半散放猎豹毛发微量元素含量比较

许多微量元素与动物生理生化机能有着密切的联系,对机体的生长发育和维持健康起着重要作用.近年来,微量元素研究日渐得到重视,如Cu、 Zn、 Mn、 Se、 Pb等微量元素参与酶、激素和维生素代谢,影响动物生殖功能(Suchocki et al., 2003).     

Monovalent cations affect the free solution mobility of DNA by perturbing the hydrogen-bonded structure of water

The free solution mobilities of single- and double-stranded DNA molecules of various molecular weights have been measured by capillary electrophoresis in solutions of constant ionic strength containing a common anion and fifteen different monovalent cations. In solutions with the same ionic composition, the mobilities of different DNA molecules can vary by up to 20%, depending on molecular weight, the number of strands, and the presence or absence of A-tracts, runs of four or more contiguous adenine residues. Importantly, the mobilities observed for the same DNA sample can vary by up to 40% in solutions containing different cations. The mobility differences observed for the same DNA in solutions containing different cations cannot be rationalized by differences in the anhydrous radii or intrinsic conductivities of the various cations, or by the sequence-dependent binding of certain cations to A-tracts. Instead, the observed mobilities are linearly correlated with the average number of water-water hydrogen bonds that are present in solutions containing different cations. The mobilities are also correlated with the viscosity B coefficients of the various cations and with the rotational correlation times frictional coefficients observed for water molecules in solutions containing different cations. Hence, monovalent cations modify the free solution mobility of DNA primarily by perturbing the hydrogen-bonded structure of water, affecting the friction experienced by the migrating DNA molecules during electrophoresis.     

琼脂糖凝胶的合适浓度对于回收酶切后质粒载体的重要性

目的：探讨琼脂糖凝胶的不同浓度对回收不同大小的酶切后质粒载体纯度的影响。方法：将2种质粒载体酶切,并经不同浓度的琼脂糖凝胶电泳分析,通过比较酶切前和酶切后载体的相对位置,研究胶浓度对回收酶切后载体纯度的影响。结果：不同浓度的琼脂糖凝胶中,酶切前和酶切后载体的相对位置会发生变化,对能否成功回收到纯度高的酶切后DNA片段有重要影响;质粒大小不同,胶浓度的影响也不同。结论：合适的胶浓度对于回收酶切后质粒载体具有重要意义,应选择合适的胶浓度回收酶切后质粒载体。     

天然赤松个体生物量的研究

对延边地区不同密度天然赤松林中不同生长势的赤松个体地上部生物量进行了研究。结果表明,不同生长势赤松生物量变化受密度影响的顺序为：优势木〈平均木〈被压木;各器官生物量分配比例受密度影响的顺序为：干〉枝〉叶〉皮。不同生长势赤松的生物量垂直分布虽然各具特点,但都表现为：树干和树皮生物量主要分布在６ｍ树高范围内,树枝则集中在６～１０ｍ范围,针叶在上、中、下３层林冠中均分,上层林冠的枝叶量受密度影响最小。     

Dominant species of dicot-weeds and weed biodiversity in spring barley in Latvia

The composition of weed species in spring barley and weed biodiversity was evaluated in experiments in different growing seasons and with different previous crops. The aim of the experiments was to evaluate the composition of weed species in spring barley during a four year period in weather conditions of different growing seasons and with different previous crop as well as to assess the biodiversity in the experiments where the different groups of herbicides were applied. Over years and previous crops, the dicotyledonous weed community was dominated by Chenopodium album, followed by Viola arvensis. The herbicides from different groups had significant influences on the biodiversity of weeds.     

Uptake of Encephalitozoon spp. and Vittaforma corneae (Microsporidia) by different cells

Microsporidia are obligate intracellular parasites infecting a broad range of vertebrates and invertebrates. Various microsporidian species induce different clinical pictures in humans. The reason for this is not clear. It has been speculated that the different microsporidian species are transmitted by various routes, thus causing infections in different organs. Another possibility is that the diverse microsporidia have different tropisms to organ-specific cells, thus causing various diseases. In this study, we investigated the uptake of microsporidian spores by different cells with an immunofluorescence staining technique to investigate whether there is a difference between microsporidian species as well as between different cells. Using this technique, we were able to distinguish between intra- and extracellular microsporidian spores. All examined cell lines were able to internalize microsporidian spores, but the extent of internalization differed significantly between the cells. Although the results showed some patterns that correlate with the distribution of the parasites in humans, the different clinical pictures cannot be sufficiently explained by this phenomenon, so it seems more likely that the various clinical manifestations caused by the different microsporidian species are a consequence of different infection routes rather than of different affinities of the microsporidian species to different cells.     

Dna-end binding activity of Ku in synchronized cells

Three different types of cells were synchronized by various methods and DNA-end binding (DEB) activities of Ku were compared with asynchronous controls. In CHO K1 cells synchronized in G1 phase by serum starvation and in S phase by serum refeeding, DEB activity was reduced in S cells but remained unchanged in G1 cells. However, the same type of cells synchronized in G1/S phase by double thymidine block and in S phase by releasing the blockage, have the same DEB activity as asynchronous controls. A similar result was found in RKO and HeLa cells synchronized by the latter method. Arresting cells in mitosis with nocodazole also generated different cell cycle effects. Ku activity was reduced in CHO K1 and RKO cells, but not in HeLa cells after treatment with nocodazole. In phase-enriched cells separated by centrifugal elutriation, DEB activities were similar at different stages of the cell cycle in all three types of cells. Thus, different synchronization procedures can give very different values of Ku activity in a cell type-dependent manner. Results from elutriated cells are consistent, and suggest DEB activity of Ku does not change with the cell cycle.     

黄土丘陵区生物结皮对土壤可蚀性的影响

在采样分析生物结皮对土壤理化属性影响的基础上,采用EPIC模型估算与模拟降雨试验相结合的方法,研究了黄土丘陵区不同生物量、不同土壤质地和不同季节的生物结皮对土壤可蚀性(K值)的影响.结果表明： 生物结皮显著降低了土壤可蚀性,生物结皮层土壤可蚀性较下层土壤降低17%;土壤可蚀性随生物结皮生物量的增加呈降低趋势,藓结皮土壤可蚀性K值较藻结皮土壤降低21%;生物结皮土壤可蚀性在不同季节因其生物活性不同而存在差异,雨季中显著高于雨季前和雨季末;不同质地土壤上生物结皮对可蚀性的影响不同,可蚀性K值为砂壤>粉壤>砂土;模拟降雨条件下测定表明,生物结皮的发育使土壤可蚀性较对照（下层5~10 cm土壤）降低约90%.
     

黄土丘陵区生物结皮对土壤可蚀性的影响

在采样分析生物结皮对土壤理化属性影响的基础上,采用EPIC模型估算与模拟降雨试验相结合的方法,研究了黄土丘陵区不同生物量、不同土壤质地和不同季节的生物结皮对土壤可蚀性(K值)的影响.结果表明： 生物结皮显著降低了土壤可蚀性,生物结皮层土壤可蚀性较下层土壤降低17%;土壤可蚀性随生物结皮生物量的增加呈降低趋势,藓结皮土壤可蚀性K值较藻结皮土壤降低21%;生物结皮土壤可蚀性在不同季节因其生物活性不同而存在差异,雨季中显著高于雨季前和雨季末;不同质地土壤上生物结皮对可蚀性的影响不同,可蚀性K值为砂壤>粉壤>砂土;模拟降雨条件下测定表明,生物结皮的发育使土壤可蚀性较对照（下层5~10 cm土壤）降低约90%.
     

Isolation by time and habitat and coexistence of distinct host races of the common cuckoo

Isolation by time occurs when different populations of a single species reproduce at different times and thereby reduce the probability of interbreeding, potentially causing divergent adaptation to timing of reproduction, eventually resulting in ecological species separated by timing of reproduction. We analysed extensive data on timing of reproduction by different host races of the common cuckoo Cuculus canorus that is an obligate brood parasite laying eggs in the nests of many different species of passerine birds. Because different hosts breed at different times, specific host races of cuckoos have adapted to specific hosts by laying eggs when nests of these hosts are available, and such divergence may be further exaggerated by differences in timing of breeding among host races with similar habitat requirements. Host species accounted for a quarter of the variance in timing of breeding by the cuckoo. Common cuckoos reproduced at a similar, but narrower subset of dates as did possible hosts, showing that only a fraction of hosts with specific breeding dates were parasitized. Common cuckoo eggs laid in the 'right' kind of nests, phenotypically matching the eggs of the host, were laid later during the season than cuckoo eggs laid in the 'wrong' kind of nests where the eggs did not mimic those of the host. Pairs of sympatric cuckoo host races differed more in timing of breeding than pairs of allopatric host races, and pairs of cuckoo host races with similar breeding habitat differed more in breeding date than pairs of cuckoo host races with dissimilar habitat, as expected from reproductive character displacement. These findings are consistent with cuckoo host races being isolated by timing of breeding and habitat.     

Heterogeneity of molecular mechanisms the olfactor reception

In experiments on the frog isolated olfactory epithelium by using vital fluorescent microscope, odorants with fruit, rank, flower and camphor smell were shown to involve intracellular signaling systems in olfactory transduction. The odorants with different qualitative smells have different messenger and activity mechanisms. Intracellular messengers do not participate in reception of odorants with piquant and rotten smells. Thus the perception of different odour substances is maintained by physical and chemical processes. Hence, not only taste, carotid, medullar, but olfactory reception as well are characterised by heterogeneity of biophysical mechanisms.     

Synthesis and inactivation of carbamyl phosphate synthetase isozymes of Bacillus subtilis during growth and sporulation.

Pyrimidine-repressible carbamyl phosphate synthetase P was synthesized in parallel with aspartate transcarbamylase during growth of Bacillus subtilis on glucose-nutrient broth. Both enzymes were inactivated at the end of exponential growth, but at different rates and by different mechanisms. Unlike the inactivation of aspartate transcarbamylase, the inactivation of carbamyl phosphate synthetase P was not interrupted by deprivation for oxygen or in a tricarboxylic acid cycle mutant. The arginine-repressible isozyme carbamyl phosphate synthetase A was synthesized in parallel with ornithine transcarbamylase during the stationary phase under these growth conditions. Again, both enzymes were subsequently inactivated, but at different rates and by apparently different mechanisms. The inactivation of carbamyl phosphate synthetase A was not affected in a protease-deficient mutatn the inactivation of ornithine transcarbamylase was greatly slowed.     

Two pools of glycogen in Saccharomyces.

The effect of different extraction procedures on the yields of water-soluble and water-insoluble glycogen fractions from a number of Saccharomyces strains was studied by using a specific method for glycogen determination. The similarity of the yields obtained by the different procedures showed that neither form of glycogen is an artifact, and variations in the relative amounts of glycogen in the two fractions during cell growth and in different yeast strains suggest that they represent different pools of storage material with specific roles in cell development and differentiation. A proportion of the water-insoluble glycogen fraction, solubilized by mechanical agitation, was shown to be strongly associated with a beta-glucan-like polysaccharide that may be a cell wall component.     

Heterogeneity of microtubules recognized by monoclonal antibodies to alpha-tubulin

A set of four monoclonal antibodies against tubulin (TU-01, TU-02, TU-03, and TU-04) were produced using pig brain microtubule protein as antigen. Their characterization shows that all recognize antigenic determinants located on the tubulin alpha-subunit. However, peptide mapping of isolated alpha-tubulin, followed by immunoblotting with the monoclonal antibodies, shows that the antigenic determinants are located on different peptide fragments in at least three cases. The immunoreactivity with tubulins from different cells and tissues, ranging from eukaryotic microorganisms to man, was studied by immunoblotting and immunofluorescence. The antigenic determinants recognized by the antibodies are not uniformly distributed but, in some instances, are absent from tubulins of lower eukaryotic cells. These antibodies also make it possible to distinguish between different sets of microtubules within individual cells. Antigenically different microtubules are particularly evident in mouse spermatozoa and in some protozoa (T. vaginalis, H. muscarum, L. tropica, N. gruberi) possessing different sets of microtubules with different functions. These monoclonal antibodies can clearly identify the heterogeneity of tubulin or microtubules both from different organisms and within the same cell.     

长期不同施肥下水稻土甲烷氧化能力及甲烷氧化菌多样性的变化

稻田内源甲烷的氧化是稻田甲烷减排的重要途径。而甲烷氧化菌是土壤中甲烷氧化的主要施动者,在长期不同施肥条件下,土壤微生物群落的演变是否影响到土壤甲烷氧化菌群落结构及其活性,进而影响到田土壤CH4向大气的实际排放强度还不清楚。为此,选择太湖地区一个长期肥料试验的稻田土壤为研究对象,分析长期不同肥料施用对土壤甲烷氧化能力的影响及其与土壤中甲烷氧化菌群落结构变化的可能关系。结果表明,长期不同的施肥措施下稻田土壤对甲烷的氧化能力产生了明显差异,伴随着土壤中甲烷氧化菌（MOBI和MOBII）的基因群落多样性的显著变化。长期单一施用氮肥为主的化肥显著降低了土壤对甲烷的氧化能力,同时显著降低了稻田土壤甲烷氧化菌的多样性和丰富度;不同施肥下甲烷氧化菌多样性的变化与土壤的甲烷氧化能力的变化趋势相一致。因此,研究显示长期不同施肥处理下甲烷氧化菌群落结构的改变可能是引起水稻土甲烷氧化能力变化的一个主要因素,有机无机配合施用可以明显降低稻田土壤甲烷的大气释放潜能。但长期不同施肥处理下甲烷氧化菌活性的变化还有待于进一步研究。     

Transcribed and nontranscribed parts of the human ribosomal gene repeat show a similar pattern of distribution in nucleoli.

The distribution pattern of the transcribed and nontranscribed parts of human ribosomal RNA genes were visualized simultaneously in the same cells by nonautoradiographic in situ hybridization. DNA probes labeled with either digoxigenin or biotin were detected in the same cells by different fluorescence systems. The signals from both the transcribed and nontranscribed parts showed a similar distribution pattern. This finding is not compatible with the conclusion, suggested by earlier studies, that the transcribed and nontranscribed parts of the rRNA genes are located at different sites within the nucleoli or in different nucleolar components.     

The Posttranslational Arginylation of Proteins in Different Regions of the Rat Brain

The posttranslational incorporation of arginine into proteins catalyzed by arginyl-tRNA protein transferase was determined in vitro in different rat brain regions. The incorporation was found in all the regions studied, although with different specific activities (pmol [14C]arginine incorporated/mg protein). Of the regions studied, hippocampus had the highest specific activity followed by striatum, medulla oblongata, cerebellum, and cerebral cortex. Electrophoretic analysis of the [14C]arginyl proteins from the different regions followed by autoradiography and scanner densitometry showed at least 13 polypeptide bands that were labeled with [14C]arginine. The radioactive bands were qualitatively coincident with protein bands revealed by Coomassie Blue. There were peaks that showed different proportions of labeling in comparison with peaks of similar molecular mass from total brain. Most notable because of their high proportions were those of molecular mass 125 kDa in hippocampus, striatum, and cerebral cortex; 112 and 98 kDa in striatum and cerebellum; and 33 kDa in hippocampus and striatum. In lower proportions than in total brain were the peaks of 33 kDa in medulla oblongata and cerebral cortex and of 125 kDa in medulla oblongata.