关键词： 久视   实验   动物模型   树鼩   睫状肌   视力疲劳  

摘要： 目的:从神经-受体-受体介导睫状肌细胞内反应角度探讨肝劳发生的机制。方法:选用与猿猴解剖特点极其接近的动物树鼠句,对其限定照明时间并予以形觉刺激诱视,造成树鼠句持续近视状态以模拟肝劳的病理变化。在实验的第3,6,9天分别处死模型组及正常对照组动物,取睫状体检测其中β-肾上腺素受体(β-AR),环磷酸腺苷(cAMP),环磷酸鸟苷(cGMP)和Na+-K+-ATP酶;以确定造模3,6,9d3个不同时段对动物的影响。结果:造模6d时,树鼠句睫状肌中β-AR发生了上行调节;造模6d时,β-AR睫状肌中cAMP含量显著升高,cGMP含量降低;造模6d时,β-AR睫状肌中Na+-K+-ATP酶活力升高。结论:持续近视状态下睫状肌双重神经支配的异常为肝劳发病的重要原因之一。

关键词： parasites   Monogenea   Trematoda   Nematoda   parasite prevalence  

摘要： As part of broader study on the helminth parasites of amphibians in the different bioclimatic zones of Nigeria, a study of the the helminth parasites of amphibians at New Bussa in the Guinea savanna zone of Nigeria was undertaken. Amphibian hosts examined included Bufo regularis, B. maculatus, Dicroglossus occipitalis and Rana galamensis. The cestode Cylindrotaenia sp. was recovered from Bufo regularis and B. maculatus. Monogeneans were represented by Eupolystoma alluaudi and Polystoma galamensis and trematodes by Haematoloechus exoterorchis, H. micrurus, Mesocoelium monodi and Diplodiscus fischthalicus. Nematode parasites included Rhabdias bufonis, Amplicaecum africanum, Camallanus dimitrovi, Cosmocerca ornata and the larvae of an ascaridoid nematode. Eupolystoma alluaudi, which has been shown to have low prevalence rates in other savanna locations, had high prevalence rates in B. regularis (68.4%) and B. maculatus (82.3%). A few Bufo specimens, which had over-dispersed infection with adult worms and the whole range of developing stages represented, confirm the internal cycle of re-infection already observed by other investigators for E. alluaudi in Bufo spp.

关键词： zooplankton   biomass   species diversity   water body pollution   atmospheric discharge   industrial   wastewater   ecological state  

摘要： The most informative characteristics of the zooplankton-community response to the effect of industrial wastewater from mines have been determined using water bodies of the Kola Peninsula as an example. It has been demonstrated that qualitative and quantitative characteristics of zooplankton depend on the degree of industrial pollution of a water body and adequately reflect differences in the conditions of zooplankton growth between the whole water bodies and their individual parts. The role of zooplankton as an indicator has been assessed and the possibility of including it in the system of monitoring of water objects has been substantiated.

关键词： Amazon   grassland   habitat   population   rat  

摘要： We investigated the relative influences of vegetation cover, invertebrate biomass as an index of food availability and the short-term effects of fires on the spatial variation in densities of the rodent Bolomys lasiurus in an Amazonian savanna. Densities were evaluated in 31 plots of 4 ha distributed over an area of approximately 10 x 10 km. The cover of the tall grass (Trachypogon plumosus), short grass (Paspalum carinatum), shrubs and the extent of fire did not explain the variance in densities of Bolomys lasiurus. Food availability alone explained about 53% of the variance in B. lasiurus densities, and there was no significant relationship between insect abundance and vegetation structure. Fires had little short-term impact on the density of Bolomys lasiurus in the area we studied. As the species appears to respond principally to food availability, habitat suitability models based on easily recorded vegetation-structure variables, or the frequency of disturbance by fire, may not be effective in predicting the distribution of the species within savannas.

关键词： Acacia drepanolobium   ant-plant interactions   East Africa   indirect defense   induced response   Kenya   mammalian herbivory   mutualism   nectaries   relaxation   swollen thorns  

摘要： Many plants offer rewards to attract ants that provide indirect defense against herbivores. These rewards include nectar and swollen thorn domatia, and their production can be inducible. Theory predicts that costly rewards should be relaxed if the risk of herbivory is reduced, although this has not been previously demonstrated. Acacia drepanolobium trees in East Africa produce two ant rewards, extrafloral nectar and swollen thorns. We compared the rewards offered by trees experimentally protected from mammalian browsing for seven years with those offered by unprotected trees. Protected trees produced 25% fewer nectaries per leaf and 25% fewer swollen thorns than did trees in browsed plots. Relaxation of indirect defenses when trees are protected from herbivores is consistent with the dual hypotheses that inducible defenses are dynamic and that plants can save costs by relaxing these defenses when they are not needed. Among trees exposed to mammalian herbivores, trees that were browsed within roughly the past year provided rewards for ants similar to those provided by trees exposed to herbivores but not browsed within the past year. This result suggests that relaxation of indirect defenses only occurs following more than one year of protection from mammalian herbivory.

关键词： Carica   Hymenostomatida   Mucuna   Phytotherapy   Plant Extracts   ProtozoanInfections   Animal  

摘要： The ciliate Ichthyophthirius multifiliis is among the most pathogenic parasites of fish maintained in captivity. In the present study, the effects of the crude methanolic extract of leaves of Mucuna pruriens and the petroleum-ether extract of seeds of Carica papaya against I. multifiliis were investigated under in vivo and in vitro conditions. Goldfish (Carassius auratus auratus) infected with the parasites were immersed for 72 h in baths with M. pruriens extract, and for 96 h in baths with C. papaya extract. There was a 90% reduction in numbers of I. multifiliis on fish after treatment in baths of each plant extract at 200 mg l(-1) compared to untreated controls. Consequently, parasite-induced fish mortality was reduced significantly. A complete interruption of trophont recruitment was achieved by immersion in the M. pruriens extract. In vitro tests led to a 100% mortality of I. multifiliis in 150 mg/l M. pruriens extract, and in 200 mg/l of C. papaya extract after 6 h. Although the active constituents of the medicinal plant extracts are still unknown, we have demonstrated that they have potential for effective control of I. multifiliis.

关键词： behavioural constraint   enemies hypothesis   generalist herbivore   grasshopper   invasive species   Sapium sebiferum  

摘要： 1. Introduced plants generally have lower generalist herbivore loads than native plants. Herbivores may be avoiding a potentially edible food source (Behavioural Constraint Hypothesis) or defences of introduced plants may be unusually toxic (Novel Defence Hypothesis). 2. To examine these hypotheses, acridid grasshoppers (Melanoplus angustipennis and Orphullela pelidna) were enclosed in a Texas grassland. Each enclosure contained native prairie vegetation and a seedling of either introduced Sapium sebiferum (Chinese tallow tree) or native Celtis laevigata (hackberry). Sapium invades many ecosystems in the south-east U.S.A. Celtis seedlings also establish in these ecosystems. 3. Although grasshoppers usually feed sparingly on Sapium, in field enclosures they fed heavily on this introduced tree species, supporting a role for behavioural avoidance. In laboratory feeding trials, M. angustipennis grasshoppers preferred Sapium foliage over the foliage of three native tree species. In a greenhouse experiment, M. angustipennis individuals fed more on Sapium in prairie mesocosms if they were conditioned on Sapium. 4. In another field experiment with single seedlings in enclosures, grasshoppers consumed similar amounts of Sapium from its introduced (Texas, U.S.A.) and native (China) ranges, suggesting that Sapium may have been a suitable host plant since it was introduced. Behavioural avoidance by generalist herbivores may contribute to Sapium's low herbivore load in its introduced range.

关键词： 丙型肝炎病毒(HCV)   树鼩(Tupaia belangeri)   动物模型   重组HCV全病毒   病毒载量   基因型  

摘要： 我们用HCV感染树鼩进行了初步的研究,初步探讨了HCV基因型和病毒载量与感染率的关系,并且初步验证了体外重组构建的HCV全病毒在动物体内的感染性.我们分别用野生病毒和体外重组全病毒进行感染树鼩的实验.野生型病毒株来源于抗HCV抗体阳性病人,排除其他肝炎感染后,进行病毒载量测定和基因分型,根据情况分成两批感染树鼩.实验结果为:第一批所有实验动物均感染了HCV,感染率100％,第二批实验动物有9只动物肯定感染了HCV,感染率为75％(9/12),从检测结果来看,有不少是发生的一过性感染,即在接种病毒后,树鼩的确是被感染了,能在某几个时间点检测到HCV-RNA病毒的存在,但是一段时间后,血浆HCV-RNA的检测结果为阴性,在较长期的跟踪检测中,没有发现再出现HCV-RNA阳性的情况;大多数感染动物血清HCV-RNA间隙性出现,即出现间断性病毒血症.用荧光实时定量的方法测定感染动物体内病毒载量,发现病毒载量水平很低,大多数低于试剂盒检测有效范围,一般在10<'2>-10<'5>copy/m1之间,但是达到10<'3>copy/ml以上的动物非常少见,说明野生型病毒株感染动物后在其体内复制效率并不高.肝功检测ALT值在感染的实验树鼩都发生一过性升高;经过分析,ALT值升高的确与感染有关,但是其升高的时间点并不与体内病毒血症现象相关.解剖后,能在组织中检测到HCV-RNA,这可进一步证明树鼩的确感染了HCV.进行组织病理切片在普通光镜观察,没有发生明显的病变.体外重组HCV全病毒原代和传代(第二代病毒)培养后,培养上清进行实时荧光定量测定其病毒载量,然后分成三组感染树鼩,检测结果表明感染率很高,达到83.3％(10/12).测定感染树鼩体内病毒载量,普遍维持在比较高的水平.感染后的情况也类似于野生型病毒株感染的情况,即发生一过性感染和间断性病毒血症.结果提示,树鼩可以作为HCV感染的动物模型,感染率与感染剂量有关,而与基因型似乎没有什么关系;我们构建的HCV全病毒不但在体外具有很高的复制效率,在体内具有同样强烈的感染力和较高的复制力.

关键词： 久视   实验   动物模型   树鼩   睫状肌   视力疲劳  

摘要： 目的：从神经-受体-受体介导睫状肌细胞内反应角度探讨肝劳发生的机制。方法：选用与猿猴解剖特点极其接近的动物树鼩，对其限定照明时间并予以形觉刺激诱视，造成树鼩持续近视状态以模拟肝劳的病理变化。在实验的第3，6，9天分别处死模型组及正常对照组动物，取睫状体检测其中β-肾上腺素受体(β-AR)，环磷酸腺苷(cAMP)，环磷酸鸟苷(cGMP)和Na^+-K^+-ATP酶；以确定造模3，6，9d3个不同时段对动物的影响。结果：造模6d时，树鼩睫状肌中β-AR发生了上行调节；造模6d时，β-AR睫状肌中cAMP含量显著升高，cGMP含量降低；造模6d时，β-AR睫状肌中Na^+-K^+-ATP酶活力升高。结论：持续近视状态下睫状肌双重神经支配的异常为肝劳发病的重要原因之一。

关键词： OAS   多态性位点   编码区   中国医学科学院基础医学研究所   基因多态性  

摘要： 载脂蛋白A5（有多种拼写形式如Apolipoprotein A5，Apolipoprotein AV，Apolipoprotein A-V，APOA5，APOAV，APOA-V或者RAP3，本文把载脂蛋白A5统一简写为APOA5）是首先在人体内被发现的一个编码载脂蛋白的新基因，与血浆甘油三酯的关系极为密切。为了系统研究树鼩不易感动脉粥样硬化的机制，本课题组已经成功克隆了多个与脂蛋白代谢相关的基因，如APOAI，APOCI，APOE，APOCII，LPL，ABCA1，PLTP，LACT和CETP等。为全面了解各种载脂蛋白的结构和功能，我们把分离、克隆树鼩APOA5基因cDNA全长以及表达树鼩APOA5基因作为本论文的研究目标。 树鼩肝组织总RNA使用Trizol试剂提取，经过PolyATractTM mRNA磁珠分离纯化系统得到了高纯度的mRNA，进一步逆转录合成cDNA第一链。通过比较人、大鼠、小鼠APOA5基因cDNA的核苷酸序列，在高度保守区设计引物进行PCR扩增。目的条带经过内侧引物PCR鉴定后克隆进入T-easy载体，转化大肠杆菌DH5α后涂在有氨苄青霉素抗性的平板上，挑选鉴定阳性克隆以后进行序列测定。将序列结果进一步与人、大鼠、小鼠APOA5基因的核苷酸序列进行同源性分析以确定是否为目的序列。通过上述方法得到尽可能长的cDNA序列，以利以后的实验。 在已经获得的cDNA序列中设计5'和3'快速扩增cDNA末端引物，利用RACE试剂盒得到5'和3'端完整的cDNA第一链，并以之为模板根据SMARTTM RACE试剂盒的说明书扩增APOA5基因cDNA的5'和3'末端，最后经过拼接得到完整的APOA5基因cDNA第一链。树鼩APOA5基因有两个转录本，一个为1948个碱基，另一个为1937个碱基，推测这是由于poly（A）尾的选择性剪接造成的，它们预测的开放阅读框是完全相同的，即1110个碱基，推测该基因编码369个氨基酸，在N—末端含有一个长23个氨基酸的信号肽。预测树鼩与人、大鼠、小鼠APOA5基因编码的氨基酸同源性分别为81.0％、68.7％和66.7％。在此基础上，再设计上游引物