Effect of anti-mosquito antibodies on the infectivity of the rodent malaria parasite Plasmodium berghei to Anopheles farauti

The effect of mouse anti-mosquito antibodies, present in the bloodmeal, on the infectivity of Plasmodium berghei Vincke to Anopheles farauti Laveran was investigated. Significantly fewer oocysts developed in mosquitoes feeding on mice immunized with sugar-fed mosquito midgut antigens than in mosquitoes feeding on control mice. Mosquitoes feeding on mice immunized with the midgut antigens derived from sugar-fed mosquitoes also showed reduced mortality and had lower infection rates than those fed on unimmunized mice. Blood-fed midgut antigen was less effective in producing these effects than sugar-fed midgut antigen.     

Immunocytochemical localization of transient DNA strand breaks in differentiating myotubes using in situ nick-translation

We have localized DNA strand breaks during in vitro chicken myogenesis by repairing nicks in nuclei of fixed cell monolayers in situ with biotin-11-dUTP, followed by immunocytochemical detection of incorporated biotin with rabbit anti-biotin and FITC-labeled goat anti-rabbit antibodies. No accumulations of biotin sufficient for immunocytochemical detection were observed in 23-hr cultures of dividing cells. In 33- and 43-hr cultures, biotin was first detected in only 3% of the nuclei, all of which appeared to be in fusing myoblasts or small myotubes. In contrast, cultures of young, highly fused myotubes (56 hr) exhibited 18% biotinylated nuclei; virtually all of these nuclei, most of which were grouped as aggregates, were within myotubes. In older cultures (73 and 94 hr) incorporation of biotin into myotube nuclei markedly decreased, while increases were noted in nuclei of mononuclear cells. These results indicate that extensive single-stranded DNA nicking occurs in nuclei of young myotubes, followed by repair as terminal differentiation ensues.     

Spermine-induced phosphorylation of myotube histones by endogenous nuclear protein kinases

The effects of spermine on phosphorylation of nuclear proteins in isolated nuclei from proliferation and myotube stage cells during differentiation of cultured chicken myoblasts have been investigated. Incorporation of phosphate from 32P-gamma-ATP was assessed by incubating nuclei with and without 2 mM spermine, which caused an approx. 1.5-fold increase in phosphorylation of total nuclear proteins in both cell types. Modification of individual proteins was assessed by extracting basic proteins in dilute acid, followed by SDS-electrophoresis on 18% acrylamide gels and radioautography. Results indicated that whereas most phosphoproteins in both cell types were increased 1.5-2.0-fold, phosphorylation of a 31 000 D band increased several-fold. Most strikingly, myotube nuclei displayed selective 3.5- and 9-fold increases in specific radioactivity of histones Hla and H3, respectively, which normally exhibit little, if any, phosphorylation.     

松嫩平原苏打盐渍土区不同潜水埋深下羊草的光合特征

通过人工控制地下水位模拟试验,研究了不同潜水埋深下羊草净光合速率和蒸腾速率。结果表明地下潜水埋深直接影响羊草的正常生理活动。潜水埋深在1.0—2.5m之间,潜水埋深越浅,羊草表现为净光合速率和蒸腾速率越高;随着潜水埋深的增加,羊草净光合速率和蒸腾速率减小,生理活动下降。不同月份羊草净光合速率和蒸腾速率与潜水埋深呈幂函数关系,不同时间羊草净光合速率和蒸腾速率与潜水埋深呈幂函数、指数函数和对数函数关系,相关系数均在0.90以上,因此可以用函数方程来估算不同潜水埋深下的羊草净光合速率和蒸腾速率。结果为松嫩平原苏打盐渍土区植被恢复与环境保护提供科学依据。     

粪肠球菌噬菌体vB_E. faecalis_IME196的生物学特性及其全基因组分析

【目的】从医院污水中分离一株能裂解多耐药粪肠球菌的噬菌体,分析该噬菌体的生物学特性,并进行全基因组测序和分析,为治疗和控制多耐药粪肠球菌感染提供基础。【方法】以耐药粪肠球菌为宿主,从医院污水分离噬菌体,双层平板法检测噬菌体效价、最佳感染复数(MOI)和一步生长曲线,纯化后负染法电镜观察噬菌体形态;蛋白酶K/SDS法提取噬菌体全基因组,酶切处理后琼脂糖凝胶电泳分析,使用Ion Torrent测序平台进行噬菌体全基因组测序,测序后进行噬菌体全基因组序列组装、注释、进化分析和比较分析。【结果】分离到一株粪肠球菌噬菌体,命名为v B_E.faecalis_IME196(IME196);其最佳感染复数为0.01,一步生长曲线显示IME196的潜伏期为30 min,暴发量为50 PFU,电镜观察该噬菌体为长尾噬菌体,结合BLASTp分析确定其属于尾病毒目长尾噬菌体科,基因测序表明,噬菌体IME196核酸类型为DNA,基因组全长为38 895 bp,G+C含量为33.9%。【结论】分离鉴定一株粪肠球菌噬菌体,进行了全基因组测序和分析,为以后预防和控制粪肠球菌的感染提供了一个新的途径,为噬菌体治疗多重耐药细菌奠定了基础。     

Hg2+对南极冰藻Chlorophyceae L-4生长和抗氧化系统的影响及藻体富集Hg2+的规律

南极冰藻Chlorophyceae L-4是南极生态系统重要的初级生产力和组成部分,其长期生长在极地环境中,有着特殊的生理机制。在生存环境和生长条件发生变化时,冰藻的膜脂系统和蛋白含量都会发生变化,而在受到重金属胁迫时,冰藻的超微结构也会发生明显变化。【目的】研究Chlorophyceae L-4在重金属离子Hg2+胁迫条件下的状态和Hg2+富集以及对其抗氧化系统的影响,为南极环境监测提供依据。【方法】绘制南极冰藻细胞在重金属离子Hg2+不同浓度胁迫条件下的生长曲线,观察其超微结构;测定丙二醛含量和SOD酶活性变化;ICP-MS法研究藻体富集Hg2+规律。【结果】Hg2+在低浓度时(≤100μg/L),细胞个数较正常条件明显偏少;在高浓度时(≥250μg/L),出现细胞死亡。丙二醛含量随Hg2+浓度升高而升高,SOD酶活性则先增强再减弱。藻体富集Hg2+在1 h达到峰值,而在Hg2+浓度持续升高时,富集量轻微降低。【结论】Hg2+离子对冰藻生长有抑制毒害作用;对Chlorophyceae L-4抗氧化系统有明显不利影响;L-4富集Hg2+在1 h内饱和,Hg2+过高时,富集量稍微降低。     

创新实践教学模式对大学生素质教育的作用

大学生素质教育要求新时代的大学生不仅要学习理论知识,更重要的是培养科学思维并掌握应用技能。我校微生物学课程教学中探索了以创新实践为主要内容的模式改革,其中"理论—技能—创新实践"同步训练的创新模式,是以将参与创新实践计入期末成绩的形式"强迫"学生进入实验室参与科研项目。实施中我们以"教师—研究生—创新小组"交互学习的方式,任课教师制定规则与目标,研究生帮助创新项目的选题、研究方案设计及实施指导,创新小组依照目标参与研究生的科研课题,最后完成创新实践并获得一定比例的成绩。实践证实创新实践教学对促进学生的理论课程学习、科学思维培养以及创新意识训练等方面都有积极的促进作用,是大学生素质教育的一种实用且高效的教学模式。     

黄土丘陵区不同土地利用下土壤释放N2O潜力的影响因素

采用室内培养试验,研究了不同水热条件对黄土丘陵区林地、草地和果园土壤释放N2O的影响,同时测定了土壤中不同氮素形态的变化,旨在探讨影响土壤释放N2O潜力的因素。结果表明：土样中N2O通量与温度显著相关（r=0.1599, P<0.05）,均随温度的升高不断增大,35℃时达到最大。N2O通量与土壤水分含量极显著相关（r=0.2499,P<0.0001）,在土壤水分含量较低时,各土样中N2O通量与土壤水分含量呈正相关,土壤水分接近田间持水量时N2O通量最大,超过田间持水量时N2O通量急剧下降。土壤水分和温度对N2O通量的影响可用拟合方程F=a bT cT^2 dT^3 eT^4 fW来描述。在培养条件下,土壤中N2O的释放总量大小依次为：果园土>林地土>草地土,果园土释放N2O的总量分别比林地土和草地土的释放总量多30%,14%。土壤氮素形态与N2O的释放量有一定关系,但规律不明显。     

西藏色季拉山垂直植被带土壤细菌群落组成及功能潜势

研究青藏高原土壤微生物群落组成和功能的空间分布特征有助于深入理解典型高寒生态系统中土壤微生物的重要生态功能.本研究采用16S rDNA高通量测序方法,分析了西藏色季拉山4个不同海拔土壤细菌群落物种组成和功能潜势的变化特征及其驱动因子.结果 表明:随着海拔的升高,土壤细菌的丰富度和Shannon多样性指数显著降低;酸杆菌...     

黄河三角洲植被空间分布特征及其环境解释

为了解黄河三角洲地区植被空间分布与环境因子之间的关系,通过局地植被样方调查、区域遥感影像提取归一化植被指数(NDVI)及地形高度、地下水位埋深、表层土壤Cl~-含量等环境数据采集,综合样地植被与环境数据进行了除趋势对应分析(DCA)和除趋势典范对应分析(DCCA),并对区域NDVI与主要环境变量进行了单因子相关性分析和多元逐步回归分析。结果显示:DCA排序可将黄河三角洲植被分为翅碱蓬、柽柳-翅碱蓬、芦苇-柽柳、芦苇4个主要群落类型(群丛),DCCA与DCA排序图总体相似,但DCCA更清晰地表明其第一轴主要代表的是潜水Cl~-浓度等关键水盐因子,且随着水土环境系统盐分含量的减小,群落由翅碱蓬逐渐向芦苇演变。区域典型植被群落和NDVI分布格局与变化趋势受地下水位埋深和潜水Cl~-浓度2个环境因素影响较大(NDVI与2个环境变量间建立的二元回归方程R~2=0.57),而土壤Cl~-含量的植被效应实际上受地下水位埋深和潜水Cl~-浓度的影响。在区域地下水普遍浅埋条件下,地下水成为影响植被生长与分布的生态环境最敏感要素,而地下水位埋深和潜水Cl~-浓度是这一要素中的2个关键因子,尤其是后者梯度变化对天然植被分布格局起重要的控制作用。