Implications of the variance effective population size on the genetic conservation of monoecious species

The concept of variance effective population size [Ne_(v)] and other expressions are reviewed and described for specific sampling steps in germplasm collection and regeneration of monoecious species. Special attention is given to procedures for computing the variance of the number of contributed gametes [V(k)] to the next generation. Drift, as it occurs between generations, was considered to contain a component due to the sampling of parents and a subsequent component due to the sampling of gametes. This demonstrates that drift, caused by reduction of seed viability, damages the genetic integrity of accessions stored in germplasm banks. The study shows how mating designs, such as plant-to-plant or chain crossings with additional female gametic control, can partially alleviate this problem. Optimal procedures for increasing Ne_(v) when collecting germplasm in the field are also discussed. The effect of different female and male gametic control strategies on Ne_(v) is considered under several situations. Practical examples illustrating the use of V(k) and Ne_(v) expressions are given.     

New technique in optical resolutions

The present paper illustrates the development of an advanced technique in optical resolution. Both of the amphetamine enantiomers can be obtained by a two-step distillation in nearly quantitative yield without any loss of the resolving agent. It is proved that the second-order interactions (H-bond) are sufficient for separation of enantiomers by distillation. © 1994 Wiley-Liss, Inc.     

热带林茎流收集及计算方法探索

热带林茎流收集及计算方法探索周光益,吴仲民,李意德,陈步峰（中国林科院热带林业研究所,广州５１０５２０）ＣｏｌｌｅｃｔｉｏｎａｎｄＣａｌｃｕｌａｔｉｏｎＭｅｔｈｏｄｓｆｏｒＳｔｅｍｆｌｏｗｉｎＴｒｏｐｉｃａｌＦｏｒｅｓｔ．￥ＺｈｏｕＧｕａｎｇｙｉ;Ｗ...     

Analytical study of the effects of some soil and plant parameters on root growth due to absorption of one mobile ion: A free-boundary model

The object of our study is: a model for root growth through a free-boundary problem and the effects resulting from differences in nutrient availability and transport of only one mobile nutrient between the root surface and the rhizosphere produced by an absorption Michaelis-Menten for low and high concentrations. The model equations are solved by two methods: the quasi-stationary method and the balance integral method. The numerical solutions are used to compute radial root growth. Curves of nutrient concentration at the root-soil interface, curve as a function of root radius as well as curves representing root radius as a function of time are plotted. The parameters which are varied are the root absorption power, flux velocity at the root surface, efflux, rhizosphere radius, diffusion coefficient, buffer power, and maximum influx. The two methods show the theoretical results for radial root growth in the range of low and high concentrations. The balance integral method provides more detailed information.     

Bayesian analysis of linkage between genetic markers and quantitative trait loci. I. Prior knowledge

Summary Prior information on gene effects at individual quantitative trait loci (QTL) and on recombination rates between marker loci and QTL is derived. The prior distribution of QTL gene effects is assumed to be exponential with major effects less likely than minor ones. The prior probability of linkage between a marker and another single locus is a function of the number and length of chromosomes, and of the map function relating recombination rate to genetic distance among loci. The prior probability of linkage between a marker locus and a quantitative trait depends additionally on the number of detectable QTL, which may be determined from total additive genetic variance and minimum detectable QTL effect. The use of this prior information should improve linkage tests and estimates of QTL effects.     

水稻悬浮细胞的超低温保存研究

本研究分析了水稻悬浮细胞的生理状态和各种冷冻前处理等因素对超低温保存后细胞存活率的影响。结果表明,继代后培养3—5天,处于对数生长期的细胞,采用二步冷冻法,超低温保存后存活率最高。电镜超微结构观察显示,0.5mol/L山梨醇预培养,10%DMSO 0.5mol/L山梨醇复合保护剂处理,液泡显著变小,数目明显减少,从而降低了细胞内自由水含量,增强细胞的抗冷冻能力。在上述合适的前处理和冷冻-化冻条件下,超低温保存水稻悬浮细胞的恢复生长率为58%,恢复生长的细胞转移到分化培养基上,可再生健壮绿苗, 移植到盆钵,在温室中长成正常结实的植株。     

天花粉蛋白与FMP复合物的晶体结构

用浸泡法得到了天花粉蛋白（ＴＣＳ）与ＦＭＰ复合物的晶体,在ＳＩＭＥＮＮＳＸ－２００Ｂ面探测器系统上收集了一套２．０分辨率的Ｘ射线衍射数据。用同晶差值傅立叶法解析了复合物的结构,经Ｘ—ＰＬＯＲ程序修正得到了ＴＣＳ—ＦＭＰ复合物的分子结构并找出了１９７个水分子,最后的Ｒ因子为０．１７２,键长和键角的ＲＭＳ偏差分别为０．０１５和２．９２２度。ＴＣＳ—ＦＭＰ复合物中,ＦＭＰ与天花粉蛋白分子有较好的结合,其结合位置正处于根据三维结构和突变体信息推测的Ｎ一糖苷酶活性口袋之中。它的类嘌呤环夹在Ｙ７０和Ｙ１１１两个侧链环之间,与Ｙ７０环近乎平行,其Ｎ７和Ｎ６分别与ＴＣＳ分子的Ｇ１０９４羰基氧和Ｉ７１的Ｎ成氢键,Ｎ３靠近Ｒ１６３的侧链,其磷酸根则伸向活性口袋的底部,与Ｅ１８９、Ｅ１６０和Ｒ１６３等残基作用。     

农田林网化地区近地面层廓线特征研究

大面积林网化地区近地面层大气的系留气球观测发现,近地面层大气的风、温、湿分为两层,即下边界层和扰动边界层,其厚度和廓线分布与理查逊数有关,在中性天气条件下均满足对数分布规律,边界层（特别是扰动边界层）内的摩擦速度Ｕ．＂与旷野对比点的摩擦速度Ｕ０增大１个数量级,而粗糙度Ｚ＂０增大２个数量级,甚至更大。     

工业固体废弃物的急性生物毒性研究

工业固体废弃物的急性生物毒性研究谢思琴,顾宗濂,周德智（中国科学院南京土壤研究所,南京２１０００８）Ａｃｕｔｅｂｉｏｔｏｘｉｃｉｔｙｏｆｉｎｄｕｓｔｒｉａｌｓｏｌｉｄｗａｓｔｅｓ￥．ＸｉｅＳｉｑｉｎ;ＧｕＺｏｎｇｌｉａｎａｎｄＺｈｏｕＤｅｚｈｉ（Ｉｎ...