Genotoxicity of chromium in vitro on yeast: Interaction with DNA†

The genotoxicity of chromium chloride was investigated in cells of D₇ strain of Saccharomyces cerevisiae harvested either from logarithmic or stationary growth phase.

A weak induction of mifotic gene conversion and point reverse mutation was obtained when the incubations were performed using phosphate buffer. No genetic effect was observed when the incubations were performed using Tris‐HCl buffer.

The experiments with ⁵¹Cr radiotracer demonstrated that Cr³⁺ ion enters the yeast cells and binds to DNA even if the incubation mixture was performed with Tris HCl buffer. This behaviour could be due to the highest concentration of CrCl₃ that cause some damages to cytoplasmatic membrane.     

Thiram‐induced toxic liver injury in male sprague‐dawley rats

Abstract

A single i.p. dose (120 mg/kg) of thiram given to male Sprague‐Dawley rats caused a significant increase in the activity of SGOT and SGPT 24 hr post‐treatment indicating liver damage. A considerable diminution in the serum cholinesterase activity was also noted in the treated rats as against the control animals. Additional evidence for thiram‐induced liver toxicity is provided by the observation that there was approximately 50% inhibition of the activity of hepatic microsomal benzphetamine N‐demethylase with a concomitant decrease in the concentration of cytochrome P‐450, an important component of the mixed‐function oxidase system. Although not significant, hepatic glutathione levels were also depleted by thiram, probably making the liver susceptible to toxic injury.     

洪水灾害损失信息系统—FLOODIS系统设计

本文借助遥感技术，设计出一个专题地理信息系统一洪灾损失信息系统ＦＬＯＯＤＩＳ，为损失评估模型提供评估区域洪水灾害损失的各种自然地理和社会经济信息以及经系统内专家模块处理后的专题信息，同时对其计算结果进行多种方式输出。     

数据库语言在震害预测中的应用

震害预测的软件程序一般都是基于结构分析的原理，大都采用ＦＯＲＴＲＡＮ语言来编写，而震害预测工作中又大量用到分组和排序，这又是数据库语言的特长。本文介绍了在震害预测工作中应用数据库语言的一些体会，主要讨论了两种语言的接口问题。     

Integrated Assessment of Air Pollution Abatement Strategies in Urban Areas: Application to the Greater Athens Area

This paper presents an integrated system for the assessmentof technical and non-technical measures that are putforward in order to reduce air pollution levels in urbanareas. In contrast to the majority of the currentlyemployed assessment tools, this system allows for theevaluation of any proposed air pollution control measure interms of its combined impact on air quality and socialwelfare, by correlating the environmental and economicaspects of alternative air pollution abatement solutions.Based on the multi-pollutant, multi-effect concept, thesystem presented aims in providing policy-makers with areliable tool for the objective assessment of the mostcost-effective packages of measures, the latter beingallocated according to the particular features and needs ofthe areas examined.     

架空管道震害预测实用方法的研究

根据震害调查分析和试验研究结果,建立了由环境因素和管道结构参数组成的,对架空管道震害预测进行二级多因素模糊综合评判的方法。文中给出了计算、评价构成二级评判因素地震烈度、场地类型、工作状态和结构种类各档次正态模糊数范数ａｋ的参数和对实际情况如何确定的方法。本文为面广量大的已建架空管道的震害预测工作提供了一套科学性强,方便实用的计算方法。     

伊朗加恩—贝尔兼德地震结构震害概述

对１９９７年５月１０日伊朗东部加恩－贝尔兼德地震中出现的几类结构的震害现象进行了初步的描述与分析,同时,就经抗震设防与未防抗震设防结构的震害现明作了对比。对震区重建及附近地区新建结构抗震问题的解决有一定的参考意义。     

Size-Dependent Selective Leaf Damage by Insects and Some Methodological Implications of This Phenomenon

The area of leaves on birch (Betula pubescens ssp. tortuosa) auxiblasts and brachyblasts and the degree of their damage by the complex of leaf-gnawing and leaf-mining insects were studied in a light birch forest. The results showed that phyllophagous insects, primarily snout beetles, prefer young leaves on the apexes of auxiblasts. Thus, selective damage is inflicted on smaller leaves, both on the auxiblasts and in the entire sample. This phenomenon is widespread and may manifest itself in different ways, depending on the pattern of leaf area distribution along the extended shoot and the feeding preferences of the insects. Thus, it is necessary to reconsider research methods and approaches based on the assumption that insects damage leaves nonselectively, irrespective of their size.     

Queen longevity,queen adoption,and posthumous indirect fitness in the facultatively polygynous ant Myrmica tahoensis

In many polygynous ant species, established colonies adopt new queens secondarily. Conflicts over queen adoption might arise between queens and workers of established colonies and the newly mated females seeking adoption into nests. Colony members are predicted to base adoption decisions on their relatednesses to other participants, on competition between queens for colony resources, and on the effects that adopted queens have on colony survivorship and productivity. To provide a better understanding of queen-adoption dynamics in a facultatively polygynous ant, colonies of Myrmica tahoensis were observed in the field for 4 consecutive years and analyzed genetically using highly polymorphic microsatellite DNA markers. The extreme rarity of newly founded colonies suggests that most newly mated queens that succeed do so by entering established nests. Queens are closely related on average (rˉ = 0.58), although a sizable minority of queen pairs (29%) are not close relatives. An experiment involving transfers of queens among nests showed that queens are often accepted by workers to which they are completely unrelated. Average queen numbers estimated from nest excavations (harmonic mean = 1.4) are broadly similar to effective queen numbers inferred from the genetic relatedness of colony members, suggesting that reproductive skew is low in this species. Queens appear to have reproductive lifespans of only 1 or 2 years. As a result, queens transmit a substantial fraction of their genes posthumously (through the reproduction of related nestmates), in comparison to direct and indirect reproduction while they are alive. Thus queens and other colony members should often accept new queens when doing so will increase colony survivorship, in some cases even when the adopted queens are not close relatives. Received: 20 February 1996/Accepted after revision: 25 May 1996