盐胁迫下欧李叶片叶绿体结构及功能与超微弱发光激发的关系

为初步探索叶绿体及其功能与超微弱发光（Ultraweak luminescence,UWL）激发的关系,揭示UWL与植物生长生理的关系及植物中UWL产生的来源,本试验以欧李（Cerasus humilis）为材料,采用室内盆栽试验,设置不同浓度盐胁迫处理,研究盐胁迫下欧李叶片的叶绿体结构和功能（叶绿素代谢、光系统Ⅱ活性、光合性能和能量水平）及UWL的变化规律和相关性。结果表明：（1）盐胁迫降低了欧李叶片的UWL强度,且盐浓度越高,UWL强度下降程度越大;（2）盐胁迫破坏了欧李叶片叶绿体结构,并降低了其功能,具体表现为叶绿素合成主要前体物质（ALA、Mg-ProtoⅨ）含量显著降低,叶绿素降解酶叶绿素酶（Chlase）活性显著升高,导致叶绿素（Chla、Chlb、Car和Chla+b）含量显著降低;同时欧李叶片FV/Fm、FV/FO、PIABS、RC/CSm、φE0和ΨE0快速下降,光系统Ⅱ活性受到严重抑制;进一步Pn、Tr、Gs下降,Ci同时升高,光合性能显著减弱;ATP含量和EC的显著降低,导致能量水平整体下降;（3）欧李叶片UWL强度与其叶绿素代谢物质及叶绿素含量（ALA、Mg-ProtoⅨ、Chla、Chlb、Car和Chla+b）、光系统Ⅱ活性（FV/Fm、FV/FO、PIABS、RC/CSm、φE0、ΨE0）、光合性能（Pn、Tr、Gs）及能量水平（ATP、EC）等参数均呈显著或极显著性正相关关系。（4）盐浓度越高,胁迫时间越长,欧李叶片UWL强度与叶绿体功能各指标变化程度越大,且高浓度处理下的相关性整体高于低浓度处理。可见,在盐胁迫条件下,欧李叶片叶绿体结构被破坏,同时其功能受到损伤活力下降,从而导致UWL强度降低;UWL强度与叶绿体及其功能关系密切,叶绿体可能是UWL的细胞器之一;UWL强度可以用来反映欧李叶片受盐胁迫伤害的程度。     

高寒矮嵩草草甸地上生物量与气象因子的关系

初级生产量是生态系统研究的主要内容之一。初级生产量的高低,决定了整个系统的生产力。初级生产量一方面取决于群落类型、种类组成、结构特征;另一方面它又受到周围环境条件的制约。高寒草甸是青藏高原上主要的植     

高寒草甸矮嵩草种群的放牧中构件种群的反应特性

研究了不同放牧强度下高寒矮嵩草草甸建群种矮嵩草 (Kobresia humilis)构件种群的数量在放牧第四年 (1991年 )和停牧 1年后 (1993年 )的季节动态特性与反应。结果表明 ,随放牧强度增加 ,矮嵩草每分株中分蘖和叶片的数量增加 ,累积存活叶片数达到最大值的时间推迟。在各放牧处理下 ,分蘖数、生殖枝数和累积总叶数具有相同的季节动态过程。分蘖出生率分别在 5月中下旬和 8月下旬各有 1个高峰期 ,死亡率高峰在生长季末。叶片出生率和死亡率的周期与分蘖同步 ,叶片出生率和死亡率大小的变化也同步。矮嵩草分蘖和叶片群体的存活曲线类型分属“Deevey I”型和“阶梯”形 ,且不受放牧强度的影响。停牧 1年后 ,矮嵩草分蘖和叶片群体在放牧强度处理间的数量差异仍然存在     

Isolation and characterization of microsatellite loci in Swietenia humilis (Meliaceae): an endangered tropical hardwood species

Microsatellites are now firmly established as an informative marker system, with increasing popularity as a tool amongst molecular ecologists. We have developed a method of constructing an enriched microsatellite library for the tropical tree species Swietenia humilis Zucc. (Meliaceae). This method is based on a precloning enrichment of SSRs using synthetic oligonucleotide probes, bound to magnetic beads and hybridizing to complementary microsatellite core sequences in digested genomic DNA. Here we describe the isolation and characterization of 10 microsatellite loci that have been used to survey the genetic diversity within a natural population of S. humilis. A total of 97 alleles were identified with an average of 9.7 alleles over all loci. Very high levels of allelic polymorphism were detected at individual loci, with 23 alleles observed at the most variable. The mean observed heterozygosity was 0.415 (range 0.038-0.815) exceeding levels of diversity detected in related species which used isozymes as the marker system. Subpopulation differentiation at a microgeographical scale was low (F_ST= 0.036) and the values of Nm, calculated from the allelic frequencies, were greater than 1 thus reflecting the extent of gene flow occurring between individual trees.     

Distribution of social wasps (Hymenoptera: Vespidae) in New Zealand in 1987

Abstract

More than 50 000 social wasps (Hymenoptera: Vespidae) were collected between March and August 1987 from throughout New Zealand. The most widespread species is the German wasp (Vespula germanica). The common wasp (V. vulgaris) has colonised about half the country and appears to be still spreading. It tends to appear in urban areas first, presumably because it is transported there with people and/or their belongings. The Asian paper wasp (Polistes chinensis) and Australian paper wasp (P. humilis), are confined to the northern half of the North Island, but the former species is spreading south.     

Mn^2＋-Fe^2＋复合胁迫对胭脂草逆境生理指标的影响

以胭脂草（Rivina humilis）为材料,采用溶液培养法,研究系列浓度的锰铁复合胁迫对其若干逆境生理指标的影响。结果表明,当锰铁复合胁迫浓度为6 mmol/L Mn2＋＋0.5 mmol/L Fe2＋时,叶绿素含量和可溶性糖含量均极显著高于对照,并达最大值;与此同时,MDA含量极显著降低,并达呈最小值。该组合处理能维持胭脂草较高水平的保护酶（SOD、POD、CAT）活性。由此说明,适宜浓度的锰铁复合处理,能在一定程度上缓解单一金属的毒害作用,提高胭脂草对锰铁复合胁迫环境的耐受性。     

矮嵩草草甸生长季节生产者亚系统分室模型

本文报道了高寒矮嵩草草甸生产者亚系统六分室模型(GCS 01模型)。六分室包括地上部分的禾草类(V1)、莎草类(V2)、杂类草(V3)、枯枝落叶(V4)四个分室以及地下部分的活根(V5)、死根(V6)两个分室。并建造了相应的微分方程组数学模型,用含有龙格库塔法的BASIC程序可求其数值解。本模型可供高寒草甸生态系统研究人员研究系统行为、探索系统内部规律使用。     

Comparison of cultural methods for the identification and molecular investigation of yeasts from sourdoughs for Italian sweet baked products

Twenty-five yeast strains isolated from sourdough samples for Panettone, Pandoro and Cornetto brioche manufactured by eight different bakeries in northern Italy were characterised. Classification was performed by the simplified identification method (SIM), Kurtzman and Fell's identification protocol, the API system from bioMérieux (France) and the MicroLog system from Biolog (USA). Genetic diversity was investigated by randomly amplified polymorphic DNA fingerprinting and mitochondrial-DNA restriction enzyme analysis. Sequences of the internal transcribed spacers between 18S and 26S rDNA genes were analysed. Candida humilis was the predominant species (56% of isolates), whereas the remaining strains (44%) were related to the Saccharomyces cerevisiae sensu stricto group. Identification systems based on phenotypic analysis proved to be unreliable to identify yeasts from sourdough. Either RAPD-PCR or mtDNA restriction analysis showed to be suitable for the identification of species, but could not be used to differentiate among the isolates at the strain level. Sequencing of the ITS region permitted a consistent classification of the sourdough yeasts.