Rapid reversal of a potentially constraining genetic covariance between leaf and flower traits in Silene latifolia

Genetic covariance between two traits generates correlated responses to selection, and may either enhance or constrain adaptation. Silene latifolia exhibits potentially constraining genetic covariance between specific leaf area (SLA) and flower number in males. Flower number is likely to increase via fecundity selection but the correlated increase in SLA increases mortality, and SLA is under selection to decrease in dry habitats. We selected on trait combinations in two selection lines for four generations to test whether genetic covariance could be reduced without significantly altering trait means. In one selection line, the genetic covariance changed sign and eigenstructure changed significantly, while in the other selection line eigenstructure remained similar to the control line. Changes in genetic variance–covariance structure are therefore possible without the introduction of new alleles, and the responses we observed suggest that founder effects and changes in frequency of alleles of major effect may be acting to produce the changes.     

How reinforcer type affects choice in economic games

Behavioral economists stress that experiments on judgment and decision-making using economic games should be played with real money if the results are to have generality. Behavior analysts have sometimes disputed this contention and have reported results in which hypothetical rewards and real money have produced comparable outcomes. We review studies that have compared hypothetical and real money and discuss the results of two relevant experiments. In the first, using the Sharing Game developed in our laboratory, subjects' choices differed markedly depending on whether the rewards were real or hypothetical. In the second, using the Ultimatum and Dictator Games, we again found sharp differences between real and hypothetical rewards. However, this study also showed that time off from a tedious task could serve as a reinforcer every bit as potent as money. In addition to their empirical and theoretical contributions, these studies make the methodological point that meaningful studies may be conducted with economic games without spending money: time off from a tedious task can serve as a powerful reward.     

黔东棉金钢钻的种类及其发生规律初步调查研究

黔东铜仁专区的思南、印江等地年平均温度18℃左右,年雨量1,000毫米以上,为贵州主要棉区。目前棉花生产中存在的重大问题之一是金钢钻的为害造成蕾铃大量脱落。为了准确掌握其发生为害时期,及时消灭其为害,经在思南棉区调查研究。已初步明确了其种类与发生规律,并据此进行了预测预报而在1959年大面积防治中起到了一定的作用。     

A Metabolite-Sensitive, Thermodynamically Constrained Model of Cardiac Cross-Bridge Cycling: Implications for Force Development during Ischemia

We present a metabolically regulated model of cardiac active force generation with which we investigate the effects of ischemia on maximum force production. Our model, based on a model of cross-bridge kinetics that was developed by others, reproduces many of the observed effects of MgATP, MgADP, Pi, and H⁺ on force development while retaining the force/length/Ca²⁺ properties of the original model. We introduce three new parameters to account for the competitive binding of H⁺ to the Ca²⁺ binding site on troponin C and the binding of MgADP within the cross-bridge cycle. These parameters, along with the Pi and H⁺ regulatory steps within the cross-bridge cycle, were constrained using data from the literature and validated using a range of metabolic and sinusoidal length perturbation protocols. The placement of the MgADP binding step between two strongly-bound and force-generating states leads to the emergence of an unexpected effect on the force-MgADP curve, where the trend of the relationship (positive or negative) depends on the concentrations of the other metabolites and [H⁺]. The model is used to investigate the sensitivity of maximum force production to changes in metabolite concentrations during the development of ischemia.     

Invalidation of Hyperamoeba by Transferring its Species to Other Genera of Myxogastria

ABSTRACT. The genus Hyperamoeba Alexeieff, 1923 was established to accommodate an aerobic amoeba exhibiting three life stages—amoeba, flagellate, and cyst. As more species/strains were isolated, it became increasingly evident from small subunit (SSU) gene phylogenies and ultrastructure that Hyperamoeba is polyphyletic and its species occupy different positions within the class Myxogastria. To pinpoint Hyperamoeba strains within other myxogastrid genera we aligned numerous myxogastrid sequences: whole small subunit ribosomal (SSU or 18S rRNA) gene for 50 dark‐spored (i.e. Stemonitida and Physarida) Myxogastria (including a new “Hyperamoeba”/Didymium sequence) and a ～400‐bp SSU fragment for 147 isolates assigned to 10 genera of the order Physarida. Phylogenetic analyses show unambiguously that the type species Hyperamoeba flagellata is a Physarum (Physarum flagellatum comb. nov.) as it nests among other Physarum species as robust sister to Physarum didermoides. Our trees also allow the following allocations: five Hyperamoeba strains to the genus Stemonitis; Hyperamoeba dachnaya, Pseudodidymium cryptomastigophorum, and three other Hyperamoeba strains to the genus Didymium; and two further Hyperamoeba strains to the family Physaridae. We therefore abandon the polyphyletic and redundant genus Hyperamoeba. We discuss the implications for the ecology and evolution of Myxogastria, whose amoeboflagellates are more widespread than previous inventories supposed, being now found in freshwater and even marine environments.     

黄芪甲苷对人骨髓间充质干细胞体外增殖及细胞因子表达的影响

目的：探讨黄芪甲苷对人骨髓间充质干细胞体外增殖及细胞因子表达的影响。方法：采用Percoll密度离心法和贴壁法分离纯化hBMSC;流式细胞术检测hBMSC表面标志;MTT法检测不同浓度黄芪甲苷干预72h后hBMSC的增殖情况;Real-timePCR法检测经黄芪甲苷干预后hBMSC对SCF、VEGF、SDF-1、GM-CSFmRNA的表达水平。结果：成功分离培养出laBMSC;不同浓度（20、40、80、160、320mg／mL）的黄芪甲苷可促进hBMSC增殖（P〈0．05）,其中160mg／mL组促增殖最明显;黄芪甲苷可促进hBMSC对SCF、VEGF、SDF-1mRNA的表达,而GM—CSFmRNA表达无明显变化。结论：黄芪甲苷可促进hBMSC体外增殖,可能与其促进hBMSC对SCF、VEGF、SDF-1mRNA表达有关。     

Radiation capture and conversion efficiencies of Miscanthus sacchariflorus,M. sinensis and their naturally occurring hybrid M. × giganteus

Miscanthus is a rhizomatous C4 grass of great interest as a biofuel crop because it has the potential to produce high yields over a wide geographical area with low agricultural inputs on marginal land less suitable for food production. At the moment, a clonal interspecific hybrid Miscanthus × giganteus is the most widely cultivated and studied in Europe and the United States, but breeding programmes are developing newer more productive varieties. Here, we quantified the physiological processes relating to whole season yield in a replicated plot trial in Wales, UK. Light capture and conversion efficiency were parameterized for four carefully selected genotypes (M. sinensis, M. sacchariflorus and Miscanthus × giganteus). Differences in the canopy architecture in mature stands as measured by the extinction coefficient (k) were small (0.55–0.65). Sensitivity analysis on a mathematical model of Miscanthus was performed to quantify the accumulative intercepted photosynthetically active radiation (iPAR) in the growing season using (i) k, (ii) variation in the thermal responses of leaf expansion rate, (iii) base temperature for degree days and (iv) date start of canopy expansion. A 10% increase in k or leaf area per degree day both had a minimal effect on iPAR (3%). Decreasing base temperature from 10 to 9 °C gave an 8% increase in iPAR. If the starting date for canopy expansion was the same as shoot emergence date, then the iPAR increases by 12.5%. In M. × giganteus, the whole season above ground and total (including below ground) radiation‐use efficiency (RUE) ranged from 45% to 37% higher than the noninterspecific hybrid genotypes. The greater yields in the interspecific hybrid M. × giganteus are explained by the higher RUE and not by differences in iPAR or partitioning effects. Studying the mechanisms underlying this complex trait could have wide benefits for both fuel and food production.     

Widespread polyphyly among Alopiinae snail genera: when phylogeny mirrors biogeography more closely than morphology

Consider a group of species that is evenly divided by an easily identifiable complex morphological character. Most biologists would assume that this character should provide better phylogenetic information than, say, the spatial distribution of these species over a fairly continuous 500-km radius area. Paradoxically, this is not the case among terrestrial snail genera in the clausiliid subfamily Alopiinae. Phylogenetic analysis using the nuclear markers ITS1/ITS2 and mitochondrial markers COI/12S reveals widespread homoplasy in the clausilial apparatus (a complex aperture-closing mechanism), and concomitant extensive polyphyly among Carinigera, Isabellaria, and Sericata. In contrast, phylogenetic relationships as revealed by molecular data are closely congruent with biogeography at a relatively small scale. A combination of extremely low vagility and extremely high morphological convergence has conspired to produce this unexpected result. Implications as to the function of the clausilial apparatus are discussed.     

A two-component modular approach for enhancing T-cell activation utilizing a unique anti-FcgammaRI-streptavidin construct and microspheres coated with biotinylated-antigen

The professional antigen presenting cell (APC) plays an essential role in the initiation and propagation of the acquired immune response. Thus, much work has been done in designing strategies that target vaccine antigen (Ag) to APC. Utilizing recombinant DNA technology, we have created a unique two-component system that delivers biotinylated Ag to the Fc gamma receptor type I (FcgammaRI) on APC. Our studies demonstrate that we can successfully engineer FcgammaRI-specific targeting element proteins that simultaneously bind both biotin and recognize FcgammaRI. Additionally, we are able to engineer biotinylated Ag, which form functional elements when adsorbed onto latex microspheres. Furthermore, the targeting and functional element components bind to each other and successfully form two-component immunogens. T-cell activation in response to targeted Ag-laden microspheres is 10- to 100-fold greater than the response to the non-targeted Ag-laden microspheres. This enhancement is 100- to 1000-fold greater than the responses generated to soluble Ag. Thus, our results suggest that specific targeting of Ag-laden microspheres to FcgammaRI may significantly enhance the adjuvant properties of microparticulate delivery systems. Further development of this system may help to elucidate the mechanisms involved in generating enhanced responses to APC-targeted vaccines and significantly advance vaccine technology.