毛竹根际分离的地衣芽孢杆菌固氮特性研究

从毛竹根际分离到36株固氮菌，经初步镜检其中17株菌为芽孢杆菌，进一步鉴定确定其主要为多粘芽孢杆菌（Bacilluspolymyxa）和地衣芽孢杆菌（Bacilluslicheniformis），本文主要就其中菌号为G－8、G－12、G－14、G－17四株地衣芽孢杆菌的鉴定及固氮特性进行研究。结果显示：四株菌均为杆状，具芽孢孢孢囊稍膨大，它们的生理生化特性相同，但菌落形态有一些差异。G－8和G－17的最佳固氮温度为35℃左右，G－12和G－14的最佳固氮温度为30℃左右；G－12、G－8和G－14的最适固氮pH为6．0左右，G－17的最适固氮pH为6.0～7.5；四株菌都可利用碳源固氮，但均以葡萄糖为碳源时的固氮活性最高，依次为64．76、437．23、65．42、90．91nmolC2H4h-1，瓶-1。G－12在培养48h，G－8、G－14在培养96h，G－17在培养60h的固氮活性最高分别为138．50、122．01、170．87、109．81nmolC2H4．h-1.瓶-1。     

鲶鱼骨酶解物的降血压肽活性研究

以鲶鱼骨蛋白为原料制备ACE抑制肽,采用碱性蛋白酶、中性蛋白酶、木瓜蛋白酶、胰蛋白酶、胃蛋白酶进行酶解,通过体外检测法测定其抑制率,优选出最佳用酶。通过单因素试验和正交试验,确定了碱性蛋白酶酶用量、pH、酶解温度、酶解时间、底物浓度等因素对ACE活性抑制效果的影响。结果表明:利用碱性蛋白酶水解鲶鱼骨,酶用量为500U/g、pH值8.5、温度为60℃、底物浓度为0.33kg/L、时间6h时酶解液对ACE的抑制活性最强,抑制率为88.36%。通过比较,最佳酶解条件下得到的降血压肽的ACE抑制率要高于降血压药尼莫地平和硝苯地平的ACE抑制率。     

基于新形势下农民健身活动引发的再思考

在新形势下,开展农民健身活动是社会可持续发展和落实科学发展观的需要,是我国国情的需要。分析了开展农民健身活动存在的问题及其有利因素,提出要坚持具体问题具体分析,以点带面,统筹兼顾。     

Size-related factors causing individual variation in seasonal reproductive success of fluvial male Dolly Varden (Salvelinus malma)

Abstract– Reproductive activities of individually identified fluvial Dolly Varden ( Salvelinus malma ) were observed during a breeding season in a small stream. Males and females both established dominance hierarchies based on body size. Females spawned from late October to late November, with no apparent peak, and larger females spawned earlier than small ones. Males competed for access to females by adopting two types of mating tactics: pairing and sneaking. The tactic used depended on the male's position in the dominance hierarchy of the breeding group. Seasonal reproductive activity and mating success of males were positively correlated with body size, with only the largest male monopolizing most of the mating opportunities, and the small males were rarely successful in mating. Smaller males, however, lost as much weight as large males during the breeding season. Females preferred the largest male in the breeding group as a mate, while males courted females of any size. It is suggested that the polygynous mating pattern is a consequence of size-related differences in competitive ability among males, and the degree of monopolization is affected by both the temporal distribution and the spawning tactics of the females.     

Etude de la persistance d'une activite du virus grippal H1N1 (swine) dans les elevages porcins en dehors des phases epidemiquesStudy of the persistence of activity of the H1N1 influenza virus in swine intensive units out of epidemical phases

Une étude est mise en place dans un groupe de 16 élevages intensifs venant de connaitre une attaque grippale et pratiquant à la fois le naissage et l'engraissement dans la région de Bretagne (France). L'objet de cette étude est de mettre en évidence une activité du virus grippal au sein des élevages en dehors des vagues épidémiques. Dans chaque élevage, 2 lots de porcelets sont individuellement suivis depuis la phase d'allaitement jusqu'à l'abattage. Des contrôles sérologiques mensuels sont pratiqués en vue de suivre l'évolution des anticorps grippaux ainsi que ceux de la maladie d'Aujeszky. En outre des écouvillonnages nasaux et des prélèvements de poumons sont réalisés en vue de recherches virales. Ces travaux sont accompagnés par la collecte de renseignements épidémiologiques dans chacun des élevages. Les anticorps grippaux d'origine colostrale inhibant l'hémagglutination décroissent assez rapidement chez le porcelet. Par la suite une conversion sérologique est observée sur près de 10% des animaux suivis. Les animaux concernés appartiennent à 4 des 16 élevages. La séroconversion intervient généralement après 3 mois d'âge. Aucun isolement viral n'a pu être réalisé. Certaines conditions semblent associées à la persistance d'une activité virale comme la démographie déséquilibrée du troupeau de truies, la conduite en continu de la porcherie d'engraissement, la préexistence d'une pathologie respiratoire sévère. Une séroconversion Aujeszky est également observée dans 3 des 4 élevages concernés par l'activité du virus grippal.     

果-草人工生态系统中土壤微生物、土壤酶与土壤养分的关系

试验研究了果-草人工生态系统中土壤生物因子与土壤养分的关系。结果表明：除全P与纤维分解菌、纤维分解酶、多酚氧化酶为负相关外，其余养分与生物因子间均呈正相关，且多数养分与生物因子呈显著或极显著相关；经通径分析发现，脲酶、硅酸盐细菌、纤维分解酶是促进有机质积存的主要生物因素，蔗糖酶是影响N、P、K速效养分的最主要因子，过氧化氢酶、多酚氧化酶、纤维分解菌只是选择性地对有机质的积存和N、P、K速效养分的形成起作用。     

城市公园土壤和植被：自然和人为因子的影响

Various soil surface components, such as trees, shrubs and biological crusts, and human recreational activities, e.g., barbecues and trampling by visitors, may divide the area of the urban park into smaller fragments/microenvironments, differentiated by their microenvironmental conditions, which may differ in soil and vegetation characteristics. The spatial changes in the soil and vegetation characteristics and their causes were investigated in an urban park located south of Tel Aviv-Jaffa, Israel. The area of the park is 0.5 km², including groves, a lake, lawns, and rest areas. Soil was sampled in nine microenvironments, of which seven were within the park: under Ceratonia siliqua trees (CsU), under Ficus sycomorus trees (FiU), rest area between tables under F. sycomorus (FiB), rest area under tables under F. sycomorus (FiT), open area with bare soil (OaS), open area with biological crust cover (OaC), and open area covered by herbaceous vegetation (OaV). Two more microenvironments, planar and sloping open areas (CoP and CoS, respectively) in the vicinity of the park, were used as the controls. Electrical conductivity, concentrations of soluble ions (Mg²⁺, Ca²⁺, Na⁺, K⁺ and HCO₃^-), pH, contents of organic carbon, calcium carbonate and moisture, and grain size distribution were determined. In addition, herbaceous vegetation cover, number and diversity of herbaceous vegetation species were measured. It was found that soil properties and herbaceous vegetation characteristics varied within the park. Soil organic carbon, electrical conductivity, soluble salts, penetration depth, and vegetation characteristics were affected by human activities, mainly in the rest area between the tables. In contrast, the above characteristics were affected by natural factors mainly in the rest of the microenvironments, which were subjected to low levels of anthropogenic intervention. The heterogeneous structure of the park, as represented by the various microenvironments, offered new habitats and promoted the preservation of natural vegetation.     

Laccase and phosphatase activities of the dominant ectomycorrhizal types in a lowland oak forest

The year-round dynamics of laccase and acid phosphatase activities of ectomycorrhizas (EM) were monitored in an oak forest, with a microplate photometric method using individual EM root tips. Among the most frequent and abundant EM morphotypes, those of Lactarius quietus and Cortinarius anomalus showed a peak of laccase activity in spring, while those of Xerocomus chrysenteron displayed highest laccase activities in summer and autumn. In comparison, less seasonal differences were observed in EM acid phosphatase activity. This suggests that the different EM types within the EM community perform complementary functions depending on season.     

酵母菌C10产菊粉酶酶学性质的研究

采用菊粉酶活力测定的方法研究了酵母菌C10所产菊粉酶的酶学性质。该酶的最适温度和最适pH分别为50℃,5.5。在此条件下,该酶酶活力达到12.0U/mL,I/S值为14.0,其水解菊粉后低聚糖得率为29%。1.5%菊芋干粉为合成菊粉酶较好的诱导物;Mn2 ,Ca2 ,Mg2 对菊粉酶有激活作用,Zn2 ,Cu2 ,Fe2 有抑制作用。该菊粉酶中胞外酶,胞壁酶,胞内酶分布为7.5∶0.5∶2.0。研究了底物浓度对酶反应的影响,当底物浓度达到20mg/mL时,产物浓度基本不变,反应初速度达到最大值。