices spectroradiometer. Vegetation indices such as the difference, simple ratio, normalized difference, renormalized difference, soil-adjusted and modified soil-adjusted vegetation indices （DVI, RVI, NDVI, RDVI, SAVI L=0.5 end MSAVI2） were calculated from the hyperspectral reflectance of various vegetation covers. The percentage of vegetation cover was estimated using an unsupervised spectral-contextual classifier automatically. Relationships between percentage of vegetation cover and various vegetation indices and red-edge parameters were compared using a linear and second-order polynomial regression. Our analysis indicated that MSAVI2 and RVI yielded more accurate estimations for a wide range of vegetation cover than other vegetation indices and red-edge parameters for the linear and second-order polynomial regression, respectively.