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1.
正空间生态位研究是群落生态学研究中的一个非常重要的领域。它能反映一定空间内生物群落中物种对环境资源的综合利用状况和种间的竞争关系(史作民和程瑞梅,1999;Ibarra et al.,2014)。小型兽类生态位的研究在国内外已有不少报道(Churchfield et al.,1999;Patrick,2000;王艳妮等,2005;付和平等,2005;申跃武等,2008;马  相似文献   

2.
灵长类动物类固醇激素的研究已经在很多物种间展开(Cariso et al.,1999;Lutz et al.,2000;He et al.,2001;Yan and Jiang,2006;Brandon et al.,2008;Lu et al.,2010;Kim et al.,2012)。特别是对于没有明显发情特征的灵长类动物,类固醇激素的变化可以为它们的繁殖状态提供更多可靠的评估(Fujita et al.,2001)。自然状态下野生动  相似文献   

3.
Dear Editor, Phosphoenolpyruvate carboxylase (PEPC; EC 4.1.1.31) islocated at an important branch point in the carbohydratemetabolism of plants. The enzyme is a homotetramer andcatalyzes the addition of bicarbonate to phosphoenolpyru-vate (PEP) to form oxaloacetate and phosphate. PEPC isregulated by metabolites and phosphorylation. AIIostericfeedback inhibition is mainly regulated by L-malate andL-aspartate which bind to a site separated from the activecenter (Kai et al., 1999; Paulus et al., 2013). Structure analy-sis of PEPC from Escherichia coli (Kai et al., 1999; Matsumuraet al., 2002), Zea rnays (Matsumura et al., 2002), Flaveria trin-ervia, and F. pringlei (Paulus et al., 2013) revealed that thesubstrate PEP and the feedback inhibitors bind to separatesites within each monomer.  相似文献   

4.
正微量元素包括Fe、Cu、Cr、Mn和Zn等,虽含量极微,但具有极重要的生理功能,涉及机体的生长发育、免疫代谢等生命活动过程(Shenkin,2008; Subrahmanyam et al.,2015),也是反映机体新陈代谢及生理功能状况的重要指标(Carpene et al.,2017)。例如Fe元素参与机体氧的运输和贮存(Abbaspour et al.,2014),血清铁被认为是动物营养评估的生化指标(Ganapathy et al.,2011); Cu元素是多种氧化酶的重要组分,参与动物新陈代谢、生长发育等(Desai et al.,2014)。  相似文献   

5.
中华绒螯蟹染色体的研究   总被引:17,自引:1,他引:16  
中华绒螯蟹(Eriocheir sinensis H.Milne Edwards)属甲壳纲(Crustacea)、软甲亚纲(Malacostraca)、十足目(Decapoda)、方蟹科(Grapsidae),俗称河蟹,是我国重要的经济蟹类,其形态解剖、生态习性及生理等方面的研究已有报道(Panning,1939;Koch,1952;堵南山,1954,1957,1958;Bauchau,1960;Leersnyder,1966,1967;Dbainaut et al.,1976;Chevigue,1976;Leeranyder et al.,1977,1978;Pequenx et al.,1982;Chapelle et al.,1982;谈奇坤等,1984.),但至今未见有关细胞遗传学方  相似文献   

6.
林天瑞 《古生物学报》2019,58(4):436-444
通过对我国己经正式发表的Mufushania三叶虫的18个种模式标本的头盖特征进行Q型聚类分析,并结合传统定性分析后,提出其中Mufushania shalangensis Zhang and Zhou inZhang et al.,1980,M.angustilimbata Zhang and Zhou inZhang et al.,1980,和M.kailiensis(Yuan in Yuan et al.,2002)(=Elrathiella kailiensis Zhou in Lu et al.,1974)等3种应从Mufushania属中删除,对余下15个种,通过修订,转移和归并为2个种:M.nankingensis Lin,1965和M.bella(Yuan in Yuan et al.,2002)。本文将对研究我国寒武纪第二世晚期褶颊虫类三叶虫系统演化、生物地理分区以及华北与华南生物地层划分和对比,提供重要依据。  相似文献   

7.
灰树花胞外多糖的结构分析*   总被引:2,自引:0,他引:2  
灰树花胞外多糖是一种具有显著生物活性的生物反应调节剂,动物实验及临床研究表明灰树花多糖在抗肿瘤、抗HIV病毒以及防治糖尿病、高血压、高血脂、肥胖症、老年痴呆症等方面具有良好的效果,有些方面甚至超过已经临床应用的香菇多糖、云芝多糖和裂褶菌多糖(邢增涛等,1999;李强等,1989;项哨等,1995;劳华均等,1997)。多糖的生物活性与其结构有着密切的关系,许多文献中报道了灰树花子实体多糖的活性及结构(Ohno et al.,1985;Ohno et al.,1987;Ohno et al.,1988;),但是关于灰树花胞外多糖的结构的分析则较少见到报道。本文…  相似文献   

8.
利用活体观察和蛋白银染色技术对近年来采自青岛、大亚湾、湛江沿岸水体的10个海洋寡毛类纤毛虫种: 侧扁急游虫Strombidium apolatum Wilbert & Song, 2005、具头急游虫Strombidium capitatum (Leegaard, 1995) Kahl, 1932、广东急游虫Strombidium guangdongense Liu, et al., 2016、拟卡氏急游虫Strombidium paracalkinsi (Lei, et al., 1999) Agatha, 2004、拟楔尾急游虫Strombidium parastylifer Song, et al., 2009、铃木急游虫Strombidium suzukii Song, et al., 2009、束腰旋游虫Spirostrombidium cinctum (Kahl, 1932) Petz, et al., 1995、杨科夫平游虫Parallelostrombidium jankowski (Song, et al., 2009) Song, et al., 2018、卡尔平游虫Parallelostrombidium kahli (Song, et al., 2009) Song, et al., 2018、最小拟盗虫Strombidinopsis minima (Gruber, 1884) Song & Bradbury, 1998的形态学开展了比较研究, 补充和厘定了有关形态特征、纤毛图式以及性状变异等分类学新信息。  相似文献   

9.
Dear Editor, Higher plants have evolved hundreds of genes encodingreceptor-like kinases (RLKs), which function as cell surfacereceptors perceiving developmental and environmental sig-nals (Shiu et al., 2004). Many RLKs have been shown to playspecific roles in hormone responses, developmental regula-tion, defense against pathogen infection, and adaptationto abiotic stresses (Chae et al., 2009; Antolin-Llovera et al.,2012). The mechanisms that ensure specific signal transduc-tion from each RLK to target cellular responses remain poorlyunderstood. Recent studies revealed that many RLKs trans-duce signals by phosphorylating receptor-like cytoplasmickinases (RLCKs), which lack the transmembrane domainsbut are anchored at the plasma membrane through lipidmodification (Tang et al., 2008; Zhang et al., 2010; Shi et al.,2013). There are over 400 RLKs and only about 150 RLCKs inArabidopsis (Shiu et al., 2004). One outstanding question iswhether each RLCK mediates signaling downstream of a spe-cific RLK, participates in multiple RLK pathways, or mediatescrosstalk between RLK pathways.  相似文献   

10.
11.
The goal of this article was to establish reference ranges of the concentration of trace elements in human serum and to compare these results with those reported by other authors. We describe the sample preparation and measurement conditions that allow the rapid, precise, and accurate determination of Al, As, B, Be, Cd, Co, Cu, Fe, Li, Mn, Mo, Ni, Rb, Se, Sr, and Zn in human serum samples (n=110) by inductively coupled plasma-mass spectrometry (ICP-MS). Accuracy and precision were determined by analyzing three reconstituted reference serum samples by comparison with other methods and by the standard addition procedure. The advantages of the ICP-MS method include short time of analysis of the elements mentioned, low detection limit, high precision, and high accuracy. Disadventages include a high risk of contamination due to the presence of some of the elements of interest in the environment, the relatively delicate sample handling, and the high cost of the equipment.  相似文献   

12.
Summary Concentration of N, P, K, Ca, Mg and S in summer groundnut crop was higher than in kharif while Zn, Fe, Mn and Cu contents were higher in summer crop. Kernel's N, P and Zn; Leaflet's Ca and Mn; Stem's K and Fe; Root's S and Cu and Petiole's Mg contents were highest. Shell's N, P, K, Mg, S, Zn and Cu; Kernel's Ca, Fe and Mn contents were the least. N, P, K, S, Zn and Cu concentrations decreased linearly as the crop grew. Ca, Mg, Fe and Mn concentrations did not display any distinct pattern. Ca concentration was positively correlated with pod yield in both the seasons.  相似文献   

13.
This report attempts to formulate reference ranges of elemental concentrations for 15 trace elements in selected human tissues and body fluids. A set of samples consisting of whole blood, blood serum, urine, milk, liver, and hair were chosen and considered for 15 elements of biological significance: As, Cd, Co, Cr, Cu, F, Fe, I, Hg, Mn, Mo, Ni, Pb, Se, and Zn. The results represent wholly or partially data received from 40 countries of the global regions of Africa, Asia, Europe, North, South, and Central America, Australia, and New Zealand. This survey, even if qualitative, has been useful in demonstrating certain trends of trace-element scenarios around the world. It is of course recognized that both diet and environment exert a strong influence on the distribution pattern of several elements, such as As, Cd, Mn, Pb, Se, and Zn. A limited comparison of the available information on soil status of different countries reflected some interesting associations for elements, such as Mn and Zn. Importantly, this study revealed that only a few countries were in a position to identify a reasonable amount of data on samples requested for this project. Regretably, for a number of countries, any dependable data for even such essential elements as Cu, Fe, and Zn were not available. In view of the nutritional importance of many elements, the time is ripe for concerted efforts by intergovernmental agencies to initiate investigations or commission task forces/projects to generate reliable reference data for selected global regions, which sadly lack data of any kind at present.  相似文献   

14.
A new polynitro cage compound 2, 4, 6, 8, 10, 12, 13, 14, 15-nonanitro-2, 4, 6, 8, 10, 12, 13, 14, 15-nonaazaheptcyclo [5.5.1.1(3,11).1(5,9)] pentadecane (NNNAHP) was designed in the present work. Its molecular structure was optimized at the B3LYP/6-31 G(d,p) level of density functional theory (DFT) and crystal structure was predicted using the Compass and Dreiding force fields and refined by DFT GGA-RPBE method. The obtained crystal structure of NNNAHP belongs to the P-1 space group and the lattice parameters are a = 9.99 ?, b = 10.78 ?, c = 9.99 ?, α = 90.01°, β = 120.01°, γ = 90.00°, and Z = 2, respectively. Based on the optimized crystal structure, the band gap, density of state, thermodynamic properties, infrared spectrum, strain energy, detonation characteristics, and thermal stability were predicted. Calculation results show that NNNAHP has detonation properties close to those of CL-20 and is a high energy density compound with moderate stability.  相似文献   

15.
The unitary conductances and permeability sequences of the rat connexin40 (rCx40) gap junction channels to seven monovalent cations and anions were studied in rCx40-transfected neuroblastoma 2A (N2A) cell pairs using the dual whole cell recording technique. Chloride salt cation substitutions (115 mM principal salt) resulted in the following junctional maximal single channel current-voltage relationship slope conductances (γj in pS): CsCl (153), RbCl (148), KCl (142), NaCl (115), LiCl (86), TMACl (71), TEACl (63). Reversible block of the rCx40 channel was observed with TBA. Potassium anion salt γj are: Kglutamate (160), Kacetate (160), Kaspartate (158), KNO3 (157), KF (148), KCl (142), and KBr (132). Ion selectivity was verified by measuring reversal potentials for current in rCx40 gap junction channels with asymmetric salt solutions in the two electrodes and using the Goldman-Hodgkin-Katz equation to calculate relative permeabilities. The permeabilities relative to Li+ are: Cs+ (1.38), Rb+ (1.32), K+ (1.31), Na+ (1.16), TMA+ (0.53), TEA+ (0.45), TBA+ (0.03), Cl (0.19), glutamate (0.04), and NO3− (0.14), assuming that the monovalent anions permeate the channel by forming ion pairs with permeant monovalent cations within the pore thereby causing proportionate decreases in the channel conductance. This hypothesis can account for why the predicted increasing conductances with increasing ion mobilities in an essentially aqueous channel were not observed for anions in the rCx40 channel. The rCx40 effective channel radius is estimated to be 6.6 Å from a theoretical fit of the relationship of relative permeability and cation radius.  相似文献   

16.
17.
The variation with age of the 18 trace element mass fractions and some histological characteristics of intact prostate glands of 50 subjects aged 0–30 years was investigated by instrumental neutron activation analysis, inductively coupled plasma atomic emission spectrometry, and a quantitative morphometric analysis. Mean values ± standard error of the mean (M ± SΕΜ) for the mass fractions (in milligrams per kilogram wet tissue) of these trace elements in pre-puberty were: Al 28.5 ± 9.0, B 0.40 ± 0.11, Ba 1.48 ± 0.44, Br 10.5 ± 1.5, Ca 241 ± 30, Cl 3,203 ± 278, Cu 3.51 ± 0.89, Fe 33.7 ± 4.1, K 2,364 ± 145, Li 0.020 ± 0.004, Mg 153 ± 23, Mn 0.46 ± 0.06, Na 2,286 ± 130, P 1,391 ± 100, S 1,698 ± 132, Si 62 ± 11, Sr 0.38 ± 0.08, and Zn 27.6 ± 2.3. During puberty and postpuberty, when there is a significant increase in circulating androgens, the mean values were: Al 7.2 ± 1.4, B 0.21 ± 0.05, Ba 0.25 ± 0.06, Br 5.8 ± 1.0, Ca 433 ± 81, Cl 2,314 ± 201, Cu 1.77 ± 0.13, Fe 20.9 ± 1.6, K 2,585 ± 118, Li 0.0088 ± 0.0014, Mg 232 ± 27, Mn 0.34 ± 0.04, Na 1,875 ± 107, P 1,403 ± 98, S 1,673 ± 73, Si 22.2 ± 3.1, Sr 0.22 ± 0.03, and Zn 93.3 ± 8.9. Mean values (M ± SΕΜ) of percent volumes (%) of the stroma, epithelium and lumen in the prostate before puberty were 73.4 ± 2.6, 20.4 ± 1.7, and 4.45 ± 0.94, respectively, versus 46.5 ± 2.5, 38.5 ± 1.9, and 14.9 ± 1.2 during puberty and postpuberty. This work’s results confirm that the Zn mass fraction in prostate tissue is an androgen-dependent parameter. For the first time it has been demonstrated that the glandular lumen is a main pool of Ca, Mg, and Zn accumulation and that the stroma is a main pool of Al, B, Ba, Br, Cl, Cu, Fe, Mn, Na, and Si accumulation in the normal human prostate, for the age range 0–30 years. It was concluded that the Ca, Mg, and Zn binds tightly within the prostatic fluid, because the volume of glandular lumen reflects the volume of prostatic fluid.  相似文献   

18.
The effect of age and gender on major, minor, and trace element contents in the intact rib bone of 80 relatively healthy 15–55-year-old women and men was investigated. Contents or upper limit of contents of 16 chemical elements in the rib bone were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES). Mean values (M?±?SΕΜ) for the mass fraction of Ba, Ca, Cu, Fe, K, Li, Mg, Na, P, S, Sr, and Zn (milligram per kilogram of dry bone) were as follows: 2.54?±?0.16, 171,400?±?4,050, 1.35?±?0.22, 140?±?11, 1,874?±?71, 0.049?±?0.011, 2,139?±?38, 5,378?±?88, 75,140?±?1,660, 1,881?±?51, 291?±?20, and 92.8?±?1.5, respectively. The upper limits of contents of Al, B, Mn, and V were <7.20, <0.65, <0.36, and <0.03, respectively. Statistically significant tendency for the Ca, Mg, and P content to decrease with age was found in the human rib bone, regardless of gender. The mass fraction of Fe in the male rib bone increases with age. It was shown that higher Ca, Mg, Na, P, and Sr mass fractions as well as lower Fe content were typical of female ribs as compared to those in male ribs.  相似文献   

19.
We investigated the uptake of inorganic elements (Be, Na, Mg, K, Ca, Sc, Mn, Co, Zn, Se, Rb, Sr, Y, Zr, Ce, Pm, Gd, and Hf) and the effect of Ca on their uptake in carrots (Daucus carota cv. U.S. harumakigosun) by the radioactive multitracer technique. The experimental results suggested that Na, Mg, K, and Rb competed for the functional groups outside the cells in roots with Ca but not for the transporter-binding sites on the plasma membrrane of the root cortex cells. In contrast, Y, Ce, Pm, and Gd competed with Ca for the transporters on the plasma membrane. The selectivity, which was defined as the value obtained by dividing the concentration ratio of an elemental pair, K/Na, Rb/Na, Be/Sr, and Mg/Sr, in the presence of 0.2 and 2 ppm Ca by that of the corresponding elemental pair in the absence of Ca in the solution was estimated. The selectivity of K and Rb in roots was increased in the presence of Ca. The selectivity of Be in roots was not affected, whereas the selectivity of Mg was increased by Ca. These observations suggest that the presence of Ca in the uptake solution enhances the selectivity in the uptake of metabolically important elements against unwanted elements.  相似文献   

20.
《Ibis》1894,36(3):447-460
  相似文献   

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