The effect of mercury accumulation on the intestinal glycosidase activity in perch <Emphasis Type=Italic>Perca fluviatilis</Emphasis> L. from aquatic bodies of European Russia with different pH

The intestinal glycosidase activities and kinetic characteristics of carbohydrate hydrolysis change in different ways with mercury accumulation in the muscles of perch from aquatic bodies of European Russia. Amylolytic activity decreases in fish from aquatic bodies with a neutral pH with a growth in Hg content (0.05–0.30 mg per 1 kg fresh weight), whereas sucrase increases. A decrease in the Michaelis constant for carbohydrate hydrolysis reflects an adaptive increase in enzyme-substrate affinity. In fish from acid lakes, the muscle Hg accumulation amounts to 0.18–0.86 mg per 1 kg fresh weight. With a growth in Hg content, the glycosidase activities and enzyme-substrate affinity decrease in most cases, having a negative effect on the assimilation rate of the carbohydrate components of food.     

Isolation of a methyl parathion-degrading strain <Emphasis Type=Italic>Stenotrophomonas</Emphasis> sp. SMSP-1 and cloning of the <Emphasis Type=Italic>ophc2</Emphasis> gene

A rod-shaped, gram-negative bacterium Stenotrophomonas sp. SMSP-1 was isolated from the sludge of a wastewater treating system of a pesticide manufacturer. Strain SMSP-1 could hydrolyze methyl parathion to p-nitrophenol (PNP) and dimethyl phosphorothioate but could not degrade PNP further. Strain SMSP-1 was able to hydrolyze other organophosphate pesticides, including fenitrothion, ethyl parathion, fenthion, and phoxim, but not chlorpyrifos. A 4395-bp DNA fragment, including an organophosphorus hydrolase encoding gene ophc2, was cloned from the chromosome of strain SMSP-1 using the shotgun technique. Its sequence analysis showed that ophc2 was associated with a typical mobile element ISPpu12 consisting of tnpA (encoding a transposase), lspA (encoding a lipoprotein signal peptidase), and orf1 (encoding a CDF family heavy metal/H⁺ antiporter). The ophc2 gene was effectively expressed in E. coli. This is the second report of cloning the ophc2 gene and the first report of this gene from the genus of Stenotrophomonas.     

Self-Interest versus Group-Interest in Antiviral Control

Antiviral agents have been hailed to hold considerable promise for the treatment and prevention of emerging viral diseases like H5N1 avian influenza and SARS. However, antiviral drugs are not completely harmless, and the conditions under which individuals are willing to participate in a large-scale antiviral drug treatment program are as yet unknown. We provide population dynamical and game theoretical analyses of large-scale prophylactic antiviral treatment programs. Throughout we compare the antiviral control strategy that is optimal from the public health perspective with the control strategy that would evolve if individuals make their own, rational decisions. To this end we investigate the conditions under which a large-scale antiviral control program can prevent an epidemic, and we analyze at what point in an unfolding epidemic the risk of infection starts to outweigh the cost of antiviral treatment. This enables investigation of how the optimal control strategy is moulded by the efficacy of antiviral drugs, the risk of mortality by antiviral prophylaxis, and the transmissibility of the pathogen. Our analyses show that there can be a strong incentive for an individual to take less antiviral drugs than is optimal from the public health perspective. In particular, when public health asks for early and aggressive control to prevent or curb an emerging pathogen, for the individual antiviral drug treatment is attractive only when the risk of infection has become non-negligible. It is even possible that from a public health perspective a situation in which everybody takes antiviral drugs is optimal, while the process of individual choice leads to a situation where nobody is willing to take antiviral drugs.     

Individual serological follow-up of patients with suspected or confirmed abdominal angiostrongyliasis

Abdominal angiostrongyliasis (AA) is a zoonotic nematode infection caused by Angiostrongylus costaricensis, with widespread occurrence in the Americas. Although the human infection may be highly prevalent, morbidity is low in Southern Brazil. Confirmed diagnosis is based on finding parasitic structures in pathological examination of biopsies or surgical resections. Serology stands as an important diagnostic tool in the less severe courses of the infection. Our objective is to describe the follow up of humoral reactivity every 2-4 weeks up to one year, in six individuals with confirmed (C) and ten suspected (S) AA. Antibody (IgG) detection was performed by ELISA and resulted in gradually declining curves of reactivity in nine subjects (56%) (4C + 5S), that were consistently negative in only three of them (2C + 1S) after 221, 121 and 298 days. Three individuals (2C + 1S) presented with low persistent reacitivity, other two (1C + 1S) were serologically negative from the beginning, but also presenting a declining tendency. The study shows indications that abdominal angiostrongyliasis is usually not a persistent infection: although serological negativation may take many months, IgG reactivity is usually declining along time and serum samples pairing may add valuable information to the diagnostic workout.     

Sanctions and mutualism stability: when should less beneficial mutualists be tolerated?

Why do mutualists perform costly behaviours that benefit individuals of a different species? One of the factors that may stabilize mutualistic interactions is when individuals preferentially reward more mutualistic (beneficial) behaviour and/or punish less mutualistic (more parasitic) behaviour. We develop a model that shows how such sanctions provide a fitness benefit to the individuals that carry them out. Although this approach could be applied to a number of symbioses, we focus on how it could be applied to the legume‐rhizobia interaction. Specifically, we demonstrate how plants can be selected to supply preferentially more resources to (or be less likely to senesce) nodules that are fixing more N₂ (termed plant sanctions). We have previously argued that appreciable levels of N₂ fixation by rhizobia are only likely to be selected for in response to plant sanctions. Therefore, by showing that plant sanctions can also be favoured by natural selection, we are able to provide an explanation for the stability of the plant‐legume mutualism.     

Changes in the Dendrite Morphology of Mauthner Neurons in Goldfish under the Conditions of Monocular Deprivation and Sensory Stimulation

Biophysics - Abstract—The effects of sensory stimulation on the model of paired Mauthner neurons of monocularly deprived goldfish have been studied by light- and electron microscopy....     

人支气管平滑肌螺旋条的制备

目的：在体外用支气管条标本测定人气管平滑肌功能。方法：外科手术后,用虹膜剪剪出４０×３×２ｍｍ的支气管螺旋条,１、２、３ｄ进行测量。结果：第２ｄ的收缩和松驰反应比第１、第３ｄ增加。结论：第２ｄ的人支气管螺旋条是进行支气管生理研究的理想材料     

Three epigenetic information channels and their different roles in evolution

There is increasing evidence for epigenetically mediated transgenerational inheritance across taxa. However, the evolutionary implications of such alternative mechanisms of inheritance remain unclear. Herein, we show that epigenetic mechanisms can serve two fundamentally different functions in transgenerational inheritance: (i) selection-based effects, which carry adaptive information in virtue of selection over many generations of reliable transmission; and (ii) detection-based effects, which are a transgenerational form of adaptive phenotypic plasticity. The two functions interact differently with a third form of epigenetic information transmission, namely information about cell state transmitted for somatic cell heredity in multicellular organisms. Selection-based epigenetic information is more likely to conflict with somatic cell inheritance than is detection-based epigenetic information. Consequently, the evolutionary implications of epigenetic mechanisms are different for unicellular and multicellular organisms, which underscores the conceptual and empirical importance of distinguishing between these two different forms of transgenerational epigenetic effect.     

Synthesis of RGD containing peptides and their bioactivities

RGDS, RGDV, and RGDF were used for the structural modification of YIGSR and YIGSK, the sequences involved in the development of metastasis disease. By use of a solution method, YIGSRRGDS, YIGSRRGDV, YIGSRRGDF, YIGSKRGDS, YIGSKRGDV, YIGSKRGDF, YIGSRYIGSK, and YIGSKYIGSR were prepared in good yield. The results of bioassay in vitro indicated that the target property of RGDS, RGDV, and RGDF to high affinity-receptors may be responsible for the enhanced anti-aggregation, anti-adhesion, and anti-invasion potency.