An ATP-driven proton pump in clathrin-coated vesicles

Clathrin containing coated vesicles prepared from bovine brain catalyzed ATP-driven proton translocation and a 32Pi-ATP exchange reaction. Both activities were measured in the presence of 5 micrograms of oligomycin/mg of protein which completely inhibited these reactions catalyzed by submitochondrial particles. Analyses performed during the purification procedure demonstrated that the oligomycin-resistant pump was concentrated and highly purified in the fractions containing coated vesicles. Moreover, vesicles precipitated by either monoclonal or polyclonal antibodies against clathrin contained the H+ pump activity. Dicyclohexylcarbodiimide (0.5 mM) and N-ethylmaleimide (1 mM) added to the assay mixture inhibited the pump completely, whereas neither vanadate, sodium azide, efrapeptin, or mitochondrial ATPase inhibitor had an effect.     

Variable Photosynthetic Metabolism in Leaves and Stems of Cissus quadrangularis L

By measuring titratable acidity, gas exchange parameters, mesophyll succulence, and ¹³C/¹²C ratios, we have shown that Cissus quadrangularis L. has C₃-like leaves and stems with Crassulacean acid metabolism (CAM). In addition, the nonsucculent leaves show the diurnal fluctuations in organic acids termed recycling despite the fact that all CO₂ uptake and stomatal opening occurs during the day. Young succulent stems have more C₃ photosynthesis than older stems, but both have characteristics of CAM. The genus Cissus will be a fruitful group to study the physiology, ecology, and evolution of C₃ and CAM since species occur that exhibit characteristics of both photosynthetic pathways.     

Shifts in the Carbon Metabolism of Xerosicyos danguyi H. Humb. (Cucurbitaceae) Brought About by Water Stress : II. Enzymology

Xerosicyos danguyi Humbert (Cucurbitaceae) is a leaf succulent endemic to Madagascar. Under well-watered conditions, the plant exhibited Crassulacean acid metabolism (CAM) but shifted to a dampened form of CAM, CAM-idling, when subjected to water stress. The purpose of this investigation was to examine the effects of a shift in carbon metabolism on phosphoenolpyruvate carboxylase and on NADP-malic enzyme in X. danguyi. Experiments were conducted to determine the diurnal patterns of enzyme activity and pH optima of both enzymes, as well as the approximate molecular mass, kinetic patterns, malate inhibition, and glucose-6-phosphate stimulation of phosphoenolpyruvate carboxylase. The two enzymes extracted from well-watered and water-stressed plants were similar in most parameters investigated; thus, CAM-idling appeared to be only a dampened form of CAM photosynthesis.     

CAM-idling in Hoya carnosa (Asclepiadaceae)

In the leaf succulent Asclepiad Hoya carnosa (L.) R. Br., CAM photosynthesis occurred under well-watered conditions, as characterized by diurnal gas exchange and changes in titratable acidity. Following 10–12 days of severe water stress, the plants shifted from CAM to a modified CAM-idling mode of metabolism. CAM-idling was characterized by complete or almost complete stomatal closure accompanied by CAM-like diurnal changes in titratable acidity. H. carnosa plants maintained this CAM-idling mode of photosynthesis for at least 8 weeks. Upon reirrigation, the plants returned to the original CAM mode within 1 week. These results suggested that CAM-idling is a reversible, intermediate form of sustained metabolism which enables plant survival under conditions of extended drought.This work was supported in part by NSF Grant PCM 8200366 and in part by the Science and Education Administration of the United States Department of Agriculture under Competitive Grant 5901-0420-8-0018-0.     

Bovine lens aldehyde dehydrogenase. Kinetics and mechanism.

Bovine lens cytoplasmic aldehyde dehydrogenase exhibits Michaelis-Menten kinetics with acetaldehyde, glyceraldehyde 3-phosphate, p-nitrobenzaldehyde, propionaldehyde, glycolaldehyde, glyceraldehyde, phenylacetylaldehyde and succinic semialdehyde as substrates. The enzyme was also active with malondialdehyde, and exhibited an esterase activity. Steady-state kinetic analyses show that the enzyme exhibits a compulsory-ordered ternary-complex mechanism with NAD+ binding before acetaldehyde. The enzyme was inhibited by disulfiram and by p-chloromercuribenzoate, and studies with with mercaptans indicated the involvement of thiol groups in catalysis.     

Chemical basis of host selection and plant resistance in oligophagous insects

Recent investigations of the Colorado potato beetle and the alfalfa weevil reveal many similarities in their modes of host selection. Many plant chemicals influence their behavioral responses and physiological processes. Chemical stimuli influencing host finding and acceptance or rejection of plants include attractants, repellents, sign stimulants, feeding stimulants and deterrents. Both species are highly sensitive to deterrent chemicals present in many plants. Feeding stimulants are indispensible for these insects and are supplied by both primary nutrients (i.e. sugars, amino acids, phospholipids and potassium salts) and secondary plant substances. The important role played by different plant chemicals in host selection and plant resistance is discussed.

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Zusammenfassung Neuere Untersuchungen am Kartoffelkäfer und am Luzerneblattnager förderten viele Übereinstimmungen in der Art ihrer Wirtswahl zu Tage. Viele Pflanzenstoffe beeinflussen ihre Verhaltensweisen und physiologische Prozesse. Chemische Reize, welche die Auffindung des Wirtes, Annahme oder Ablehnung der Pflanzen beeinflussen, umfassen Attractants, Repellents, Signalstoffe, Fraß-Stimulatoren und Abschreckstoffe. Beide Arten sind hochempfindlich gegenüber abschreckenden Verbindungen in vielen Pflanzen. Fraß-Stimulatoren sind für beide Insekten unabdingbar notwendig und werden sowohl von primären Nährstoffen (wie Zucker, Aminosäuren, Phospholipiden und Natriumsalzen) wie von sekundären Pflanzenstoffen gestellt. Die bedeutsame Rolle, welche Pflanzenstoffe bei der Wirtswahl und der Resistenz der Pflanzen spielen, wird diskutiert.

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Journal paper No. ...., Utah Agricultural Experiment Station, Logan, Utah.     

倭竹属地理分布的研究

倭竹属Shibataea Makino隶于禾本科之竹亚科,现已知有8种,分布于我国东南部的浙江、福建、江苏、安徽、江西等省,广东、台湾两省有少量栽培,日本产1种。苏联、西德、印尼等国所栽培的倭竹均系自我国或日本引入。我国浙-闽地区产8种,且都有野生发现,是本属的现代分布中心。倭竹属植物体型矮小,常植于庭院或公园中供观赏。近年来盆景艺术迅速发展,微型园林日益兴起,倭竹属植物体态优美,常绿,耐寒且易于栽培,为广大园林工作者所垂青。     

用免疫荧光单克隆抗体对脊髓灰质炎病毒抗原表位的分析

用间接免疫荧光与中和试验筛选出来的抗脊髓灰质炎2型与3型不同毒株的12个单克隆抗体,其中3个仅有免疫荧光活性,9个具有中和与免疫荧光活性。用免疫荧光活性的单克隆抗体进行试验,发现它们在识别特异性抗原表位方面与中和性单克隆抗体相似,显示出株特异的、几个毒株共同特异的或型特异的抗原表位。根据表位分布关系及特征,可以用来鉴别型内毒株的特征、毒株的抗原分析、抗原变异的研究以及疫苗相关病例的鉴别。所得结果与中和性单克抗隆抗体及T1-寡核苷酸指纹图谱分析一致。而免疫荧光单克隆抗体识别抗原表位的活性范围比中和性单克隆抗体更广。另外还发现某些兼有荧光与中和两活性的同一个单克隆抗体,用不同方法(IF与NT)进行试验时,与相同毒株出现不同表位反应,这点是值得引起注意需待进一步证实的重要问题。     

Tolerance of tannin by the shiitake mushroom,Lentinus edodes

Summary Tannin at 1% (w/v) did not inhibit the growth ofLentinus edodes, but did inhibitPleuroius florida, P. sajor-caju, P. cystidosus, Agaricus bisporus andVolvariella volvacea. The inhibition was not due to its acidity.

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Tolérance de Lentinus edodes aux ajouts de tannin

Résumé Le tannin à la concentration de 1% (p/v) n'inhibe pas la croissance deLentinus edodes, mais inhibe celle dePleurotus florida, P. sajor-caju, P. cystidosus, Agaricus bisporus, etVolvariella volvacea. L'inhibition n'est pas due à son acidité.