科尔沁沙地盐生植物群落复合体中主要植物群落的盐分生态

本文探讨了科尔沁沙地土壤盐分对该区盐生植物群落复合体的形成、种类组成、水平分布格局和物种多样性的影响,阐明了在不同土壤盐分条件下同种植物体内K、Na、Ca、Mg总量的恒定性和Na含量的变化规律。根据植物体内Na含量和K、Na、Ca、Mg的组成比例,提出了植物对盐碱地的适应类型及其划分方法,并以此法将本区草甸植物归为4种类型:Na>K>Ca>Mg型;K>Na>Ca、Mg型;K>Na、Ca、Mg型和K>Ca、Mg>Na型。     

Population management and bone structural effects in composition and radio-opacity of Iberian red deer (<Emphasis Type="Italic">Cervus elaphus hispanicus</Emphasis>) antlers

Antlers are costly bone structures whose size and external characteristics are influenced by nutrition, climatic variability, and other factors. In this study, we examined the effects of a well-managed captive population vs unmanaged free-ranging herds (greatly differing in food availability and energetic and immunological expenditures) on antler structural characteristics of Iberian red deer. We assessed the effect of management and sample position in the antler on cortical bone depth, bone mineral and protein content, and radiographic bone opacity. Cortical bone depth and mineral percent was greater in captive animals on greater food availability and lower energetic and immunological expenditures. After removing the inverse relationship with mineral content in the model, protein percent was also higher in antlers from captive than in those from free-ranging deer. Management system also influenced radio-opacity indirectly as interaction with other factors and cortical bone depth effects. Structural properties also differed between antler points that are very close in the antler and seem to differ only in the role they play. In conclusion, captive management can affect antler structure and composition, possibly as a result of different availability of food and immunological costs.     

石蒜鳞茎中氨基酸和矿质元素的含量分析

石蒜(Lycoris radiata Herb.)是一种传统的中药.分别利用HP高效液相色谱仪(LC1100)和原子吸收分光光度计(TAS-986),测定石蒜鳞茎中17种氨基酸和7种矿质元素的含量;在测定的17种氨基酸中7种未检测到;除Zn以外,石蒜鳞茎中K、Ca、Mg、Fe、Mn、Cu都相对较低.     

磁场对螺旋藻营养成分的影响及机理分析

对磁场作用下钝顶螺旋藻中蛋白质、氨基酸以及矿物质含量的变化进行研究,同时从水溶液性质改变和离子结合的角度对电磁场效应的机理进行了分析,研究发现：B＝0．25T的电磁场处理虽然对蛋白质和氨基酸总含量影响不大,却使必需氨基酸总含量明显提高;此外还可显著增加螺旋藻中矿物质,尤其是微量元素的含量。电磁场的生物效应可能来源于磁化水性质和离子吸收过程的改变,磁处理培养是进一步提高螺旋藻营养价值的一种较有效手段。     

Bio-available amino acids and mineral nitrogen forms in soil of moderately mown and abandoned mountain meadows

Summary. The abandonment of traditional mowing methods of mountain meadows in the Czech Republic at the end of the last century has resulted in secondary re-colonization of these areas. Altered accumulation of plant biomass resulted in a deceleration of N turnover. A mountain meadow may be regarded as a N-limited ecosystem in which plant nutrition is dependent on direct uptake of soil amino acids. The composition and distribution of ammonium ions, nitrate ions and the 16 bio-available proteinaceuous amino acids were investigated in the top 7 cm of the Ah horizon of a Gleyic Luvisol in a long-term moderately mown meadow and an eleven year old, abandoned or uncut meadow. Ammonium N has a dominant role in both ecosystems. The moderately mown meadow showed accelerated N-turnover and higher net ammonization. The plant community showed a dependence on this form. Plant utilization of nitrates and amino acids appeared to be negligible. The uncut or abandoned meadow showed net ammonization from May (start of the experiment) through August, after which plant N-uptake consisted only of amino acids due to microbial immobilization. The release of bio-available nitrogen from spring until the beginning of summer in the Ah horizon was too low to explain total plant N-uptake. Glutamic acid, arginine and aspartic acids had the highest concentrations of any of the amino acids analyzed. Authors’ address: Pavel Formánek, Department of Geology and Pedology, Mendel University of Agriculture and Forestry, Zemedelska 3, 613 00 Brno, Czech Republic     

长江口安氏白虾与日本沼虾营养成分比较

本文对长江口安氏白虾和日本沼虾的营养成分和营养品质进行了比较.结果表明:安氏白虾的水分和粗灰分含量显著低于日本沼虾 (P<0.05),而粗脂肪和粗蛋白含量显著高于日本沼虾(P<0.05);安氏白虾和日本沼虾的氨基酸组成基本一致,均含有17种氨基酸,必需氨基酸指数(EAAI)分别为52.77和52.67,其构成比例符合联合国粮农组织/世界卫生组织(FAO/WHO)的标准;安氏白虾脂肪酸中二十碳五烯酸(EPA)与二十二碳六烯酸(DHA)的总量明显高于日本沼虾,分别为28.32%±0.49%和14.89%±0.63%;矿物元素中常量和微量元素含量均较丰富,微量元素之间的比例较合理,其中,安氏白虾的常量元素含量较高,而日本沼虾的微量元素含量较高,而日本沼虾的微量元素含量较高,从以上结果可见,安氏白虾和日本沼虾均含有较丰富的各种营养成分,但从EPA和DHA的含量来看,脂肪酸的营养价值安氏白虾高于日本沼虾;从Fe、Cu、Zn和Se的含量来看,微量元素营养价值日本沼虾高于安氏白虾.     

NeuN immunoreactivity in the brain of Xenopus laevis

Neuronal nuclear antigen (NeuN), discovered in mice brain cell nuclei by Mullen et al. (1992), is used as an excellent marker of post-mitotic neurons in vertebrates. In this study, the expression pattern of NeuN was examined in the Xenopus brain to explore phylogenetic differences in NeuN expression. Anti-NeuN antibody showed selective staining in mouse and Xenopus brain extracts, but the number and molecular weight of the bands differed in Western blotting analysis. In immunostaining, anti-NeuN antibody showed selective staining of neurons, but not glial cells, in the Xenopus brain. Most neurons, including olfactory bulb mitral cells and cerebellar Purkinjie cells, which show no immunoreactivity in birds/mammals, showed NeuN immunoreactivity in Xenopus. This study revealed that anti-NeuN antibody is a useful marker of post-mitotic neurons in amphibians, but it also stains neurons that show no reactivity in more derived animals.     

Magnesium deficiency in sugar beets alters sugar partitioning and phloem loading in young mature leaves

Magnesium deficiency has been reported to affect plant growth and biomass partitioning between root and shoot. The present work aims to identify how Mg deficiency alters carbon partitioning in sugar beet (Beta vulgaris L.) plants. Fresh biomass, Mg and sugar contents were followed in diverse organs over 20 days under Mg-sufficient and Mg-deficient conditions. At the end of the treatment, the aerial biomass, but not the root biomass, of Mg-deficient plants was lower compared to control plants. A clear inverse relationship between Mg and sugar contents in leaves was found. Mg deficiency promoted a marked increase in sucrose and starch accumulation in the uppermost expanded leaves, which also had the lowest content of Mg among all the leaves of the rosette. The oldest leaves maintained a higher Mg content. [¹⁴C]Sucrose labelling showed that sucrose export from the uppermost expanded leaves was inhibited. In contrast, sucrose export from the oldest leaves, which are close to, and export mainly to, the roots, was not restricted. In response to Mg deficiency, the BvSUT1 gene encoding a companion cell sucrose/H⁺ symporter was induced in the uppermost expanded leaves, but without further enhancement of sucrose loading into the phloem. The observed increase in BvSUT1 gene expression supports the idea that sucrose loading into the phloem is defective, resulting in its accumulation in the leaf.     

Guard cells undergo constitutive and pressure-driven membrane turnover

Summary. During stomatal movement, guard cells undergo large and reversible changes in cell volume and consequently surface area. These alterations in surface area require addition and removal of plasma membrane material. How this is achieved is largely unknown. Here we summarize recent studies of membrane turnover in guard cells using electrophysiology and fluorescent imaging techniques. The results implicate that membrane turnover in guard cells and most likely in plant cells in general is sensitive to changes in membrane tension. We suggest that this provides a mechanism for the adaptation of surface area of guard cells to osmotically driven changes in cell volume. In addition, guard cells also exhibit constitutive membrane turnover. Constitutive and pressure-driven membrane turnover were found to be associated with addition and removal of K⁺ channels. This implies that some of the exo- and endocytic vesicles carry K⁺ channels. Together the results demonstrate that exo- and endocytosis is an essential process in guard cell functioning. Correspondence and reprints: Institute of Botany, Darmstadt University of Technology, Schnittspahnstrasse 3, 64287 Darmstadt, Federal Republic of Germany.