Resource-mediated effects of stream pollution on food absorption of Asellus aquaticus (L.) populations

The role of interactions between chemical perturbations and biological constraints on detritivores occurring in polluted streams were investigated by analysing food absorption variation with stress. Absorption rate and efficiency of four Asellus aquaticus (L.) populations from differently polluted habitats were quantified with respect to the microbial guilds colonizing detritus. A twin tracer method was used. Detritus was microbially colonized in standard conditions and on each stream bottom to control for potential resource-independent variations among individuals. The relationship between length and weight was also determined on a random sample of individuals of each population. Differences of 14.6% in potential absorption efficiency and 11.3% in potential absorption rate were observed between populations from the least and the most polluted habitat. Actual (realized) variations were much stronger: from a minimum of a 60.1% reduction in absorption efficiency to a maximum of 93.8% for the rate. The realized food absorption and the individual weight per length showed the same pattern of variation among populations. This suggested that the availability of energy to isopods in nature was related to stream pollution and resource quality. Bottomup interactions appear to be the most relevant pathway through which chemical water pollution affects the Asellus populations studied. The potential resource-independent variations among individuals are also likely to be explained by temporal cascading of resource-mediated effects.     

人抑胃肽的研究：合成和性质

人抑胃肽的研究：合成和性质崔大敷,崔恒苒,徐明华,曹蕙婷,朱尚权（中国科学院上海生物化学研究所,２０００３１）陈可靖,邓华云（上海医科大学附属中山医院,２０００３２）关键词人抑胃肽,合成,生物活性抑胃肽（简称ＧＩＰ）最早由Ｂｒｏｗｎ等’”从猪小肠分离...     

酶化学法制备AraA

AraA中文名称为9-β-D-阿拉伯呋喃糖基腺嘌呤,通常简称为阿糖腺苷,是一种广谱嘌呤核苷类抗病毒药,具有抑制病毒和肿瘤细胞生长的能力。目前,我国主要采用化学全盛法生产AraA。然而用化学合成法生产AraA反就步骤多,使用的试剂对人体危     

Description of a New Species of Microsporidia from Muscidifurax raptor (Hymenoptera: Pteromalidae), a Pupal Parasitoid of Muscoid Flies

ABSTRACT. A microsporidian parasite, Nosema muscidifuracis n. sp., has been found in Muscidifurax raptor , a parasitoid of muscoid flies. Stages of the parasite developed in direct contact with the host cell cytoplasm and were detected in midgut epithelium, Malpighian tubules, ovaries (including oocytes) and fat body of larvae and adults. Spores were also detected within eggs deposited on the host. Light and electron microscopy revealed a developmental cycle with diplokaryotic stages dividing by binary fission and disporous sporulation sequences producing diplokaryotic spores of three morphological classes, differing significantly only in length of the polar filament. Two of the classes were found in larvae, pupae and adults. One of these, with about five turns in the coiled polar filament, is presumed to be responsible for transmission from cell to cell within the host (autoinfection) and the other, with about 10 turns, responsible for transmission from host to host. A third class, with about 15 turns in the polar filament, was found in eggs of M. raptor . It is, presumably, either involved in initiation and spread of the infection at eclosion or is responsible for horizontal transmission to a new host individual when eggs are cannibalized.     

番茄种子经激光和咖啡因处理后其当代生物效应的研究

咖啡因具有抑制一些酶的活性,可减弱或消除生物体自身对激光引起的生物效应的修复作用。试验证明咖啡因对番茄种子萌发有强烈的抑制作用,咖啡因和激光复合处理生物效应显著,可降低番茄种子的发芽,并促进番茄果实增大和生长前期速率加快。     

Morphological and biological characteristics of the Korean population of Leptoglossus occidentalis Heidemann (Heteroptera: Coreidae), an invasive insect pest of conifer cones

In this study, we investigated the morphological and biological characteristics of a serious insect pest of conifer cones, the western conifer seed bug (WCSB), Leptoglossus occidentalis Heidemann (Heteroptera: Coreidae), in Korea. WCSB adults shared external morphology with overseas populations, including zig-zag fascia on the coria, dilation of the hind tibiae, and color pattern on the abdominal dorsum. The average body length and width of WCSB adults were 17.20 and 4.85 mm, respectively, in males and 19.05 and 5.55 mm in females. The average body weights were 111.27 and 169.89 mg in adult males and females, respectively. On average, eggs were 2.12 mm long and 1.17 mm wide. The average body lengths of the first- to fifth-instar nymphs were 3.07, 4.76, 8.77, 13.56, and 15.53 mm, respectively. For biological characteristics, developmental durations of the egg and five nymphal instar stages were 8.6, 3.7, 7.6, 5.8, 5.8, and 9.1 days, respectively, in laboratory conditions. Nymphal mortality was 47.5% in total. The average life expectancy of WCSB adults was 58.2 and 63.9 days in males and females, respectively. Oviposition of the adult females started 23.4 days after emergence, and the total number of eggs laid by a single adult female was 68.6 on average. The results of this study offer basic morphological and biological information that can be used to design an effective control strategy to manage the WCSB population in Korea.     

Biological comparative study between Wolbachia-infected Aedes aegypti mosquito and Wolbachia-uninfected strain,Jeddah city,Saudi Arabia

In this study, samples of Wolbachia-infected Aedes aegypti mosquitoes were collected from Al-Safa district in Jeddah city, Saudi Arabia. The presence of Wolbachia bacteria in mosquitoes was confirmed by PCR technique and they were reared and propagated in the laboratory. Comparative studies were conducted between Wolbachia-infected A. Aegypti and the Wolbachia-uninfected laboratory strain in terms of their ability to withstand drought, resist two types of insecticides and the activities of pesticide detoxification enzymes. The Wolbachia-infected A. aegypti strain proved less able to withstand the drought period, as the egg-hatching rate of the Wolbachia-uninfected strain was greater than that of the Wolbachia-infected strain after one, two and three months of dry periods. Compared to the Wolbachia-uninfected strain, the Wolbachia-infected strain demonstrated a relatively greater resistance to tested pesticides, namely Baton 100EC and Fendure 25EC which may be attributed to the higher levels of the detoxification enzymes glutathione-S-transferase and catalase and the lower levels of esterase and acetylcholine esterase.     

黑木耳8808菌株生物学特性研究

黑木耳8808菌株,是笔者几年来,从黑龙江省15个地区,采集的32个样本中,分离的59个野生菌株中,经多次培养、比较,栽培试验选出的一株优质、高产菌株。该菌株1992年,在本省五常县长山乡生产150万袋,全省生产近1000万段,均获丰收,产量、质量均明显优于原生产菌株。为更好的为生产提供科学依据,本文研究了该木耳孢子弹射及萌发特征,菌丝、子实体、孢子形态,不同温度、pH、氮碳源浓度,不同培养料配方对该木耳菌丝生长及产实影响。     

树鼩主动脉内皮细胞株的建立及其生物学特性的研究

将树鼩胸主动脉分层剥离,用组织块贴壁法,体外培养出主动脉内皮细胞,历经一年,传至23代,命名为TSaec-8910。倒置显微镜下细胞单层生长,呈铺路石样镶嵌排列,第Ⅷ因子相关抗原阳性,透射电镜观察,细胞质内未找到Weibel-Palade小体。细胞生长曲线及分裂指数示9～12d汇合成单层,按1:2或1:3传代,传代间隔为lO～14d,细胞冻存复苏后接种存活率为31.5％,细胞染色体检查为二倍体细胞,2n=62,雄性。内皮细胞生长因子、上皮细胞生长因子、条件培养基和附着底物对TSaec-8910细胞有明显影响,细胞在玻璃瓶壁上贴壁时间为24～18h,而在涂有鼠尾胶瓶壁则为4h左右,内皮细胞生长因子、上皮细胞生长因子能促进TSaec-8910细胞贴壁和增殖,20％TSaec-8910细胞条件培养基亦能良好地维持细胞形态。     

Experimental evidence of size-selective harvest and environmental stochasticity effects on population demography,fluctuations and non-linearity

Theory and analyses of fisheries data sets indicate that harvesting can alter population structure and destabilise non-linear processes, which increases population fluctuations. We conducted a factorial experiment on the population dynamics of Daphnia magna in relation to size-selective harvesting and stochasticity of food supply. Harvesting and stochasticity treatments both increased population fluctuations. Timeseries analysis indicated that fluctuations in control populations were non-linear, and non-linearity increased substantially in response to harvesting. Both harvesting and stochasticity induced population juvenescence, but harvesting did so via the depletion of adults, whereas stochasticity increased the abundance of juveniles. A fitted fisheries model indicated that harvesting shifted populations towards higher reproductive rates and larger-magnitude damped oscillations that amplify demographic noise. These findings provide experimental evidence that harvesting increases the non-linearity of population fluctuations and that both harvesting and stochasticity increase population variability and juvenescence.