Questions and possible new directions for research into the biology of terrestrial isopods

New directions for research identified during the final plenary discussion of the Sixth Symposium on the Biology of Terrestrial Isopods included: locating enzymes buffering pleon fluids during excretion of ammonia and the use of isopods in ecotoxicology including how they adapt to or tolerate high contaminant levels; how they interact with free living and endosymbiotic microbiota and how Wolbacchia avoids the immune response of isopods. New analyses of mating behaviour raised questions concerning mate choice while new microsatellite techniques may help resolve issues of multiple paternity and sperm competition. In relation to their ecology and biogeography new questions included how does the ability to learn the location of high quality food patches in spatially heterogeneous environments and the existence of an Allee effect, influence the population biology of isopods in the field and how do patterns of invasion and colonisation vary between species with different motility and life history strategies?     

Significance of earthworms in stimulating soil microbial activity

 The stimulatory effect of earthworms (Lumbricus terrestris L.) on soil microbial activity was studied under microcosm-controlled conditions. The hypothesis was tested that microbial stimulation observed in the presence of a soil invertebrate would be due to the utilization of additional nutritive substances (secretion and excretion products) that it provides. Changes in microbial activity were monitored by measuring simultaneously CO₂ release and protozoan population density. The increase in CO₂ released in the presence of earthworms was found to result from both earthworm respiration and enhanced microbial respiration. The stimulation of microbial activity was confirmed by a significant increase in protozoan population density, which was 3–19 times greater in the presence of earthworms. The respiratory rate of L. terrestris was estimated to be 53 μl O₂ g^–1 h^–1. Earthworm respiration significantly correlated with individual earthworm weight, but there was no correlation between the increase in microbial respiration and earthworm weight. This finding does not support the hypothesis given above that enhanced microbial respiration is due to utilization of earthworm excreta. A new hypothesis that relationships between microbial activity and earthworms are not based on trophic links alone but also on catalytic mechanisms is proposed and discussed. Received: 26 August 1997     

Bioaccumulation and interrelationship of manganese and zinc in horse mussel Modiolus modiolus fromEastern Canada

ABSTRACT:   Bioaccumulation and distribution of Mn and Zn in the total softtissues, digestive glands, residuals and adductor muscles of thehorse mussel Modiolus modiolus from three sites, includingindustrialized and non-industrialized locations in Eastern Canada,were investigated. Extremely high digestive gland metal concentrationswere found in individual mussels, as high as 1819 µg/gMn wet weight and 1964 µg/g Zn wet weight,with mean values from 358 to 404 µg/gMn and from 399 to 614 µg/g Zn for thecollection sites. High Mn to Zn interrelationships were observed inall types of tissues and at all sites. Between different tissues,Zn was interrelated by linear relationships, and Mn was best describedby power curve relationships for all tissue types. In the totalsoft tissue, Mn and Zn interrelations were fitted to power regressioncurves with different slopes between the three study sites. Thisindicated that horse mussel was exposed to different metal levels inthe environments and could be useful for monitoring these metals.The uptake of both metals at extremely high concentrations, thelack of regulation and the occurrence of interactions all suggest thatMn and Zn may play a biological role in horse mussels. Zn and Mninteractions, surprisingly, were not disrupted at the very highconcentrations of either metal, which proves that the mechanism ofmetal interactions does not involve a detoxification role.     

Interactions of fungicide-insecticide combinations against Rhizoctonia solani in vitro and in soil

The inhibition of mycelial growth of Rhizoctonia solani in vitro was strongest with pencycuron, followed by tolclofos-methyl, carboxin and thiabendazole. Against cowpea seedling rot in soil infested with R. solani, tolclofos-methyl was most effective, followed by pencycuron, thiabendazole and carboxin. Of nine insecticides tested, only parathion-methyl and quinalphos suppressed mycelial growth of R. solani in vitro, although their activity was much lower than that of the four tested fungicides. The inhibition of mycelial growth by fungicide-insecticide mixtures was antagonistic in only two out of 36 combinations; it was additive in most cases or synergistic, e.g. for most mixtures of pencycuron and insecticides. Quinalphos, applied to the soil, was the only insecticide which reduced cowpea seedling rot in soil infested with R. solani. Soil application of parathion-methyl, phorate, aldicarb or carbofuran and seed treatment with phosphamidon, monocrotophos, endosulfan or dimethoate had little or no effect on seedling rot. Carboxin gave better disease control when applied to the seed already coated with phosphamidon, monocrotophos, endosulfan or dimethoate and when carboxin-treated seeds were sown in soil treated with quinalphos, parathion-methyl, aldicarb or carbofuran. Efficacy of thiabendazole seed treatment was slightly higher in the presence of insecticides, particularly dimethoate. Pencycuron and tolclofos-methyl as seed treatment gave nearly 100% disease control both in the presence and absence of insecticides. The synergistic interactions detected between fungicides and insecticides represent interesting opportunities for the control of R. solani.     

An Epidemiologic and Economic Study of Respiratory Diseases in Two Conventional Danish Swine Herds. II: Associations Between Lesions Present at Slaughter and Mean Daily Gains During Specific Intervals of the Growth Period

A total of 578 slaughter pigs from 2 Danish conventional farrow-to-finish operations (Herds a and B) were followed from an age of 14 days to slaughter. Pigs were weighed at 3 weeks intervals and at slaughter and extended post mortem examination of the plucks was done. Regression models with second and third order interaction terms demonstrated that Mycoplasma-like pneumonia, complicated pneumonia, anterio-ventral pleuritis, pericarditis, fissures and atrophic rhinitis, separately and through interactions with other lesions, significantly reduced mean daily gains during specific intervals of the growth period in 2 conventional swine herds. It is likely that the periods of reduced growth reflect the times when the diseases were in the acute and early recovery stages. Maximum estimated reductions in daily gains associated with the combined lesions were 82 grams and 283 grams during the interval 120-140 days in Herds A and B, respectively. Although dorso-caudal pleuritis and parietal pleuritis had minor negative effects during 2 intervals neither had a significant adverse effect on total growth rate in either herd (Paisley et al. 1993). R² values for the regression models were less than 0.27 showing that the lesions present at slaughter explained less than 27% of the variation in herd mean daily gains during any interval.     

Is the decline of birds and amphibians in a steppe lake of northern Patagonia a consequence of limnological changes following fish introduction?

• 1. Laguna Blanca, in Laguna Blanca National Park, is a lake in Patagonia which has been designated as a Ramsar site since 1971 because of bird diversity and abundance and importance for nesting, particularly for the black neck swan, Cygnus melanocoryphus. It is also valued for its populations of endemic amphibians, Atelognathus patagonicus and Atelognathus praebasalticus.
• 2. Avian and amphibian populations have decreased dramatically in recent years. Percichthys colhuapiensis, Percichthys trucha (Pisces, Percichthyidae), Salmo trutta and Oncorhynchus mykiss (Pisces, Salmonidae) were introduced into Laguna Blanca in 1965. Since 1986, no Atelognathus frogs have been found. The abundance of swans and coots, which are strongly associated with macrophytes for nesting and feeding, has diminished drastically, whereas piscivorous birds have increased.
• 3. The fishless condition of some neighbouring small lakes with abundant pond weeds, aquatic birds and endemic amphibians, was assessed in order to compare the physical and chemical characteristics and the quantitative composition of the benthos among lakes. Fish presence at Laguna Blanca and its absence at El Burro, Antiñir and Jabón lakes, were confirmed. Compared with previous results, it seems that the abundance of Amphipoda (Hyalella), Copepoda and Cladocera at Laguna Blanca has decreased, while Acari has increased and Notostraca has disappeared. Water transparency has diminished in Laguna Blanca and now is lower than that of fishless lakes.
• 4. P. colhuapiensis were captured only in Laguna Blanca, with the highest captures in the littoral zone. The population shows rapid individual growth in the early years and an absence of fish older than 6 years. The preponderance of benthos and the presence of macrophytes in the gut contents of adult P. colhuapiensis appear to indicate that they are important consumers of these resources.
• 5. This paper concludes that fish introduction in Laguna Blanca led to a complex trophic cascade effect (fish predation on tadpoles, fish competition for avian food, bottom disturbance, zooplankton reduction) producing deleterious effects on the amphibian and bird populations.

Copyright © 2006 John Wiley & Sons, Ltd.     

基因型、环境及其互作对烤烟主要致香成分的影响

在河南(许昌)、云南(玉溪)、贵州(贵阳)3个不同的生态类型区种植NC89、K326、NC297和中烟1004个烤烟品种,探讨基因型、环境及其互作对烤烟5种主要致香物质含量的影响。结果表明,环境因素是影响美拉德反应产物、苯丙氨酸类降解产物含量的关键因素,基因型控制着西柏烷类产物的含量,基因型对类胡萝卜素降解产物和新植二烯的影响主要通过与生态因素互作起作用。互作分析显示,NC89与河南许昌环境条件互作,苯丙氨酸类化合物的含量较高;K326与云南玉溪环境条件互作,高西柏烷类产物降解产物的含量较高;NC297与云南玉溪的环境条件互作,类胡萝卜素降解产物的含量较高。中烟100与河南许昌、云南玉溪环境条件互作,美拉德反应产物、新植二烯的含量较高。     

有机聚合物中场诱导激子解体的动力学过程

目的通过理论计算及其结果分析,对影响有机太阳能电池光电转换效率的主要因素提供有价值的理论线索。方法基于包含链间相互作用的扩展的Su—Schrieffer-Heeger（SSH）模型,利用非绝热分子动力学方法,研究了两条耦合的有机共轭聚合物链中场诱导链间极化子激子的动力学演化过程。结果当电场达到临界值,链间极化子激子将克服链间相互作用而形成自由的带电极化子。结论由于链间极化子比链内极化子激子更容易被电场解体,从而有利于荷电载流子的生成。     

Anticipating the species jump: surveillance for emerging viral threats

Zoonotic disease surveillance is typically triggered after animal pathogens have already infected humans. Are there ways to identify high‐risk viruses before they emerge in humans? If so, then how and where can identifications be made and by what methods? These were the fundamental questions driving a workshop to examine the future of predictive surveillance for viruses that might jump from animals to infect humans. Virologists, ecologists and computational biologists from academia, federal government and non‐governmental organizations discussed opportunities as well as obstacles to the prediction of species jumps using genetic and ecological data from viruses and their hosts, vectors and reservoirs. This workshop marked an important first step towards envisioning both scientific and organizational frameworks for this future capability. Canine parvoviruses as well as seasonal H3N2 and pandemic H1N1 influenza viruses are discussed as exemplars that suggest what to look for in anticipating species jumps. To answer the question of where to look, prospects for discovering emerging viruses among wildlife, bats, rodents, arthropod vectors and occupationally exposed humans are discussed. Finally, opportunities and obstacles are identified and accompanied by suggestions for how to look for species jumps. Taken together, these findings constitute the beginnings of a conceptual framework for achieving a virus surveillance capability that could predict future species jumps.     

The influence of essential oil of aniseed (Pimpinella anisum, L.) on drug effects on the central nervous system

Anise (Pimpinella anisum L.; Apiaceae) and its essential oil have been widely used in folk medicine, pharmacy and food industry. Since there are some data about the impact of anise on functions of central nervous system (CNS), the issue of possible interactions with drugs acting in CNS should be considered. This survey aimed to examine the influence of aniseed essential oil (EO) intake on the effects of drugs that act in CNS.