ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1992.tb00259.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractIsolated internodes ofChara corallinaandNitella flexilishave been used to determine the concentration of one passively permeating solute in the presence of non‐permeating solutes. The technique was based on the fact that the shape of the peaks of the biphasic responses of cell turgor (as measured in a conventional way using the cell pressure probe) depended on the concentration and composition of the solution and on the permeability and reflection coefficients of the solutes. Peak sizes were proportional to the concentration of the permeating solute applied to the cell. Thus, using the selective properties of the cell membrane as the sensing element and changes of turgor pressure as the physical signal, plant cells have been used as a new type of biosensor based on osmotic principles. Upon applying osmotic solutions, the responses of cell turgor (P) exactly followed the P(t) curves predicted from the theory based on the linear force/flow relations of irreversible thermodynamics. The complete agreement between theory and experiment was demonstrated by comparing measured curves with those obtained by either numerically solving the differential equations for volume (water) and solute flow or by using an explicit solution of the equations. The explicit solution neglected the solvent drag which was shown to be negligible to a very good approximation. Different kinds of local beers (regular and de‐alcoholized) were used as test solutions to apply the system for measuring concentrations of ethanol. The results showed a very good agreement between alcohol concentrations measured by the sensor technique and those obtained from conventional techniques (enzymatic determination using alcohol dehydrogenase or from measurement of the density and refraction index of beer). However, with beer as the test solution, the characean internodes did show irreversible changes of the transport properties of the membranes leading to a shift in the responses when cells were treated for longer than 1 h with diluted beer. The accuracy and sensitivity of the osmotic biosensor technique as well as its possible applications are discus

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1992.tb00260.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractSenescent leaves ofGingko bilobaaccumulate fluorescent compounds which may contribute to the golden luminous appearance of the autumnal foliage. Apart from the putative effect of such optical brighteners, the changes of spectral optical properties associated with senescence are due to the breakdown of chlorophyll in conjunction with a remarkably high retention of carotenoids. Carotenoid esters accumulate concomitant with chlorophyll breakdown. Optical properties in the infrared range of the spectrum illustrate the intactness of leaf tissue to the end of the senescence period.

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1992.tb00261.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractThe amount of the phytoalexin glyceollin I in root exudate and root hairs of individual seedlings ofGlycine max(L. Merr. cv. Preston) was analysed using a radioimmunoassay.Bradyrhizobium japonicum110spc4, which is able to form nitrogen fixing nodules with this plant, caused an increase of up to 50‐fold in glyceollin I levels in root exudate relative to uninfected control seedlings. Maximum glyceollin I levels were reached within 10 h of incubation. Elevated glyceollin I levels were also observed after incubation of soybean roots in sterile bacterial supernatant, a suspension of autoclaved bacteria or the supernatant from broken cells ofBradyrhizobium japonicum. Increased glyceollin I production is not due to the process of active root hair penetration by the microsymbiont since living bacterial cells are not necessary for the induction. The observed glyceollin I production in response toBradyrhizobium japonicumis several times lower than that after pathogenic infection. Infection with zoospores of the phytopathogenic oomycete,Phytophthora megaspermaf. sp.glycinearace 1, leads within 20 h to an accumulation of 7 nmol glyceollin I/seedling in the root exudate of the compatible cultivar Kenwood and 48 nmol glyceollin I/seedlings in that of the incompatible cultivar Maple Arrow. These results support the idea that phytoalexins are implicated in determination of compatibility in pathogenic interactions. Crude cell extracts of different symbiotic bacteria (Bradyrhizobium japonicum110spc4,Rhizobium meliloti2011,Rhizobium leguminosarumPRE 8,Sinorhizobium frediiHH 103) were found to induce different amounts of glyceollin I in the root exudate. The observed glyceollin I levels could not be correlated with the ability of these rhizobial strains to nodulateGlycine max. Inhibition of flavonoid and phytoalexin synthesis by (R)‐(1‐amino‐2‐phenylethyl)phosphonic acid (APEP), a specific inhibitor of the phenylalanine‐ammonia‐lyase (PAL), during the first 20 h of the symbiotic interaction dramatically decreased the number of nodules formed in root regions that had been in contact with the inhibitor. This effect was observed at concentrations that inhibited neither bacterial nor plant growth. The implications of these findings for the process of nodule initation

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1992.tb00262.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractProtein bodies (PBs) from the epidermis and cortex of the radicle, as well as from coleorhizal and scutellar parenchyma of dry maize seeds were studied with the emphasis on presence and elemental composition of globoid crystals. PBs with variable structure were found in investigated tissues. Radicular epidermis was the only investigated tissue containing structurally uniform populations of PBs. They were filled by a homogeneous matrix without globoid crystals or their remnants. PBs structure and amount of proteinaceous matrix varied in the same cell of coleorhiza and scutellum. In the case of radicular cortex, the structure of PBs differed between analyzed individuals. Globoid crystals of various sizes were found in PBs from scutellum, coleorhiza, and from inner layers of radicular cortex. The largest globoid crystals (up to 2.0 μ in diameter) were seen in the scutellum. Energy‐dispersive X‐ray microanalysis revealed the presence of P,K. Mg, and some traces of Fe and Zn in the majority of globoid crystals from the scutellum. Globoid crystals from coleorhiza and radicular cortex were rich in Zn and Ca. The presence of considerable Zn was usually accompanied by high Ca, at the expense of K and Mg. As EDX analyses revealed significant differences in Zn and Zn/P values between analyzed tissues, it is probable that the majority of Zn is preferably accumulated in globoid crystals of some tissues of maize

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1992.tb00263.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractThe shift from C3to CAM was investigated as a function of both leaf and plant age in well‐watered and salt‐stressed (300 mM NaCl solution) plants ofMesembryanthemum crystallinum. Initiation of a night‐time accumulation of malic acid, the decisive criterion of CAM, was followed in plants that were continuously stressed at different points in their life cycle. The deinducibility of CAM was examined after the release from stress by extensively rinsing the potting soil with de‐mineralized water.Our results show that inM. crystallinumCAM is under strict developmental control, since CAM appeared only when a certain stage of development of the whole plant was reached. CAM was not present in any plant before this threshold, which was the same in salt‐stressed as well as in well‐watered plants. The metabolic shift coincided with the change from the seedling to the juvenile growth phase, and not with that from vegetative to reproductive growth, represented by the start of branching. The latter is timed to the end of extension growth.In well‐watered plants, after this decisive point in development, a weak nighttime accumulation of malic acid could be measured (≅ 0.05 mol kgDW−1) in the oldest, mature leaves but not in young, developing ones. This “CAM capacity” gradually increased up to 0.2 mol kgDE−1with further plant ageing. Leaf senescence, characterized by wilting and yellowing, diminished the CAM activity. In mature leaves salt stress drastically enhanced the magnitude of diurnal fluctuation in malic acid content.Removal of salt stress did not deinduce CAM activity, but diminished the amplitude of malic acid oscillations to some extent in those plants which had been stressed from early in their life cycle. In these plants, salt stress delayed plant development and growth thus retarding the life cycle. Well‐watered plants, for example, branched about three weeks earlier than those that had been stressed continuously from one week after germination. After removal of stress a quasi‐preserved earlier developmental stage in relation to the control plants determine

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1992.tb00264.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractThe supralittoral green algaPrasiola crispa, collected in Antarctica, was grown at salinities ranging from 0.35 %o to 175 %o. Its ultrastructure was examined by electron microscopy and compared with the ultrastructure of plants grown under standard conditions (35 %o).The thalli had very thick cell walls, making up approximately 50% of the thallus volume. Most of the protoplast was occupied by a single chloroplast. Numerous starch granules in the chloroplast were enlarged under hypo‐osmotic conditions and reduced in volume when subjected to hyperosmotic stress indicating a metabolic shift towards low molecular weight organic osmolytes under the latter conditions. Whilst vacuoles were lacking in plants cultured at salinities between 0.35 %o and 35 %o, they developed under hyperosmotic conditions and possibly may serve as compartments accumulating inorganic ions.Growth, photosynthesis and dark respiration were strongly inhibited under higher salinities, whilst they remained almost unaffected under lower salinities (Jacob et al., 1991

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1992.tb00265.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractAmoebae of the cellular slime moldDictyostelium discoideum(strain AX2) produce a pigment with an absorption spectrum that closely resembles the action spectrum for phototaxis. The protein‐pigment complex was isolated and purified by sucrose gradient centrifugation, fast protein liquid chromatography (FPLC) and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS PAGE). It is tightly membrane‐bound and the bulk of it is located in the mitochondrial membrane fraction, while a small part is located in the cytoplasmic membrane fraction, as indicated by marker enzyme tests (succinate dehydrogenase for mitochondria and alkaline phosphatase for the cytoplasmic membrane). It is speculated that the pigment bound to the cytoplasmic membrane acts as photoreceptor and that bound to the mitochondria operates as a shading pigment in the light direction perception mechanism ofDictyosteliumamoe

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1992.tb00266.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractThe monoclonal antibody Z‐3Bl (Schneider‐Poetsch et al., Planta 173 [1988] 61–72) was used to localize phytochrome in theMougeotiacell by indirect immunofluorescence. The antibody detected a protein of about 110 kD in the immunoblot. Immunofluorescence indicated abundant phytochrome throughout the cytoplasm. InMougeotia, a large cytoplasmic pool of phytochrome is presumably in equilibrium with a probably reactant‐bound Pfr‐pool at the plasmalemma, the latter being responsible for the physiological

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1992.tb00267.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractPreviously we have demonstrated the dynamic change of microtubules (MTs) during cell cycle progression using highly synchronized tobacco BY‐2 cells and characterized the specific transition points of MT organization (Hasezawa and Nagata, 1991). In this study the effect of okadaic acid (OA), a specific inhibitor of protein phosphatase 1 and 2A, on such changes of MTs during cell cycle was examined. These experiments revealed that cell cycle was arrested before the formation of the preprophase band (PPB), at anaphase and at the border of M/G1. Although the block at the anaphase seemed to be analogous to that observed in animal cells (Yamashita et al., 1990), the other two blocks were specific to plant cells. It is interesting that these two blocks coincided with the transition points of MT organization, as revealed in the previous study (Hasezawa and Nagata, 1991). Thus it is proposed that phosphorylation is involved in MT organization, although the effect of OA has been shown mainly to be the activation of cdc‐2/histone H1 kinase in animal cells. Another inhibitor of protein phosphatase 1 and 2A, calyculin A (CLA), showed very similar effects on the cell cycle progression. The use of such inhibitors to dissect the cell cycle progression of plant cells is discus

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1992.tb00268.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY