Sampling strategies for using female gametophytes to estimate heterozygosity in conifers

Summary Unbiased estimators of genotype and allele frequencies and their respective variances are obtained for loci identified by mendelian segregation in haploid female gametophytes from individual trees. By a minimum sampling variance criterion, the allocation of experimental effort between the number of female gametophytes analysed per tree and the number of trees sampled per population is examined for a fixed total amount of experimental effort. For estimating heterozygosity, the optimum sampling design for many (generally most) cases is three female gametophytes per tree, but may be more than three depending upon the true genotype frequencies in the population. For estimating allele frequencies, the optimum sampling design is one female gametophyte per tree except in cases where a strong negative correlation exists between alleles within genotpyes. Guidelines are discussed for determining a suitable number of female gametophytes to be analysed per tree in order to estimate heterozygosity.     

Induction of Complementary Function Reductase Enzymes in Colon Cancer Cells by Dithiole‐3‐thione versus Sodium Selenite

Cellular induction of reductase enzymes can alter the susceptibility of cells toward drugs and chemicals. In this study, we compared the capacity of a single dose of sodium selenite and 3H‐1,2‐dithiole‐3‐thione (D3T) to influence the drug‐relevant reducing capacity of HT29 cells over time, and defined the protein‐specific contribution to this activity on the basis of selected reaction monitoring mass spectrometry. Thioredoxin reductase 1 (TrxR1) protein levels and activity were inducible up to 2.2‐fold by selenium. In contrast, selenium had only a minor influence on prostaglandin reductase 1 (PTGR1) and NAD(P)H:quinone oxidoreductase 1 (NQO1) activity and protein levels. D3T, a strong Nrf2 inducer, induced all the reductases and additionally increased the cytotoxicity of hydroxymethylacylfulvene, a bioreductive DNA‐alkylating drug. The data and experimental approaches allow one to define induction potency for reductase enzymes PTGR1, TrxR1, and NQO1 in HT29 cells and link these to changes in drug cytotoxicity.     

Modelling mate-finding Allee effects and populations dynamics,with applications in pest control

In this paper, we review how mate-finding Allee effects enter population dynamical models that consider both sexes, highlight possible limitations of the more widely used “one-sex” models, and outline the links between the different model classes. We further explore interactions between the mate-finding Allee effect and other mechanisms relevant to pest-control strategies: release of natural enemies, sterile male release, and culling. Many of these strategies impose an additional component Allee effect on the population, and we discuss which of them might be efficient in the control of pest species that also suffer from the failure to locate mates. We focus primarily on eradication thresholds; our simple models show that most of the strategies yield similar results, and depending on the costs, one strategy or a combination of several can lead to the most efficient control.     

磁性固位体可摘局部义齿咀嚼效能初探

目的分析可摘局部义齿患者在安置磁性固位体前、后对义齿咀嚼效能的变化。方法十四例患者在初戴义齿一个月后,再安放磁性固位体并分别测得其安放磁性固位体前、后的咀嚼效能值。结果十四例患者在安放磁性固位体前、后的吸光度均值分别为0.59和0.82,有显著性差异。结论采用磁性固位体的义齿能明显提高患者的咀嚼效能。     

我国体细胞克隆牛的研究进展

近年来,由于体细胞克隆技术在畜牧业生产、疾病治疗、生物学基础理论研究及濒危动物保护等诸多领域所蕴藏的巨大应用价值,克隆效率成为科学界研究的热点问题。本文对克隆技术的相关影响因素进行了综述,研究表明,不同细胞系影响到体细胞克隆牛效率,胎儿细胞和颗粒细胞重构胚的囊胚发育率、犊牛成活率比成年成纤维细胞高。关于卵母细胞和克隆胚胎冷冻保存的研究表明,玻璃化冷冻法可以用于克隆胚胎以及卵母细胞的冷冻保存。在此基础上,讨论了国际上哺乳动物体细胞克隆研究新进展和体细胞克隆的效率,指出体细胞克隆中亟待解决的问题。     

Energy cost and efficiency of sculling a Venetian gondola

Oxygen uptake was measured on four male subjects during sculling gondolas at constant speeds from approximately 1 to approximately 3 m.s-1. The number of scullers on board in the different trials was one, two or four. Tractional water resistance (drag, D, N) was also measured in the same range of speeds. Energy cost of locomotion per unit of distance (C, J.m-1), as calculated from the ratio of O2 uptake above resting to, increased with v according to a power function (C = 155.2.v1.67; r = 0.88). Also D could be described as a power function of the speed: D = 12.3.v2.21; r = 0.94). The overall efficiency of motion, as obtained from the ratio of D to C, increased with speed from 9.2% at 1.41 m.s-1 to 14.5% at 3.08 m.s-1. It is concluded that, in spite of this relatively low efficiency of motion, the gondola is a very economic means. Indeed, at low speeds (approximately 1 m.s-1), the absolute amount of energy for propelling a gondola is the same as that for waking on the level at the same speed for a subject of 70 kg body mass.     

Directed walk designs for dose-response problems with competing failure modes

We examine adaptive allocation designs for the problem of determining the optimal therapeutic dose for subjects in early-phase clinical trials. A subject can fail due to lack of efficacy or due to a toxic reaction. Successful subjects will have both a positive response and no toxic side effects. Thus, we seek to maximize the product of the nontoxicity and efficacy dose-response curves. We are interested in sampling rules that perform well along several criteria, including the ethical criterion that, as often as possible, experimental subjects be treated at or close to the maximum in question. Statistically, we wish to identify the optimum dose with high probability at the close of the experiment. Here, we propose designs that combine new allocation policies, directed walks, with new smoothed shape-constrained curve-fitting techniques. These are compared with a variety of other curve-fitting techniques and with up-and-down and equal allocation rules.     

Misconceptions About the Relation Between Plant Growth and Respiration

Abstract: The relation between plant growth rate and respiration rate is readily derived from the overall chemical reaction for aerobic metabolism. The derived relation can be used to show that separation of respiration into growth (g) and maintenance (m) components is not a useful concept. g and m cannot be unambiguously measured or defined in terms of biochemical processes. Moreover, because growth yield calculations from biochemical pathway analysis, from biomass molecular composition, from biomass heat of combustion, and from biomass elemental composition have not included all of the energy costs for biosynthesis, they are not accurate measures of the carbon cost for plant growth. Improper definitions of growth-respiration relations are impeding the use of physiological properties for prediction of plant growth as a function of environmental variables.     

几组有优和无优杂交组合中杂交稻及其亲本光合功能的比较

研究了３个杂交组合的杂交稻及其亲本的光合功能。实验结果表明,杂交稻的叶绿素（Ｃｈｌ）和类胡萝卜素（Ｃａｒ）的含量高于其亲本。在２组有优杂交组合中,杂交稻的ＰＳⅡ活性、ＰＳⅡ原初光能转化效率和叶片潜在光合作用量子转化效率,以及光合电子传递能力和对两个光系统之间激发能分配的调节能力,均高于其各自的亲本。此外,上述各光合功能又以母本优于父本。然而,在无优组合中,上述的光合功能却是父本高于母本和它们的子一代。根据所得的实验结果,进一步证实在配置杂交组合时,选择具有优良光合功能的母本,是获得在生产上可推广应用的杂交稻的重要途径之一。