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.     

Arachidonic acid mobilization and phosphoinositide turnover by the terminal complement complex, C5b-9, in rat oligodendrocyte x C6 glioma cell hybrids

Previously, we have shown that rat oligodendrocytes release phospholipid and generate arachidonic acid (AA) and leukotriene B4 in response to sublytic C5b-9 formation. In the present study, we investigated the biochemical pathways by which C5b-9 generates AA from clone ROC-1, a fusion product of rat oligodendrocytes and C6 glioma. Cells were incubated for 24 h in the presence of [3H]AA or [3H]myoinositol. They were then sensitized with antibody against hybrid cell stroma and treated for 1 h with C9-depleted human serum (C9D-HS) or C9D-HS reconstituted with C9. Alternatively, cells were treated with C8,C9D-HS or C8,C9D-HS reconstituted with C8 or C8 plus C9 for 1 h. Qualitative and quantitative analysis of the released [3H]AA and [3H]myoinositol radiolabeled products were performed by thin layer chromatography/autoradiography and anion exchange chromatography, respectively. The major [3H]AA radiolabeled products after C5b-9 stimulation comigrated with intact phospholipid and AA standards, and the major [3H]myoinositol radiolabeled product was inositol-1-phosphate. Treatment of cells with phospholipase A2 inhibitors, mepacrine and bromophenacyl bromide, abolished AA release by C5b-9. In the absence of extracellular Ca2+, C5b-9 also failed to induce the release of AA. Interestingly, 1-(5-isoquinolinsulfonyl)-2-methylpiperazine (H-7), a potent inhibitor of protein kinases, inhibited AA release by C5b-9, whereas AA release stimulated by the calcium ionophore A23187 was not blocked by H-7. The results suggest that AA generation by C5b-9 from the ROC-1 clone involves activation of Ca2+-dependent phospholipase A2 which is regulated by protein kinase-dependent mechanisms.     

放牧对祁连山高寒典型草原土壤质量的影响

土壤质量是维持陆地生态系统稳定性与功能多样性的基础。放牧作为草地资源最广泛的利用方式之一,其对草地土壤质量的影响却缺乏量化标准,且两者之间的作用机理尚不明确。以祁连山高寒草原两个季节性牧场为研究对象,结合生态系统耦合与生态系统多功能性,探究了放牧对高寒草原土壤质量的影响与潜在机制。试验结果表明：基于最小数据集,不同放牧率下土壤质量指数差异显著(P<0.05),冬季牧场和春秋季牧场放牧率分别在2.45头月^-1 hm^-2和0.80头月^-1 hm^-2时土壤质量指数最高。土壤速效磷、有机碳、氮磷比和土壤pH是决定冬季牧场土壤质量的关键因子,而春秋季牧场中则是土壤有机碳、碳氮比和土壤pH;两个季节性牧场土壤质量指数与物种丰富度指数(P<0.05)和香浓维纳多样性指数(P<0.0001)呈显著正相关。高寒草原季节性牧场放牧地植物群落物种多样性与土壤因子耦合度在0.67—0.81之间,平均耦合度为0.74,属于中度协调;随着放牧率的增加,生态系统多功能性指数逐渐减低且与土壤质量指数变化趋势相似,...     

黄土高原不同人工林型微生物残体碳对土壤有机碳组分的积累贡献及影响因素

为探究不同人工林型微生物残体碳(Microbial necromass carbon, MNC)对土壤有机碳组分的积累贡献及影响因素,在黄土高原选取刺槐林、山杏林、油松林为研究对象,分析了三种人工林0-60 cm土层真菌残体碳(Fungal necromass carbon, FNC)、细菌残体碳(Bacterial necromass carbon, BNC)、MNC对颗粒态有机碳(Particulate organic carbon, POC)和矿物结合态有机碳(Mineral-associated organic carbon, MAOC)的积累贡献及其影响因素。结果表明:(1)三种人工林POC、MAOC中FNC、BNC、MNC含量均随土层深度的增加而降低;(2)刺槐林和山杏林MNC对MAOC的积累贡献(60.9%,52.0%)高于POC(33.5%,49.5%),其中FNC对MAOC的积累贡献分别是BNC的4.4和2.5倍,油松林在0-10 cm土层MNC对POC的积累贡献(73.8%)高于MAOC(48.2%),其中FNC对POC的积累贡献是BNC的3.5倍,而在10-60 cm土层MNC对MAOC的积累贡献(30.9%)高于POC(24.4%),其中FNC对MAOC的积累贡献是BNC的3.4倍;(3)总有机碳和全氮含量与MNC/POC、MNC/MAOC呈显著正相关关系(P ＜ 0.05),黏粒含量与MNC/MAOC呈显著正相关关系(P ＜ 0.05),pH值、砂粒含量与MNC/MAOC呈显著负相关关系(P ＜ 0.05)。说明黄土高原三种人工林0-60 cm土层MNC主要贡献MAOC的积累,油松林0-10cm土层除外,且与细菌残体碳相比,真菌残体碳在土壤有机碳组分积累中的贡献更大,土壤总有机碳、全氮、黏粒、砂粒含量、pH值是影响该区不同人工林型微生物残体碳贡献土壤有机碳组分积累的主要因素。     

海南五指山热带山地雨林植物物种多样性研究

王指山热带山地雨林的物种种类十分丰富,在１ｈｍ＾２样地中共出现５４个科,１００个属的乔木树种１７７种,１３３７个个体。区系地理分析表明属的分布区类型以热带分布型成分占优,为８９．０％,充分体现了五指山山地雨林的热带性质。多样性指数分析结果为：样地１Ｍａｒｇａｌｅｆ指数１７．８２２,Ｓｈａｎｎｏｎ－Ｗｉｅｎｅｒ指数５．６２１,均匀度０．８２３,Ｓｉｍｐｓｏｎ指数０．０５０,均匀度６．７７５,表明五指     

不同植物群落下酸化尾矿养分状况及土壤酶活性

调查不同植被群落下铜尾矿的养分状况及土壤酶活性的变化动态,通过常规方法测定了尾矿的pH和电导率,以及有机质,总氮,有效磷,速效钾的含量。用底物反应法测定了过氧化氢酶,芳基硫酯酶,脲酶,酸性磷酸化酶和脱氢酶的活性。结果表明,与酸化的裸露尾矿相比,定居其上的芦苇(Phragmites australis)、狗牙根(Cynodon dactylon)和双穗雀稗(Paspalum distichum)均能显著增加尾矿基质pH值(从3.6上升到5.4),降低电导率,减缓尾矿酸化过程。芦苇和狗牙根能够显著提高尾矿基质中N、K和有机质含量(P<0.05),增加尾矿中的养分。3种植物群落下有效磷较裸露尾矿没有显著增加。植物的定居显著提高了尾矿中过氧化氢酶、芳基硫脂酶和脲酶的活性(P<0.05);但酸性磷酸化酶和脱氢酶活性没有显著提高。研究表明,植物对尾矿有明显的改良作用,而且芦苇和狗牙根优于双穗雀稗。在各种植被条件的尾矿中除酸性磷酸化酶以外的其它实验土壤酶活性均与尾矿中有机质和总氮呈极显著正相关(P<0.01)。     

Comparative investigation on spindle behavior and MPF activity changes during oocyte maturation between gynogenetic and amphimictic crucian carp

The spindle behavior and MPF activity changes in the progression of oocyte maturation were investigated and compared with cytological observation and kinase assay between gynogenetic silver crucian carp and amphimictic colored crucian carp.MPF activity was measured by using histone H1 as phosphorylation substrate.There were two similar oscillatory MPF kinase activity changes during oocyte maturation in two kinds of fishes with different reproductive modes,but there existed some subtle difference between them.The subtle difference was that the first peak of MPF kinase activity was kept to a longerlasting time in the gynogenetic silver crucian carp than in the amphimictic colored crucian carp.It was suggested that the difference may be related to the spindle behavior changes,such as tripolar spindle formation and spindle rearrangement in the gynogenetic crucian carp.     

水华杀藻微生物的分离与分子生物学鉴定

正除藻方法一般分为工程物理方法、化学药剂法和生物方法三大类。作为庞大的富营养化湖泊的藻类控制技术,利用工程物理方法和化学药剂法显然是行不通的,对环境友好的生物控藻技术受到越来越多的关注,国内外许多富营养化湖泊水华的控藻技术的研究热点转向生物控藻技术。在利用生物控藻上,目前主要有三个方面,一是以鱼类控制藻类的生长;二是以水生高等植物控制水体富营养盐及藻类; 三是以微生物来控制藻类的生长。其中由于微生物易于繁殖的特点,使得微生物控藻是生物控藻里最有前途的一种控藻方式。这些杀藻微生物主要包括细菌(溶藻细菌)、病毒 (噬藻体)、原生动物、真菌和放线菌等五类。国内外对杀藻微生物的分离和鉴定有一些报道,但都不够系统和全面, 本文以本实验室的工作为基础,较全面、系统地介绍前三类水华杀藻微生物的分离与纯化及其分子生物学鉴定方法。       

水电开发对鱼类种群分布及生态类型变化的影响——以溪洛渡至向家坝河段为例

梯级水库修建后自然河流形成了河相段和湖相段,而河流生境的改变对鱼类种群空间分布和生态类型变化产生了重要影响。为探究金沙江梯级水电开发对鱼类资源的影响,结合2018年5月渔获物和文献记载水库修建前后的渔获物数据,分析了鱼类群落组成及变化,优势物种及群落多样性特点,以及鱼类在河相、湖相段生态类型的变化。结果表明,梯级水库建设后溪洛渡至向家坝鱼类的种类数减少,随着水库的运行该减少趋势放缓,而大型鱼的种类数占比呈增长趋势。受生境变化的影响,鱼类优势物种发生变化,水库河相段和湖相段生态类型差异较大。生态类型组成上以缓流型、生活于水流中下层、产卵初始水温高于18℃等生态类型占优。研究表明,高坝大库的运行会造成鱼类种群以生态需求为目标,形成明显的空间分布和群落结构特征,而梯级水库建设导致的水动力条件差异是鱼类群落生态类型差异的内在驱动力。