摘要:

An evaluation of minimal surface structures formed in lipid‐water systems and in lipid‐protein‐water systems in relation to electron microscopic data on the prolamellar body are reported. It is suggested that the characteristic square and hexagonal patterns seen in electron micrographs of prolamellar bodies constitute minimal surfaces of the P‐ and D‐type, respectively. The existence of the G‐ and the H‐surface in the membrane systems of prolamellar bodies

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1990.tb04366.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Two soybean [Glycine max(L.) Merr.] cultivars, Essex and Williams, were grown in the field for 6 consecutive seasons under ambient and supplemental levels of ultravio‐Set‐B radiation to determine the potential for alterations in yield or seed quality with a reduction in the stratospheric ozone column. The supplemental UV‐B fluences simulated a 16 or 25% ozone depletion. The data presented here represent the first field experiment conducted over multiple seasons which assesses the effects of increased UV‐B radiation on seed yield. Overall, the cultivar Essex was found to be sensitive to UV‐B radiation (yield reductions of 20%) while the cultivar Williams was tolerant. However, the effectiveness of UV‐B radiation in altering yield was strongly influenced by the seasonal microclimate, and the 2 cultivars responded differently to these changing factors. Yield was reduced most in Essex during seasons in which water availability was high and was reduced in Williams only when water was severely limiting. The results of these experiments demonstrate the necessity for multiple‐year experiments and the need to increase our understanding of the interaction between UV‐B radiation and other environmental stresses in order to assess the potential consequences of stratospheric

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1990.tb04367.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Distribution pattern and levels of nitrogenase (EC 1.7.99.2) and glutamine synthetase (GS, EC 6.3.1.2) were studied in N2‐, NO3−and NH4+grownAnabaena cylindrica(CCAP 1403/2a) using immunogold electron microscopy. In N2‐ and NO3−grown cultures, heterocysts were formed and nitrogenase activity was present. The nitrogenase antigen appeared within the heterocysts only and showed an even distribution. The level of nitrogenase protein in the heterocysts was identical with both nitrogen sources. In NO3−grown cells the 30% reduction in the nitrogenase activity was due to a corresponding decrease in the heterocyst frequency and not to a repressed nitrogenase synthesis. In NH4−grown cells, the nitrogenase activity was almost zero and new heterocysts were formed to a very low extent. The heterocysts found showed practically no nitrogenase protein throughout the cytoplasm, although some label occurred at the periphery of the heterocyst. This demonstrates that heterocyst differentiation and nitrogenase expression are not necessarily correlated and that while NH4+caused repression of both heterocyst and nitrogenase synthesis, NO3−caused inhibition of heterocyst differentiation only. The glutamine synthetase protein label was found throughout the vegetative cells and the heterocysts of all three cultures. The relative level of the GS antigen varied in the heterocysts depending on the nitrogen source, whereas the GS level was similar in all vegetative cells. In N2‐ and NO3+grown cells, where nitrogenase was expressed, the GS level was ca 100% higher in the heterocysts compared to vegetative cells. In NH4+grown cells, where nitrogenase was repressed, the GS level was similar in the two cell types. The enhanced level of GS expressed in heterocysts of N2and NO3−grown cultures apparently is related to nitrogenase expression and has a role in assimilation of

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1990.tb04368.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Seeds ofPhaseolus vulgarisL. cv. White Kidney were germinated and grown either in a nitrogen‐free or in an ammonia‐supplied medium. The changes in the soluble protein concentration and in the levels of glutamine synthetase (GS, EC 6.3.1.2), NADH–glutamate synthase (NADH‐GOGAT, EC 1.4.1.14), ferredoxin‐glutamate synthase (Fd‐GOGAT, EC 1.4.7.1) and glutamate dehydrogenase (GDH, EC 1.4.1.2), both NADH‐ and NAD+‐dependent, were examined in cotyledons and roots during the first 10 days after sowing. Soluble protein declined rapidly in the cotyledons and increased slightly in the roots. GS activity was initially high both in cotyledons and roots but subsequently decreased during seedling growth. Exogenous ammonia hardly affected GS activity. High levels of NADH‐GOGAT were present both in cotyledons and roots during the first days of germination. The activity then gradually declined in both organs. In contrast, Fd‐GOGAT in cotyledons was initially low and progressively increased with seedling development. In roots, the levels of Fd‐GOGAT were higher in young than in old seedlings. Supply of ammonia to the seedlings increased the levels of NADH‐GOGAT and Fd‐GOGAT both in cotyledons and roots. NADH‐GDH (aminating) activity gradually increased during germination. In contrast, the levels of NAD+‐GDH (deaminating) activity were highest during the first days of germination. Exogenous ammonia did not significantly

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1990.tb04369.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

New macro and microelement solutions were formulated for stimulation of growth and embryogenesis in white and chlorophyllous megagametophyte and embryo callus lines ofPicea abies(L.) Karst. Macroelement media with different NH4+and NO3−ratios (1:2 and 1:4), the increased level of several microelements and the effect of organic nitrogen (100 mg 1−1casein hydrolysate, 0.25 mMarginine and 0.5 mMglutamine) were tested with 4 combinations of growth regulators (2,4‐dichlorophe‐noxyacefic acid or indole‐3‐butyric acid, kinetin). Green chlorophyll‐containing, in contrast to white callus lines, grew quite well without exogeneously added organic nitrogen. The ratio between NH4+and NO3−was not significant. The increased levels (μM) of several microelements: B (200), Zn (50), I (25), Cu (1), Co (0.5) and in addition Ni (0.1) improved callus growth in some lines more than 50% (DW) compared to cultures grown on the micronutrients of Murashige and Skoog. The response of different callus lines varied with the combinations of growth regulators. Embryogenesis did not occur in chlorophyllous callus lines in any of the 24 media combinations tested, but some very good media could be found for white megagametophyte and embryo callus lines. Microelements, favourable combination of growth regulators and organic nitrogen were especially important. A megagametophyte callus subcultured for 4 years was also able to form num

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1990.tb04370.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Growth characteristics of a spontaneous mutant of shiitakeLentinula edodes(Berk.) Pegler were studied. The mutant was first detected as a result of changes in the growth habit of the normal strain in the liquid medium. Abundant formation of aerial hyphae was distinctive. In sawdust logs the mutant strain produced abnormal basidiocarps, lacking stipe, gill and spore formation.Growth rates of the normal and the mutant strain were compared in two liquid media: malt‐yeast extract and Leatham's medium. The increase in dry weight of the mutant's mycelium was much higher than that of the wild type in both media, which indicated better adaptation to liquid culture. In the sawdust, however, growth of the mutant was slower than that of the normal strain. The mutant's intracellular protein content was lower than that of the normal strain. The pH of the liquid cultures differed: the wild type decreased the pH during growth, while the mutant increased the pH. Comparison of the protein and esterase isoenzyme profiles of the vegetative hyphae of both strains indicated profound differences. One protein (pI 6.5, 39 kDa), which in earlier studies has been found to be typical ofL. edodesspecies, was absent from the mutant's profile. Differences in the esterase profile were also clea

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1990.tb04371.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

The requirement of ovule development for fruit growth inCucumis sativusL. was studied using different cultivars of gherkin and cucumber. The latter, particularly, show considerable ovary growth already prior to flowering. With non‐parthenocarpic cultivars, this growth stops and the fruitlets wither in ca 2 weeks post‐anthesis if no pollination occurs, whereas ovaries of non‐pollinated, parthenocarpic varieties may develop into maturity nearly as well as pollinated ones. Fruit growth turned out to be correlated with the number and size of seeds or, in the case of parthenocarpy, of empty seed‐like structures, the pseudo‐seeds. Fruit growth is enhanced beyond the parthenocarpic level by pollination. Sectorially different fruit growth, as observed in pollinated cucumber, can be ascribed to the inability of pollen tubes to reach the ovules at the pedicel end of the elongated ovary. Experiments with irradiated pollen and with style removal indicate that fertilization of ovules is not required, physical contact with the pollen tubes suffices to stimulate ovary growth. The nature of the stimulating factor i

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1990.tb04372.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Abscisic acid (ABA) concentrations of guard cells, subsidiary cells and epidermis cells ofComrnelina communisL. andTradescantia virginianaL. were determined in cell sap samples extracted by means of micro glass capillaries. Concentrations up to 6.7 mMwere indicated by commercial immunoassay test kits. A gradient of ABA concentration was found between guard cells (2,49 ± 1.81 mM, n = 25), subsidiary cells (1.25 ± 1.46 mM, n = 21) and epidermis cells (0.86 ± 0.76 mM, n = 20; mean values ±

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1990.tb04373.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

The red light (R)‐induced swelling of mesophyll protoplasts, isolated from dark‐grown wheat (Triticum aestivumL. cv. Arminda) leaves, was inhibited by guanosine‐5′‐0‐(2‐thiodiphosphate) (GDP‐β‐S). In darkness or after control irradiation with far‐red light (FR), guanosine‐5′‐O‐(3‐thiotriphosphate) (GTP‐γ‐S) induced swelling to the same extent as after R. Both GDP‐β‐S and GTP‐γ‐S were introduced into the cytoplasm by means of electroporation. The possibility of R‐induced activation of the phosphatidylinositol pathway of transmembrane signalling was investigated. Neomycin, Li+and l‐(5‐isoquinolinesulfonyl)‐2‐methylpiperazine (H7) inhibited the R‐induced swelling. Phorbol 12‐myristate 13‐acetate (PMA) induced swelling after control irradiation with FR. Neomycin and Li+also inhibited GTP‐γ‐S‐induced swelling. These results suggest that a GTP‐binding protein is involved in the phytochrome‐regulated swelling response. Addition of N6, 2′‐0‐dibutyryladenosine 3′:5′‐cyclic monophosphate (DB‐cAMP) induced swelling to the same extent as R‐irradiation. The calmodulin antagonist N‐(6‐aminohexyl)5‐chloro‐l‐naphthalenesulfonamide (W7) induced swelling after FR, while R‐induced swelling was not affected. The less active analogue N‐(6‐aminohexyl)‐l‐naphthalenesulfonamide (W5) induced no swelling after F

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1990.tb04374.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Broad‐band radiation from a high‐pressure Hg‐vapor lamp, including ultraviolet wavelengths from 290 to 400 nm, blue, green and red wavelengths, did not induce the synthesis of H2O2in cultured rose cells. This was in contrast to the effects of shortwave (254 nm) ultraviolet radiation, even though, like shortwave ultraviolet radiation, the UV‐B component of the broadband radiation induced a striking K+efflux from the cells, and this efflux has been associated with H2O2synthesis in a previous report. The UV‐A and visible wavelengths were shown to inhibit the synthesis of H2O2. This effect was associated with inhibition of peroxidase, an enzyme reported to be involved in the synthesis of H2O2in cell walls. UV‐B radiation inhibited the alternate pathway for mitochondrial electron transport, but there was no evidence that this effect contributed to the inhibition of H2O2synthesis in cells treated with broad‐b

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1990.tb04375.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY