果蝇幼虫气味编码的分子基础

全球农业经济的损失主要来自昆虫幼虫的取食,而昆虫幼虫的取食主要是依靠气味介导的嗅觉作用。耶鲁大学的昆虫嗅觉神经生物学家对黑腹果蝇Drosophila melanogaster幼虫嗅觉分子基础进行了研究。RT—PCR扩增出23个气味受体基因,其中13个基因,同成虫触角和下颚须内的气味受体基因相同,     

甲醚菊酯和溴氰菊酯在果蝇幼虫外周神经系统的协同毒理作用

本文运用细胞内微电极记录技术研究了甲醚菊酯和溴氰菊酯对果蝇Drosophila melanogaster幼虫神经一肌肉突触兴奋性接点电位(EJP₅)的影响。用甲醚菊酯(1.49x10^-8m01/L)处理后引起果蝇EJP₅的自发释放增加和刺激后的重复后自发释放。而用溴氰菊酯(1.0x10^-8mol/L)处理的则无明显影响。这显示甲醚菊酯对果蝇外周神经主要为I型毒理作用。而溴氰菊酯则主要为Ⅱ型作用,甲醚菊酯和溴氰菊酯联合应用后,则产生兼具I型和II型特征的自发释放或诱发EJP₅发放。自发释放或重复后自发释放的频率和幅值随联合处理中甲醚菊脂和溴氰菊酯的配比而变化。这些结果说明甲醚菊酯和溴氰菊酯对果蝇幼虫外周神经的毒理具有协同作用。     

果蝇脑对2个视觉特征的清晰记忆痕迹

果蝇能够辩认和记住视觉目标。它能根据一小部分的模式参数,例如大小、颜色或者是等高方位,分析它可视环境中所选定的部分,并且贮存这些特定的参数值。像人类一样,果蝇在获得图案的过程中能够独立地识别存在于视网膜上的图案。在这里我们显示了果蝇脑一这个扇形体中心的大部分区域,包括介导视觉模式识别的网状部分。我们已经证明短期记忆有2个模式参数,即在全景中的海拔和等高方位。     

培养果蝇三龄幼虫的小技巧

笔者在进行果蝇唾腺染色体实验培养三龄幼虫时,根据多年的经验发现了2项很实用的小技巧.现介绍如下: 1 选择果蝇的小技巧 果蝇的选择,以野生为宜,一般不要选用长期在实验室培养的果蝇.野生果蝇通常出现在有不新鲜或腐烂的水果周围,所以水果摊或有坏烂水果的垃圾堆是捕获果蝇的首选地点,当然也可以用切成碎片的果肉招引果蝇.     

视觉和嗅觉信号对果蝇食物搜寻行为的协同作用

为了探索视觉和嗅觉信号在昆虫食物搜寻过程中的作用, 本研究利用杨梅和橘子为引诱物, 在实验室条件下测定了嗅觉和视觉信号诱集到的黑腹果蝇Drosophila melanogaster数量, 分析了嗅觉经历对果蝇嗅觉和视觉食物搜寻的影响。发现同源性嗅觉和视觉信号存在的杨梅诱集到的果蝇数量显著大于单一的视觉信号和嗅觉信号, 但异源性嗅觉和视觉信号组合诱集到的果蝇数量和单独的嗅觉信号相似。嗅觉信号预处理不仅能够显著增加嗅觉信号诱集到的果蝇数量, 其中杨梅嗅觉信号对杨梅预处理果蝇的吸引能力与视觉和嗅觉信号存在的杨梅相似, 而且异源性嗅觉和视觉信号组合诱集到的预处理果蝇数量也不低于视觉和嗅觉信号存在的杨梅。另外杨梅嗅觉信号预处理也能够显著增强杨梅视觉信号诱集到的果蝇数量。但嗅觉预处理并不会改变同源性视觉和嗅觉信号组合诱集到的果蝇数量。本研究表明, 果蝇同时利用视觉和嗅觉信号进行食物搜寻, 因此同源性视觉和嗅觉信号在果蝇诱集过程中具有协同作用。另外果蝇具有较强的记忆和学习能力, 能够将记忆中的嗅觉信号应用于食物搜寻。本研究结果不仅有利于我们了解果蝇在自然状态下的食物搜寻机制, 而且有利于开发更有效的果蝇新型诱捕器。     

果蝇视觉学习记忆能力与脑部cAMP水平的相关性

利用闭环飞行模拟系统研究果蝇视觉飞行定向行为的操作式条件化 ,证明正常果蝇视觉学习记忆能力与日龄有关 ,即 3～ 4d龄果蝇的学习记忆能力明显优于1～ 2d龄果蝇 ,蝇脑内的cAMP含量也呈现随果蝇日龄增加而增加的趋势 .同时对学习记忆缺陷型果蝇进行检测 ,其脑内cAMP含量高于正常对照组果蝇 .通过喂食PDEase抑制剂咖啡因扰乱cAMP代谢 ,使果蝇cAMP水平异常提高 ,导致果蝇学习记忆能力显著下降 ,表明果蝇视觉学习记忆需要脑内cAMP水平处于一适当范围 ,过高或过低的cAMP水平都将影响果蝇的视觉学习记忆能力     

果蝇唾液腺染色体试材准备及观察方法的改进

果蝇唾液腺观察实验中大量活体试材的准备与学生剖取腺体的操作是该实验的难点,用甲醇(或乙醇):醋酸=3:1的固定液将果蝇幼虫杀死,变活体解剖为固定后解剖,降低了实验操作的难度;将固定的幼虫置30%的甘油中,放入-20℃冰箱保存,有效地解决了大量优质试材的供给问题,提高了实验教学的效果。     

甲醛对果蝇发育和繁殖的影响

甲醛已被广泛用于人们的日常生活中,成为室内环境的主要污染源.为探讨甲醛对动物不同发育阶段的毒性,本文以模式生物果蝇Drosophila melanogaster为对象,研究了饲料中添加不同浓度甲醛对果蝇生长发育的影响.结果显示,当对照组发育至3龄幼虫（孵化后3d）时,与未添加甲醛的对照组相比,饲料中添加0.25％或0....     

研究称果蝇蛆浑身布满光敏细胞

果蝇幼虫通常都会将它们短暂的生活一头扎在一块腐烂的水果中贪食酵母。这是很危险的：如果不能看到太阳,它们很可能在环境中枯萎。幸运的是,这些蛆在它们脑后以及身体的其他许多地方都长了眼睛。     

Two imported cases of cutaneous larva migrans

Cutaneous larva migrans (CLM) is a rare serpiginous cutaneous eruption caused by accidental penetration and migration in the skin with infective larvae of nematode that normally do not have the human as their host. Although CLM has a worldwide distribution, the infection is most frequent in warmer climates. More recently, they have been increasingly imported from the tropics or subtropics by travelers. We experienced two patients who had pruritic serpiginous linear eruption in their skin for a few weeks after traveling to the endemic areas (Brazil and Thailand, respectively). After the treatment with albendazole, the skin lesions resolved with post-inflammatory hyperpigmentation. We report herein two cases of cutaneous larva migrans successfully treated with albendazole.     

Activity labeling patterns in the medulla of Drosophila melanogaster caused by motion stimuli

Summary We quantitatively describe 2-deoxyglucose (2-DG) neuronal activity labeling patterns in the first and second visual neuropil regions of the Drosophila brain, the lamina and the medulla. Careful evaluation of activity patterns resulting from large-field motion stimulation shows that the stimulus-specific bands in the medulla correspond well to the layers found in a quantitative analysis of Golgi-impregnated columnar neurons. A systematic analysis of autoradiograms of different intensities reveals a hierarchy of labeling in the medulla. Under certain conditions, only neurons of the lamina are labeled. Their characteristic terminals in the medulla are used to differentiate among the involved lamina monopolar cell types. The 2-DG banding pattern in the medulla marks layers M1 and M5, the input layers of pathway p1 (the L1 pathway). Therefore, activity labeling of L1 by motion stimuli is very likely. More heavily labeled autoradiograms display activated cells also in layers M2, M9, and M10. The circuitry involved in the processing of motion information thus concentrates on pathways p1 and p2. Layers M4 and M6 of the distal medulla hardly display any label under the stimulus conditions used. The functional significance of selective activity in the medulla is discussed.     

Computer simulation study on the cyclicities ofTribolium population dynamics

Under a set of assumptions, a mathematical model was constructed to investigate the effect of cannibalistic behavior and medium renewal schedule on Tribolium population dynamics, and the results of simulation analyses were presented to show how modelling can contribute to a better understanding of experimental study. The analyses of the present model, the main concern of which is the cyclicity in Tribolium population. showed that there are two distinct factors which create cyclicity, the cannibalistic behavior in Tribolium itself, and the medium renewal schedule. Cannibalism per se does not necessarily cause cyclicity, but the combinations of cannibalistic behavior among various life stages and their relative intensities among them can cause cyclicity and can also determine the period of cycle. External factors also can generate cyclicity, but their interaction with cannibalistic behavior has a more significant effect in modifying the period of cycle. Some discrepancies between the model and experimental results were discussed.     

The effect of larval age range on survival of twoTribolium castaneum strains in mixed cultures,through pupal cannibalism

The effect of larval age range on survival of two Tribolium castaneum strains in mixed cultures was studied in an experimental situation in which other selective forces were reduced to a minimum. Increasing the difference in larval age setween the strains by one day resulted in a reduction of survival of the faster-developing mutant strain, because more of its earlier pupae were cannibalized by the larvae. General aspects of the effects of pupal cannibalism by larvae on the outcome of intra-specific competition (sensu lato) in Tribolium are discussed.     

Regulatory processes and population cyclicity in laboratory populations ofAnagasta kühniella (Zeller) (Lepidoptera: Phycitidae) IV. The sequential steps in the behavioral process of host finding and parasitization by the entomophagous parasite,Venturia canescens (Gravenhorst) (Hymenoptera: Ichneumonidae)

Summary The sequential steps in the behavioral process of a California stock of the entomophagous parasite,Venturia canescens (Grav.), parasitizingAnagasta kühniella (Zeller) was studied. In host-habitat finding, food media infested with hosts were very attractive to the parasites. Host finding was not covered in detail in this paper as it is presented in subsequent papers. Briefly, in all experiments host density was the most influential factor affecting the efficiency of the parasite. When three age stages of the host were exposed to a parasite, all tests showed that the large, last instar larvae was the preferred age stage but it was not the most suitable (when parasitized) for successful parasite development. Small larvae were less preferred but more suitable for parasite development when accepted. These studies were conducted as a partial fulfillment in the Ph. D. program of one of us (B. M. Matsumoto) and form a part of a broad investigation into the processes operating in the dynamics of arthropod populations under grants toC. B. Huffaker from the U. S. Public Health Service, National Institutes of Health and the U. S. Department of Agriculture.