共查询到20条相似文献,搜索用时 15 毫秒
1.
本文旨在研究福建闽南地区汉族和畲族指长比(R)的特点。随机选择福建闽南地区汉族506例(男性173例,女性333例),畲族450例(男性231例,女性219例),采用体质测量法,测量并计算左右侧6项指长比(R2/3、R2/4、R2/5、R3/4、R3/5、R4/5)。福建闽南地区汉族和畲族左、右侧指长比均呈R2/3<R2/4<R3/4<R2/5<R4/5<R3/5的趋势;汉族女性指长比左侧R2/3、R2/4、R2/5、R3/4、R3/5和右侧R2/3、R2/4、R2/5高于汉族男性(P<0.05);畲族女性指长比左侧的R2/3、R2/4、R2/5和右侧R2/3、R2/4高于畲族男性(P<0.05);畲族男性指长比左、右侧R2/3、R2/4、R2/5、R3/5、R4/5高于汉族男性(P<0.05);畲族女性指长比左侧R2/3、R2/4和右侧R2/3、R2/4、R2/5、R4/5高于汉族女性(P<0.05)。同民族不同性别两侧R2/4百分比分布差异有统计学意义,不同民族同性别右侧R2/4百分比分布差异有统计学意义。福建闽南地区汉族和畲族指长比存在性别、侧别的不同,与其他地区、族群也存在差异。 相似文献
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Olavi Junttila Einar Jensen David W. Pearce Richard P. Pharis 《Physiologia plantarum》1992,84(1):113-120
Cessation of shoot elongation in seedlings of Salix pentandra L. is induced by short photoperiod. Gibbereliin A9 (GA9 ) applied either to the apical bud or injected into a mature leaf, induced shoot elongation under a short photoperiod of 12 h, and GA9 could completely substitute for a transfer to a long photoperiod. When [3 H]GA9 or [2 H2 ]GA9 was injected into a leaf, no [3 H]GA9 was detected in the elongating apex and only traces of [3 H]GA9 were found in the shoot above the treated leaf. By the use of gas chromatography-mass spectrometry (GC-MS), [2 H2 ]GA20 was identified as the main metabolite of [2 H2 ]GA9 in both the shoot and the treated leaf. In addition, [2 H2 ]GA1 and [2 H2 ]GA29 were also identified as metabolites of [2 H2 ]GA9 . These results are consistent with the hypothesis that exogenous GA, promotes shoot elongation in Salix through its metabolism to GA20 and GA,. 相似文献
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C.E. DEANE-DRUMMOND 《Plant, cell & environment》1985,8(2):105-110
Abstract. Net NO3 uptake by NO− 3 deficient Chara cells was used to calculate [NO− 3 ]c assuming that the cytoplasm occupies 10% total volume and that nitrate reduction and storage are negligible (i.e. maximum [NO− 3 ]c was calculated). A linear relationship was found between NO− 3 efflux and [NO− 3 ]c . There was an initial burst of NO− 3 efflux when NH+ 4 was added, followed by a slower efflux rate which matched influx rate such that net NO− 3 uptake was zero. Over 50% of NO− 3 that had been taken up in 2 h was lost within the first 5 min of NH+ 4 addition. The Nernst equation was used to predict the direction of the electrochemical driving force for NO− 3 entry. Under the experimental conditions used NO− 3 efflux is actively transported. The differential involvement of both NO− 3 influx and NO− 3 efflux in the regulation of NO− 3 uptake is discussed and a model is proposed to account for these results which envisages discrete NO− 3 influx and NO− 3 efflux carriers. 相似文献
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Abstract: We studied the action of H2 O2 on the exocytosis of glutamate by cerebrocortical synaptosomes. The treatment of synaptosomes with H2 O2 (50–150 µ M ) for a few minutes results in a long-lasting depression of the Ca2+ -dependent exocytosis of glutamate, induced by KCl or by the K+ -channel inhibitor 4-aminopyridine. The energy state of synaptosomes, as judged by the level of phosphocreatine and the ATP/ADP ratio, was not affected by H2 O2 , although a transient decrease was observed after the treatment. H2 O2 did not promote peroxidation, as judged by the formation of malondialdehyde. In indo-1-loaded synaptosomes, the treatment with H2 O2 did not modify significantly the KCl-induced increase of [Ca2+ ]i . H2 O2 inhibited exocytosis also when the latter was induced by increasing [Ca2+ ]i with the Ca2+ ionophore ionomycin. The effects of H2 O2 were unchanged in the presence of superoxide dismutase and the presence of the Fe3+ chelator deferoxamine. These results appear to indicate that H2 O2 , apparently without damaging the synaptosomes, induces a long-lasting inhibition of the exocytosis of glutamate by acting directly on the exocytotic process. 相似文献
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Low-K+ , high-Na+ cells of strain RL21a of Neurospora crassa , in steady state with 25 m M Na+ , were used to study K+ /Na+ exchanges in the presence or absence of Ca2+ and Mg2+ . In the presence of Ca2+ and Mg2+ , a low concentration of K+ (0.3 m M ) triggered a rapid exchange, but in the absence of the divalents, a high K+ concentration (30 m M ) was required to initiate the exchange at a rapid rate. In the absence of Ca2+ and Mg2+ , K+ uptake did not occur at low K+ concentration, internal K+ did not regulate Na+ influx in the presence of external K+ , and the efflux of Na+ proceeded at maximum activity at very low-K+ contents. 相似文献
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Na+ influx and efflux in Neurospora crassa RL21a can be studied separately to calculate net Na+ movements. In the absence of external K+ , Na+ influx was independent of the K+ content of the cells, but when K+ was present, the inhibition of Na+ influx by external K+ was higher the higher the K+ content. Efflux depended on the K+ and Na+ content, and on the history of the cells. Efflux was higher the higher the Na+ and K+ contents, and, in low-K+ cells, the efflux was also higher in cells grown in the presence of Na+ than when Na+ was given to cells grown in the absence of Na+ . Addition of K+ to cells in steady state with external Na+ resulted in a net Na+ -loss. In cells grown without Na+ this loss was a consequence of the inhibition of Na+ influx. In Na+ -grown cells, addition of K+ inhibited Na+ influx and increased Na+ efflux. 相似文献
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Addition of small amounts of Fe2 + , Zn2 + , Cu2 + and thiamine-HCl to the culture medium was required for promoting the galacto-oligosaccharide (Gal-OS)-producing activity of Sterigmatomyces elviae CBS8119, when the concentration of yeast extract in the medium was lowered to 0·1 g l−1 . Galacto-oligosaccharide production using a recycling cell culture was performed in a medium containing 360 mg ml−1 of lactose supplemented with optimal concentrations of Fe2 + (1·5 mg l−1 of FeSO4 .7H2 O), Zn2 + (15 mg l−1 of ZnSO4 .7H2 O), Cu2 + (0·5 mg l−1 of CuSO4 .5H2 O) and thiamine-HCl (1 mg l−1 ) . Galacto-oligosaccharide production was maintained at high levels during six cycles of production, with the amount of Gal-OS produced in each cycle being more than 216 mg ml−1 (weight yield of more than 60%). 相似文献
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In higher plant cells, there are some enzymes capable of utilizing pyrophosphate (PPi ) as an energy donor. Among these, membrane-bound proton pumping pyrophosphatases (H+ -PPi ase) have been identified. In addition to the well-known vacuolar H+ -PPi ase (V-PPi ase), there is evidence for the presence of a mitochondrial H+ -PPi ase. This enzyme is localized on the inner surface of the inner membrane and catalyzes the specific hydrolysis of PPi , coupled to proton transport, with a H+ /PPi stoichiometry of ca 2. This activity is Mg2+ -requiring, is stimulated by monovalent cations, and is inhibited by Ca2+ , F− and diphosphonates. The H+ -PPi ase contains a catalytic head which is constituted by a 35-kDa protein which is loosely bound to the inner membrane. This protein exhibits a PPi ase activity, stimulated by phospholipids, with characteristics very similar to the membrane-bound enzyme. The mitochondrial PPi ase is distinct from the V-PPi ase, because an antibody raised against the 35-kDa protein does not react with tonoplast membranes. The mitochondrial H+ -PPi ase seems to have an F-type structure, similar to the F-ATP synthase and the membrane-bound PPi ases from mammalian and yeast mitochondria. It is suggested that, beside synthesizing PPi , this enzyme may act as a buffer for the electrochemical proton gradient, by hydrolyzing PPi, during conditions of oxygen deprivation. 相似文献
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MICHAEL J. LINKE ALAN A. ASHBAUGH JUDITH V. KOCH LINDA LEVIN REIKO TANAKA PETER D. WALZER 《The Journal of eukaryotic microbiology》2009,56(1):58-65
ABSTRACT. We examined the effects of surfactant protein A (SP-A), a collectin, on the interaction of Pneumocystis murina with its host at the beginning, early to middle, and late stages of infection. Pneumocystis murina from SP-A wild-type (WT) mice inoculated intractracheally into WT mice (WTS -WTR ) adhered well to alveolar macrophages, whereas organisms from SP-A knockout (KO) mice inoculated into KO mice (KOS -KOR ) did not. Substitution of WT mice as the source of organisms (WTS -KOR ) or recipient host macrophages (KOS -WTR ) restored adherence to that found with WTS -WTR mice. In contrast, when immunosuppressed KO and WT mice were inoculated with P. murina from a homologous source (KOS -KOR , WTS -WTR ) or heterologous source (WTS -KOR , KOS -WTR ) and followed sequentially, WTS -KOR mice had the highest levels of infection at weeks 3 and 4; these mice also had the highest levels of the chemokine macrophage inflammatory protein-2 and neutrophils in lavage fluid at week 3. Surfactant protein-A administered to immunosuppressed KOS -KOR mice with Pneumocystis pneumonia for 8 wk as a therapeutic agent failed to lower the organism burden. We conclude that SP-A can correct the host immune defect in the beginning of P. murina infection, but not in the middle or late stages of the infection. 相似文献
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光下最大荧光(Fm′)是植物生理生态研究中的重要参数,一般采用饱和脉冲(RF)方案来估计.然而,光系统Ⅱ(PSⅡ)受体库的反馈调节会影响RF方案对Fm′估计的准确性.为消除PSⅡ受体库反馈调节的影响,根据光脉冲强度(Q′)与叶绿素荧光(F′)的线性关系提出多相脉冲(MPF)方案,估算Q′无穷大时的F′(即Fm′).本研究采用MPF和RF方案分别对苦槠、青冈和乌桕3个树种叶片的叶绿素荧光和气体交换数据进行同步测量,并对两种方案估计的Fm′及其计算参数PSⅡ光化学效率(ΦPSII)、PSⅡ的电子传递速率(J)、最大电子传递速率(Jmax)、叶肉导度(gm)和叶绿体内CO2浓度(Cc)等光合参数进行比较,分析两种方案对3个树种叶片6个光合参数的影响.结果表明: 当光合有效辐射(PAR)<200 μmol·m-2·s-1时,两种方案对苦槠、青冈和乌桕叶片Fm′、ΦPSII和J的估计无显著影响;当PAR>200 μmol·m-2·s-1时,采用MPF方案获得的苦槠、青冈和乌桕的Fm′分别比RF方案获得的Fm′高3.5%~5.2%、11.7%~18.0%和3.2%~7.1%;当PAR>200 μmol·m-2·s-1时,采用MPF方案获得的ΦPSII、J和Jmax分别不同程度地大于RF方案获得的参数,gm和Cc分别不同程度地小于RF方案获得的参数.说明当PAR较低(<200μmol·m-2·s-1)时,MPF与RF方案对植物叶片Fm′、ΦPSII、J的估计没有显著影响;当PAR较高(≥200μmol·m-2·s-1)时,MPF与RF方案对植物叶片Fm′、ΦPSII、J、Jmax、gm和Cc的估计有显著影响,且RF方案对植物叶片的Fm′、ΦPSII、J和Jmax比MPF方案分别有不同程度的低估,对gm和Cc则有不同程度的高估. 相似文献
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繁殖是植物生命活动的重要环节, 了解植物的繁殖特征是解释植物生态适应性和制定有效管理措施的重要依据。该研究以荒漠草原猪毛蒿(Artemisia scoparia)种群为研究对象, 通过测定不同土壤类型的理化性质和猪毛蒿的繁殖特征, 以期探讨影响其繁殖特征的主要土壤驱动因子。结果表明: 灰钙土、风沙土和基岩风化残积土的水溶性碳含量、全氮含量、全磷含量、全盐含量、土壤水分含量、土壤硬度存在显著差异。猪毛蒿平均个体大小、单株头状花序的平均质量和数量均以灰钙土生境下最大, 基岩风化残积土最小。繁殖分配在不同土壤类型下无显著差异, 但与单个头状花序质量、单株头状花序数量和质量间呈极显著正相关关系。单株头状花序数量与单个头状花序质量间呈负相关关系。在风沙土生境下, 单株头状花序质量主要受到土壤水溶性碳含量、土壤水分含量以及pH值的共同影响; 单株头状花序数量受全盐含量的影响最大; 繁殖分配和单个头状花序质量主要受全碳含量的影响。灰钙土生境下, 单株头状花序质量与土壤水溶性碳含量、土壤水分含量和有机碳含量呈正相关关系; 速效氮含量显著影响着单株头状花序数量。而基岩风化残积土生境下, 繁殖特征的变异主要受到土壤水溶性碳含量、土壤硬度、土壤水分含量、全磷和速效磷含量的影响。综合分析发现, 土壤因子对猪毛蒿繁殖特征的影响程度不同, 其中单株头状花序数量和质量极显著地受到土壤水溶性碳含量和土壤水分含量的影响, 繁殖分配和单个头状花序质量与土壤水溶性碳含量、土壤水分含量呈负相关关系。因此, 土壤水溶性碳含量和土壤水分是荒漠草原地区影响猪毛蒿种群繁殖特征的主要土壤因子。 相似文献
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1,10-Phenanthroline-5,6-dione (C12H6N2O2 (1)) reacts with V(η6-mesitylene)2 and Ti(η6-toluene)2 affording coordination compounds of general formula M(O,O′---C12H6N2O2)3 (M=Ti (2); M=V (3)) which further react with TiCl4 or TiCp2(CO)2 yielding the tetrametallic species M(O,O′---C12H6N2O2---N,N′)3(M′Ln)3 (M=V, M′Ln=TiCl4 (4); M=Ti, M′Ln=TiCp2 (5); M=V, M′Ln=TiCp2 (6)). The complex salt [Fe(N,N′---C12H6N2O2)3][PF6]2 (7) has been obtained from iron(II) chloride tetrahydrate and 1 in the presence of NH4PF6. The reaction of 7 with TiCp2(CO)2 affords the tetrametallic derivative [Fe(N,N′---C12H6N2O2---O,O′)3(TiCp2)3][PF6]2 (8). TiCl2(THF)2 reacts with MCp2(O,O′---C12H6N2O2) to give MCp2(O,O′---C12H6N2O2---N,N′)TiCl2 (M=Ti (9); M=V (10)). By reaction of TiCp2(O,O′---C12H6N2O2---N,N′)TiCl2 (9) with C12H6N2O2, the bimetallic derivative TiCp2(O,O′---C12H6N2O2---N,N′)TiCl2(O,O′---C12H6N2O2) (11) has been prepared, which readily adds to TiCl4, to give the trimetallic titanium derivative TiCp2(O,O′---C12H6N2O2---N,N′)TiCl2(O,O′---C12H6N2O2---N,N′)TiCl4 (12). VCp2(O,O′---C12H6N2O2---N,N′)TiCl2 (10) reacts with the tris-chelate iron(II) cation 7 affording the heptametallic cationic complex [Fe(N,N′---C12H6N2O2---O,O′)TiCl2(N,N′---C12H6N2O2---O,O′)VCp2]3 +2 isolated as the hexafluorophosphate 13. 相似文献
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Root ammonium transport efficiency as a determinant in forest colonization patterns: an hypothesis 总被引:3,自引:0,他引:3
H. J. Kronzucker M. Y. Siddiqi A. D. M. Glass D. T. Britto 《Physiologia plantarum》2003,117(2):164-170
Ratios of ammonium (NH4 + ) to nitrate (NO3 – ) in soils are known to increase during forest succession. Using evidence from several previous studies, we hypothesize that a malfunction in NH4 + transport at the membrane level might limit the persistence of early successional tree species in later seral stages. In those studies, 13 N radiotracing was used to determine unidirectional fluxes and pool sizes of NH4 + and NO3 – in seedlings of the late-successional species white spruce ( Picea glauca ) and in the early successional species Douglas-fir ( Pseudotsuga menziesii var. glauca ) and trembling aspen ( Populus tremuloides ). At high external NH4 + , the two early successional species accumulated excessive NH4 + in the root cytosol, and exhibited high-velocity, low-efficiency (15% to 22%), membrane fluxes of NH4 + . In sharp contrast, white spruce had low cytosolic NH4 + accumulation, and lower-velocity but much higher-efficiency (65%), NH4 + fluxes. Because these divergent responses parallel known differences in tolerance and toxicity to NH4 + amongst these species, we propose that they constitute a significant driving force in forest succession, complementing the discrimination against NO3 – documented in white spruce (Kronzucker et al. 1997). 相似文献
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Eric N. Powell George M. Staff Robert J. Stanton Jr W. Russell Callender 《Lethaia: An International Journal of Palaeontology and Stratigraphy》2001,34(2):97-118
We evaluate onshore-offshore trends in age-frequency distributions and trophic transfer efficiencies using 11 modern death assemblages off the Texas coast. Trophic transfer efficiencies within trophic levels offer little insight over that achieved by a size-frequency distribution. Production/biomass ratios will always be 1 in the fossil record. Within trophic-level estimates of paleogrowth efficiency, the ratio of paleoproduction to paleoingestion (Piglt/Iilt where i indicates the ith trophic level and lt indicates the time-averaged value) follow the expected ecological trend precisely in that paleogrowth efficiency is consistently higher in primary consumers than in predators in all 11 death assemblages. Paleoutilization efficiency, the ratio of predator paleoingestion to prey paleoproduction, I2lt°/P1glt°, may provide information on the degree of bias in the preservation of primary (1 °) and secondary (2 °) consumer trophic groups. I2lt°/P1glt° fell below 0.1 in most cold-seep and bay assemblages, indicating a large surplus of primary consumers. In sharp contrast, I2lt°/P1glt° 相似文献
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J. Hojný 《Animal genetics》1973,4(3):161-168
The haemolytic reagent allowing direct serological detection of He homozygous pigs was obtained by the immunization of a Landrace sow. Another monospecific reagent prepared from immune serum of a Miniature pig made possible the evidence for a new factor of the H system - He. This factor is genetically controlled by the allele H be . Its frequency in Miniature pigs was 0.099.
The H system with alleles H1 =Ha , H2 = Hb , H3 = Hab , H4 =Hcd , H5 = Hbd , H6 =Hbe and H7 = H- continues to be a genetically open system. 相似文献
The H system with alleles H