Ethylene and IAA interactions in the inhibition of photoperiodic flower induction of <Emphasis Type="Italic">Pharbitis nil</Emphasis>

It has been shown that both IAA and ethylene application inhibit flower induction in the short-day plant Pharbitis nil. However application of IAA has elevated ethylene production in this plant, as well. Strong enhancement of ethylene production is also correlated with the night-break effect, which completely inhibits flowering. In order to determine what the role of IAA and ethylene is in the photoperiodic flower induction in Pharbitis nil, we measured changes in their levels during inductive and non-inductive photoperiods, and the effects of ethylene biosynthesis and action inhibitors on inhibition of flowering by IAA. Our results have shown that the inhibitory effect of IAA on Pharbitis nil flowering is not physiological but is connected with its effect on ethylene biosynthesis.     

Effects of nitrous oxide on mitochondrial and cell respiration and growth in Distichlis spicata suspension cultures

The reversible inhibition of respiratory activity could provide a novel approach to the preservation of traditionally hard to store plant germplasm such as clonal materials and recalcitrant seed. The gaseous anesthetic nitrous oxide caused a reversible, dose-dependent, partial inhibition of dioxygen utilization in mitochondrial particles isolated from cell suspension cultures of the salt-tolerant marsh grass Distichlis spicata, with maximal inhibition of 33% after 30 minutes exposure to an atmosphere of 80% nitrous oxide plus 20% oxygen. Respiration of whole cells required longer time to be affected by the anesthetic, and was reversibly inhibited an average of 19% when measured using a differential respirometer. Exposure to 80% nitrous oxide plus 20% oxygen for up to 10 days caused no measurable effect on cell growth.Abbreviations PCV packed cell volume - EDTA sodium ethylenediaminetetraacetic acid - BSA bovine serum albumin - MOPS 3(N-morpholino) propanesulfonic acid - TMPD N,N,N',N'-tetramethyl-p-phenylene diamine - STP standard temperature and pressure     

Physiology of F-Pilin Synthesis and Utilization

Sodium dodecyl sulfate-polyacrylamide gel electrophoresis was used to study the synthesis and turnover of F-pilin in membrane preparations of Escherichia coli K-12 under conditions which have been reported to affect the production of F-pili. Incorporation of [³⁵S]methionine into membrane F-pilin by cells in log phase was barely detectable at 25°C, but increased with temperature. The labeled pilin band was prominent in membranes from 37°C cultures and even more prominent if the growth temperature was raised to 42°C. The appearance of other tra products in the membranes was similarly temperature dependent. In cultures grown in glucose minimal medium at 37°C, the relative amount of membrane pilin and traT product synthesis remained unchanged from early log phase through early stationary phase; provision of glycerol or arabinose as a substitute carbon source had no obvious effect. Turnover of traT product and membrane F-pilin, as assessed in an Flac tra mutant strain which is incapable of elaborating pili, was not rapid. Both traT product and pilin subunits labeled in mid-log phase cells were still apparent in the membranes after growth of the cells to stationary phase. The relative amount of labeled pilin decreased with prolonged incubation in stationary phase, but the relative amount of traT product did not decrease even after the culture was incubated for 24 h. When wild-type Flac piliated cells were used, a similar result was obtained, but in this case, loss of F-pilin from the preparations could be acclerated by blending the cells. Although intermittent blending during culture growth caused a slow depletion of the labeled pilin pool, continuous blending resulted in the rapid disappearance of this pool from our preparations. Loss of other membrane polypeptides was not accelerated by our blending procedure, and blending did not affect the turnover of the pilin pool of the Flac tra mutant. Our data are consistent with a model in which pilin subunits are assembled transiently into pili, conserved by retraction, and made available for subsequent reassembly. Growth in 0.01% sodium dodecyl sulfate did not accelerate loss of pilin from the Flac strain compared with the Flac tra strain, and we suggest that in the presence of sodium dodecyl sulfate at this concentration, F-pili are not elaborated from cell surfaces.     

我国微茎类吸虫研究:ⅩⅢ.微茎类吸虫成虫结构特征排序

对我国52种微茎类吸虫的18项成虫形态学特征进行主成分分析,结果表明:卵巢位置、子宫延伸位置等7项性状对第一主成分贡献较大,提示描述器官位置的指标是重要的分类依据。52个虫种在前三个主成分上的排序图显示应将其划分成4个亚科。     

柱萤叶甲属研究（Ⅰ）鞘翅具黑色刻点的种类记述（鞘翅目：叶甲科）

本文就萤叶甲亚科中柱萤叶甲属鞘翅具黑色刻点的种类进行研究,共记述４种,我国已记录３种,其中１种为新种。     

我国微茎类吸虫的研究Ⅻ.类茎属及多黄属二新种报道：复殖目：微茎科

本文报道在湛江市附近海域海鸟体内获得的两种吸虫,经鉴定为新种,命名为巨口类茎吸虫,新种Ｍｉｃｒｏｐｈａｌｌｏｉｄｅｓ ｍａｃｒｏｓｔｏｎｒｓ ｓｐ．ｎｏｖ．,珊瑚多黄吸虫,新种Ｍｕｌｔｉｖｉｔｅｌｌｕｓ ｃｏｒａｌｉｕｓ ｓｐ．ｎｏｖ．     

以化学纯饲料饲养北京的桃蚜

应用修改后的Dadd和Mitter(1966)全纯饲料配方配制成人工饲料饲养定居在北京温室烟草上的桃蚜 Myzus persicae可完成生活史井连续饲养3代。本文描述饲料配制、饲养和取食量测定的方法。这3代初羽化无翅孤雌胎生雌蚜的平均体重分别为:440±90.7μg,264±104.9μg和312±127.9μg。用放射性同位素稀释法测定取食量的结果得悉若虫期的总取食量每蚜约为1.74μg,相当于1.16μl。     

小麦倒春寒研究现状与进展

由于全球气候变暖,近年来小麦低温灾害事件频发,尤其是拔节-孕穗期的倒春寒灾害已成为制约小麦产量和品质的重要因素之一。本文综述了小麦倒春寒灾害的发生特点(鉴定与分级、时空特征),倒春寒对小麦生理特性(叶片、茎秆、穗部、根系)和产量、质量的影响,总结了抗倒春寒小麦育种、倒春寒危害的分子生物学机制及灾害的监测预警与风险评估等方面的研究进展,并从小麦抗倒春寒遗传基础、倒春寒危害小麦评价体系和防控技术体系等方面进行了展望,以期为抗倒春寒小麦品种的遗传改良和栽培调控新措施的建立提供理论依据。