摘要:

AbstractThein vivouptake of31Si‐silicic acid and68Ge‐germanic acid by cell organelles ofNitzschia albaLewin and Lewin andCylindrotheca fusiformisReimann and Lewin was demonstrated. The organelles were isolated by fractionation of pre‐labeled cells by differential centrifugation in 0.4Msucrose medium. Electron micrographs showed that the isolated organelles were intact, with the exception of the N. alba mitochondria which appeared swollen and the C. fusiformis chloroplasts which had ruptured outer membranes and lacked stroma material. The amount of31Si or68Ge per mg protein of the subcellular fractions decreased in the following general order for both organisms: cell wall, mitochondria, chloroplasts, vesicles, and microsomes. A portion of the31Si or68Ge in the organelle fractions could be extracted into a distilled water wash. The uptake of silicon by the organelles suggests that silicon may be involved in some processes of the compartmentalized systems of the

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1974.tb03654.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractThe time course of sulfate uptake in relation to respiration is shown for aging slices of potato,Solanum tuberosumL. cv. Russet. For comparative purposes, a time course for phosphate uptake is also shown. Malonic acid depressed both the respiratory rise and the sulfate accumulating ability of aging discs. A low dose of ultraviolet radiation given at the onset of aging reduced sulfate uptake by one‐half without lowering respiration. We hypothesize that sulfate uptake is controlled by at least two mechanisms: one associated with oxidative metabolism and the other mediated by protein synthesi

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1974.tb03655.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractAescin in phosphate buffer reduced, to some extent, the production of14CO2from uniformly labelled glucose in mycelia ofOphiobolus graminisandNeurospora crassa, whereas aescin in succinate buffer had no effect. The enzymatic hydrolysis of sucrose was, however, severely affected, no production of14CO2from labelled sucrose being found after treatment of mycelia ofO. graminiswith 100 mg/l of aescin andN. crassawith 300 mg/l for 90 and 300 min, respectively. InAspergillus nigerthe production of14CO2from glucose or sucrose was not affected. The ATPase in whole cells and isolated plasma membranes was not inhibited by the aescin treatment, on the contrary, the ATPase in whole cells ofN. crassawas somewhat stimulated.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1974.tb03656.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractThe action of abscisic acid on the kinetics of auxin transport throughZea maysL. (cv. Goudster) coleoptiles has been investigated. Abscisic acid applied simultaneously with indoleacetic acid‐2‐14C in the donor block reduced the transport intensity without materially affecting the basipetal velocity or the uptake. No effect on acropetal transport was observed. The data have been used to discuss the similarities in effects of abscisic acid and visible radiation and a hypothesis is proposed to explain the phenomena of phototrop

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1974.tb03657.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractLipid depletion of berseem seed treated with 100 mg/1 gibberellic acid or maleic hydrazide was studied during germination. During the first 3 days after germination there was little lipid consumption but thereafter the depletion of lipid was rapid. Gibberellic acid was found to enhance the lipid utilization of total lipids and triglyceride components during germination. On the other hand, maleic hydrazide reduced the utilization of triglycerides of the germinating seed. The rate of utilization was rapid for unsaturated fatty acids and slower for saturated ones in treated seeds as compared to untreated seeds.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1974.tb03658.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractAbscisic acid inhibited the rate of14CO2fixation in leaves ofPennisetum typhoides(Burm. f.) Stapf&Hubbard seedlings, but increased the activities of phosphoenol‐pyruvate‐carboxylase and malic enzyme. The leaves of the seedlings grown in the presence of abscisic acid incorporated, in comparison to the control, more radioactivity in the fraction of organic acids, but less radioactivity was recorded in the amino acid fraction. On the other hand, gibberellic acid which also inhibits photosynthetic14CO2assimilation and decreases the activities of photosynthetic enzymes, favours greater incorporation in alanine, and reduces that in malate. It is deduced that bio‐regulants can greatly influence the flow of14C into individual photosynthetic products. As in growth, abscisic and gibberellic acids in combination tended to antagonize each other in their effects on enzyme activity as well as in incorporation of14CO2into photosynthetic pro

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1974.tb03659.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractIn experiments with intact tomato plants the effect of potassium on the translocation of photosynthates was studied. Four series of plants were grown in nutrient solutions with two different potassium levels (K1and K2treatments). When the fruits of the first truss had developed the plants were treated with labelled CO2for 2 h in a glove box. The plants were then divided in roots, stems, fruits and leaves, which were prepared for chemical analysis.In all experimental series the plants with the higher K supply grew better and therefore assimilated higher amounts of labelled CO2(cpm/plant). The assimilation rates per g fresh material, however, were not increased in each experimental set by the K2treatment. The absolute quantities of labelled photosynthates transported from leaves and stems to the fruits were also greater in the plant with the higher potassium supply. In all experimental series the proportion of labelled material found in the fruits was higher in the plants of the K2treatment (total label of the plant=100%) than in the plants of the K1treatment. This beneficial effect of potassium was also observed in cases, where potassium had not affected the CO2assimilation rate. Expressing the distribution of labelled material in relative terms (percentage proportions) means that the effect of CO2assimilation on the transport of photosynthates was excluded to a high extent. The higher percentage proportions of labelled material found in fruits and roots of the K2as compared to the K1treatment is, therefore, predominantly dependent on a specific effect of potassium on the translocation of assimilates.The labelled material found in the soluble fraction of the stems consisted of about 90% sugars, nearly half of which was sucrose, the rest being mainly glucose and fructose. This finding suggests that sucrose is the most important transport form of carbohydrates in tomatoes.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1974.tb03660.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractPeroxidases oxidizing indoleacetic acid (IAA) are present in the resting grains of barley, rye and wheat. The grains also contain small molecular inhibitors of the enzymes. A partly purified preparation of barley seed proteins was shown to contain at least two IAA oxidases about pI 5 and pI 10, mol. weight 30,000 and with a pH optimum 5.1–5.7. The enzymes require Mn2+, 2,4‐dichlorophenol and orthophosphate for the maximum activity. Attempts to separate IAA oxidase and peroxidase activities of the enzymes were unsuccess

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1974.tb03661.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractBarley roots take up choline sulfate constitutively via 3 separate, homogeneous mechanisms which obey Michaelis‐Menten kinetics and have, respectively, low, high, and very high affinity for the sulfate ester. Leaf slices possess only the low‐and the high‐affinity mechanism. These are both inhibited by dini‐trophenol and NaF but are differently affected by solute analogues. Uptake via the high‐affinity mechanism is active; the low‐affinity mechanism has also characteristics of facilitate

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1974.tb03662.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractThe permeability of a psychrophilicAchromobacterstrain to calcium ions was examined with the radioisotope45Ca2+. The amount of radioactivity that remained associated with the cells after exposure to 5 to 200 mMsolutions of radioactive calcium was determined. The concentration of45Ca2+of the cells compared to that of the surrounding medium gave a ratio larger than one, and this ratio increased with decreasing ambient calcium concentration. The same results showed that the higher the external calcium concentration was, the more calcium remained with the cells. The radioactivity of the cells had the following characteristics: 1. It was rapidly lost when the cells were washed with40Ca‐solution. 2. Most of it was retained after water washings. 3. It was not affected by the presence of 2,4‐dinitrophenol. 4. It was only slightly affected by temperature. 5. It increased when the cells were treated with toluene or heat and reached a maximum of 2–3 times the value of untreated cells. The same treatment brought about a smaller increase of the uptake of22Na+. 6. Approximately 60% of the radioactivity of whole cells was associated with isolated cell enve

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1974.tb03663.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY