Replication pattern of double minutes derived from an insect cell line

Summary The DNA replication pattern of double minutes derived from an established cell line ofAedes albopictus is described. Although the vast majority of double minutes replicate semiconservatively once during the S phase, some double minutes appear to exhibit different pattern(s). Two theories are suggested as possible explanations of our findings.This work was supported by a grant from the Whitehall Foundation, Inc. awarded to A.B.M.     

Sclerotization of mosquito cuticle

Summary The mode of sclerotization ofAedes aegypti pupal and adult cuticle was examined by employing biochemical and radioactive techniques. During larval-pupal metamorphosis, tyrosine is converted to tanning precursors and is incorporated into aryl-amino adducts and -crosslinks. The major hydrolysis product of -crosslinks in pupal cases is identified to be arterenone. Examination of tanning modes in five different mosquito species shows that the ratio of quinone to -sclerotization not only differs within the life stages of the insects, but also differs between species.Study supported by N.I.H. Grant ROI-AI-14753.     

中华六索线虫的生物学观察

用光镜研究了中华六索线虫生活史各期形态,包括其生长和蜕皮;结合扫描电镜观察成虫期形态并应用组织切片技术研究其内部的组织结构。实验室人工感染成功 4 种昆虫宿主,其中家蚕(Bombyx mori)和伊蚊属(Aedes)幼虫为新纪录,同时也研究了相关的昆虫宿主病理及症状。     

白纹伊蚊自然种群生命表研究

本研究设计了一套能排除外界新蚊卵产入的特定年龄生命表的研究方法。从1984年至1988年,共组建了15个自然种群生命表。通过生存曲线分析得出,在食物营养丰富生境下,曲线呈明显的上弓形,虫体大多活到生理寿命后死亡;而在食物营养贫乏生境下的生存曲线上弓形不明显,虫体在幼虫期便大量死亡。结合医学昆虫研究特点,采用上下代成虫数建立种群趋势指数,并提出两项趋势指数,较全面地揭示了种群的趋势动态。关键因子及虫期分析得出,种群关键虫期为3～4龄幼虫期,其次为1～2龄幼虫期,而食物营养因子是整个自然种群的关键因子。种群密度制约性分析得出,1～2龄幼虫致死因子的作用是密度制约的。     

The endogenous regulation of mosquito reproductive behavior

Summary Most female mosquitoes require a meal of blood that provides protein for egg maturation. For reproduction to occur, two behavioral sequences are essential. One is concerned with finding a host for the blood meal and the other in finding a site on which to lay the eggs that result. Stimuli from both hosts and oviposition sites initiate the reproductive behaviors of host-seeking and pre-oviposition, respectively, that are discussed in this review. After sensory receptors perceive these stimuli, the central nervous system must integrate the information and associate it with a biologically appropriate response. Host-seeking appears to be the default behavior, expressed whenever host stimuli are present. However, if the female is successful in locating a host and ingesting blood, subsequent host-seeking is inhibited when the meal distends the abdomen above a certain threshold. Host-seeking inhibition continues during egg development as a result of a humoral mechanism even after the blood volume has been reduced by digestion. At the time when eggs are maturing and host-seeking is inhibited, pre-oviposition behavior predominates if the central nervous system receives oviposition site stimuli. This behavior is also initiated by a humoral factor. Several physiological states, including insemination, age, and nutrition, can modulate both host-seeking and pre-oviposition behaviors.