摘要:

AbstractThe aim of the investigation was to study the differences in the metabolism of substances that are utilized in the synthesis of glucosinolates between theBrassica napuscv. Bronowski, which is very low in glucosinolate content, and a cultivar (cv. Regina II) that contains approximately average amounts of these compounds.By experiments in which the plants were grown in nutrient solutions supplied with sulphate‐35S, it was shown that the rate of sulphate uptake was similar in the two cultivars. No accumulation of intermediate metabolites could be demonstrated by autoradiography in Bronowski.Sulphate‐35S, methionine‐35S, methionine‐2‐14C, 2‐amino‐6‐(methylthio)caproic acid‐2‐14C, and S‐(β‐d‐glucopyranosyl)‐4‐pentenethiohydroximic acid (desulpho‐3‐butenylglucosinolate) (glucose‐U‐14C or35S) were fed to shoots of the two cultivars. After incubation, the plant material was extracted with methanol. The extracts were separated into various fractions, and in some experiments glucosinolates or derivatives of their degradation products were isolated. When measuring the radioactivity of the various fractions or isolated products, the incorporation of radioactivity into glucosinolates was found to be poor in Bronowski from sulphate, methionine, and 2‐amino‐6‐(methylthio)caproic acid. Desulpho‐3‐butenyl‐glucosinolate was an efficient precursor of 3‐butenylglucosinolate in Bronowski, but a poor precursor of 2‐hydroxy‐3‐bute‐nylglucosinolate, which suggests a metabolic block at the hydroxylation step in this cultivar. In Regina II desulpho‐3‐butenylglucosinolate was a good precursor of both 3‐butenylglucosinolate and of 2‐hydroxy‐3‐butenylglucosinolate, which demonstrates that these glucosinolates may be synthesized without prior formation of the corresponding co‐methylthioalkyl glucosinolates and that the hydroxylation can take place after the formation of desulpho‐3‐butenylglucosinolate.The results indicate that the low glucosinolate content of Bronowski is caused by

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1971.tb03473.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

AbstractThe effect of kinetin on protein synthesis of isolated chloroplasts was investigated by following the incorporation of14C‐leucine into isolated chloroplasts fromNicotiana tabacum. The incorporation activity varied greatly during the year, being largest in the winter and smallest in the summer. Conversely, the relative effect of kinetin on the incorporation of14C‐leucine, whether applied as a pretreatment to the leaves or directly in the incubation medium, was largest in the summer and smallest or absent altogether in the winter. Kinetin did not prolong the net incorporation period, which lasted about 40 min, but only enhanced the initial rate of the reaction. Chloroplasts extracted from leaves that had been detached for 24 or 48 h displayed very little of their original, pre‐aged incorporation activity and treating the leaves with kinetin did not, essentially, prevent this loss. It was concluded that the major effect of kinetin upon chloroplasts may be related primarily to an effect upon hydration and permeability of the chloroplast and its membranes, and not to an effect directly upon its machinery for protein synt

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1971.tb03474.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

AbstractThe coupling and uncoupling properties of isolated corn mitochondria were analyzed using three substrates in Tris buffered sucrose and KC1 reaction medias containing inorganic phosphate (Pi), bovine serum albumin (BSA), or Piand BSA. In these media, without other cofactors, respiratory control (RCR) and ADP/O ratios, and the respiratory burst affected by dinitrophenol (DNP), gramicidin D, calcium chloride and ADP were measured. Bovine serum albumin enhanced the respiratory burst caused by DNP and gramicidin D in the absence of Pi, and in most instances enhanced the stimulation of oxygen uptake by ADP and calcium chloride in the presence of Pi. Mitochondria oxidizing succinate, malate‐pyruvate or NADH exhibited better RCR and ADP/O ratios in buffered 200 mMKCl than they did in buffered 300 mMsucrose. In all instances RCR and ADP/O ratios were enhanced in reaction medias containing BS

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1971.tb03475.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

AbstractThe applicability of synchronous cultures ofChlorella fuscaas a reproducible experimental system for the study of growth regulators has been investigated using indole‐3‐acetic acid (IAA) and gibberellin.1None of these compounds stimulated growth or sporulation.2IAA inhibited growth and sporulation at concentrations higher than 6 × 10−5M, the effect increasing with increasing acidity. Gibberellin had no

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1971.tb03476.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

AbstractA procedure for extracting and identifying plant hormones, particularly abscisic acid (ABA) and the gibberellins (GA) was developed through modification of methods described in the literature. The procedure is particularly useful for studying more than one hormone simultaneously in a given sample, and when the supply of plant material is limited.The procedure was used to isolate ABA and GA‐like substances from olive tissue (i.e., leaves, buds and inflorescences). Gibberellin‐like substances were identified by their action on α‐amylase release from embryoless barley half‐seeds.Characterization of an acidic inhibitor extracted from olive inflorescences by thin‐layer chromatography, fluorescence under ultraviolet light, gas chromatography, and physiological effects on wheat coleoptile sections indicate that this inhibitor, or at least a component of it, is very similar if not identical with at least one isomeric form of synthetic abs

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1971.tb03477.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

AbstractThe amino acid and protein metabolism of roots of maize has been studied. The important role of the free amino acids and proteins of the roots as active agents in nitrogen assimilation is pointed out. Nitrogen supplied as nitrate is preferably incorporated into α‐ketoglutaric acid, and then by trans‐aminases transferred to other ketoacids. In the case of ammonia supply the function of a nitrogen‐accumulating assimilation system leading to the formation of Arg, Glu‐NH2and Asp‐N

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1971.tb03478.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

AbstractShoots grown out from aspen root sections in light or in darkness were extracted and the content of growth‐regulating substances in various fractions was determined with the Avena coleoptile straight‐growth assay. The most obvious difference was obtained for the inhibitor β fraction. This was about ten times more active in the light‐grown than in the dark‐grown shoots. Some indications of more growth inhibitory material in ether‐insoluble fractions of light‐grown plants were also obtained. The stimulation obtained at the Rf of indol‐3‐yl‐acetic acid was somewhat lower in the etiolated shoots than in th

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1971.tb03479.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

AbstractThe carbohydrate nutrition ofOphiobolus graminis, the cause of the take‐all disease of wheat, was investigated in growth and respiration experiments. In a synthetic medium, d‐mannitol was the only carbohydrate of thirteen studied which the fungus could not use for growth. However, the fungus was found to take up mannitol by an active mechanism, which was stopped by 2,4‐dinitrophenol.Di‐ and trisaccharides were hydrolyzed extracellularly, and the monosaccharides were assimilated at differen

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1971.tb03480.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

AbstractBark samples were removed from 1‐year‐old stems of Italian prune trees at intervals throughout the growing season (June–August). Glucose, fructose, sucrose, traces of raffinose and a polyol were detected in ethanolic extracts of the bark. The polyol was isolated and shown to be d‐glucitol. The use of insoluble polyvinylpyrrolidone proved to be the best method for decolorizing bark extracts prior to quantitative analysis of ethanol‐soluble carbohydrates by paper chromato‐graphic methods. Glucitol was the major carbohydrate in the bark throughout the season. Sucrose was the major sugar, decreasing gradually as the season advanced. Fructose and glucose were found in lesser and about equal amounts. The amount of glucitol, glucose and fructose was high in June, decreased to a minimum in mid‐July, increased sharply in late July and early August and decreased later

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1971.tb03481.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

AbstractThe CO2and H2O vapour exchange of single attached orange,Citrus sinensis(L.), leaves was measured under laboratory conditions using infrared gas analysis. Gaseous diffusive resistances were derived from measurements at a saturating irradiance and at a leaf temperature optimum for photosynthesis. Variation in leaf resistance (within the range 1.6 to 60 s cm‐1) induced by moisture status, or by cyclic oscillations in stomatal aperture, was associated with changes in both photosynthesis and transpiration.At low leaf resistance (ri less than 10 s cm‐1) the ratio of transpiration to photosynthesis declined with reduced stomatal aperture, indicating a tighter stomatal control over H2O vapour loss than over CO2assimilation. At higher leaf resistance (ri greater than 10 s cm‐1) changes in transpiration and photosynthesis were linearly related, but leaf resistance and mesophyll resistance were also positively correlated, so that strictly stomatal control of photosynthesis became more apparent than real.This evidence, combined with direct measurements of CO2diffusive resistances (in a ‐O2gas stream) emphasised the presence of a significant mesophyll resistance;i.e., an additional and rate limiting resistance to CO2assimilation over and above that encountered by H2O vapour escaping from t

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1971.tb03482.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY