摘要:

AbstractAqueous extracts of blue‐green algae were fractionated by electrofocusing. In all algae investigated, fractions with iso‐electric points at or near 4.6 showed photochromic behaviour analogous to that of phytochrome, although they were sensitive to light of shorter wavelength. Three main types of photochromic pigments were found: Phycochrome a (inTolypothrix distorta, Phormidium luridum, Nostoc muscorum1453/12, andAnacystis nidulans) has one form absorbing maximally at about 590 nm (formed under red light) and one absorbing maximally at about 630 nm (formed under green light). Phycochrome b (inTolypothrix distorta) has one form absorbing maximally near 510 nm and one form absorbing maximally at 570 nm (formed in yellow‐green and blue‐green light, respectively). Phycochrome c (inNostoc muscorumA and probably inTolypothrix tenuis) has one form absorbing maximally at 650 nm (formed under green light) and one absorbing very weakly in the green region (formed under red light). The conversion ofPhormidiumphycochrome a from its red‐absorbing form to its green‐absorbing form causes the same spectral change as if an f‐chromophore of phycocyanin were transformed into an s‐chromophore. The quantum yield for this conversion is estimated to be 0.1, while the quantum yield for the reversion is estimated to be 0.4 on the assumption that the absorption coefficients are those of f‐ and s‐chromophores. Phycochrome c is less light‐sensitive than

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1976.tb02246.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractBlue (or green) light induced reversible and irreversible absorption changes in etiolated wheat (Triticum aestivum) coleoptiles. Immediately after a 10 s pulse of blue light there was an absorbance increase at 440 nm and a decrease at 420 nm. The absorbance at 440 nm returned to the original level in a biphasic way, with first‐order rate constants of 0.05 s−1and 0.006 s−1at 25°C. The change at 440 nm was partly, but not completely, inhibited by iodide. In the 500–600 nm region complex changes occurred, indicating the participation of at least two different cytochromes, one of which was oxidized during a 10 s light pulse and the other oxidized more slowly during the following dar

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1976.tb02247.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractChanges of the Specific Activities of Glutamate Dehydrogenase Malate Dehydrogenase and Isocitrate Dehydrogenase in Light‐ and Dark‐Grown Suspension Cultures of Root Cells from Pisum sati

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1976.tb02248.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractSerido bean (Vigna sinensis(L.) Savi) seeds were sown in water and in NaCl solution of —4.3 bars water potential. Total, insoluble and soluble proteins as well as soluble amino nitrogen and proteolytic activity of cotyledons were studied after 0, 1, 3, 5, 7, and 9 days of germination. Protein breakdown and turnover was delayed by the NaCl treatment as compared to the control. This was not due to the total amount of proteolytic activity, which was unchanged by salinity; even though the specific activity decreased due to the delayed breakdown of proteins under salt stress. The inhibitory effects of salinity on seed protein reserve mobilization may be due more to inhibition of translocation of hydrolysis products than to inhibition of protease activit

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1976.tb02249.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractThe model proposed by E. Komor and W. Tanner for hexose proton cotransport inChlorella(Planta 123: 195–198. 1975) is shown to be incorrect. Their data cannot represent hexose uptake via a protonated and a deprotonated form of the carrier, but may be precisely represented by a single bi‐ or triphasic mechan

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1976.tb02250.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractThe enzymes responsible for nitrate reduction inChlamydomonas reinhardii, namely NADH‐nitrate reductase and ferredoxin‐nitrite reductase, have been further characterized. The first activity of the nitrate reducing complex, NADH‐diaphorase, is protected by FAD against thermic inactivation. This fact suggests an important structural and functional role for this nucleotide in the first moiety of the nitrate reductase complex. The effect ofp‐hydroxymercuribenzoate on the diaphorase activity and the protection by NADH against its inactivation indicate that some—SH groups participate in the electron transfer mediated by diaphorase.Radioactive labelling of nitrate reductase with99Mo and185W as well as competition experiments between Mo and W indicate that molybdenum is an essential component of terminal nitrate reductase activity. Iron seems to participate in the redox processes mediated by both nitrate and nitrite reductases as suggested by experiments performed at physiological level. Finally a tentative mechanism for the whole process of nitrate assimilation inChlamydomonasis

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1976.tb02251.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractPinpoint applications of labeled and non‐labeled indoleacetic acid (IAA) on resin beads were made, without injury, to vertical roots of intact seedlings ofZea mays.Points of application were at the extreme tip of the root, 0.5, 2 and 5 mm from the root tip. The movement of label and bending of the roots was recorded. Radiolabel was found to move basipetally from the extreme tip and 0.5 mm applications to a similar extent, reaching 8 mm from the tip. The level of label in the growing zone after 4 h was 10% of that found in the extreme tip. Movement from 2 and 5 mm applications was equal in both directions. Higher amounts of non‐labeled IAA caused bending towards the point of application if applied at 0.5 or 2 mm but not at 5 mm from the tip. It is proposed that any endogenous IAA in the root cap could move to the growing zone and cause a unilateral inhibition of growth, provided that it was in the same transport pool as the exogenously applied

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1976.tb02252.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractAn experiment was carried out to study whether low‐light‐induced damage to the photosynthetic system in leaves of cotton (Gossypium hirsutumcv. Deltapine) which are below the compensation point in the canopy can be arrested and reversed by increased illumination. In addition it was intended to find out whether the photosynthetic system in leaves of shade plants show a greater resistance to low‐light‐induced damage than leaves of plants from more exposed habitats.The plants were grown at high density, and increased illumination to the shade leaves in the canopy was achieved by thinning the stand. Thinning was carried out at two stages and its effects on the decline in the photosynthetic capacity of the 4th leaf were followed. An early thinning was carried out shortly after the 4th leaf dropped below the compensation point and a late thinning 2 weeks later. Comparison was also made between the low‐light‐induced damage to the photosynthetic capacity of the 4th leaf in plants grown under two light regimes during the progressive increase in self‐shading of the 4th leaf within the canopy.It was observed that both types of thinning arrested the low‐light‐induced damage to the photosynthetic system in shade leaves. The decline in photosynthetic capacity of the 4th leaf was stopped after both early and late thinning. The dry weight of the shoot system in the early and late thinned plants was not significantly different. It was double that of the control plants. The plants thinned early did not have higher shoot weight than the late thinned plants since there was a rapid shedding of flowers and fruits after early thinning. The 4th leaf in the early thinned plants showed a 30% increase in chlorophyll content and dry weight per unit leaf area. It is suggested that shedding of flowers and fruits, and increases in chlorophyll and dry weight per unit leaf area in the early thinned plants were caused by a change in the hormonal balance of the plants.The photosynthetic system in leaves of shade plants showed a greater resistance to damage by low light intensity than the photosynthetic system in leaves of plants grown at higher

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1976.tb02253.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractLow temperature and long day regimes applied during seed development and maturation of red beet (Beta rulgaris var. rubraL.) increased the proportion of empty seed balls and reduced the germination ability of normally developed seeds. Low seed development temperatures also greatly increased the bolting susceptibility of seedlings grown at low temperatures or temperatures which are marginal for bolting, but were not able to bring about bolting under conditions which are not themselves inducive to flowering. In a field experiment a significant reduction of the root tuber yield was associated with these effects.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1976.tb02254.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractThe effect of Zn on the formation of ribulose diphosphate carboxylase (RuDPCase was investigated in the leaf discs from Zn‐deficient Sanilac navy bean plants (Phaseolus rulgarisL.). The incorporation of14C‐leucine into the partially purified RuDPCase was found to be a quantitative equivalent of the level and activity of the enzyme. Zn as ZnSO4at 10uMstimulates the formation of RuDPCase by at least 2‐fold. Neither CuSO4nor CdSO4at the same concentration substitutes for ZnSO4. The enhancement of RuDPCase formation by added Zn is greater with increasing severity of Zn deficiency, suggesting that Zn is a limiting factor in this system. Suppression of the Zn‐stimulated formation of RuDPCase by actinomycin D and cycloheximide suggests that the Zn‐mediated formation of RuDPCase most likely representsde novosynthesis. Also, the possible site(s) of action of Zn is

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1976.tb02255.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY