二噁英的生物降解及其机理

利用微生物降解二噁英是一种具有广阔前景的治理二噁英污染的方法。近年来利用微生物降解二噁英已经引起众多研究者的重视,国外在这方面的研究已取得了一定成果。介绍了能降解二噁英的微生物种类及其所能降解的二噁英类型,对近年来提出的微生物降解(包括氧化降解和还原降解)的可能途径,中间产物及其降解效果进行了综述。并对土壤在被污染后如何进行生物修复等方面进行了探讨。     

长江下游重点江段水质污染及对鱼类的毒性影响

通过对长江下游安庆,南京,镇江和长江口4江段水质及其对鱼类毒性影响的调查发现,长江下游江段主航道的水质符合国家地面II类标准,但近岸的污染带水质受到一定程度的污染,其主要污染物为石油烃类和挥发酚等,这些污染物对鱼类有一定的毒性影响,可引起鱼类的急性中毒,并可诱导鱼类产生微核,同时在上述几个江段内的鱼体内可检出较高的污染物残留,这表明长江下游江段已受到不同程度的污染,这种污染对区域性渔业有影响。     

鱼类的胃排空率及其影响因素

鱼类的胃排空率是研究鱼类能量学的重要参数,近年来国外有关研究结果表明,鱼类的胃排空率除了受鱼体自身生理状况和实验方法的影响以外,还受许多其它因素,如：鱼的种类,鱼体重,温度,食物,摄食频率以及饥饿时间等的影响。这些资料将为我国开展该方面的研究工作提供有价值的参考作用。     

饥饿对鱼类生理生态学影响的研究进展

由于自然界中食物分布在空间上的不均匀性、季节更替或环境剧变等原因,鱼类经常会在生活周期的一定阶段面临食物资源的缺乏而受到饥饿胁迫。不同种类的鱼对饥饿的耐受力和适应性特征不同。有关饥饿对鱼类生理生态学状况影响的研究有助于了解鱼类适应饥饿胁迫的生态对策,具有重要的理论意义;该方面的资料对渔业资源管理及水产养殖等方面的实践也有重要的指导意义。本文综述了近年来有关饥饿对鱼类代谢、身体组成、形态结构、行为、繁殖习性、 作用。l饥饿对鱼类代谢水平的影响鱼类可调节自身的能量分配以适应食物的缺乏,饥饿状态下鱼…     

微囊藻毒素对鱼类毒性影响的研究进展

微囊藻毒素 (Microcystins,简称MC)是一些有毒蓝藻,如微囊藻、颤藻和鱼腥藻等,产生的一种具有肝毒性的环状七肽。       

光照对鱼类生理活动影响的研究进展

在自然界,光的变化具有稳定性和规律性,它的变动能触发动物的一些生理机制［１］。关于光对鱼类生理活动影响的研究,国内的报道极少,而国外的研究相对多一些。近年来,虽然在这方面的工作取得了一些进展,但从整体上看,还仅仅处在初步探索阶段。本文根据国内外的研究报道,综述了光照对鱼类繁殖、代谢和内分泌活动的影响。１　光照周期对鱼类繁殖的影响光是影响动物繁殖的一个重要生态因子。许多热带鱼类全年繁殖,因为热带地区的昼长基本上是稳定的［２］。大量的实验室工作也证明,光照对动物繁殖的影响不仅因种而异,而且还因动物的…     

鱼类同工酶研究进展

综述了近年来鱼类同工酶的研究 ,包括胚胎发育过程中同工酶的变化、鱼类机体中同工酶的组织特异性研究、利用同工酶进行种质鉴定、遗传育种、病理研究 ,以及影响同工酶的因子等方面 ,以便为科学研究和养殖生产提供参考。     

手术植入发射器对鱼类影响研究进展

手术植入已成为开展长期鱼类遥测技术研究的最佳发射器附着方式,但其对鱼类的负面影响却不容忽视.鱼类遥测技术研究成功的关键在于发射器的存在及附着方式不会影响鱼类的生理状况及行为特征.因此,开展鱼类遥测技术研究之前,必须科学评估手术植入发射器可能对鱼类造成的负面影响.本文综述了国外关于手术植入发射器对鱼类影响的报道,阐述了发射器、手术程序、环境因素及人为因素在鱼类手术植入发射器过程中可能对鱼类造成的负面影响及影响程度.在此基础上,提出了若干减少负面影响的措施,并展望了我国在该领域未来的研究方向.     

热污染对鱼类行为的影响

热污染,由于热(核)电站和工矿企业等热废水排入江、湖等天然水域,使水温升高而影响水生物的正常生长,甚至造成生物死亡的严重后果。由热污染引起死鱼事件,在国内外早有记述。例如1975年日本沿海的50座核电站所排放出大量的热废水,曾导致大批鱼类死亡;1978     

Increasing effect of nori on the fecal excretion of dioxin by rats

The effects of nori (Porphyra yezoensis), a kind of red alga, on the gastrointestinal absorption and reabsorption of 17 types of dioxin were investigated in male Wistar rats. The rats were fed with 4 g of the control diet or 4 g of the nori diet containing a standard dioxin solution (233 ngTEQ/kg of body weight) for five consecutive days. In the group fed with the 10% nori diet, the fecal excretion of dioxin from days 1 to 5 was higher (p<0.01) than that of the control group by 5.5-fold for 2,3,7,8-TCDD, 6.6-fold for 1,2,3,7,8-pentaCDD, and 6.0-fold for 2,3,4,7,8-pentaCDF. In another experiment, the rats were fed with 4 g of the control diet containing a standard dioxin solution (2991 ngTEQ/kg of body weight) on the first day of the experiment and then given the control diet for 7 consecutive days, before being given either the control diet or the nori diet for 28 consecutive days more. In the group fed with the 10% Nori diet, the fecal excretion of dioxin during the period from days 8 to 35 was higher (p<0.01 or p<0.05) than that of the control group by 2.4-fold for 2,3,7,8-TCDD, 2.3-fold for 1,2,3,7,8-pentaCDD, and 2.4-fold for 2,3,4,7,8-pentaCDF. These results suggest that the administration of nori prevented dioxin from being efficiently absorbed and reabsorbed from the gastrointestinal tract, and might be useful for protecting humans exposed to dioxin from ill effects.     

小檗碱的抗菌作用研究进展

小檗碱在临床上广泛运用于抗痢治疗,其抗菌作用被认为是其发挥抗痢作用的主要药理学机制.小檗碱的体内外抗茵活性明显,其抗茵机制可能涉及对多种酶蛋白活性抑制,肠毒素拮抗作用和抗粘附作用等机制.小檗碱的直接抗茵作用可能与其非特异性蛋白抑制作用有关.     

鱼类对晶体氨基酸利用的研究进展

随着鱼粉供应的紧张和价格的上扬,有关植物蛋白源取代鱼粉的研究也逐渐增加,与鱼粉等优质动物蛋白源相比,植物蛋白源通常表现为某些必需氨基酸缺乏或不足,如赖氨酸、蛋氨酸等,因而向饲料中添加晶体氨基酸成为解决这一问题的有效途径.但是在水产饲料中添加晶体氨基酸的作用效果,目前尚无定论,研究和生产中对氨基酸的使用也存在许多模糊认识.本文就水产饲料中氨基酸的研究现状作一综述,为晶体氨基酸在生产中的合理使用提供指导,为鱼类的氨基酸营养研究提供思路.     

自噬在抗原加工呈递中作用的研究进展

细胞自噬在固有免疫和获得性免疫中发挥重要作用。自噬一方面通过溶酶体清除胞质内微生物,发挥天然抗感染免疫作用;另一方面可通过调节抗原加工、呈递,在获得性免疫反应中发挥效应。自噬除可参与并增强组织相容性复合物(MHC)Ⅱ类分子的抗原呈递外,在经典和非经典MHCⅠ类抗原呈递中也发挥辅助作用。     

The effect of fish on planktonic rotifers

The dynamics, community structure, and productivity of planktonic rotifers were studied during 3 years in two lakes near St. Petersburg (Russia). One lake was repeatedly stocked with larvae of the fish Coregonus peled; the other contained no fish. Fish addition led to a shift in plankton community structure. Population densities of some rotifer species (Keratella cochlearis, K. irregularis, Asplanchna priodonta) increased as a result of the elimination of large crustaceans by fishes during summer and autumn. An inverse relationship was found between the biomass of rotifers and Daphnia.     

对流层臭氧浓度升高对植物光合特性影响的研究进展

作为重要的空气污染物之一,对流层臭氧浓度平均以每年2%的速率递增.高浓度臭氧可抑制植物的生长发育,影响生物量和产量的形成,且响应程度随O3设置浓度、试验平台和品种的不同而异.光合作用作为植物最基本的生理过程,同时也是对O3最敏感的生理过程之一.从植物损伤症状、光合作用的光反应、暗反应等方面概括了高浓度臭氧对植物光合特性影响的研究进展,为阐述O3损伤机理、耐性品种的选育提供理论依据.     

Modeling the long-term effect of PCBs on Everglades fish communities

Fish communities are regularly exposed to a large number of natural and synthetic toxic chemicals, whose harmful effects, both short-term and long-term, need to be studied. Mathematical simulation models are known to be useful tools in the assessment of both acute and chronic effects. A time-concentration-effect model has been developed to assess the long-term effect of PCBs on multi generations of fish communities in the Florida Everglades. The term fish is used here generically to refer to five functional fish groups (FGs), two having small and two having large adult size, and a crustacean (crayfish), each of which are further composed of several age classes. Several contaminant concentration scenarios are analyzed in the simulations, subject to mortality and hatchability failure. The model predicts the population response time series for each FG, based upon exposure concentration and duration. Model results indicate that a concentration of 0.1 gl^–1 could have adverse effects on survival and reproduction success for Everglades fish communities. For comparison, the USEPA has stipulated a standard of 0.014 gl^–1 for the protection of freshwater fish from chronic effects and a standard of 1.0 gl^–1 from acute effects. Hopefully, the model may be further developed to assist in the formulation of policy or regulations concerning aquatic ecological risk to protect the aquatic ecosystem of the Everglades.     

A direct advance on advance directives

Advance directives (ADs), which are also sometimes referred to as 'living wills', are statements made by a person that indicate what treatment she should not be given in the event that she is not competent to consent or refuse at the future moment in question. As such, ADs provide a way for patients to make decisions in advance about what treatments they do not want to receive, without doctors having to find proxy decision-makers or having recourse to the doctrine of necessity. While patients can request particular treatments in an AD, only refusals are binding. This paper will examine whether ADs safeguard the autonomy and best interests of the incompetent patient, and whether legislating for the use of ADs is justified, using the specific context of the legal situation in the United Kingdom to illustrate the debate. The issue of whether the law should permit ADs is itself dependent on the issue of whether ADs are ethically justified; thus we must answer a normative question in order to answer the legislative one. It emerges that ADs suffer from two major problems, one related to autonomy and one to consent. First, ADs' emphasis on precedent autonomy effectively sentences some people who want to live to death. Second, many ADs might not meet the standard criteria for informed refusal of treatment, because they fail on the crucial criterion of sufficient information. Ultimately, it transpires that ADs are typically only appropriate for patients who temporarily lose physical or mental capacity.