摘要:

AbstractThe light‐stimulated absorption of86Rb+byPhaseolus vulgarisL. leaf slices was found to be sensitive to dichlorophenyldimethylurea in air as well as in nitrogen, whereas light‐stimulated22Na+absorption in nitrogen was not sensitive to this inhibitor. The absorption of22Na+is not affected by light in air. The absorption of42K+is enhanced by a dichlorophenyldimethylurea‐insensitive light effect under anaerobic conditions and further increased by light in the absence of the inhibitor. Light‐enhanced42K+absorption in air was also inhibited by dichlorophenyldimethylurea. Previous work showed that light‐stimulated86Rb+and42K+absorption by Phaseolus vulgaris leaf slices is restricted to the guard cells. The present results are discussed with reference to the effect of light on stomata

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1975.tb03857.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractAn instrument is described which functions as a spectrophotometer, In addition it measures action spectra of photobiological processes, excitation and emission spectra of fluorescence, and gives data for calculation of action spectra of partial reactions of photosynthesis and photocontrolled enzymatic reactions. The instrument has a Bausch and Lomb 250 mm grating monochromator. Equal numbers of quanta at different wavelengths are adjusted electronically with control of the slit through a quantacorrected photocell and a servo motor which is programmed by a cam connected to the wavelength drive.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1975.tb03858.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractAbscisic acid (ABA) inhibited the activity of α‐amylase from bothAspergillusandBacillus subtilis in vitroif ABA and enzyme solutions were allowed to react with each other before adding to the starch solution. If the ABA solution was put to starch before adding the enzyme, no inhibition occurred.The inhibition increased with increasing time between mixing ABA and enzyme solutions and adding the mixture to starch. It was not the absolute amounts of enzyme and ABA which were of importance for the inhibition, but the concentrations of ABA and enzyme in the ABA + enzyme mixture. Within certain limits the inhibition was proportional to the concentration of ABA, so that it should be possible to use the inhibition in quantitative tests for inhibitors.Dialysis of a mixture of ABA and enzyme showed that ABA is bound to the enzyme. The enzyme was still inhibited after dialysis for 25 h. On the other hand, partitioning with diethylether from acid water solution could free the enzyme from all ABA. Supposedly ABA acts as an allosteric inhibitor.The results may offer the foundation for one possible way to explain why inhibitors in plants sometimes inhibit growth and sometimes do not. If inhibitor, enzyme and substrate are compartmentalized, the degree of reaction should depend upon the sequence in which the three components meet each oth

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1975.tb03859.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractThin explants composed of the epidermis and underlying collenchyma excised from leaf veins ofBegonia rexand culturedin vitroare capable of neoformation of unicellular hairs, roots and buds. Unicellular hairs were formed over the entire surface of the explant when 10−6Mindole acetic acid or 10−7Mnaphthaleneacetic acid (NAA) was added to the basal medium; each epidermal cell was potentially involved. The epidermis was most sensitive to a NAA treatment during the first few days of culture but 30% of the explants could still react after 4 days of culture without NAA. When NAA (5 × 10−7M) and a cytokinin, zeatin (10−7M), were added together, roots were formed from epidermal tissue after numerous divisions in the original cells. Their initiation was not related to particular cells. Buds were formed when a cytokinin (10−6M) was added to the basal medium; bud meristems were formed from small groups of cells surrounding basal cells of glandular hairs. Hair formation was inhibited by either high (32–27°C) or low (12°C) temperatures applied continuously. 32–27°C seemed to inhibit elongation of the hairs specifically, whereas 12°C inhibited earlier phases in hair formation. This hypothesis was supported by short temperature treatments applied at different times dur

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1975.tb03860.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractA résumé is given of the cylindrical platinum electrode technique for measuring the rate of oxygen release from the submerged roots of intact plants.Methods are then described for manipulating the oxygen flux data to quantify the following root characteristics: total effective internal diffusional resistance, non‐metabolic (pore‐space) resistance, internal apical oxygen concentration, effective diffusion coefficient of internal transport and fractional porosity, and the respiratory contribution to internal transport. The diffusional resistance of the root wall is discussed and the method formerly suggested for converting low temperature flux data to the appropriate room temperature values (Armstrong 1971) is revised. Finally, suggestions are made for overcoming the difficulties encountered in using flux data for comparative work if the roots differ in their apical

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1975.tb03861.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractThe cytokinins, 6‐benzylaminopurine and kinetin, markedly enhanced the yield of both free and membrane‐bound 80S ribosomes per unit weight of radish (Raphanus sativus) cotyledon tissue. The response was observed only after the induction of growth by cytokinin; during the lag period preceding cytokinin‐induced growth, ribosome yields from both control and cytokinin‐treated cotyledons were below detectable levels. Mannitol depressed both growth and ribosome yield to the same degree. The enhanced ribosome yield appeared to be an indirect effect of cytokinin and was probably a consequence of cytokinin‐induced growth. The effect of 6‐benzylaminopurine on ribosome yield was not reflected in enhanced levels of cytoplasmic ribosomal RNA, while recently synthesized ribosomes were found to be more readily recovered from cytokinin‐treated tissue than from control tissue. It was concluded that cytokinin‐enhanced ribosome yield resulted from enhanced ribosome recovery or extractability and that ribosome yield is an unreliable indication of ribosome level

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1975.tb03862.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractIntact and excised samples of corn root tissue were subjected to water stress either by incubation in solutions of osmotica or by desiccation, after which they were transferred to CaSO4solution for various time periods for recovery. Osmotic agents used were either mannitol or polyethylene glycol 6000 at concentrations adequate to depress rubidium absorption to less than 30% of that of controls. During 6 h following release from osmotic stress, rubidium absorption by samples from intact seedlings treated with mannitol increased to 44% of that of controls, while those treated with polyethylene glycol increased to 79% of that of controls. Recovery of root samples excised prior to stress was very nearly the same as that of samples from intact roots. When water stress was produced by desiccation, recovery was about the same as from polyethylene glycol, attaining a rate of 76% of that of controls after 8 h. Whereas desiccated samples almost completely regained their water content during recovery, none showed correspondingly complete recovery of ion absorption capacity. Finally, during the recovery period, the submerged controls, but not controls in humid air, showed an increase in ion absorption capacity with time, confirming that the widely observed “aging effect” or “washing effect” is due to submersion and not to time

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1975.tb03863.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractIn a cold‐requiring variety of endive (chicory,Cichorium intybusL. ev. Witloof) we could demonstrate a relationship between the variations in the content of chlorogenic acid during the cold treatment of the roots and their disposition to produce flowersin vitro. An increase in the level of chlorogenic acid in the roots preceded the development of their aptitude to form flower buds. In addition, the three main forms of “isochlorogenic’ acid are present in the roots of this cultivar: 3,5‐dicaffeoyl‐quinic acid, 3,4‐dicaffeoyl‐quinic acid, and traces of 4,5‐dicaffeoyl‐quinic acid. The variations in the levels of chlorogenic and “isochlorogenic’ acids indicate that part of the chlorogenic acid (3‐caffeoyl‐quinic acid) is converted to 3

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1975.tb03864.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractRates of protein synthesis in normal callus tissues (either tight or loose morphological form), in crown gall callus tissues and in cultured pith cells were measured for both the lower surface cells (those in contact with the original growth medium) and upper surface cells (those never in contact with the growth medium until labeling). Cells of both surfaces of loose and crown gall callus and the upper‐surface cells of tight callus had similar rates of protein synthesis, 29–31 mg of protein synthesized × (g protein)−1× h−1. The lower surface cells of tight callus had a 35% lower rate of synthesis, 20 mg × g−1× h−1.Pulse‐chase experiments suggested that rates of protein degradation for all tissues were the same, 21–23 mg protein × (g protein)−1× h−1. Thus, there probably was no accumulation of protein in the lower surface cells of tight callus tissue, but the other tissues had rates of accumulation equaling 10 mg × (g protein)−1× h−1. Autoradiography and electron‐microscopic examination of cells in tight callus labeled with3H‐leucine show that: (a) the lower‐surface cells were more degenerate than cells within the callus or on the upper surface; and (b) the first few cell layers nearest the medium were preferentially labeled.Pulse‐chase experiments were also used to quantitate the nonprecursor pool (defined as that tritium in the soluble amino acid pool that does not equilibrate with protein during a pulse‐chase experiment). The nonprecursor pool increased linearly with time at the same rate as incorporation of3H‐leucine into protein. Furthermore, the nonprecursor pool copurified with leuc

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1975.tb03865.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractThe N‐trifluoroacetyl‐L‐prolyl‐leucyl methyl ester (TFA‐L‐prolyl‐leucine) was synthesized to quantitate the amounts of D‐ and L‐leucine in the amino acid pool fraction of tobacco callus tissue. TFA‐L‐prolyl‐D‐leucine and TFA‐L‐prolyl‐L‐leucine could be separated on gas liquid chromatography, with the former eluting about 45 s before the latter. The chromatographed TFA‐L‐prolyl‐L‐leucine was collected from the gas liquid chromatograph and found to contain equal molar amounts of leucine and proline. The identity of the two gas liquid chromatography peaks was confirmed by gas liquid chromatography/mass spectrometry.Although callus tissue incorporated both exogenously added D‐ and L‐leucine into its amino acid pool fraction, the rate of uptake of D‐leucine appeared to be substantially less than that of L‐leucine.When callus tissue was labeled on3H‐L‐leucine medium for 24 h and then transferred to nonradioactive medium for 24 h, about 50% of the tritium remaining in the leucine pool was not available for protein synthesis (nonprecursor pool fraction). However, all of the tritium was associated with L‐leucine, and the specific radioactivity of leucine in collected TFA‐L‐prolyl‐leucine was the same as that of leucine in the

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1975.tb03866.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY