ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1990.tb00151.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractAttention is drawn to literature evidence that leaf virus infection may interfere with synthesis of ribulose‐1,5‐bisphosphate carboxylase oxygenase, and with the activity of photosystem II, two main requirements for shade‐sun acclimation. Preliminary experiments which show that virus infections resulting in these interactions can lead to photosynthetic physiology diagnostic of nitrogen limited plants and/or shade ecotypes are presented. Other observations on the diversity of virus infections in sun populations of wild species commonly found in the shade are presented. Together, this evidence leads to the hypothesis that virus infection may well confine individuals of some species to shaded habitats because infection prevents acclimation to bright light, and predisposes them to photoinhib

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1990.tb00152.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractDuring the last 3 years, genes for plasma membrane H+‐ATPases from fungi, protozoa and plants have been isolated. Sequence similarities indicate that H+‐ATPases constitute a separate group with the family of ATPases with phosphorylated intermediates. Yeast is a convenient model system to approach the physiology of H+‐ATPases by recombinant DNA methodologies. A mutational analysis of yeast H+‐ATPase has demonstrated that the enzyme is essential and rate‐limiting for growth. Intracellular pH homeostasis is one of the crucial functions of H+‐ATPase. In addition, there are indications for the direct energization of some essential transport system. The regulation of ATPase activity is probably mediated by an interaction between the active site and an inhibitory domain at the carbox

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1990.tb00153.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractThe distribution of a 125 kg . mol−1protein recognized by a monoclonal antibody raised against phytochrome of maize was analyzed in the sporophyte of the fernPsilotum nudum. Highest amounts (up to 5 μg per fresh weight) of this protein were found in the tips of expanding shoots. Green sporangia as well as the pale tips of the rhizome contained this 125 kg . mol−1protein, too. In the brown parts of the rhizome it was more rarely contained. Unlike phytochrome from etiolated higher plants, thePsilotumprotein appeared to be scarcely degraded by the illuminated plants. In this respect the protein ofPsilotumseems to resemble the small fraction of phytochrome contained in green and illuminated higher plants. Moreover, after illuminating thePsilotumrhizome for 3 d, higher amounts of this protein were detected therein as be

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1990.tb00154.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractThe time course of appearance of competence to phytochrome (Pfr) was studied in cotyledons of mustard (Sinapis albaL.) with regard to the light‐mediated accumulation of mRNAs encoding for SSU, CAB and the 23 kDa protein of the oxygen evolving complex of photosystem II (OEC). For each gene family a specific starting point of Pfr‐induced mRNA accumulation was observed (SSU: 42 h; CAB: 36 h; OEC: 30 h). An increase of SSU‐mRNA levels can be detected 24 h after sowing in dark‐grown seedlings whereas for OEC the time points for the increase of mRNA are the same whether the seedlings are kept in darkness or induced by light via Pfr. For all gene families a responsiveness to Pfr(coupling point) could be demonstrated before the starting points. The coupling points are also gene specific (SSU: ca. 12 h; CAB and 23 kDa peptide of OEC: ca. 24 h). The responsiveness to light before the starting point indicates that the light‐induced signal must

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1990.tb00155.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractThe supramolecular organization of the thylakoid membranes of the thallus stage in the red algaPorphyra leucostictais studied in replicas of rapidly frozen and fractured cells. Freeze‐fractured thylakoid membranes exhibit only two types of fracture faces (EF and PF), because the lamellae in red algal chloroplasts are not stacked. The PF reveals numerous, tightly packed, but randomly distributed particles (density range from 2970 to 3550 particles/μm2). In contrast, the EF particles appear organized into parallel rows, the spacing of which is about 60–70 nm (about 8–9 particles occur along 100 nm of the line that is formed). Significant numbers of single EF particles are randomly distributed between the EF particle rows. The particles on both fracture faces (PF and EF) fall into two size classes: 10 to 11 nm (major size class) and 14 to 15 nm (minor size

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1990.tb00156.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractThe structure and arrangement of phycobilisomes of the unicellular red algaPorphyridium cruentumis compared with the organization of the thylakoid freeze‐fracture particles in order to determine the relationship between phycobilisomes and photosystem II. The hemi‐ellipsoidal phycobilisomes, 20 nm thick, are predominantly organized into rows; their centre to centre periodicity is 30–40 nm, so that they are well separated by a gap of 10–20 nm. The phycobilisomes are cleaved by a central faint furrow, parallel to the long axis from top to base.The organization of the exoplasmic particles in rows is similar to the arrangement of the phycobilisomes so that a structural relationship between both systems, previously demonstrated in cyanobacteria, is evident. Within the rows, the 10 nm EF‐particles are grouped in tetrameric complexes separated by distances similar to those observed for phycobilisomes. We propose that the tetrameric EF‐particle complexes correspond to tetrameric photosystem II complexes which bind one hemi‐ellipsoidal phycobilisome on the stroma exposed surface of the thylakoid. A hypothetical model of this photosystem II‐phycobilisome compl

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1990.tb00157.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractThe small subunit of ribulose‐1,5‐bisphosphate carboxylase/oxygenase is encoded by a nuclear multigene family (rbcSgenes). We have cloned and characterized threerbcScDNA sequences fromBrassica napus. These cDNA clones all appear to encode the same protein, but they differ in their nucleotide sequence, which has been exploited in the construction of clone‐specific oligonucleotides as selective hybridization probes. By using a nonselective RNA probe, the temporal expression of the entirerbcSgene family was analyzed during seedling development ofBrassica napusand ofSinapis alba. In both crucifer species,rbcStranscripts show transient peak levels and then decrease, although to a different degree. Only a moderate (twofold) difference in transcript pool sizes is observed in light‐grown versus dark‐grown seedlings at the time of peak levels, while a much higher light/dark ratio is found in late‐stage seedlings. The oligonucleotide probes reveal three subsets of transcripts which differ in their accumulation kinetics and light/dark ratio. Assessment of the spatial distribution by usingin situhybridization indicates thatrbcStranscripts are uniformly localized in cross‐sections of cotyledons from either light‐grown or dark‐grown seedlings, whereas they are undetectable

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1990.tb00158.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractPhosphoenolpyruvate carboxylase fromAmaranthus viridisleaves was activated by inorganic orthophosphate in a concentration‐ and pH‐dependent manner. Maximal activation at pH 7.0 was achieved at phosphate concentrations above 20 mM, and a positive cooperativity was observed for the binding of the anion at this pH. At pH 8.0 the maximum of activity was achieved at 10 mM phosphate; higher concentrations reduced the activation. KMfor phosphoenolpyruvate‐Mg at pH 7.0 was lowered by phosphate in all concentrations tested up to 30 mM. While at pH 8.0 the KMvalues were lower than that of the control up to 10 mM phosphate; higher anion concentrations raised the minimum value of KMat this pH. VMAXincreased at pH 7.0, and remained unchanged at pH 8.0. A KAvalue of 0.41 mM was calculated for phosphate at the alkaline pH. The phosphate analogue arsenate also behaved as an activating agent, while other anions (e.g. nitrate, nitrite, sulfate, tetraborate) were ineffective. The phosphate‐activated enzyme was shown to be insensitive to glucose‐6‐phosphate, but was inhibited byl‐malate to the same extent a

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1990.tb00159.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractPinitol (1d‐3‐O‐methyl‐chiro‐inositol) and 1d‐1‐O‐methyl‐muco‐inositol, two cyclitols wide‐spread in the plant kingdom, were isolated from plant sources in order to test their compatibility with malate dehydrogenase activity. Both compounds had no inhibitory effect on malate dehydrogenase fromRhizophora manglein a range of 100 to 1000 mol . m−3.Their influence on malate dehydrogenase activity from different plant sources (Rh. mangleL.,Mesembryanthemum crystallinumL.,Cicer arietinumL. andSpinacia oleraceaL.) was also small and similar to that observed for a number of well established compatible solutes (e.g. proline, glycine betaine). A possible role of cyclitols as cryoprotectants or radical

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1990.tb00160.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY