Adaptive protein evolution at the Adh locus in Drosophila

Proteins often differ in amino-acid sequence across species. This difference has evolved by the accumulation of neutral mutations by random drift, the fixation of adaptive mutations by selection, or a mixture of the two. Here we propose a simple statistical test of the neutral protein evolution hypothesis based on a comparison of the number of amino-acid replacement substitutions to synonymous substitutions in the coding region of a locus. If the observed substitutions are neutral, the ratio of replacement to synonymous fixed differences between species should be the same as the ratio of replacement to synonymous polymorphisms within species. DNA sequence data on the Adh locus (encoding alcohol dehydrogenase, EC 1.1.1.1) in three species in the Drosophila melanogaster species subgroup do not fit this expectation; instead, there are more fixed replacement differences between species than expected. We suggest that these excess replacement substitutions result from adaptive fixation of selectively advantageous mutations.     

Spontaneous forward mutation versus reversion frequencies for maize Adh1 in pollen

Reliable quantitative data on spontaneous, specific gene mutation frequencies in higher plants and animals are few. Detergents include low natural frequencies and difficulty in obtaining in excess of 10(6) scorable organisms or gametophytes. The alcohol dehydrogenase-1 gene (Adh1 gene; ADH enzyme EC 1.1.1.1.), as expressed in pollen grains, is among the exceptionably suitable; much is known about the maize ADHs, Adh1 function is totally dispensible in an aerobic environment and maize pollen is a trinucleate gametophyte which expresses much of its haploid genome, including Adh1. In particular, there have been two recent methodological advances. First, I am able to cytochemically stain pollen, before or after in vitro germination, for the presence of above 5% normal ADH activity. And second, ADH1- pollen grains survive allyl alcohol (C=C-C-OH) vapour concentrations which kill ADH1+ grains; this selection scheme was developed for yeast by Megnet. My genetic resolution is approximately one mutant (Adh1+-->ADH-) per 10(7) chemically selected, viable gametophytes, and one (phenotypic) revertant (Adh1--->ADH+) per 10(8) unselected gatetophytes. In this note, I compare spontaneous forward mutant frequency with previously published revertant frequencies for one naturally occurring and six ethyl methanesulphonate-induced Adhl-deficient (Adh1-) alleles.     

利用乙醇脱氢酶基因证据揭示稻属CCDD异源四倍体中染色体组的起源

对稻属异源四倍体中染色体组C和D以及稻属现存的所有二倍体染色体组A、B、C、E、F的乙醇脱氢酶基因（Adh1）片段分别进行PCR扩增、克隆和序列测定，并以G染色体组序列作为外类群，采用PAUP运算软件中的简约性方法对所测定的序列进行了系统发育分析．结果表明：（1）3个CCDD四倍体是同一次杂交事件的产物；（2）四倍体中的C染色体组和亚洲二倍体中的C染色体组表现出更近的系统发育关系；（3）D染色体组和E染色体组表现出较近的亲缘关系，二者可能有共同的祖先．     

Rho激酶抑制剂诱导PC12和PC12Adh细胞突起生长的差异比较

 PC12细胞是研究神经分化最常用的细胞之一.在rho激酶(ROCK)抑制剂的作用下,PC12细胞能够长出神经样突起.最近,美国菌种保存中心(ATCC)同时提供PC12细胞和PC12 Adh细胞.研究的主要目的是观察ROCK抑制剂诱导这2种细胞长突起是否存在差异.PC12细胞和PC12Adh细胞按照ATCC方法进行培养,用神经生长因子(NGF,1000ng/mL)或ROCK抑制剂(33μmol/L Y27632,33μmol/L法舒地尔)处理细胞1~4d.结果发现NGF能够诱导这2种细胞生长突起,而ROCK抑制剂只诱导PC12Adh细胞长突起,对PC12细胞不明显.因此,ROCK抑制剂诱导这2种细胞突起生长存在明显差异,PC12Adh细胞更适合用于ROCK抑制剂的神经诱导分化实验.     

我国东部沿海地区黑腹果蝇醇脱氢酶座位的多态性和渐变群研究

应用标准琼脂糖平板电泳技术,对我国东部沿海地区9个地方黑腹果蝇自然群体的醇脱氢酶座位的等位基因频率进行了测定。结果发现,在全部的群体中,该座位皆是多态的,且基因频率表现出纬度渐变群分布。还对这种多态性和渐变群形成的可能机理进行了讨论。     

小麦族拟鹅观草属Adh基因PCR扩增条件优化

拟开发适用于小麦族拟鹅观草属植物系统发育研究的低拷贝核基因,即Adh基因.通过探索模板DNA、Mg2+、dNTP和引物的浓度,以及退火温度等因素对Adh基因扩增的影响,建立最优PCR体系.在25 μL最优 PCR 反应体系中包括如下成分:2.5 μL 10 × PCR 缓冲液,0.6 μL模板DNA(约15 ng),1.5 mmol Mg2+,0.15 mmol dNTP 混合液,0.12 μmol 正向和反向引物,0.75 U Ex Taq 酶;退火温度为55℃.优化后的体系得到清晰目的条带,可用于后续研究.     

黑腹果蝇杂合体中ADH杂二聚体的形成

研究了醇脱氢酶基因 (Adh)诱变体与正常基因相互作用后的部分显性现象 .所有 8个由乙基亚硝基尿素 (ENU)和 1个 X-射线诱变体仅为单碱基置换体 ,其余 3个 X-射线诱变体则为 9～2 1个碱基的缺失体 .这 1 2个诱变体 (除 1个外 )都能产生可测的突变肽 ,其中 7个不能与正常肽形成二聚体 ,杂合体酶活性约为正常纯合体的 1 /2 ;另 4个形成二聚体 .形成二聚体突变基因产物中所有氨基酸突变均发生在肽链 1 82～ 1 94氨基酸区域 ,可见该区域对于二聚化不是必需的 ,该序列可能是重要的催化表面功能区     

Low host specificity of herbivorous insects in a tropical forest

Two decades of research have not established whether tropical insect herbivores are dominated by specialists or generalists. This impedes our understanding of species coexistence in diverse rainforest communities. Host specificity and species richness of tropical insects are also key parameters in mapping global patterns of biodiversity. Here we analyse data for over 900 herbivorous species feeding on 51 plant species in New Guinea and show that most herbivorous species feed on several closely related plant species. Because species-rich genera are dominant in tropical floras, monophagous herbivores are probably rare in tropical forests. Furthermore, even between phylogenetically distant hosts, herbivore communities typically shared a third of their species. These results do not support the classical view that the coexistence of herbivorous species in the tropics is a consequence of finely divided plant resources; non-equilibrium models of tropical diversity should instead be considered. Low host specificity of tropical herbivores reduces global estimates of arthropod diversity from 31 million (ref. 1) to 4 6 million species. This finding agrees with estimates based on taxonomic collections, reconciling an order of magnitude discrepancy between extrapolations of global diversity based on ecological samples of tropical communities with those based on sampling regional faunas.     

关帝山林区森林植被生物多样性研究

根据物种多样性测度公式,把19块标地按乔木层、灌木层、草本层3个层次,分别计算各标地的物种多样性指数。根据计算结果,指出：各森林群落物种丰富度均表现为草本层〉灌木层〉乔木层的特点。多样性指数总体趋势因森林群落不同而有所差异：落叶松森林群落表现为草本层〉灌木层〉乔木层;油松、桦树、杨树森林群落表现为灌木层〉草本层〉乔木层;各森林群落中草本层与灌木层多样性指数均比较接近。并根据研究结果对关帝林区今后的森林经营方向提出了几点可行性建议。     

基于Species机制的多目标遗传算法

多目标优化算法设计正在成为当前进化算法领域的一个研究热点.考虑将最初用于多峰优化的Species机制引入到多目标遗传算法中,通过借鉴现有多目标算法的相关思想,设计并提出了一种新的Species方法,包括基于Pareto最优性和拥挤度思想的Species种子确定策略及适应性的Species构造策略.一组标准多目标测试函数的仿真实验结果表明,提出的基于Species机制的多目标遗传算法表现出比经典的非支配排序遗传算法Ⅱ(NSGA Ⅱ)更好的性能.     

酯酶同工酶在冰草属分类中的应用

本文运用聚丙烯酰胺凝胶电泳分析了冰草属5个种的酯酶同工酶。结果表明:属内种间具有明显的酶谱差异,每个种都有其特征酶谱,从而支持了蒙古冰草和西伯利亚冰草为两个独立种的观点,并用聚类和排序的方法对冰草属的5个种酶谱的相似程度进行了分析研究,结合染色体的数目,作者认为在冰草属中二倍体类群为原始类群,然后逐渐向四倍体和六倍体方向演化,演化是沿着两条不同的路线进行的,一条以蒙古冰草为基础,一条以二倍体的冰草为基础。     

青藏高原高寒草地常见植物叶属性对氮、磷添加的响应

基于海北站氮磷添加实验平台,研究青藏高原高寒草地常见植物叶片干物质含量(LDMC)、比叶面积(SLA)和叶片碳、氮、磷含量(LC,LN,LP)属性对N添加、P添加和NP同时添加的响应。从10个物种总体来看,N添加使LN显著增加9.4%。P添加使LP显著增加81.8%。N添加和P添加对LDMC和SLA有显著的交互作用。在无N添加条件下,P添加使LDMC减小2.3%,SLA增加3.5%;在N添加条件下,P添加使LDMC减小10.1%,SLA增加15.3%。N添加和P添加对基于叶经济谱的物种排序无显著影响,而NP同时添加显著改变了基于叶经济谱的物种排序。结果表明,通过提高SLA和叶片NP含量,使高寒草地植物对光、土壤可利用性N和P的获取与利用能力增强。NP同时添加可以显著改变叶属性的种间变异,进而导致青藏高原高寒草地常见植物在叶经济谱上形成新的分布格局。因此,在利用叶属性预测群落结构和生态系统功能对NP同时添加的响应时,应该考虑物种的特异性响应。     

退耕还林树种选择的探讨

介绍了退耕还林的重要意义，指出退耕还林树种的选择要立足于乡土树种和水土保持树种，坚持乔灌草相结合的原则，提出了适宜太原市选用的树种及配置模式。     

On cyclic oscillation in granular gas

In a Maxwell‘s demon experiment on a dilute granular gas made up of two species of particles placed in two closely connected containers, a cyclic oscillation similar to the chemical oscillations is recognized that the two species of particles cluster alternately in the two containers. Then the nonlinear behavior is qualitatively explained based on a flux model.     

湖北省五峰后河国家级自然保护区蛾类昆虫调查初报

报道了后河国家级自然保护区蛾类昆虫的初步调查结果．已鉴定出17科152种．其中天蛾科3种．木蠹蛾科1种,刺蛾科2种,毒蛾科7种．斑蛾科1种．虎蛾科3种．舟蛾科3种．鹿蛾科2种．钩蛾科6种,枯叶蛾科3种．灯蛾科18种．蚕蛾科1种,波纹蛾科2种,夜蛾科40种,尺蛾科41种,螟蛾科18种,燕蛾科1种．56种为湖北省新记录种．根据调查结果．对该自然保护区内蛾类昆虫的区系结构进行了分析,该地区蛾类昆虫以东洋种为主．     

关于山西省发展灌木林的几点建议

灌木是乔木树种不能代替的造林树种。为更好地发挥灌木林在山西省森林生态建设中的作用,在阐述灌木林生态价值、经济价值的基础上,提出了山西省发展灌木林的几点建议。     

Coexistence and relative abundance in forest trees

Contemporary acceleration of biodiversity loss makes increasingly urgent the need to understand the controls of species coexistence. Tree diversity in particular plays a pivotal role in determining terrestrial biodiversity, through maintaining diversity of its dependent species and with them, their predators and parasites. Most theories of coexistence based on the principle of limiting similarity suggest that coexistence of competing species is inherently unstable; coexistence of competitors must be maintained by external forces such as disturbance, immigration or 'patchiness' of resources in space and time. In contrast, storage theory postulates stable coexistence of competing species through temporal alternation of conditions favouring recruitment of one species over the other. Here we use storage theory to develop explicit predictions for relative differences between competitors that allow us to discriminate between coexistence models. Data on tree species from a primary forest on the Mexican Pacific coast support a general dynamic of storage processes determining coexistence of similar tree species in this community, and allow us to reject all other theories of coexistence.     

后河国家级自然保护区蝶类名录及区系的初步研究

报道了后河国家级自然保护区蝶类名录．该地区蝴蝶共有106种,隶属9科55属．凤蝶科3属8种,环蝶科1属1种,喙蝶科1属1种,粉蝶科7属13种,眼蝶科6属21种,蛱蝶科16属32种,灰蝶科7属10种,弄蝶科13属19种,蚬蝶科1属1种．其中,有20种为湖北省新记录．根据调查结果,对蝶类的区系结构进行了分析,该地区蝴蝶以东洋种为主。     

活性氧与植物防卫反应

目的：总结分析活性氧在植物防卫反应中的作用。方法：根据近10年内公开发表的20篇中英文文献对活性氧的种类、特性，以及在植物抗病过程中所起的作用进行较全面的总结。结果：介绍活性氧的种类、性质，着重讨论了活性氧的产生和消除机理；并对当前该领域今后的研究方向进行了展望。结论：活性氧在植物防卫反应过程中起双重作用，即高浓度时对植物起伤害作用，低浓度时起信号传递作用诱导植物抗性基因和防卫基因的表达。