摘要:

AbstractActivation by Ca2+, Mg2+, Zn2+, or Mn2+of adenosine triphosphatases in a microsomal fraction from wheat roots depends upon the growth temperature when the plants are grown under low salt conditions, but not when the plants get a full‐strength culture medium. At low ionic strength, cultivation at 25°C gives only half as high activation as cultivation at 18°C or at high ionic strength at both temperatures.Corresponding data for activation of ATPases from oats also show that low ionic strength during growth gives the highest temperature dependence. Low temperature together with low salt conditions during growth gives the highest ATPase activity after stimulation with divalent cations. High growth temperature and full‐strength medium decrease the ATPase activity.Activation energies (Ea) were calculated for the two temperature intervals 35–20°C and 20–5°C. The dominating ATPase stimulation (Ca2+in wheat, Mg2+in oats) is characterized by high specific activity combined with a low Ea value.The differences in ATPase activity between oats and wheat can be correlated with different cultivation requirements known from

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1976.tb03982.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

Abstract65Zn labelled seeds of broad beans (Vicia fabaL.) germinated and grown in a complete nutrient solution containing the radioisotope were used to investigate the change in the subcellular distribution of this trace element during subsequent development of the labelled seeds. Homogenates of leaves, stems and roots were fractionated into cell‐wall debris, nuclei, chloroplasts, mitochondria, ribosomes and “soluble” fraction. The concentration of the radioisotope in these fractions, expressed as cpm/mg dry weight, was highest in the soluble fraction and in the ribosomes isolated from young tissues. However, as roots and leaves aged, a general decrease in the overall zinc concentration was followed by a similar drop in the concentration of the metal associated with the “soluble” fraction and ribosomes, causing a more or less uniform zinc distribution pattern. On the other hand, there was a general increase in the zinc concentration of the “soluble” and in the particulate fractions of relatively high sedimentation coefficient from older stem samples. Taking also into consideration the dry weight change per unit volume of the tissues under investigation, the relationship between these variations and the metabolism of the plant

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1976.tb03983.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractThe factors affecting the absorption and translocation of14C‐dalapon (2.2‐dichloropropionic acid) in johnsongrass were studied. Johnsongrass [Sorghum halepense(L.) Pers.] was first pot‐grown in a greenhouse and then treated and placed in controlled‐environment chambers.Absorption of14C‐dalapon into johnsongrass leaves and subsequent translocation occurred continuously within the plant during a 48‐h period after treatment. Gas chromatographic analysis of johnsongrass extracts showed that the dalapon molecule was translocated intact. Absorption and translocation of14C‐dalapon increased as the droplet volume of the diluent was increased from 0.2 to 5.0 μl per treated spot.At 21 and 32°C, translocation of14C‐dalapon from a 2‐cm treated leaf section into the plant was greater at 100% than at 35% relative humidity. At 38°C, translocation was greater at 35% than at 100% relative humidity. The addition of 0.5% surfactant to the dalapon solution increased translocation under all environmental conditions studied. The addition of 0.1 M KH2PO4to dalapon‐surfactant solutions increased4‐dalapon translocation under high temperature (38°C), especially

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1976.tb03984.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractChilling damage was examined in the chilling‐sensitive plantGossypium barbadense. Between 30 and 36 h of germination at 34°C, the seedlings are extremely sensitive to temperatures below 10°C. The initiation of chilling damage by exposure to 2°C for 5 h during the sensitive period resulted in a large reduction in DNA synthesis. The reduction was correlated with a reduced efficiency of nuclear DNA polymerase activity. Comparing a more chilling resistant genotype to a more sensitive variety indicated that the resistant genotype nuclear DNA polymerase activity is more efficient when exposed to a chilling stress. Resistance was also correlated with a higher degree of unsaturated fatty acid content in the nuclear membranes of the resistant var

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1976.tb03985.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractGerminating seeds with the highest specific activity (24 hour germination) were used for isolation of alcohol dehydrogenase, ADH, from rape (Brassica napusL. cv. Třebičská). The rape ADH was purified by fractionation with ammonium sulphate, desalting on Sephadex G 25, chromatography on DEAE cellulose and gel filtration on Sephadex G 150. Using this isolation procedure, enzyme with a specific activity 85.6 times higher than that of the crude extract was obtained. The molecular weight of the enzyme obtained is 66.000. The enzyme is a metallo‐enzyme containing sulfhydryl groups as evidence by the inhibitory effect of chelating compounds and thiol reagents. The optimum pH for the oxidation of ethanol is 8.5 and for reduction of acetaldehyde 7.0. The enzyme exhibits a relatively wide substrate specificity towards alcohols. Dimethyl‐sulphoxide (DMSO), some amides and oximes and some intermediates of the carbohydrate metabolism act as ADH inhibitors, ATP as analogue of NAD also exhibits an inhibitory effect. The inhibitory effect of heterocyclic substances (pyrazol, imidazol, pyridine) is similar to the effect on liver alcohol dehydro

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1976.tb03986.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractPlastids prepared from dark‐grown spruce seedlings showed a negligible activity of photosystem II, and no fluorescence variation was observed during actinic illumination. The photosystem II reaction centre, however, was present in primary thylakoids. Exposure of such seedlings to continuous light induced the development of photosystem II activity via three stages (rapid, lagged and gradual), and the variable fluorescence appeared. The rapid development of photosystem II may be attributed to the activation of the oxygen‐evolving system, possibly the manganese‐catalyzing site, and the lagged and gradual developments may be closely related to the formation of thylakoid membranes and their assembly to

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1976.tb03987.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractGrafted clones ofPicea abies(L.) Karst. were used for the study. A very rapid and conspicuous rise in the content of gibberellin‐like substances chromatographically similar to gibberellin A1, and of indole‐3‐acetic acid, occurred during the brief period of most rapid shoot elongation. A few days later, when the shoot growth had terminated, very small amounts of both compounds could be detected. The changes in the qualitative pattern of gibberellin‐like substances were consistent with a suggested interconversion pathway leading from non‐polar to increasingly polar

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1976.tb03988.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractAn enzymatic method was used to determine ATP extracted from anaerobically incubated samples of the blue‐green algaAnabaena variabilis. The dark‐light‐dark transients of the ATP level in the whole cells were studied in the presence and in the absence of 3 (p‐chlorophenyl)‐l.l‐dimethylurea (CMU). When O2evolution was completely inhibited by CMU, there was no significant difference between the transient under illumination of a low intensity and that of fourfold intensity. On the other hand in the absence of CMU, the ATP level decreased more rapidly after high intensity illumination than after low intensity one. The increase in ATP content during the first 5 s illumination was smaller in the absence of CMU than in the presence of CMU. With or without CMU the increase was saturated at the vicinity of the intensity at which photosynthetic O2evolution compensates for respiratory O2consumption. The calculated quantum requirement of cyclic photophosphorylationin vivowas 2.2 qua

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1976.tb03989.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractEither red light or millimolar levels of gibberellic acid promoted germination of seeds of yellow rocket (Barbarea vulgarisR. Br.), and their effects were generally additive. Buffering the substrate pH at 3.0, addition of 20 mMnitrate to the substrate, preliminary incubation at 10 or 30°C, and brief scarification of the seeds increased responsiveness of the seeds to gibberellic acid. Scarification increased several thousandfold the sensitivity of the seeds to gibberellic acid. Pretreatment of the seeds in darkness or far‐red light did not lower their responsiveness to gibberellic acid. These results suggest that uptake of gibberellic acid is a limiting factor in the stimulation of germination in intact seeds and that there is only a minimal requirement for active phytochrome to express gibberellic acid acti

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1976.tb03990.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractUptake of gibberellic acid as a function of duration of exposure, external concentration, and seed lot was measured in seeds of yellow rocket (Barbarea vulgarisR. Br.) by means of lettuce hypocotyl bioassays of the acidic, basic, or neutral fractions of seed extracts and by uptake of14C‐GA3. In intact seeds, where mMlevels of GA3promoted only 25% germination, uptake was completed within 24 h of exposure. The maximum uptake was about 0.2% of external amount. Although germination promotion by GA3differed among seedlots of yellow rocket, relative uptake (percentage of the external GA3) was nearly the same.The relative rate of uptake of GA3was similar for scarified and intact seeds, but germination was promoted in scarified seeds by much lower levels of GA3than in intact seeds. Total uptake in scarified seeds was much higher, however (about 10% of the external amount). In seeds imbibed in H2O, practically no endogenous GA‐like activity was detected in either the acidic, basic, or neutral fractions.It was also apparent that intact seeds could take up quantities of GA3that failed to promote germination, but were comparable to quantities that promoted germination in scarified se

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1976.tb03991.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY