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81.
In Vietnam a green strain of tobacco mosaic virus was isolated having TIP 89°C (10 min) and causing systemic necrosis in tobacoo ‘Xanthi-nc’ and sometimes also inDatura stramonium. In symptomless tomato plants an elongated virus belonging apparently to the Carlavirus group (NL 630 nm) was found. In papaya trees showing severe symptoms of mosaic and/or ringspot elongated virus particles (NL 730 nm) were observed; this virus being apparently a member of the Potyvirus group, resembled as far as its symptoms in papaya are concerned, the papaya ringspot or the distortion ringspot. In Cambodia some young rubber trees showed malformed leaves (esp. edges and veins) with yellow discolorations along the veins. Such leaves contained elongated virus-like particles (rigid or slightly flexible) of various length (60 to 880 nm), so that their normal length (NL) could not be established precisely. Particles 120 to 150 nm long occurred very frequently.  相似文献   
82.
In nocturnal treefrogs, mate choice implies the use of acoustic and visual signals. Multimodality is suspected to have evolved for either information redundancy or information complementariness. It is essential to explore multimodality in a natural context to understand the selection pressures operating on the signals. In the present study, we investigated calling and coloration in relation to male biometry and condition in four populations of European treefrog (Hyla arborea) varying in size and genetic isolation. We compared the signal intensity between core and satellite populations to estimate the impact of genetic diversity on male secondary sexual traits. The results obtained show important regional variations in both traits, likely as a result of local adaptations. Call and coloration are weakly correlated within an individual, implying that these traits likely convey different information about the signaller's identity or quality, thus supporting the hypothesis of complementariness of multiple messages. By contrast to the experimental evidence, we find that call and coloration are not related to male condition (as estimated by the residual of mass over size), suggesting that the condition‐dependence of these traits may be mediated by complex mechanisms not accurately reflected by the chosen estimator. Finally, male call and colour phenotypes present no robust pattern of variation with isolation status, probably because of variation in local selective pressures and in history of population dynamics. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 103 , 633–647.  相似文献   
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84.
苜蓿银纹夜蛾核多角体病毒(Autographa californica nucleopolyhedrovirus,AcMNPV)基因组含有3个细胞凋亡抑制基因,即p35,iap1和iap2.其中,p35作为一个有效的依赖于天冬氨酸的半胱氨酸蛋白酶(caspase)抑制因子,能够抑制多种因素诱发细胞凋亡,而iap1和iap2的功能仍未完全明晰,本研究对IAP1和IAP2的功能进行了详细分析.缺失了p35的AcMNPV仍可抑制棉铃虫核多角体病毒(Helicoverpa armigera single nucleocapsid NPV,HearNPV)诱导的BTI-Tn-5B1-4(Tn-Hi5)细胞凋亡并挽救HearNPV在Tn-Hi5细胞中复制及HearNPV出芽型病毒粒子的产生.进一步构建了瞬时表达质粒以及分别表达AcMNPV的p35,iap1和iap2基因的重组HearNPV,转染瞬时表达的IAP1和IAP2对HearNPV感染诱导的Tn-Hi5细胞凋亡有抑制效果,而重组病毒感染Tn-Hi5细胞也可抑制其凋亡并在其中复制,然而重组HearNPV表达的p35,iap1和iap2并未能挽救出芽型病毒粒子的产生.结果表明,AcMNPV的iap1和iap2基因表达产物作为细胞凋亡抑制因子是有功能的。  相似文献   
85.

Background  

The ARE insertion/deletion polymorphism of PPP1R3A has been associated with variation in glycaemic parameters and prevalence of diabetes. We have investigated its role in age of diagnosis, body weight and glycaemic control in 1,950 individuals with type 2 diabetes in Tayside, Scotland, and compared the ARE2 allele frequencies with 1,014 local schoolchildren.  相似文献   
86.
目的研究抗菌肽KSL及其衍生物KSL—W对种植体周围炎主要致病菌的体外抑菌效果。方法应用二倍稀释法检测KSL和KSL—W对血链球菌、具梭核杆菌和牙龈卟啉单胞菌的最小抑菌浓度(MIC)和最小杀菌浓度(MBC);MTT法检测KSL和KSL—W对成骨样细胞MG-63的细胞毒性。结果KSL和KSL—W对具梭核杆菌的MIC和MBC分别为0.0156mg/mL和0.0313mg/mL,对牙龈卟啉单胞菌的MIC和MBC分别为0.125mg/mL和0.5mg/mL,在0.5mg/mL的浓度范围内对血链球菌没有抑制作用;KSL和KSL-W在0.5mg/mL的浓度范围内没有细胞毒性。结论KSL和KSL—W没有细胞毒性,对具梭核杆菌和牙龈卟啉单胞菌具有抑制作用。  相似文献   
87.
Diagnostic morphological characters of the juvenile Panchaetothripinae in New Zealand are illustrated. Keys developed enable colonies with only immature stages to be identified without needing to rear adults. Live larvae or larvae in ethanol are distinguished by the presence of expanded tips of body setae (Parthenothrips dracaenae), the absence of setae at the abdomen tip (Hercinothrips bicinctus), setae at abdomen tip not longer than abdominal tip width (Heliothrips haemorrhoidalis) and abdominal tip setae longer than abdominal tip width (Sigmothrips aotearoana, endemic species). The presence or absence of spine-like setae on abdominal segments 9 and 10, and the number and length of setae on the wing buds, enable identification of pupae. Abdominal spine-like setae were on the prepupa and pupa of H. bicinctus and S. aotearoana, species that pupate off the plant, and are probably defensive structures. This is the first record of spine-like setae on segment 10 of terebrantian pupae.  相似文献   
88.
We present a general framework for modelling adaptive trait dynamics in which we integrate various concepts and techniques from modern ESS-theory. The concept of evolutionarily singular strategies is introduced as a generalization of the ESS-concept. We give a full classification of the singular strategies in terms of ESS-stability, convergence stability, the ability of the singular strategy to invade other populations if initially rare itself, and the possibility of protected dimorphisms occurring within the singular strategy's neighbourhood. Of particular interest is a type of singular strategy that is an evolutionary attractor from a great distance, but once in its neighbourhood a population becomes dimorphic and undergoes disruptive selection leading to evolutionary branching. Modelling the adaptive growth and branching of the evolutionary tree can thus be considered as a major application of the framework. A haploid version of Levene's soft selection model is developed as a specific example to demonstrate evolutionary dynamics and branching in monomorphic and polymorphic populations.  相似文献   
89.
弦音器是昆虫类特有的一种机械感受器,亦称弦音感受器或剑梢感受器。它主要具有感知外界声压和体内肌肉运动的听觉功能,研究弦音器的机能结构对揭秘昆虫听觉的神经机制有重要的科学意义。本文从弦音器多样性和进化入手,重点综述了弦音器的微细结构、基因功能定位、声音感受分子机制及其声压增幅分子生物物理学原理,为昆虫听觉仿生学的研究提供了理论依据。  相似文献   
90.
小黑麦抗真菌蛋白组分的分离纯化和性质研究   总被引:3,自引:0,他引:3  
以木霉为指示菌,小黑麦中饲237种子中的蛋白提取物经过分离纯化后,得到了3种主要的抗真菌蛋白组分,经酶活检测鉴定,分别是分子量为30.5 kD的ClassⅡ型几丁质酶,两种分子量为51kD和23 kD的β-1,3-葡聚糖酶。其中几丁质酶的最适反应pH为6.0,最适反应温度为37℃,测定的N末端氨基酸序列与大麦几丁质酶的有很高的同源性。在一定条件下,这3种蛋白组分都有较强的抗木霉活性,并且有明显的协同作用,同时它们对离体易感小麦叶片上白粉菌有很好的生长抑制作用。  相似文献   
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