Effects of nitrogen supply and high temperature on the growth and physiology of the chickpea

Chickpeas were grown with or without nitrate nitrogen feeding, or nodulated with Rhizobium leguminosarum. High [40°C day, 25°C night (HT)] and moderate [25°C day, 177°C night (LT)] temperature regimes were employed during growth. Growth rates, photosynthetic capacity and enzymes of carbon and nitrogen metabolism were monitored to assess the acclimatory capacity of the chickpea. Initial growth rates were stimulated by high temperatures, particularly in nitrate-fed and nodulated plants. Older HT plants had fewer laterals, smaller leaves, and fewer flowers were produced than in LT plants. There was some indication of an acclimation of photosynthesis to high temperatures and this was independent of nitrogen supply. Rubisco activity was increased by high growth temperatures. However, HT plants also had higher transpiration rates and lower water use efficiency than LT plants both in respective growth conditions and when compared in a common condition. High temperatures reduced shoot nitrate reductase activity but had little effect on root activity, which was the same if not greater than activity in LT roots. The amino acid, asparagine, was found at high concentrations in all treatments. Concentrations were maintained throughout growth in HT plants but declined with age in LT plants.     

Myosin light chain kinase expression during smooth muscle development

The expression of smooth muscle myosin light chain kinase (MLCK) was investigated during chicken gizzard development. The molecular weight and the antigenic properties of MLCK did not change during development. The use of anion exchange high performance liquid chromatography (HPLC) enabled us to distinguish between MLCKs from post-hatched and adult chickens. A partial amino acid sequence determination of 4-day-old gizzard MLCK failed to disclose differences in the primary sequences of the two proteins. The results suggest that MLCK has the same primary sequence in all sequences of the two proteins. The results suggest that MLCK has the same primary sequence in all stages of gizzard development, although charge variants due to post-translational modifications may exist.     

Flash-induced reduction of cytochrome b-559 by Q infB sup− in chloroplasts in the presence of protonophores

Flash-induced, fast (t _1/2 1 ms), reversible reduction of the high potential cytochrome b-559 (cyt b-559HP) was observed in chloroplasts in the presence of 2 M protonophore, FCCP (carbonylcyanide p-trifluoromethoxyphenylhydrazone), CCCP (carbonylcyanide 3-chlorophenylhydrazone) or SF 6847 (2,6-di-(t-butyl)-4-(2,2-dicyanovinyl)phenol). These protonophores promote autooxidation of cyt b-559HP in the dark (Arnon and Tang 1988, Proc Natl Acad Sci USA 85: 9524). No fast photoreduction could, however, be observed if the molecules were oxidized with ferricyanide in the absence of protonophores. This suggests that the molecules must be deprotonated to be capable for fast photoreduction.Photoreduction of cyt b-559HP was largely insensitive to DBMIB (2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone), but was inhibited by DCMU (3-(3,4-dichlorophenyl)-1,1-dimethylurea). With a train of flashes, no oscillation could be observed in the amplitudes of photoreduction. These data strongly suggest that cyt b-559HP is reduced by the semireduced secondary quinone acceptor (Q_B ^–) of Photosystem 2.Abbreviations ADRY- acceleration of the deactivation reactions of the water-splitting enzyme system Y of photosynthesis - Ant 2p- 2-(3-chloro-4-trifluoromethyl)anilino-3,5-dinitrothiophene - cyt- cyto-chrome - CCCP- carbonylcyanide 3-chlorophenylhydrazone - DBMIB- 2,5-dibromo-3-methyl-6-iso-propyl-p-benzoquinone - DCMU- 3-(3,4-dichlorophenyl)-1,1-dimehtylurea - FCCP- carbonylcyanide p-trifluoromethoxyphenylhydrazone - FeCy- ferricyanide - HP- high potential form - HQ- hydroquinone - PQ- plastoquinone - PS 2- Photosystem 2 - SF 6847- 2,6-di-(t-butyl)-4-(2,2-dicyanovinyl)-phenol     

NaN_3对叶绿体Mg~（2＋）－ATPase的抑制作用再探

ＮａＮ３能抑制新鲜菠菜叶片叶绿体经ＤＴＴ和光激活的Ｍｇ２＋－ＡＴＰａｓｅ活力。这种抑制属非竞争性抑制。ＮａＮ３还能降低新鲜菠菜叶片叶绿体的反映光合磷酸化高能态的毫秒延迟发光和减少反映类爱体膜质子吸收变化的叶绿体的９－氨基吖啶的荧光猝灭。菠菜叶片经低温贮存几天后其叶绿体的超微结构发生变化,ＮａＮ３对叶绿体的上述影响就消失或基本消失。本实验指出ＮａＮ３是新鲜叶片叶绿体Ｈ＋－ＡＴＰａｓｅ的一个强有力的抑制剂。其影响受叶绿体制剂的内源无机磷酸盐含量调节。     

世居及移居高原青少年最大有氧能力的特征

本文报道海拔３４１７ｍ和４２８０ｍ地区世居藏族和移居汉族青少年运动状态下心肺功能的对比研究。结果显示：３４１７ｍ和４２８０ｍ世居藏族的最大氧耗量、无氧阈值及最大心输出量都明显大于汉族,血氧饱和度（Ｓａｏ２）随运动负荷的增加而降低。海拔３４１７ｍ藏、汉族的△Ｓａｏ２分别为７．４６％和１０．０３％,４２８０ｍ处为８．５７％和１３．７５％,最大心率随海拔升高而下降。研究提示,藏族青少年有较高的最大有氧能力,反映了他们对低氧环境的适应优势。     

Clutch size, offspring performance, and intergenerational fitness

It is now generally recognized that clutch size affects morethan offspring number. In particular, clutch size affects asuite of traits associated with offspring reproductive performance.Optimal clutch size is therefore determined not by the numericallymost productive clutch but by the clutch that maximizes collectiveoffspring reproductive success. Calculation of optimal clutchsize thus requires a consideration of ecological factors operatingduring an intergenerational time frame, spanning the lifetimeof the egglaying adult and the lifetimes of her offspring. Theoptimal clutch cannot define reproductive values in advance,but instead requires that the strategy chosen is the best responseto the set of reproductive values that it itself generates.In this article, we introduce methods for solving this problem,based on an iterative solution of the equation characterizingexpected lifetime reproductive success. We begin by consideringa semelparous organism, in which case lifetime reproductivesuccess is a function only of the state of the organism. Foran iteroparous organism, lifetime reproductive success dependsupon both state and time, so that our methods extend the usualstochastic dynamic programming approach to the evaluation oflifetime reproductive success. The methods are intuitive andeasily used. We consider both semelparous and iteroparous organisms,stable and varying environments, and describe how our methodscan be employed empirically.     

Postharvest disease control in mangoes using high humidity hot air and fungicide treatments

The disease control efficacy of quarantine heat treatments developed for fruit fly disinfestation in mangoes cv. Kensington Pride was evaluated in this study. Heat was applied using high humidity (>95% r.h.) hot air (HHHA) at temperatures ranging from 47–49°C. Anthracnose, caused by Colletotrichum gloeosporioides, was well controlled in mangoes heated to a core temperature of 46°C, 47°C or 48°C for 24, 10 or 8 min respectively, prior to ripening at 23°C for 16 days. Stem end rot, caused by Dothiorella dominicana and Lasiodiplodia theobromae, was not satisfactorily controlled by these treatments. In a subsequent experiment, fruit were immersed in a hot benomyl (0.5 g a.i. litre“¹ at 52°C for 5 min) or unheated prochloraz (0.25 ml a.i. litre¹ at 28°C for 30 s) dip before or after the application of HHHA (core temperature of 47°C for 10 min). During storage at 23°C for 15 days, the incidence of stem end rot was reduced by HHHA alone, although immersion in hot benomyl either before or after HHHA treatment greatly improved stem end rot control. HHHA treatment (core temperature of 46.5°C for 10 min) alone reduced the incidence of anthracnose in mangoes stored at 13°C for 14 days prior to ripening at 22°C, although a combination treatment consisting of HHHA and either hot benomyl or unheated prochloraz gave complete control of anthracnose under these storage conditions. HHHA treatment alone gave no control of stem end rot in mangoes stored at 13°C prior to ripening at 22°C. A supplementary hot benomyl treatment was required for acceptable control of this disease in cool-stored mangoes. The development of yellow skin colour in fruit was accelerated by HHHA treatment.     

Issues in the culture of the extremely thermophilic methanogen, Methanothermus fervidus

Basic issues in the culture of the extremely thermophilic archaeon, Methanothermus fervidus, have been investigated, including culture medium formulation, substrate yield and product yield coefficient, growth rate and stoichiometry, and H(2) uptake kinetics. The pH optimum for growth of this organism was estimated at 6.9. Growth medium buffered with PIPES instead of bicarbonate supported both increased growth rate and maximum biomass concentration. Substitution of titanium(III) citrate for the reducing agent sodium sulfide improved culture performance as well. However, independent adjustment of iron and nickel concentrations from 11 to 111 muM, respectively, and carbon dioxide partial pressure from 5 to 20 psia did not impact the culture of M. fervidus significantly. An elemental balance approach was utilized to aid in design of a defined medium to support growth to a target maximum biomass concentration of at least 1.0 g dry wt/L. The growth of this organism was limited by H(2) availability in this reformulated culture medium. The maximum growth rate and biomass concentration achieved in anaerobic vials with the defined medium was 0.16 h(-1) and 0.74 g dry wt/L, respectively. This maximum biomass concentration was a 72% improvement over that obtained with a literature-based defined medium. The Monod parameter, K(s), with H(2) as limiting substrate, was estimated at 1.1 +/- 0.4 psia (55 +/- 20 muM in the broth), based on a H(2) consumption study. Representative values for the substrate yield, Y(X/CO(2) ), and product yield coefficient, Y(CH(4)/) (X), were determined experimentally to be 1.78 +/- 0.04 g dry wt/mol CO(2), and 0.52 +/- 0.01 mol CH(4)/g dry wt, respectively. A bench-scale fermentation system suitable for the culture of extremely thermophilic anaerobes was designed and constructed and proved effective for the culture of M. fervidus. (c) 1993 Wiley & Sons, Inc.     

Factors affecting bio-oxidation of sulfide minerals at high concentrations of solids: a review

Bio-oxidation has proved to be a viable process for the oxidative pretreatment of refractory gold-bearing sulfides. Generally, the oxidation rate is maximal at 20% solids for high sulfide content materials [ca. 30% sulfur]. Low grade ores [1% sulfur] have been successfully oxidized at 55% solids, indicating a link between the sulfide grade of the material and the optimal solids concentration for operation. Concentrations of high solids have been reported to lower oxidation rates, increase lag times, and decrease the ultimate extent of oxidation. This review discusses the various factors that have been proposed as causes of these phenomena. The factors include oxygen and carbon dioxide availability, low bacteria-solids ratio; mechanical damage or inhibition of the bacteria, inhibition of bacterial attachment, and the buildup of toxic leach products or other detrimental substances such as some flotation reagents. (c) 1993 John Wiley & Sons, Inc.     

Emulsion liquid membrane extraction of lactic acid from aqueous solutions and fermentation broth

Studies on the batch extraction of lactic acid using an emulsion liquid membrane system are reported. The membrane phase consists of the tertiary amine carrier Alamine 336 and the surfactant Span 80 dissolved in n-heptane/paraffin and aqueous solutions of sodium carbonate in the internal phase. The effects of internal phase reagent, extraction temperature, and initial external phase pH on the extraction efficiency and the emulsion swelling are examined. A statistical factorial experiment on extraction from clarified lactic acid fermentation broth was carried out to obtain knowledge of the performance of the extraction system from a broth. The extraction efficiency from the fermentation broth is found to be lower as compared to aqueous solutions of pure lactic acid. The effect of pH and the presence of other ionic species on selectivity are discussed. (c) 1993 John Wiley & Sons, Inc.