PVA和PEG(6000)预处理对大豆胚轴生长、蛋白质合成和ATP含量的影响

在低温吸胀阶段,经PVA(聚乙烯醇)和PEG(聚乙二醇6000)预处理的大豆胚轴蛋白质合成和ATP含量均比对照高。在萌发阶段,胚轴生长增快,蛋白质合成明显加快,ATP迅速被消耗,而对照胚轴则相反。试验结果表明,预处理大豆种子萌发和生长与其蛋白质合成、ATP水平和消耗能力有密切关系。     

Plasma selenium levels in rheumatoid arthritis

The plasma selenium (Se) levels were determined in patients with rheumatoid arthritis (RA) and healthy controls. Plasma Se levels in 60 patients were found to be significantly lower than those in 60 normal, healthy controls (p<0.001). Similar significant differences were determined in sex-matched comparisons between patients and controls (p<0.001) but there was no significant difference in plasma Se levels in sex-matched comparisons in both groups (p>0.05). Our results suggest that Se is an important factor in RA.     

Cold acclimation and photoinhibition of photosynthesis in Scots pine

Cold acclimation of Scots pine did not affect the susceptibility of photosynthesis to photoinhibition. Cold acclimation did however cause a suppression of the rate of CO₂ uptake, and at given light and temperature conditions a larger fraction of the photosystem II reaction centres were closed in cold-acclimated than in nonacclimated pine. Therefore, when assayed at the level of photosystem II reaction centres, i.e. in relation to the degree of photosystem closure, cold acclimation caused a significant increase in resistance to photoinhibition; at given levels of photosystem II closure the resistance to photoinhibition was higher after cold acclimation. This was particularly evident in measurements at 20° C. The amounts and activities of the majority of analyzed active oxygen scavengers were higher after cold acclimation. We suggest that this increase in protective enzymes and compounds, particularly Superoxide dismutase, ascorbate peroxidase, glutathione reductase and ascorbate of the chloroplasts, enables Scots pine to avoid excessive photoinhibition of photosynthesis despite partial suppression of photosynthesis upon cold acclimation. An increased capacity for light-induced de-epoxidation of violaxanthin to zeaxanthin upon cold acclimation may also be of significance.Abbreviations APX ascorbate peroxidase - DHA dehydroascorbate - DHAR dehydroascorbate reductase - Fm maximal fluorescence when all reaction centres are closed - Fv/Fm maximum photochemical yield of PSII - GR glutathione reductase - GSH reduced glutathione - Je rate of photosynthetic electron transport - MDAR monodehydroascorbate reductase - q_N nonphotochemical quenching of fluorescence - q_P photochemical quenching of fluorescence - SOD superoxide dismutase This work was supported by the Swedish Natural Science Research Council and the National Natural Science Foundation of China.     

Heme geometry in the 10 K photoproduct from sperm whale carbonmonoxymyoglobin

We have measured the Soret band of the photoproduct obtained by complete photolysis of sperm whale carbonmonoxymyoglobin at 10 K. The experimental spectrum has been modeled with an analytical expression that takes into account the homogeneous bandwidth, the coupling of the electronic transition with both high and low frequency vibrational modes, and the effects of static conformational heterogeneity. The comparison with deoxymyoglobin at low temperature reveals three main differences. In the photoproduct, the Soret band is shifted to red. The band is less asymmetric, and an enhanced coupling to the heme vibrational mode at 674 cm⁻¹ is observed. These differences reflect incomplete relaxation of the active site after ligand dissociation. The smaller band asymmetry of the photoproduct can be explained by a smaller displacement of the iron atom from the mean porphyrin plane, in quantitative agreement with the X-ray structure analysis. The enhanced vibrational coupling is attributed to a subtle heme distortion from the planar geometry that is barely detectable in the X-ray structure.     

Simple models for trail-following behaviour; Trunk trails versus individual foragers

Social insects such as ants use trial-marking and trail-following to organize the behaviour and movement patterns of a large population. Since behaviour has to meet needs of the population in a changing environment, the type of trail networks formed must be adaptable. Both solitary foraging as well as mass migration along a system of trunk trails are behaviours essential for survival of the colony, and the population must be able to switch from one behaviour to the other, depending on conditions. Using a mathematical model for trail following we show that subtle changes in individual behaviour can give rise to dramatic differences in the behaviour of the population, including the ability to switch from solitary movement to organized group traffic. The model incorporates biological parameters associated with the organism, the trail-marker, and the population. Ordinary differential equations are formulated for the density of the trails and for the number of individuals following trails or exploring randomly. It is assumed that the followers reinforce trails by pheromone marking, and that individuals respond to the strength of the trails by becoming more efficient followers. The model is analyzed by qualitative phase-plane methods.     

Developments in tomographic methods for biological trace element research

Neutron-induced γ-ray emission tomography for quantitative determination of the concentration and distribution of elements in a selected plane through a biological specimen is briefly explained and applied by way of illustration to the analysis of gallstones. A system capable of carrying out studies of the binding site of⁷⁵Se in different matrices using time differential perturbed angular correlation spectroscopy is also briefly described. Developments in the detector technology of positron emission tomography have allowed small-diameter imaging devices to be built for in vivo preclinical evaluation of new tracers in small animals and are discussed in the context of a proposed experiment combining the techniques mentioned above.     

几种濒危植物及其近缘类群总DNA的提取与鉴定

用低ｐＨ 介质,高盐沉淀蛋白质方法成功地从银杉（Ｃａｔｈａｙａ ａｒｇｙｒｏｐｈｙｌｌａ Ｃｈｕｎ ｅｔＫｕａｎｇ）、矮牡丹（Ｐａｅｏｎｉａ ｓｕｆｆｒｕｔｉｃｏｓａ ｖａｒ． ｓｐｏｎｔａｎｅａ）、南川升麻（Ｃｉｍ ｉｃｉｆｕｇａ ｎａｎｃｈｕａｎｅｎｓｉｓＨｓｉａｏ）、裂叶沙参（Ａｄｅｎｏｐｈｏｒａ ｌｏｂｏｐｈｙｌｌａ）的同属种泡沙参（Ａ． ｐｏｔａｎｉｎｉｉ）等植物中提取和部分纯化了细胞总ＤＮＡ,并对其产率、质量和纯度作了鉴定。此方法的关键是用了一个低ｐＨ提取介质,它能有效防止组织破碎及沉淀大量材料时的电离化作用及酚化合物的进一步氧化。所得ＤＮＡ 不需经氯化铯梯度离心或柱层析,直接可用于限制性片断长度多态性（ＲＦＬＰ）及随机扩增的ＤＮＡ多态性（ＲＡＰＤ）等分子水平的遗传标记。为检测濒危植物的遗传多样性提供了一套迅速、简便和可靠的技术方案     

Soil boron and selenium removal by three plant species

High concentrations of boron (B) and selenium (Se) naturally found in the environment are detrimental to sustainable agriculture in the western USA. Greenhouse pot experiments were conducted to study B and Se uptake in three different plant species; Brassica juncea (L.) Czern (wild brown mustard), Festuca arundinacea Schreb. L. (tall fescue), and Brassica napus (canola) were grown in soil containing naturally occurring concentrations of 3.00 mg extractable B kg^–1 and 1.17 mg total Se kg^–1 soil. During the growing season, four intermediate harvests were performed on wild mustard and tall fescue. Final harvest I consisted of harvesting wild mustard, canola, and clipping tall fescue. Final harvest II consisted of harvesting wild mustard, which had been planted in soil in which wild mustard was previously grown, and harvesting previously clipped tall fescue. The greatest total amount of above ground biomass and below surface biomass was produced by tall fescue. Plants were separated into shoots and roots, weighted, and plant tissues were analyzed for total B and Se. The highest concentrations of tissue B were recovered in shoots of wild mustard and canola at final harvest I, while roots from tall fescue contained the highest concentrations of B irrespective of the harvest. Tissue Se concentrations were similar in all plants species. Soils were analyzed for residual B and Se. Extractable soil B concentrations at harvest times were lowered no less than 32% and total Se no less than 24% for all three species. The planting of wild mustard, canola, or tall fescue can reduce water-extractable B and total Se in the soil.     

Effect of selenium and protein deficiency on selenium and glutathione peroxidase in rats

Twenty-four weanling male Wistar rats were divided into four groups fed diets containing adequate or deficient levels of selenium (0.5 ppm [+ Se] or <0.02 ppm [−Se] and protein (15% [+Pro] or 5% [−Pro]), but adequate levels of all other nutrients for 4 wk to determine the effects of Se deficiency and protein deficiency on tissue Se and glutathione peroxidase (GSHPx) activity in rats. Plasma, heart, liver, and kidney Se and GSHPx were significantly lower in Se-deficient groups in relation to Se-sufficient groups. In Se-deficient groups, Se and GSHPx were significantly higher in −Se−Pro rats in heart, liver, and kidney. Data analysis showed that there were significant interaction effects between dietary Se and protein on Se and GSHPx of rats. It is assumed that under the condition of Se deficiency. a low level of protein may decrease Se and GSHPx utilization, increase GSHPx synthesis, and result in Se redistribution. This could account for high levels of Se and GSHPx in the −Se−Pro rats compared to −Se+Pro rats.     

Low temperature compartment formation in feline immunodeficiency virus-infected and uninfected feline kidney cells

Summary This study was to determine if feline immunodeficiency virus (FIV)-infected and uninfected Crandall feline kidney (CRFK) cells exhibited a low temperature (16°C) block in membrane trafficking between transitional endoplasmic reticulum and Golgi apparatus represented by intermediate compartment formation. Cells were cultured at different temperatures and membrane changes involving the Golgi apparatus and Golgi apparatus-associated membrane structures were monitored by electron microscopy and quantitated. With 30 min of incubation, membranes of the Golgi apparatus stack increased in amount at temperatures of 16°C and below compared to temperatures above 18°C. The increase was greatest along the major polarity axis as evidenced by an increased stack height. Neither the number of cisternae per stack nor the average stack diameter (width) was affected by temperature. The response was maximal between 15 and 30 min of low temperature treatment of the cells. Results with cells infected and uninfected with feline immunodeficiency virus were similar. The increase in stack height was due primarily to an increase of membranes at the cis face (cis Golgi apparatus network). At 18°C, membranes of the trans Golgi apparatus network accumulated suggesting that import from the cis Golgi network could proceed at this temperature, whereas exit from the trans Golgi network was still at least partially blocked. Also increased at 16°C and below were numbers of transition vesicles in the space between the Golgi apparatus and the transitional endoplasmic reticulum associated with the cis Golgi apparatus face. The results suggested interruption of the orderly flux of membranes into the Golgi apparatus at 16°C and below. Moreover, the block appeared to be reversible. Upon transfer from 16°C to 37°C, there was a time-dependent decrease in the accumulations of cis compartment membrane accompanied by a corresponding equivalent increase in the membranes of the trans Golgi apparatus compartment.