Alterations in the rabbit lymphoid tissue after bendiocarb administration

Various pesticides have immuno-suppressive effects, and thus the organisms become responsive to viral, bacterial and parasitic diseases and neoplasm. The aim of the study was to observe the structure of the small intestine (height of enterocytes and crypts), mucosal lymphoid tissue (Payer's patches, lymphocytes in lamina propria) and a lymph node after administration of bendiocarb (2,2-dimethyl-1,3-benzodioxol-4-yl-methylcarbamate) on days 3, 10, 20, 30 and 60 of the experiment. The height of the observed enterocytes showed an increasing tendency. On days 20, 30 and 60 we also observed an increase in diameter of crypts located in intestinal epithelium. The number of cells in lamina propria mucosae was significantly reduced on days 20 and 30 after administration of bendiocarb. Observations of the lymph node showed that on days 10 and 20 there was a significant increase in relative volume of medulla at the expense of the relative volume of the cortex and a decrease in the number of lymphocytes. However, we recorded an increase in diameter of lymphocytes. The intracellular parasite Toxoplasma gondii (T. gondii) belongs to the most common pathogenic parasites in the world and it can cause serious health complications in pregnant and immunodeficient individuals. DNA isolation, standard polymerase chain reaction (PCR) and visualization in a 2.5 % agarose gel, the presence of DNA T. gondii was detected in no examined rabbit brain samples. Using real time PCR T. gondii DNA was detected and quantified in the three rabbit brain samples (10 %).     

CAN SCRAP SAVE US FROM DEPLETION?

Old scrap constitutes varied proportions of consumption of different metals. The authors construct a model in which the share of scrap in total supply is explained by three factors, the growth rate in overall demand for the metal; the share of metal contained in scrapped products actually recovered; and the durability of metal containing products. The model is used to study the impact on the share of scrap in total supply from changes in each of the factors. The strongest impact appears to follow from changes in the growth rate of overall demand. Inserting empirical data for copper into their model, the authors suggest, for instance, that in the long run old scrap could satisfy 100 per cent of copper demand, provided that this demand contracted by 1 per cent per year. La ferraille constitue des proportions variées d'utilisation de différents métaux. Les auteurs de cet article ont construit un modèle dans lequel la part de ferraille dans 'approvisionnement total est expliquée par le jeu de trois facteurs: le taux de croissance de la demande globale pour le métal, la part de métal contenue dans des débris de métaux effectivement récupérés et la durabilité des métaux renfermant des produits. Le modèle est utilisé pour étudier les incidences des changements dans chacun des facteurs sur la part de ferraille dans 'offre totale. L'incidence la plus importante semble provenir de modifications dans le taux de croissance de la demande globale. En introduisant des données empiriques pour le cuivre dans leur modèle, les auteurs suggèrent par exemple, qu' à longue échéance, la ferraille pourrait répondre à la demande totale en cuivre pourvu que cette demande se réduise d'un pour cent par année. El uso de chatarra representa una proporción variable del consumo de los diferentes metales. En este artículo los autores presentan un modelo en el que la proción de la chatarra en la oferta de un metal depende de tres factores: la tasa de crecimiento de la demanda global del metal, la proción del metal contenido en la chatarra recuperada, y la durabilidad o vida económica de los productos que contienen el metal en cuestión. El modelo se utiliza para estudiar el impacto sobre la proporción de chatarra en la oferta total causado por las variaciónes de cada uno de estos factores. El mayor impacto parece ocurrir debido al cambio en la tasa de crecimiento de la demands global. Al utilizar el modelo con datos para el cobre, los autores sugieren, por ejemplo, que en el largo plazo la chatarra de cobre podría satisfacer el cien por ciento de la demanda de este metal siempre que dicha demanda se contraigo en uno por ciento por año.     

Environmental Persistence of Chemicals

- DOI: http://dx.doi.org/10.1065/espr2006.01.008 Background The hazard criterion of persistence as it applies to chemicals in the environment is reviewed and discussed. This quantity can not be measured directly in the environment, thus it must be estimated using models that synthesise information on chemical half-lives and partitioning properties, the nature of the environment and how the chemical is released into the environment. Main Features It is suggested that the preferred criterion is the average residence time of the chemical in the environment, i.e. conceptually the sum of the life-times of all molecules (attributable only to losses by degrading reactions) divided by the number of molecules. If all chemical fate processes are first order, this persistence is independent of the quantity of chemical introduced and whether introduction is steady- or unsteady-state in nature. It is shown that in a multimedia environment persistence is affected not only by degradation kinetics, but also by mode-of-entry and partitioning. For screening level purposes a Level II equilibrium model may be adequate but a Level III model is generally preferable for estimating the average persistence. If a distribution of persistences is required a dynamic Level IV model must be used. Discussion The implications for regulating chemicals on the basis of persistence are discussed. Conclusion It is concluded that the preferred strategy is to use Level II, III, and IV models and that the use of only degradation kinetics or media-specific half-lives can be misleading and uneconomical.     

Why insects swarm: testing the models for lek mating systems on swarming Empis borealis females

Summary Female dance-flies, Empis borealis L., gather to swarm, and males carrying nuptial gifts visit swarms for mating. Field observations and experiments were performed on this behaviorally sex-role reversed species to test models of lekking behavior. The key predictions were: (1) female preference model: male visiting rate and mating rate should increase with the number of females in swarm (swarm size), (2) hotspot model: male visiting rate should be independent of swarm size, and (3) hotshot model: swarm size should be positively correlated with the body size of the largest female in swarm. We found that male visiting rate and mating rate increased with swarm size, and that mating rate per female increased with swarm size. Males also mated more often in larger swarms than in smaller ones. Both males and females visited swarm sites even in the absence of other individuals. When females were successively removed from swarm sites more males than females on average arrived at these sites: 2.25 males per female. When no individuals were present at the swarm site, arriving males moved on to another site, whereas arriving females generally stayed. Larger experimental swarm-markers attracted both more males and more females and even more males when swarming females were present. There was no correlation between mean or median female size in swarms and the number of females in swarms. Thus, the female preference model and the hotspot model were corroborated, while other models were judged unlikely to explain swarming behavior in E. borealis. Correspondence to: B.G. Svensson     

Functional responses of copepod nauplii using a high efficiency gut fluorescence technique

To investigate copepod nauplii ingestion rates on phytoplankton, we have adapted the traditional gut fluorescence technique as it can be used with lower gut pigment concentrations. With the improved technique, laboratory experiments were performed to estimate functional responses for nauplii of Calanus helgolandicus and Centropages typicus. Nauplii were raised from eggs to copepodites and the experiments were performed with stages NIV-NV. Gut evacuation rates and ingestion rates were measured on Isochrysis galbana at different concentrations. Specific ingestion rates ranged between 0.038–0.244 μg C μg⁻¹ nauplii C d⁻¹ for C. typicus and 0.041–1.412 μg C μg⁻¹ nauplii C d⁻¹ for C. helgolandicus. Both species showed a type III functional response, reaching a saturation concentration at around 600 μgC l⁻¹ for C. typicus and 800 μgC l⁻¹ for C. helgolandicus. An erratum to this article can be found at     

中东欧消费方式的改变

在中东欧,人、商品、金钱与时间之间的关系发生了迅速的变化 .货币流通速度加快了,日常生活更紧张了,产品和人本身与 10年前都不同了 .耗能多的国产旧冰箱已经被效率更高(价格更高)的新冰箱所代替;老式的苏联 "拉达"和波兰 "菲亚特"已经被"欧宝"和"现代"所代替;街道和媒体充斥着广告;菜单上的国产食品越来越少 .洗碗机和衣物干燥机等先前不知道的新产品以及新包装文化代替了资源消耗少的朴素的消费行为 .     

Synthetic attractants for the bark beetle parasitoid Coeloides bostrichorum Giraud (Hymenoptera: Braconidae)

Coeloides bostrichorum Giraud parasitoids (Hymenoptera: Braconidae) attack late larval stages of various bark beetle species breeding in spruce. Volatile compounds collected from Norway spruce (Picea abies) infested by Ips typographus L. (Coleoptera: Scolytidae) were analysed by coupled gas chromatography-mass spectrometry (GC-MS) and GC-electroantennographic detection (GC-EAD). Monoterpene hydrocarbons are the predominant volatile compounds of fresh Norway spruce, while the presence of oxygenated monoterpenes indicates damaged trees. Between one and eight EAD-active oxygenated monoterpenes were used, in amounts reflecting their natural abundance in spruce trees containing bark beetle larvae, to prepare five synthetic baits which were tested in wind tunnel bioassays. Odour samples collected from spruce logs containing the preferred host stage were attractive, while similar samples from uninfested logs failed to elicit any flight activity. However, when a four- or an eight-component synthetic bait was added to volatiles collected from uninfested spruce logs, this combination was as attractive as volatiles collected from infested spruce logs.