ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1996.tb00545.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1996.tb00546.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1996.tb00547.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Abstract:In this review we compared the electrophysiological properties of plant K+uptake channels from different plants and tissues. Taking into account the detailed knowledge of K+channel properties, which has emerged since the application of the patch‐clamp technique on plant cells, as well as results from our recent studies we were able to extract features common among plant K+channels. In addition, we focused on the diversity that could create plant or tissue‐specificity. Functional fingerprints for the voltage‐dependent K+uptake channels were generated on the basis of their voltage‐dependence, kinetics, permeability, conductance and pharmacology as well as regulation of K+channels studied in their natural environment and cloned channels in heterologous expression systems. Finally, sequence information on plant and animal K+channels cloned so far was used to identify structural motifs that may be related to functional phe

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1996.tb00548.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Abstract:Pollen tubes ofNicotiana tabacumandPetunia hybridashow pulsatory growth. Phases of slow growth lasting minutes are interrupted by pulse‐like elongations lasting 10–20 seconds involving an increase of growth rate by up to 24‐fold. Inhibition of dictyosome activity with brefeldin A or monensin did not result in an inhibition of pulsatory growth but eventually stopped pollen tube elongation. In contrast to this the inhibition of the cytoskeletal elements with cytochalasin D and colchicine caused the pollen tubes to abandon the pulse‐like elongations. It was concluded that the activity of the dictyosomes does not have a controlling function in the mechanism of pulsatory growth, even though it is necessary for pollen tube elongation, since cell wall material is provided by secretory vesicles deriving from the Golgi apparatus. In contrast the cytoskeletal elements, actin and microtubules, seem to play an important regulatory role in the pulse‐like elongations. In addition, it was observed that during the experiments several pollen tubes burst upon the completion of a pulse‐like expansion, indicating on the one hand that the internal turgor is the driving force of the pulse‐like expansions. On the other hand, the bursting shows that the pollen tube cell wall is rather weak at the end of a pulse, indicating that at this point of time it is either thinner or less stable than during the slow growth phase or at the beginni

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1996.tb00549.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Abstract:Intra‐ and intercellular movement of the fluorochrome Lucifer Yellow (LY), microinjected into the shield cells of male sex organs, was examined at different stages of spermatogenesis inChara vulgarisL. Two distinct stage‐associated types of probe movement were noted: (I) a fast and uniform spreading of fluorescence within the shield cell injected, followed by centripetal transport of LY into the adjoining manubrium and the capitular cells, and subsequent redistribution into the other manubria and shield cells in young antheridia (up to the stage of 4‐cellular filaments), and (II) limited spreading of fluorescence, restricted to the triangle‐shaped area of the impaled shield cell in more mature antheridia with multicellular filaments. These results confirm earlier electron microscopic observations on plasmodesmatal connections indicating an intensive solute movement between all cell types in young antheridia ofChara. Developmental changes appearing at later stages, during differentiation of sperm cells, strongly reduce the capacity for intercellular symplasmic tr

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1996.tb00550.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Abstract:A new cyanobacterial isolate, morphologically closely resemblingAphanocapsa, was characterized for its growth requirements, as well as pigmentation, photosynthetic activity and dynamics of the D1 protein in the reaction center (RC) of photosystem II (PSII). It was shown to be able to grow on glucose in the dark in the presence of DCMU. The cyanobacterium turned light yellow at high light intensity in the absence, and dark emerald green in high light in the presence of sublethal concentrations of the DCMU‐type inhibitor atrazine. While total carotenoids per cell slightly decreased with increasing light intensity during growth, the cells still turned pale yellow due to decreased levels of chlorophyll and phycocyanin. In contrast to β‐carotene, zeaxanthin and echinenone which decreased with increasing light intensity during growth, the carotenoid glycoside, myxoxanthophyll, continuously increased in concentration.Extremely high rates of light‐saturated O2evolution were recorded for the high light cultures after a 0.5 h recovery period in the dark. The recovery measured after 2.5 h was shown to be less effective in darkness than in dim light and was prohibited by chloramphenicol. The degree of recovery was dependent on the light intensity during growth. A fast light intensity‐dependent RC II‐D1 protein turnover was found for the bleached yellow cells rich in myxoxanthophyll. The half‐life of the RC II‐D1 protein, plotted against the light intensity during growth and experimentation, yielded a curve the slope of which was considerably steeper forAphanocapsathan forAnacystis. Apparently, the isolated strain ofAphanocapsareacts more vigorously to changes in the environment than other strains tested and may, therefore, turn out to be a suitable organism in the attempt to elucidate the molecular mechanism of light intens

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1996.tb00551.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Abstract:When segments of rye leaves (Secale cerealeL.) grown at 90 μmol m−2s−1PAR were incubated at a higher photon flux of 400–500 μ mol m−2s−1PAR in the presence of 0.2‐0.6 M NaCl, a preferential loss of catalase activity was induced. The extent of this decline increased with the concentration of NaCl. In addition, the accumulation of alternative antioxidative components, such as ascorbate, glutathione, glutathione reductase, or peroxidase, was inhibited. The total content of H2O2was, however, lower in catalase‐depleted than in untreated control leaves. The occurrence of strong oxidative stress in NaCl‐treated leaves was indicated by marked declines in the ratios of reduced to oxidized ascorbate and glutathione and by the degradation of chlorophyll in light. The specific elimination of catalase activity by the inhibitor aminotriazole was also accompanied by a rapid decline in the ratio of reduced to oxidized glutathione but other symptoms of oxidative stress were much less severe than in the presence of NaCl. However, all symptoms of photooxidative damage seen in NaCl‐treated leaves were closely mimicked by treatment with the translation inhibitor, cycloheximlde, in light. The results suggest that NaCl‐induced oxidative damage in light was predominantly mediated by the inhibition of protein synthesis. By this inhibition the resynthesis of catalase, which has a high turnover in light, was blocked and the leaves were thus depleted of catalase activity and, in addition, the intensification of alternative antioxidative syste

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1996.tb00552.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Abstract:Transformed root lines ofDatura stramoniumwere established following infection of aseptic stem segments withAgrobacterium rhizogenesstrain A4. These root lines were examined for their alkaloid productivity in relation to growth rate and the presence in the nuclear genome ofrol(A, B and C) andtmsgenes. The amount of polypeptides coded byrolB androlC genes, and the transcript levels ofrolA,rolB androlC genes were also investigated. Southern blot analysis using [32P]‐la‐belled fragments of the T‐DNA as probes, revealed the lack oftmsgenes and the presence of the threerolgenes in the genome of the all root lines. The growth rates of these transformed root lines were not always correlated with their hyoscyamine biosynthesis ability. However, all transformed root lines, showed a positive correlation between hyoscyamine production and the level of polypeptide coded byrolC

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1996.tb00553.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Abstract:Total DNA was extracted from 25 species (8 genera) of the subfamily Lamioideae sensu Erdtman (family Labiatae). Using rbcL‐specific primers, the rbcL gene was amplified by polymerase chain reaction (PCR) and 1420 bp were sequenced directly, or after cloning. RbcL sequences were evaluated with character‐state (maximum parsimony; PAUP) and distance methods (neighbour‐joining; MEGA). In agreement with classical systematics all taxa studied cluster outside the Nepetoideae. The following clades are apparent: I ‐Westringia/Prostanthera, II ‐Ajuga/Teucriumand III ‐Scutellaria, Stachys, LamiumandMarrubium. Lamium album, L. amplexicauleandL. garganicumappear as a sister clade toMarrubium. Both share a common ancestor with a secondLamiumclade (includingL. purpureum, L. maculatumandL. galeobdolon). The phylogenetic relationships are discussed with regard to the systematic classification of the subfamilies Lamioideae and Nepetoideae (sen

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1996.tb00554.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY