稀土元素对土栖动物群落结构的影响及对蛴螬的生态毒性

采用土施法和OECD推荐的滤纸接触法研究了稀土(ReCl₃·6H₂O)对豆田土栖动物群落结构的影响以及稀土对蛴螬的生态毒性.结果表明,对照与各处理之间动物种类数、主要动物种群数量、多样性指数差异均不显著;急性和慢性毒性试验表明,对照与各处理间的死亡率差异不显著.在稀土有效施用范围内,稀土对蛴螬的生态毒性很小,不会明显改变蛴螬种群结构.     

湖北珍稀危植物保存现状及对今后开展研究的建议

本文在《国家重点保护植物名录》的基础上,提出了湖北地区有关保护植物的种类和分布,并以植物园和自然保护区为重点,调查了湖北珍稀危植物的保存现状和存在问题,提出了今后开展研究工作的建议。     

Functional ecology of rare and common epigeic lichens in alvar grasslands

The autecology of rare species can be derived using similarities among functional traits and environmental conditions observed for common species, i.e. we employed the ‘matching analogy approach’ with the analytical scheme ‘common species → driver → trait → driver → rare species’. We addressed the driver–trait relationship for common epigeic lichens of thin-soil calcareous grasslands, which are endangered by cessation of traditional land use. Common lichens were suppressed by encroaching herbs and shrubs, and were supported by ground disturbances. The lichens of open low-productivity alvars are predominantly calciphilous, epibryic, crustose-squamulose, sexually reproducing and contain UV-protective pigments. Lichens of encroached alvars are soil-type generalists, fruticose, reproduce vegetatively and contain herbivore-deterring compounds. Rare lichens resemble the species of open low-productivity alvars, except their more limited niche space, i.e. they are restricted to arctic-alpine habitats. The conservation practices on alvars should support the formation of crust-forming communities by suppressing the growth of shrubs and herbs, and by promoting recurrent small-scale soil disturbances.     

天然植物铁芒萁体内稀土元素的分布及其叶绿素镧的结构表征

Ｌａ、Ｃｅ、Ｎｄ、Ｔｂ、Ｄｙ 等稀土元素在铁芒萁（ Ｄｉｃｒａｎｏｐｔｅｒｉｓｄｉｃｈｏｔｏｍａ Ｕｎｄｅｒｗ） 体内的分布规律是叶＞ 根＞ 茎, 而Ｐｒ、Ｓｍ 、Ｅｕ、Ｇｄ、Ｈｏ 和Ｙ等稀土元素在铁芒萁体内的分布规律是根＞ 叶＞ 茎。轻、中稀土元素容易被吸收和积累,并表现出选择性吸收。铁芒萁叶绿素中结合有较多的稀土元素,且主要是轻稀土元素,其中Ｌａ 含量最高,占５６ ．０８％ ,其次是Ｃｅ,占１９ ．４０％ 。利用荧光Ｘ射线吸收精细结构（ＦＸＡＦＳ）光谱表征出,在铁芒萁体内Ｌａ 是与两个卟啉环配位的,推断叶绿素镧为双层结构     

井冈山稀有濒危植物区系探讨

本文分析了井冈山稀有濒危植物39个种的地理分布和35个属的分布区类型及其区系特征,并认为:①稀有濒危植物的古老成份,反映了井冈山自侏罗纪以来地史与气候比较稳定,植物区系区的,演化具有一定的连续性;泥盆纪至侏罗纪可能是井冈山植物区系发生的重要时期。②稀有濒危植物的区系特点是,现代植物区系的种、属成份与华南联系紧密,与华东次之;区系的起源与古热带区系有重要关系。③井冈山特有种的形成可能是生态分异成因多于历史成因,并且温带性物种在井冈山的生态分异比热带性物种更趋强烈。     

影响泽泻蕨孢子培养的环境因素研究

为了解环境因子对泽泻蕨(Hemionitis arifolia Moore.)培养的影响, 采用孢子培养技术研究温度、光照、pH、密度等对其有性繁殖的影响。结果表明, 泽泻蕨孢子为需光萌发, 孢子萌发和配子体发育的最适环境条件为:温度25℃, 日光灯光照强度为150 μmol m^-2s^-1, pH 为6.5, 播种密度为5~8 grains cm^-2, 幼苗管护简单, 成活率较高, 未见病虫害。这为保护和开发我国泽泻蕨资源提供了理论依据和技术支持。     

Protective Effect of Rare Earth Against Oxidative Stress Under Ultraviolet-B Radiation

The effects of lanthanum (III) (La(III)) in protecting soybean leaves against oxidative stress induced by ultraviolet-B (UV-B) radiation were investigated. The increase in contents of hydrogen peroxide (H₂O₂) and superoxide () due to UV-B radiation suggested oxidative stress. The increase in the content of malondialdehyde (MDA) and the decrease in the index of unsaturated fatty acid (IUFA) indicated oxidative damage on cell membrane induced by UV-B radiation. La(III) partially reversed UV-B-radiation-induced damage of plant growth. The reduction in the contents of H₂O₂, , and MDA and increase in the content of IUFA, compared with UV-B treatment, also indicated that La(III) alleviated the oxidative damage induced by UV-B radiation. The increase in the activities of superoxide dismutase and peroxidase and the contents of ascorbate, carotinoids, and flavonoids were observed in soybean leaves with La(III) + UV-B treatment, compared with UV-B treatment. Our data suggested that La(III) could protect soybean plants from UV-B-radiation-induced oxidative stress by reacting with reactive oxygen species directly or by improving the defense system of plants.     

Genetic,structural, and functional analysis of pathogenic variations causing methylmalonyl-CoA epimerase deficiency

Human methylmalonyl-CoA epimerase (MCEE) catalyzes the interconversion of d-methylmalonyl-CoA and l-methylmalonyl-CoA in propionate catabolism. Autosomal recessive pathogenic variations in MCEE reportedly cause methylmalonic aciduria (MMAuria) in eleven patients. We investigated a cohort of 150 individuals suffering from MMAuria of unknown origin, identifying ten new patients with pathogenic variations in MCEE. Nine patients were homozygous for the known nonsense variation p.Arg47* (c.139C > T), and one for the novel missense variation p.Ile53Arg (c.158T > G). To understand better the molecular basis of MCEE deficiency, we mapped p.Ile53Arg, and two previously described pathogenic variations p.Lys60Gln and p.Arg143Cys, onto our 1.8 Å structure of wild-type (wt) human MCEE. This revealed potential dimeric assembly disruption by p.Ile53Arg, but no clear defects from p.Lys60Gln or p.Arg143Cys. We solved the structure of MCEE-Arg143Cys to 1.9 Å and found significant disruption of two important loop structures, potentially impacting surface features as well as the active-site pocket. Functional analysis of MCEE-Ile53Arg expressed in a bacterial recombinant system as well as patient-derived fibroblasts revealed nearly undetectable soluble protein levels, defective globular protein behavior, and using a newly developed assay, lack of enzymatic activity - consistent with misfolded protein. By contrast, soluble protein levels, unfolding characteristics and activity of MCEE-Lys60Gln were comparable to wt, leaving unclear how this variation may cause disease. MCEE-Arg143Cys was detectable at comparable levels to wt MCEE, but had slightly altered unfolding kinetics and greatly reduced activity. These studies reveal ten new patients with MCEE deficiency and rationalize misfolding and loss of activity as molecular defects in MCEE-type MMAuria.     

A Matched Pairs Selection method for the analysis of abundance data with many zero values

Abstract. A simple method is described to analyze plant species abundance data with many zero values. To investigate the impact of an environmental factor on rare species, two subsets of sampling plots are selected pair-wise from the original data set. They differ in the value of the particular factor under consideration but are similar with respect to all other factors. Subsequently, the botanical composition of these subsets, including rare species, is compared using non-parametric tests. An example is given from a study on ditch bank vegetation. Some limitations, and a method for taking into account the dependence of the statistical tests, are discussed.     

Fusion of human erythrocytes induced by uranyl acetate and rare earth metals

Incubation of human erythrocytes with either uranyl ions (UO₂²⁺) or rare earth metals (La³⁺, Nd³⁺, Sm³⁺, Eu³⁺, Tb³⁺, Dy³⁺ and Yb³⁺) at 37°C for 30–45 min resulted in the fusion of erythrocytes. Redistribution of membrane-associated particles was observed using colloidal-iron charge labelling and freeze-fracture electron microscopy. The fusion of erythrocytes induced by these agents, unlike Ca²⁺, did not exhibit the absolute requirement for phosphate. Moreover, agglutination and fusion by these agents was observed in neuraminidase-treated erythrocytes in contrast to Ca²⁺- and phosphate-induced fusion. Inhibitors of intrinsic transglutaminase activity partially inhibited (35–45%) the fusion induced by UO₂²⁺ suggesting that cross-linking of membrane proteins results in protein-free areas of lipid where fusion may be initiated.