The Breeding Season of the Multimammate Mouse Praomys (Mastomys) Natalensis (A. Smith) in the Transvaal Highveld

Certain aquatic Oligochaeta live successfully in organic-polluted waters while others cannot tolerate such conditions. Tubifex tempUtoni Southern and Llmnodrttus hoffmeisteri (Clap.), two non-gilled species, are compared to Branchiura sowerbyi (Beddard) and Dero nivea (Aiyer), two gilled species, concerning their haemoglobin concentration, the influence of low oxygen availability on the respiration rate and their reactions in an oxygen gradient. In contrast with L. hoffmeisteri and T. templetoni where a very narrow range of respiration dependency (pO₂, 0-12 mm Hg) is found, B. sowerbyi and D. nivea have a level of respiratory dependence from pO₂, 0-131 mm Hg. Haemoglobin concentrations are 6,238 - and 6,452 g/100 cm² blood in L. hoffmeisteri and T. templetoni and 3,011 and 1,611 g/100 cm² in B. sowerbyi and D. nivea respectively. In the oxygen gradient all four species have a preference for water with a high oxygen content.     

Life Histories of Frogs in the Namib Desert

Four anuran taxa inhabit the central Namib: Xenopus laevis, Tomopterna delalandei cryptotis, Phrynomerus annectens and Bufo vertebrate hoeschi. Xenopus is confined to permanent pools in the Kuiseb river canyon. Tomopterna extends further into the Namib, but is restricted to the Kuiseb river bed. The Kuiseb is normally dry, receiving water only briefly (as floods) during the rainy season. These floods are responsible for moving adults and larvae. Phrynomerus and Bufo occur on granite inselbergs. The inselbergs provide shelter mainly in the form of cracks under granite exfoliations. Large runoff surfaces collect the low rainfall (25 mm per year) in depressions in which the frogs breed. Phrynomerus is only active at night; males are aggressive towards one another; oviposition takes place in deep pools and development takes at least eight weeks. Bufo is active during the heat of the day; oviposition takes place in warm shallow pools; development takes about three weeks.     

A correction factor for,and its application to,visual censuses of littoral fish

Visual estimation techniques were used between October 1976 and May 1977 on the fish fauna of an enclosed mid-intertidal pool in the eastern Cape, South Africa, to test the usefulness and accuracy of this non-consumptive census method. In January, 1977, two pools were censused for fish, then poisoned using the ichthyocide ‘pronoxfish’ and all fish collected. Forty species in 21 families were obtained from the two stations. The accuracy of visual estimates varied with the species of fish. Secretive and cryptically coloured types, as well as species which Inhabit crevices, were underestimated, between 0 and 86% being counted. Other fish with protective colours but that occur more openly and do not react adversely to divers, as well as schooling species, were also underestimated, but up to 100% of the total were observed. Those which occur singly or in small groups in the water column were counted more accurately, with 57 to 100% of the actual number being seen. Correction factors were calculated from these data and applied to a census taken of one pool in May. Comparisons of corrected and actual numbers Indicate that these factors were relatively accurate for non-secretive species. The factors will, however, vary for each species, from observer to observer, depending on their personal experience, and from area to area.     

Direct impacts of recent climate warming on insect populations

Effects of recent climate change have already been detected in many species, and, in particular, in insects. The present paper reviews the key impacts of global warming on insect development and dispersal. The effects of climate change appear to be much more complex than a simple linear response to an average increase in temperature. They can differ between seasons and bioclimatic regions. Earlier flight periods, enhanced winter survival and acceleration of development rates are the major insect responses. Differential response of insects and hosts to warming up might also lead to disruption of their phenological synchrony, but adaptive genetic processes are likely to quickly restore this synchrony. In a number of cases, warming results in removing or relocating the barriers that limit present species' ranges. It is also likely to facilitate the establishment and spread of invasive alien species. Finally, knowledge gaps are identified and future research interests are suggested.     

黄土高原撂荒地植物群落共存种光合特性对土壤水分变化的响应

植物群落共存种的环境适应性和相对竞争能力差异是植物群落动态和演替的两个决定性因素,其中光合特性与二者都有紧密关联,因此研究群落共存种光合特性的差异对理解群落演替机理具有重要意义。以黄土丘陵区10种主要的撂荒地植物群落共存种为研究对象,测定其在不同的生长月份(8-10月)和不同水分条件下(适宜水分及中度、重度干旱胁迫)光合速率、蒸腾速率和水分利用效率等的变化,分析植物群落共存种光合特性对土壤水分变化的响应。结果表明:1)3种水分条件下,无芒隐子草、白羊草、小花棘豆和达乌里胡枝子的净光合速率日变化均呈单峰曲线,而冰草和阿尔泰狗娃花的则呈双峰曲线,有光合“午休”现象,10种群落共存种以无芒隐子草的日光合能力峰值最大,冰草的最小;2)除中华隐子草和阿尔泰狗娃花外,多数种的蒸腾速率日变化在3种水分条件下均呈单峰曲线,其中,无芒隐子草的日蒸腾能力峰值最大,小花棘豆的最小;3)日均净光合速率和日均蒸腾速率存在显著种间差异和生长月份差异(P<0.05),其中,无芒隐子草的日均净光合速率和日均蒸腾速率最大,而日均水分利用效率在不同物种和生长月份之间则无显著差异(P>0.05);4)在演替生态位置上,10种群落共存种以演替前期种的日均蒸腾速率和日均水分利用效率相对较低,而演替后期种相对较高,表明演替后期的植物水分利用性能较高。在干旱半干旱的黄土高原丘陵区,伴随演替进程的土壤环境旱化,演替后期序列种凭借其较高的水分利用能力,将在撂荒地群落中占据优势地位,从而逐渐代替演替前期种。     

深圳市公园绿地暖季型草坪春夏季杂草的调查

对深圳地区暖季型草坪台湾草及假俭草春夏季草坪进行普查，发现春夏季草坪杂草共66种，分属22科55属，其中台湾草草坪杂草63种，假检草草坪杂草38种。阔叶杂草种类占全部杂草种类的79％。通过抽样、统计，分析了台湾草、假俭草草坪精细管理区、粗放管理区春夏季杂草的优势种和对草坪构成危害的主要杂草种类。结合秋季草坪杂草的调查，总结了深圳地区草坪杂草的发生规律。     

优良豆科牧草--东方山羊豆的研究与利用

开发新豆科牧草资源不仅是改善饲草料品质，提高草地畜牧业生产力的基础，还可为我国实施退耕还林还草，恢复生态环境建设的战略部署提供草本植物物种。东方山羊豆是自1980年后，在前苏联、北欧等国家得到重视的一种新兴豆科牧草，它具有产量高，植株蛋白质含量高，生态适应性强，草地持续稳定性好的特点。本文综述了国内外对该草种的产量及饲用价值评定，回顾了影响山羊豆草地建植和生长的因素，提出了在我国西北地区开展东方山羊豆研究和利用推广的潜力和前景。     

东洞庭湖冬、夏两季湿地鸟类多样性比较分析

2007年8月—2009年1月对东洞庭湖湿地鸟类资源进行调查,从物种丰富度指数、多样性指数、均匀性指数、G-F指数等方面对比分析了冬夏两季鸟类的群落多样性。将物种数、多样性指数、均匀性指数作为基数,运用欧氏和最短距离法进行了聚类分析,结果表明:夏季树林灌丛和居民区生境鸟类群落结构十分相似,而水域和沼泽生境鸟类群落结构相似,冬季树林灌丛和芦苇、草滩沼泽生境鸟类群落结构十分相似,而水域和居民区生境鸟类群落结构相似。     

多种动物血清中生物活性LH/CG的放射受体测定法(RRA)

利用绵羊卵巢黄体细胞膜作为 LH / CG受体来源 ,以放射性12 5 I- h CG作为示踪标记配体 ,以高纯度的h CG为标准品建立标准曲线 ,建立了一种有效的 LH- RRA测定方法。它能够直接检测多种动物血清中与受体结合的具有生物活性的 LH的动态变化。该法测定程序简单 ,在 2 h内完成并获得可重复性结果。测定方法的灵敏度为 0 .3ng/管 ,批内和批间误差分别为 ( 3.4 1± 3.14 ) %和 ( 8.70± 7.93) %。动物 (牛、兔、猪 )垂体液中 LH含量反应曲线和 h CG标准曲线平行良好。牛、羊、猪、兔、鼠和仓鼠血清中 LH的剂量反应曲线和h CG标准曲线的平行性表明 ,该 LH- RRA可以用来检测不同动物血清中的具有生物活性的 LH变化。回收试验表明 ,在该测定方法中加入 3、10、30 ng h CG时的回收率分别为 ( 10 0 .59± 5.55) %、( 99.55± 9.86 ) %、( 10 4 .2 8± 7.4 5) %,说明测定结果的正确性。该 LH - RRA的测定结果反映了动物正常的生理状态。本试验垂体中有活性的 LH水平远远高于外周循环中的水平 ,雌、雄动物循环血液中的 LH含量不一致。     

日粮镁对肉仔鸡腿肌中活性氧产量的影响

本试验目的是研究日粮镁水平对肉仔鸡腿肌中活性氧(reactive oxygen species , ROS)产量的影响。96只AA肉仔鸡随机分配到低镁日粮组和对照组,每组6个重复,每个重复8只鸡,分别喂以镁含量1 .2 g/kg或2 .4 g/kg的日粮。与对照组相比,低镁组肉仔鸡腿肌中谷胱甘肽(glutathione , GSH)的含量降低了27 %(P<0 .01) ,丙二醛(malondialdehyde, MDA)的含量提高了40 %(P<0 .01)。采食低镁日粮的肉仔鸡腿肌匀浆液的ROS信号峰的高度显著高于对照组(P<0 .01)。对照组腿肌镁的浓度(30 .27 mg/kg)显著高于低镁组腿肌镁的浓度(27 .40 mg/kg)。腿肌中铁、钙的含量在两组之间差异不显著(P>0 .05)。与对照组相比,低镁组腿肌线粒体复合酶Ⅰ、Ⅱ、Ⅲ、Ⅳ的活性分别提高了28 %、23 %(P<0 .01)、35 %(P<0 .01)和30 %,线粒体复合酶Ⅰ、Ⅱ、Ⅲ、Ⅳ的活性与ROS产量之间呈显著的负相关关系(P<0 .05)。除C18∶2的含量显著高于对照组外,其他多不饱和脂肪酸含量在两组之间没有差异。本试验结果表明低镁日粮实质性地提高肉仔鸡腿肌中ROS的产量,低镁日粮降低腿肌中镁的浓度,诱导了线粒体呼吸链酶活性升高,从而提高了ROS的产量。