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1.
R. K. Chesser  R. J. Baker 《Genetics》1996,144(3):1225-1235
Models to determine the temporal dynamics and spatial heterogeneity for maternally and paternally inherited genes were derived for populations that may or may not exhibit spatial subdivision. Results were compared to those for diparentally inherited genes. The models permit definition of parameters for mean and variance of litter sizes, breeding group (subpopulation) sizes, and numbers of female mates per male, dispersal rates, and multiple paternity. Exact solutions for asymptotic effective size and spatial divergence (F(LS)) for maternal and paternal genes are derived. It is shown that solutions for effective size and F(LS) are transformations of the same quadratic equation. When compared to values for diparentally inherited genes, it is shown that effective sizes for maternal genes may be considerably higher when female dispersal is low as in many mammalian taxa. Likewise, effective sizes for paternal genes may be higher than for diparentally inherited traits when male dispersal is relatively low, as in many species of birds. The traditional assumption that the effective size for maternal genes is approximately equal to the number of females is seldom realized. Spatial heterogeneity and temporal dynamics of genes are inextricably linked as is shown by the interdependency of effective size and spatial heterogeneity.  相似文献   

2.
Summary Acetylene was reduced to ethylene by effective white clover nodules and by fully and partially effective intact nodules, nodule homogenates, and bacteroids of soybeans. Succinate and several amino acids markedly stimulated the reduction by effective soybean bacteroids, but the stimulation was slight with partially effective bacteroids. Acetylene metabolism by effective soybean bacteroids was also enhanced by excretions of in vitro-grown Rhizobium japonicum, excretions of bacteria derived from effective and ineffective nodules, and the soluble fraction from these nodules. Inhibitors of nitrogen fixation were not found in ineffective nodules. Ineffective soybean and white clover nodules and homogenates or isolated bacteria from ineffective soybean nodules did not reduce acetylene. Additions of succinate, amino acids, the soluble fraction of effective nodules, or excretions of effective bacteroids or of in vitro-grown cells of an effective R. japonicum strain did not promote nitrogen fixation by bacterial cells obtained from ineffective soybean nodules.  相似文献   

3.
香椿的休眠特性与生产应用   总被引:4,自引:0,他引:4  
香椿萌发所需的有效积温一般随着温度的降低而不断增加;香椿于落叶前和落叶后移栽对萌芽时间和所需有效积温影响不大,香椿休眠属于非生理性休眠类型;恒温比变温处理萌发时间明显缩短;伤根处理萌发期推迟和有效积温增加.  相似文献   

4.
Various cytokinins and purines were ineffective in reversing glyphosate (0.25 millimolar)-induced growth inhibition of carrot (Daucus carota L.) cell suspension cultures. Aspartate was particularly effective in reversing glyphosate inhibition, but asparagine and various combinations of lysine, methionine, threonine, and homoserine (eventual products of aspartate metabolism) were not effective. When organic acids of the tricarboxylic acid cycle were added to the medium, particularly good reversal of inhibition could be obtained with α-ketoglutarate, succinate, and malate. Citrate provided only moderate reversal but the reversal given by glutamate was comparable to that of aspartate and the more effective tricarboxylic acid cycle intermediates. Pyruvate was somewhat toxic to cells when added early in the cell cycle but was most effective at reversing glyphosate inhibition when added at this time. If pyruvate addition was delayed, it was less toxic but was also a less effective reversing agent for glyphosate inhibition.  相似文献   

5.
Abstract: The effects of 17 nucleotides and nucleotide analogs and 11 other compounds on the glutamate-promoted inactivation of brain glutamate decarboxylase were examined. Among the nucleotides, the major determinant of potency was the polyphosphate chain, Glutamate-promoted inactivation was strongly enhanced by low concentrations (<100 μM) of adenosine tetraphosphate and all eight nucleoside triphosphates tested. Nucleoside diphosphates enhanced inactivation, but were much less effective than the nucleoside triphosphates; nucleoside monophosphates were not effective. Modification of the polyphosphate chain of the nucleoside triphosphates also affected potency; adenylylimidodiphosphate and α,β-methylene ATP were about as effective as nucleoside diphosphates, but α,β-methylene ATP was nearly as effective as ATP. The nucleoside base had only a small effect on potency; purine nucleotides were more potent than pyrimidine nucleotides, and one nucleotide with a tricyclic base, 1, N6-etheno ATP, was as effective as the purine nucleoside triphosphates. The 2'-hydroxyl group of ribose was unimportant, since deoxy ATP was as effective as ATP. Three nonnucleotide polyanions were strong promoters of inactivation; inositol hexasulfate and 5-phosphorylribose 1-pyrophosphate were at least as effective as ATP; inositol hexaphosphate (phytate) was as effective as the nucleoside diphosphates. These results suggest that a major determinant of potency was a strong negative charge on the molecule. Negative charge was not sufficient, however, since fructose 1,6-bisphosphate did not promote inactivation. Inactivation by all of these compounds was slow, requiring more than 20 min for full effect. Two competitive inhibitors, chloride and glutarate, acted immediately and also reduced rather than enhanced glutamate-promoted inactivation.  相似文献   

6.
Larsen U  Yan S 《Social biology》2000,47(1-2):34-50
This paper analyzes the age pattern of effective fecundability from populations with no evidence of deliberate fertility control using a new convolution model of fecundability. The analysis is based on a sample of Hutterite birth histories from the mid-20th century, and birth histories of French Canadians from the 17th and 18th centuries. The main findings are as follows: 1) the level of effective fecundability is higher among the French Canadians compared to the Hutterites; 2) effective fecundability peaks at age 20 for the Hutterites, and in the early to mid-20s for the French Canadians; 3) Hutterite effective fecundability declines almost linearly from age 20 to 45, and French Canadian effective fecundability declines slowly from its peak to the early 30s, and more rapidly at older ages; and 4) the duration of postpartum amenorrhea is longer for the French Canadians than for the Hutterites. Because of the shorter periods of postpartum amenorrhea the Hutterites have about the same average number of children as the French Canadians, even though the French Canadians have higher effective fecundability.  相似文献   

7.
PurposeTo evaluate the feasibility and accuracy of a model for tissue characterization with dual source computed tomography (DSCT).Methods and MaterialsA model for tissue characterization in CT was used with a parameterization of linear attenuation coefficients. Sixteen chemical substances with effective atomic numbers between 5.21 and 13.08 and electron densities between 2.20 and 4.12 x1023 electrons/cm3 were scanned at energies of 80 and 140 kV on a DSCT. From the reconstructed dual energy data sets, effective atomic numbers and electron densities of the substances were calculated.ResultsOur presented model using DSCT approximated the effective atomic numbers and effective electron densities of 16 substances very well. The measured effective atomic numbers deviated 3.4 ± 6.8% (R2 = 0.994) from theoretical effective atomic numbers. In addition, measured effective electron densities deviated ?0.6 ± 2.2% (R2 = 0.999) from theoretical effective electron densities.ConclusionEffective atomic numbers and effective electron densities can be determined with a high accuracy with DSCT. Therefore the model can be of potential benefit for clinical applications of quantitative tissue characterization with DSCT.  相似文献   

8.
《Plant and Soil》1971,35(1):39-45
Summary 1. Auxotrophic mutants of 2 strains ofRhizobium meliloti have been isolated: among them 4 are purine or pyrimidine-dependent (adenine, cytosine), 4 are sulfur amino acid-dependent (methionine, cysteine) and 3 glycine-dependent. 2. All of these mutants induce nodule formation on lucerne (variety ‘Du Puits’). 3. There are associations between nutritional requirements and effectiveness in nitrogen fixation on this host. All the amino acid-dependent mutants are effective. Glycine-dependent mutants are more effective than the wild-type strain, whereas cyste?ne and methionine-dependent mutants are as effective as the wild-type strain. On the other hand, purine and pyrimidine-dependent mutants are ineffective. 4. All the prototrophic revertants of ineffective auxotrophic strains are effective. Some of them are more effective than wild-type strain.  相似文献   

9.
目的观察解毒排毒泄毒消肿法内外合治蝮蛇咬伤的临床疗效。方法对2005年4月~2011年12月收治的611例蝮蛇咬伤患者采用中医药解毒排毒、泄毒消肿为主的综合治疗方法治疗,观察分析其临床疗效。结果 611例患者中,治愈553例,显效34例,有效22例,无效(死亡)2例,总有效率99.67%,痊愈率90.51%。结论解毒排毒泄毒消肿法内外合治蝮蛇咬伤具有良好的疗效。  相似文献   

10.
An ineffective Rhizobium leguminosarum strain capable of forming green nodules of similar size and number as normally effective strains was tested for its ability to compete with an effective strain in nodule formation on the pea. The ineffective strain was found to be more competitive and influenced the pattern of nodulation by the effective strain on the same root system. Nodules containing both strains were pink and able to reduce acetylene.  相似文献   

11.
锐劲特防治水稻二化螟的效果及技术   总被引:10,自引:0,他引:10  
范仰东  莫小平 《昆虫知识》1999,36(3):161-164
锐劲特对水稻三化螟有显著的防治效果。每 666.7m_2用锐劲特 30mL,防治适期较宽,最佳防治时间在1~2龄幼虫高峰期。使用不同防治方法都能有效控制二化螟为害。锐劲特对稻象甲成虫有很好的兼治效果。  相似文献   

12.
Genetic drift and estimation of effective population size   总被引:3,自引:2,他引:1       下载免费PDF全文
Nei M  Tajima F 《Genetics》1981,98(3):625-640
The statistical properties of the standardized variance of gene frequency changes (a quantity equivalent to Wright's inbreeding coefficient) in a random mating population are studied, and new formulae for estimating the effective population size are developed. The accuracy of the formulae depends on the ratio of sample size to effective size, the number of generations involved (t), and the number of loci or alleles used. It is shown that the standardized variance approximately follows the chi(2) distribution unless t is very large, and the confidence interval of the estimate of effective size can be obtained by using this property. Application of the formulae to data from an isolated population of Dacus oleae has shown that the effective size of this population is about one tenth of the minimum census size, though there was a possibility that the procedure of sampling genes was improper.  相似文献   

13.
A stereocontrolled synthetic route has been used to prepare two of the geometric isomers of all-trans-GGPP. Neither of these isomers is effective substrates for mammalian GGTase I, but 3 is a potent inhibitor of this enzyme (IC(50)=100 nM). Surprisingly, both compounds are effective substrates for mammalian FTase.  相似文献   

14.
双斑长跗萤叶甲Monolepta hieroglyphica(Motschulsky)已成为新疆北疆棉区的一重大新害虫,至今该虫各虫态的发育历期都不清楚。在室内5个恒温下(19,22,25,28和31℃),利用有效积温法则和"最小二乘法"对双斑长跗萤叶甲各虫态的发育起点温度和有效积温进行研究。结果表明,卵期、幼虫期、蛹期和产卵前期的发育起点温度分别为9.8,10.8,12.6和10.1℃;有效积温分别为1 182.2,401.2,111.9和269.0日.度;整个世代完成发育所需要的有效积温为1 971.6日.度,预测在新疆北疆1年发生1代。  相似文献   

15.
甘蓝型油菜若干农艺性状与单株产量的关系分析   总被引:12,自引:0,他引:12  
以38个甘蓝型油菜品种为材料,对单株产量、有效分枝部位高度、主轴花序长度等11个农艺性状进行了方差分析、通径分析和聚类分析.结果显示:所有调查性状在品种间存在显著的差异;主花序长度、主序有效角果数与单株产量都有显著的遗传相关性,两者都通过有效分枝部位高度对单株产量产生较大的正向间接作用;有效分枝部位高度对单株产量的影响也较显著,高产品种具有相对较高的有效分枝部位高度;总角果数对单株产量的直接遗传通径系数虽小,但它具有最大的直接表型通径系数,它通过主序有效角果数和有效分枝数对单株产量产生了两个较大的间接作用;要获得3130kg/hm~2的产量,重点应具备果多、枝多的特征,总角果数不少于657个,有效分枝数不少于18个.  相似文献   

16.
 In this note we calculate the effective drift velocities and the effective diffusivities of swimming microorganisms in an external flow field. It is shown that if the ambient velocity field is incompressible then the effects of reorientation of the cells can under certain circumstances enhance the effective drift velocity along the preferred direction. Received: 4 January 1999  相似文献   

17.
Two entomogenous fungi, Metarrhizium anisopliae and Beauveria bassiana, were cultured in liquid culture media containing various commercial peptone sources to determine the effect of the sources on growth and sporulation. Each fungus responded differently to the various peptone sources. Tryptone, Casitone, and yeast extract were effective for mycelial growth of M. anisopliae; however, yeast extract was the most effective in production of spores. Soytone Casitone, Neopeptone, and casein hydrolysate were used effectively for mycelial growth of B. bassiana, but the latter two were not as effective for production of spores. Gelatone and Peptone (Bacteriological) were not effective for production of growth or sporulation for either fungus.  相似文献   

18.
There is a simple relationship between the radioprotective effectiveness of sulfur-containing preparations and chemical structure of the compounds. It is established that the administration of the protector to the organism is just as effective as introduction of certain portion of information which should exceed some threshold for the effective radioprotectors.  相似文献   

19.
In this study, new Schiff bases and β-lactam derivatives containing morpholine and thio morpholine nuclei were synthesized. Antimicrobial, antioxidant, antimicrobial and antioxidant properties of all synthesized compounds were investigated and highly effective products were obtained. In this context, new effective structures were introduced to the literature.  相似文献   

20.
A halo-blight epidemic model based on the equation of Van der Plank (1963) is described. The model has been used to determine tolerance levels for seed infection and to compare the effectiveness of chemical control measures based on foliar sprays and seed treatments.
Reduction of primary inoculum, derived from infected seed, by disease exclusion through seed testing, or by chemical seed treatment will give effective disease control under British conditions (i.e. with an expected apparent infection rate ( r ) of 0.15 per infected plant per day). Under climatic conditions more favourable for the disease where higher r values would occur, control treatments directed against primary inoculum only would be less effective. Under such conditions, it is predicted that chemical sprays, which have no effect on primary inoculum but cause a reduction in the rate of disease increase, would be more effective. The most effective disease control, however, would be a combination of treatments.  相似文献   

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