Response of Soybean [Glycine max (L.) Merr.] Cultivars to Genistein-Preincubated Bradyrhizobium japonicum: Nodulation and Dry Matter Accumulation under Canadian Short-Season Conditions

The addition of genistein, a plant-to-bacteria signal molecule, to Bradyrhizobium japonicum cells prior to use as inocula has been shown to increase nodule number and promote soybean N₂ fixation at low root zone temperatures. Previous greenhouse and field experiments involving only two cultivars have indicated that soybean [ Glycine max (L.) Merr.] cultivars can vary in their response to genistein application. The objective of this study was to evaluate a range of soybean cultivars for response to genistein application under short-season cool-spring Canadian conditions. A 2-year field study was conducted in 1997 and 1998 with a range of soybean cultivars recommended for Quebec. The 11 cultivars tested represented a range of yield potentials and maturity groups. They were inoculated with genistein-preincubated B. japonicum inocula or regular inocula, applied into the furrow at the time of planting. The results of these experiments indicated that neither maturity nor yield was correlated with increases in nodulation, biomass, and plant total nitrogen content resulting from genistein treatment and that all maturity groups responded to genistein application in essentially the same way. Thus, response of soybean cultivars to genistein addition is regulated by genotype characteristics other than maturity or yield level.     

Restriction endonuclease analysis of canine herpesviruses isolated in Japan

Eighteen canine herpesvirus (CHV) isolates from Japan and two reference strains were compared by restriction endonuclease analysis technique using total DNA extracts from cells infected with the viruses. In order to select the suitable restriction endonucleases for differentiation of CHV isolates, ten enzymes were used and three of them, HindIII, XbaI, and PvuII, were found to be useful for strain differentiation. With these enzymes, CHV isolates from unrelated individuals were readily differentiated from each other. In contrast, all the isolates derived from the same litter were not distinguishable on the basis of restriction cleavage patterns. However, slight mobility shifts were observed among the isolates from the same litter or the same individual. The results showed that this method provides a powerful tool for epidemiological surveys of CHV infection.     

Comparison between dialysis methods and centrifugation/filtration for collecting fecal fluid from calves

Faecal samples of different consistency from 15 calves were subjected to two methods to separate faecal fluid. Osmolality as well as the concentrations of electrolytes and short chain fatty acids were determined for each of the fluid samples obtained and the results compared. For dialysis the following procedure was used: small dialysis bags filled with dextran 10% were placed in the cooled (4 degrees C) faecal sample to which gentamycin was added to inhibit fermentation. Equilibrium between dialysate and surrounding fluid was reached after 24 hours. However, depending on the consistency of the faeces, after 6 hours 90 to 95% of the final osmolality at 24 hours was reached. In regard to osmolality, sodium, potassium and chloride concentrations as well as to concentrations of short chain fatty acids no significant differences could be observed between the faecal fluid obtained by dialysis or by centrifugation (3500 g, 20 min, 4 degrees C) and subsequent filtration. Distinctly higher concentrations of calcium and inorganic phosphate were measured in the filtrates; the probable explanation is that these ions in faeces are largely present as poorly diffusible compounds (in particular with faeces of a more solid consistency) or bound to the cell membranes.     

圆截面压电曲杆在冲击载荷作用下的动力响应

对三维压电圆截面曲杆受到冲击荷载时的动力响应进行了研究.在正交曲线坐标系中建立了压电圆环形曲杆中波传播的空间运动方程.通过Fourier级数展开对冲击应力进行模拟,结合已得到的频散关系和边界条件求出径向位移响应的波幅系数,再通过频散方程确定了各位移电势幅值系数之间的关系,得到曲杆受冲击荷载作用下的波幅系数.应用本构关系得到所需的应力、电势及位移响应.     

超越现代与后现代：构建课程的精神家园

课程在其发展史上从没建立起自身体系的精神家园。现代主义视野强调课程的统一，受到政府、课程专家的主宰；后现代视野强调课程的开放性、不确定性、整体性。大杂烩的课程理论不可能对实践产生指导作用。课程作为独立的体系，不能局限于以往的理论，而要超越现代主义与后现代主义，建立自己的精神家园。     

水稻粒型调控基因功能研究进展

水稻是世界上的重要谷类粮食作物之一，其产量和品质一直都是育种学家关注的重点，关系到全球粮食安全和人类健康。水稻粒型主要包括粒长、粒宽、粒厚等，是受多基因控制的重要数量性状，不仅直接影响水稻产量，还与水稻品质密切相关。深入了解水稻粒型的形成与调控机理将有助于进一步提升水稻单株产量、改善稻米品质。分子生物学的发展和基因组学的研究为探究水稻内部调控机制带来了新的变革。大量水稻粒型的数量性状遗传位点（Quantitative trait locus，QTL）成功被鉴定与解析，并验证了与之有关的基因功能。目前，已有几条调控粒型的通路得到鉴定，如泛素 - 蛋白酶体降解途径、G 蛋白信号途径、丝裂原活化蛋白激酶途径、转录因子调控途径、植物激素途径以及表观遗传途径等。然而，粒型调控网络极其复杂，多数基因上下游的调控组件作用机制尚不清楚，甚至影响粒型的各条通路间均存在一定的交叉互作。本文综述了影响水稻粒型的不同信号通路相关基因研究进展及关键粒型基因间的互作关系，总结了近年来粒型基因在育种上的应用情况，并提出结合多组学解析水稻粒型的调控机理研究，以期更好地服务于分子设计育种，为开发新的高产优质稻育种提供支撑。     

玉米生长与地面覆盖栽培试验

在广州秋播玉米采用稻草覆盖与地膜覆盖和无覆盖相比，稻草覆盖的玉米产量和穗行数性状明显优越，穗长，行粒数，穗粗，千料重等性状也有较好的趋势。稻草和黑色地膜覆盖，均可减少杂草萌发，稻草覆盖处理中萌发的杂草，仍然会不断生长，但个体数量已大大减少。     

不同超排时间对母羊冲胚数的影响研究

超数排卵是胚胎移植的重要环节,经辽宁省朝阳市10个肉羊场,夏洛莱、萨福克、德美、无角陶赛特和波尔山羊等484只超排羊只的超排试验,回收胚胎4752枚,其中可用胚3140枚,未受精卵1446枚,退化细胞166枚。经统计分析,9月中旬至11月上旬为超排最佳时间,主要表现为冲胎数多(平均冲胚数7.8枚/只~12.1枚/只),可用胚率高(平均达53.2%~77.7%)。     

维生素D_3疯狂上涨的背后

<正>1维生素D3价格的井喷也许没有多少人会想到,维生素D3———这个维生素大家族中的小品种会搅的整个饲料养殖行业如此躁动不安,突然无货可供,价格陡然飙升。2009年7月下旬,饲用级50万单位维生素D3粉的价格(下同)在50元/kg左右徘徊,虽显启动迹象,但市场关注度不高。当时有先见之明的市场人士预测,其价格可能在9月份升至300元/kg,但也