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1.
Telomeres and telomere-associated satellites of rice were genetically and physically analyzed by pulsed-field gel electrophoresis (PFGE) using Arabidopsis telomeric DNA and rice satellite sequences as probes. We demonstrate that Arabidopsis telomeric sequences hybridize to rice telomeres under the conditions of high stringency. Using the Arabidopsis probe, multiple, discrete telomeric fragments could be identified on pulsed-field gel blots of rice DNAs digested with rare-cutting restriction enzymes. Most of the telomeric bands larger than 300 kb are physically linked with satellite bands as revealed by PFGE. Some of the telomeric and satellite bands segregate in a Mendelian fashion and are highly reproducible. Three such telomeric bands have been mapped to the distal ends of RFLP linkage groups: Telsm-1 on chromosome 8, Telsa-1 on chromosome 9 and Telsm-3 on chromosome 11. One segregating satellite band was mapped to an internal region of chromosome 10. Telomeric fragments were shown not only to be genetically linked to but also physically linked (based on PFGE) to the terminal RFLP markers. The physical distance from telomeric sequences to a distal RFLP marker, r45s gene, on chromosome 9, is 200 kb while the distance from telomeric sequences to RG98, a terminal RFLP marker on chromosome 11, is 260 kb. Physical maps of the telomere regions of chromosome 9 and chromosome 11 are presented. 相似文献
2.
Popular hypothesis based on the idea of simple feedback mechanism that correlates gravity level and weight of test mass cannot explain the variety of the effects of altered gravity on development and function of gravireceptors. The reaction of organisms to the change of gravity depends on the gravisensitivity of the physical and chemical processes corresponding to specific phases of development and may have no relation to any feedback mechanisms of compensation of altered weight of the test mass. The present work analyzes the hypothesis of feedback and shows the ambiguity of possible effects of the altered gravity on formation and function of gravireceptors basing on the data from mollusks and fish. 相似文献
3.
放牧对牧草光合作用、呼吸作用和氮、碳吸收与转运的影响 总被引:9,自引:1,他引:8
研究放牧对草地植物生理活动的影响,对于揭示草地放牧演替的生理机制有重要意义.大量研究表明,家畜放牧对牧草光合作用、呼吸作用以及C和N吸收与转运的影响,可以分为生理伤害和生理恢复2个阶段.放牧通过改变草地冠层结构影响牧草光合作用,净光合作用速率短期内迅速下降,随着叶面积指数增加又逐渐上升,呼吸作用有相似的变化趋势.牧草放牧后再生长所需的C和N最初主要来自根系和留茬中的贮藏物质,此后随着牧草生长恢复逐渐由同化作用供给,C代谢与土壤N水平负相关.放牧后牧草生理活动变化与牧草遗传特性、种间竞争、家畜放牧特征、非生物环境等因素密切相关. 相似文献
4.
V S Rodionov 《Biology bulletin of the Academy of Sciences of the USSR》1979,6(2):198-209
Data in the literature on chromatography of glycerolipids of plant leaves on columns of DEAE-cellulose, Sephadex LH-20, silica gel, florisil, in a thin layer of silica gel, paper are generalized. Methods of obtaining chromatographically pure glycerolipids, their subfractionation, and the quantitative analysis of glycerolipids are described. Experimental data are presented on fractionation of lipids of potato leaves on columns of DEAE-cellulose, silica gel, on paper, and the quantitative determination of phospholipids. A method of rapid division of lipids into classes by means of their elution with silica gel KSC by different solvents is described. 相似文献
5.
《Electromagnetic biology and medicine》2013,32(4):375-381
Pulsed electromagnetic fields (PEMF) can promote bone healing, while use of dexamethasone induces bone loss and osteoporosis. There is no report available on the combined effects of PEMF and dexamethasone on the activity of osteoblasts. Here, we investigated the effects of PEMF and dexamethasone on the proliferation and differentiation of MC3T3-E1 osteoblasts. Our results showed that PEMF and dexamethasone respectively increased and decreased the proliferation of MC3T3-E1 osteoblasts, meanwhile PEMF eliminated the effect of dexamethasone on MC3T3-E1 osteoblasts. Moreover, we also found that dexamethasone combined with PEMF upregulated the mRNA expression of IGF-1 at the early stage after the stimulation of PEMF and improved the decrease of COX-2 mRNA expression induced by dexamethasone at the late stage after the stimulation of PEMF. PEMF may be beneficial to improve dexamethasone-induced bone loss and osteoporosis. 相似文献
6.
Germination and emergence characteristics of triazine-susceptible and triazine-resistant biotypes of Solanum nigrum 总被引:1,自引:0,他引:1
1. Seedling emergence patterns of triazine-susceptible and triazine-resistant Solanum nigrum in the field were studied in Wageningen, the Netherlands. Emergence patterns were similar in the first year, but in the second year resistant seedlings emerged faster and the number of resistant seedlings was higher. To explain emergence patterns, a germination experiment was carried out.
2. Seeds from two populations with triazine-susceptible and -resistant biotypes were buried in late autumn and exhumed monthly during spring. Germination was assessed in incubators at different constant temperatures.
3. The lowest temperatures for germination of seeds from the Achterberg population ranged from 20°C on 1 February to 10°C on 1 May for the susceptible biotype, and from 15°C on 1 February to 10°C on 1 May for the resistant biotype. The lowest temperatures for germination of seeds from the Zelhem population ranged from 25°C on 1 February to 10°C on 1 May for the susceptible biotype, and from 15°C on 1 February to 10°C on 1 May for the resistant biotype. The minimum germination temperature of seeds from the resistant biotype appeared to be lower than that of the susceptible biotype.
4. Emergence patterns in the field could be explained by soil temperature and different minimum germination temperature requirements of seeds from the triazine-susceptible and -resistant biotype. This knowledge can be used to manage triazine-resistant biotypes of S. nigrum by the timing of soil cultivation. 相似文献
2. Seeds from two populations with triazine-susceptible and -resistant biotypes were buried in late autumn and exhumed monthly during spring. Germination was assessed in incubators at different constant temperatures.
3. The lowest temperatures for germination of seeds from the Achterberg population ranged from 20°C on 1 February to 10°C on 1 May for the susceptible biotype, and from 15°C on 1 February to 10°C on 1 May for the resistant biotype. The lowest temperatures for germination of seeds from the Zelhem population ranged from 25°C on 1 February to 10°C on 1 May for the susceptible biotype, and from 15°C on 1 February to 10°C on 1 May for the resistant biotype. The minimum germination temperature of seeds from the resistant biotype appeared to be lower than that of the susceptible biotype.
4. Emergence patterns in the field could be explained by soil temperature and different minimum germination temperature requirements of seeds from the triazine-susceptible and -resistant biotype. This knowledge can be used to manage triazine-resistant biotypes of S. nigrum by the timing of soil cultivation. 相似文献
7.
Three successive crops of winter wheat or barley were grown as second, third and fourth cereals. Communities of fungi on shoot bases, identified after isolation on agar media, were more diverse (determined by number of taxa identified) on wheat than on barley, and their diversity increased from year to year. Diversity was not affected by seed treatments containing fluquinconazole or prochloraz. Eyespot (caused by Tapesia spp.) and brown foot rot (caused by Fusarium spp. or Microdochium nivale ) increased from year to year. Eyespot, brown foot rot (after the first year) and sharp eyespot (which remained infrequent), assessed in summer (June), affected wheat more than barley. Eyespot severity was increased slightly on barley by treatments containing fluquinconazole, formulated with or without prochloraz, in the second year (third cereal), when it was also decreased slightly on wheat by fluquinconazole plus prochloraz, except in plots where the treatment had been applied for two successive years. The increases or decreases in eyespot in the second year were accompanied by, respectively, decreases or increases in the frequency of Idriella bolleyi where fluquinconazole was applied alone. Although the eyespot pathogen Tapesia yallundae (but not Tapesia acuformis ) is sensitive to fluquinconazole in vitro , seed treatment, applied principally to control take-all disease, is likely to have only a small effect against eyespot (or other stem-base diseases), and then only on wheat and when formulated with prochloraz. 相似文献
8.
Narukawa Yoshiko Iida Shigeo Tanouchi Hiroyuki Abe Shin Yamamoto Shin-Ichi 《Ecological Research》2003,18(3):267-277
Fallen logs on the forest floor play an important role in tree seedling establishment in boreal and subalpine old-growth forests. We examined the abundance and state (degree of decay, moss coverage on their surfaces) of fallen logs on the forest floor and compared the occurrence of conifer seedlings and saplings on soil and fallen logs in old-growth evergreen boreal (Taisetsu) and subalpine (Yatsugatake) coniferous forest stands in Japan. The forest floors of both stands were covered mostly by soil, and fallen logs covered only a small proportion (4.5% in Taisetsu and 2.5% in Yatsugatake) of the forest floor. In both stands, no seedlings were found on freshly fallen logs. Both moss coverage and the occurrence of seedlings or saplings on fallen logs increased with decay in both stands. In Taisetsu, the occurrence of all conifer seedlings and saplings was, in general, restricted to fallen logs. In contrast, in Yatsugatake, Picea and Tsuga seedlings occurred much more frequently on fallen logs than on soil, whereas Abies seedlings and saplings became established on both soil and fallen logs. Seedlings were taller on decayed fallen logs, but taller saplings were rare on fallen logs in Yatsugatake. Results indicate that species characteristics, the condition of the fallen logs and environmental factors determine the preponderance of seedling and sapling establishment on fallen logs. The condition of fallen logs varies with the degree of decay, and fallen logs that function as seedling establishment sites on the forest floor are thought to be limited by time and space. 相似文献
9.
有机无机肥长期配合施用对冬小麦籽粒品质的影响 总被引:13,自引:0,他引:13
提高籽粒品质和产量是当前国内小麦生产的核心。小麦品质和产量取决于基因型、生态环境 (如土壤肥力等 )和栽培技术(尤其是养分管理技术 )。长期肥料试验是研究养分管理对小麦产量和品质影响的有效手段 ,迄今 ,长期施肥对小麦产量的影响报道很多 ,但对籽粒品质的影响报道很少。在 2 0 a长期定位肥料试验的基础上 ,研究了有机无机肥长期配合施用对不同类型小麦籽粒品质性状的影响。结果表明 ,有机肥主效应对小麦籽粒产量有显著作用 ,而对大部分品质指标无影响 ;无机肥处理主效应及有机无机肥交互效应对籽粒产量和大部分品质性状均有显著影响。有机无机肥料配合施用与单施无机肥处理相比提高了小麦大部分品质性状 ,有利于强筋小麦籽粒产量和品质的同步提高 ,但不利于弱筋小麦品质的改善。进一步分析了土壤肥力及磷钾肥对小麦籽粒品质的影响 相似文献
10.
Petter Saxegaard Britta Renstrm Carter Litchfield Synnve Liaaen-Jensen Gunner Borch Yoshito Tanaka 《Biochemical Systematics and Ecology》1981,9(4):325-327
The identity of the carotenoids tedaniaxanthin and allopurpurin from marine sponges has been demonstrated by a direct quantitative comparison of their I2-catalysed stereomutation mixtures (HPLC and visible spectra). Studies on the geometrical isomerism are reported. The 2R-configuration is assigned on the basis of a CD-correlation of the HPLC-purified all-trans isomer and (3R,3′R)-aloxanthin. 相似文献
11.
本文就有关山茱萸中的挥发性成分、环烯醚萜苷、鞣质、有机酸等化学成分,山茱萸的抗菌消炎、调节免疫、降血糖、保肝、抗癌、抗休克、抗氧化、抗艾滋病等药理作用,以及国内外开发应用状况进行了文献综述,并对山茱萸的基础研究和进一步开发利用提出建议。 相似文献
12.
We present ab-initio periodic Hartree–Fock calculations (crystal program) of small molecules on TiO2 and MgO. The adsorption of the molecules may be molecular or dissociative. This depends on their acid and basic properties in the gas phase. For the molecular adsorption, the molecules are adsorbed as bases on Ti(+IV) sites, the adsorption energies correlate with the proton affinities. The dissociations on the surface correlate with the gas phase cleavages: thus, the dissociation of MeOH leads to a preferential basic cleavage (the fragment HO– is adsorbed on a Ti+4 ion and the fragment Me+ is adsorbed on a O2– ion of the oxide). The opposite result is obtained with MeSH. Another important factor is the adsorbate–adsorbate interaction: favorable cases are a sequence of H-bonds for the hydroxyl groups resulting from the water dissociation and the mode of adsorption for the ammonium ions. Lateral interactions also force the adsorbed CO2 molecules to bend over the surface so that their mutual orientation resembles the geometry of the CO2 dimer. With respect to water adsorption, MgO appears to be a basic oxide. As experimentally observed, NH3 adsorbs preferentially on TiO2 and CO2 on MgO. However, this difference of reactivity should not be expressed in terms of acid vs. basic behaviour but in terms of hard and soft acidity. The MgO surface is a 'soft' acidic surface that reacts preferentially with the soft base, CO2. 相似文献
13.
Magnus Hahlin 《Plant and Soil》1982,64(1):79-83
Summary The effect of increasing potassium and magnesium fertilization during 15 years on the amounts of K and Mg extracted by AL-solution
and desorbed by Electro-Ultrafiltration (EUF) was determined in four Swedish soils.
In all soils, with increasing potassium fertilization the amounts of K extracted by AL and desorbed by EUF increased, and
the amounts of Mg-AL and Mg-EUF decreased. Magnesium fertilization had no significant effect on the K values but increased
both Mg-AL and Mg-EUF.
The EUF-values were lower than the corresponding AL-values, but the ratio of EUF-desorbed to AL-extracted amounts of K and
Mg varied depending on soil type as well as on fertilization rate. The ratio of K-EUF to K-AL increased and the ratio of Mg-EUF
to Mg-AL decreased with increasing potassium fertilization, whereas magnesium fertilization decreased the ratio of Mg-EUF
to Mg-AL. 相似文献
14.
叶面独特的生物学特征引起了越来越多研究者的关注。对植物叶面微环境和叶面微生物的研究动态进行了综述,重点介绍了叶面环境的特点、叶面微生物群落的特征、叶面微生物的入侵方式和定居位置。最后对叶面微环境的研究和应用前景进行了展望。 相似文献
15.
M Otani H Yamauchi T Meguro S Kitazawa S Watanabe H Orimo 《Journal of biochemistry》1976,79(2):345-352
Calcitonin was extracted from the pericardium and esophagus of eel in quantities sufficient to permit purification and chemical characterization. Homogeneous calcitonin could be isolated by a six-step fractionation starting from acetone powder of the organs. The fractionation procedure consisted of acid extraction, gel filtration on Sephadex G-75, chromatography on SP-Sephadex C-25, gel filtration on the Sephadex G-50, chromatography on carboxymethylcellulose, and gel filtration on Sephadex G-50. Fractionation of the hormone was monitored by assay of its biological activity and from its behaviour on thin layer chromatography and polyacrylamide gel disc electrophoresis. The hormone contained 32 amino acid residues, like calcitonins from other species of animals, but its amino acid composition was different from those of previously characterized hormones. Eel calcitonin possessed almost the same, or higher, biological activity as the salmon or chicken hormone, which show the highest specific activity among calcitonins so far isolated. 相似文献
16.
生态系统服务供给和需求研究评述及框架体系构建 总被引:1,自引:0,他引:1
生态系统服务供给和需求联系着自然生态系统与社会经济系统,对生态系统服务供给和需求的研究有助于加强生态系统管理和实现资源优化配置,从而保障区域生态安全与社会经济可持续发展。本文在系统梳理国内外相关研究的基础上,对生态系统服务供给和需求的概念内涵、评估方法和实践应用等方面进行全面综述。从理论发展的角度看,虽然目前已取得较为丰富的研究成果,但是现有研究仍较为分散,缺乏统一的生态系统服务供需研究框架体系。鉴于此,本文在对生态系统服务供给和需求的研究范畴进行拓展的基础上,按照“理论-方法-实践”相统一的研究脉络,构建了“定性-定位-定量-定策”的生态系统服务供给和需求研究框架体系,最后提出未来研究应围绕“重点关注生态系统服务供给和需求的空间转移规律、加强生态系统服务供给和需求的定量方法研究、深化生态系统服务供给和需求应用管理实践和建立生态系统服务供给和需求应用评价机制”等方面展开,以期促进生态系统服务供给和需求的理论与实践研究。 相似文献
17.
Acidophilic actinomycetes are shown to possess a special mechanism of adaptation to low pH conditions, which shows up in their ability to grow faster on acidified than on neutral media and to adjust the pH of the medium to a level favorable for the formation of aerial mycelium and spores. On nutrient media with pH below 5, neutrophilic actinomycetes either fail to grow or grow much slower than on neutral media; they do not alkalize the medium and do not form aerial mycelium. 相似文献
18.
茄子不同品种对茄二十八星瓢虫及瓢虫柄腹姬小蜂的影响结果表明 ,上海紫茄、呼杂 3 4# 、托塔姆 3 # 、洋红茄 4个品种中 ,取食上海紫茄的瓢虫发育历期明显短于取食其它 3个品种的瓢虫。其幼虫-蛹历期比在托塔姆 3 # 上取食的瓢虫发育历期快 5 69d。瓢虫柄腹姬小蜂在取食上海紫茄的瓢虫幼虫内发育出蜂数多、性比高 ,但寄生率稍低。而在托塔姆 3 # 上取食的幼虫内发育出蜂数少、羽化率低、蜂体小、但寄生率稍高。该蜂喜在 3 ,4龄幼虫内寄生 ,在其上寄生蜂出蜂多、性比高、蜂的个体大 相似文献
19.
Basing on the natural affinity of skin keratinocytes toward extracellular matrix proteins, we have attempted to dissect the
population of these cells by varying the time of their adhesion to substrates from fibronectin and collagen of types I and
IV. After selection for 10, 20, and 30 min, the keratinocytes were cultivated for 24 h under standard conditions. The area
of cell projection on the substrate and the spreading coefficient were measured. Statistically significant morphological differences
between cells selected on different substrates were found. The size of cells growing on type-I collagen was twice as large
as that of the cells cultivated on collagen type-IV or on fibronectin. Independent of the substratum, up to 60–65% of the
cells had a round shape. Keratinocytes cultivated on collagens revealed heterogeneity both in the control and after selection
in their adhesion times, while the cells grown on fibronectin behaved as a homogeneous population. These results suggest that,
contrary to fibronectin, collagens stabilize some physiological states of keratinocytes corresponding to their interactions
with extracellular matrix proteins in the organism.
Original Russian Text O.G. Spichkina, G.P. Pinaev, Y.P. Petrov, 2008, published in Tsitologiya, Vol. 50, No. 2, 2008. 相似文献
20.
Quality of life and chronotherapy 总被引:3,自引:0,他引:3
Pugliese P Garufi C Perrone M Aschelter AM Zappalà A Terzoli E 《Chronobiology international》2002,19(1):299-312
The importance of evaluating patient's quality of life (QoL) in clinical practice and research is recognized clearly in oncology. In the advanced phase of disease such an evaluation represents an endpoint as important as survival. Quality of life is both a subjective and multidimensional concept evaluated mainly by validated questionnaires. In colorectal trials involving advanced stage disease the effects of different chemotherapy treatments on QoL were evaluated. Almost all the studies found no deterioration in QoL during chemotherapy. The European Organization for the Research and Treatment of Cancer (EORTC) Chronotherapy Study Group utilized three different approaches to assess QoL. The first centered on the stability of QoL during a 6mon treatment period in patients undergoing chronotherapy. The second centered on research of the biological and clinical determinants of QoL involving features of the circadian activity rhythm and patient survival and the relationship between QoL and patient performance status, response to therapy, and psychosocial variables as well as drug-induced toxicity. The third centered on the clinical effectiveness of psychological intervention on patients undergoing chronotherapy to improve psychosocial status during treatment. This papers reviews the results of EORTC Chronotherapy Group studies on QoL. 相似文献