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Wedel, N.; Bartling, D.; Herrmann, R. G.
doi: 10.1111/j.1438-8677.1988.tb00047.xpmid: N/A
We report the isolation and characterization of a recombinant cDNA phage from a lambda gt11 expression library made from polyadenylated spinach RNA that encodes the entire precursor polypeptide of ferredoxin I. The deduced sequence predicts a molecular mass of 10.5 kDa (97 amino acid residues) for the mature protein and a transit peptide of 50 residues (5.2 kDa). In vitro synthesized ferredoxin precursor was used for import experiments with isolated unbroken spinach chloroplasts. The polypeptide was correctly directed to the organelle stroma and processed to the size of the mature protein. Northern analysis indicates a mRNA size of ca. 850 nucleotides which is close to the size of the cDNA insert (ca. 700 bp).
Pottiez, B.; Krippahl, G.; Ninnemann, H.
doi: 10.1111/j.1438-8677.1988.tb00048.xpmid: N/A
Chemically inactivated nitrate reductase of Neurospora crassa strain al‐2, bd can be photoreactivated by blue light. The quantum requirement for this reaction in the presence of exogenous FMN was determined with different light intensities. The results are discussed with the alternate assumptions that free FMN or photoactivated FAD bound to the nitrate reductase molecule is the reactivating species.
Büchel, C.; Wilhelm, C.; Lenartz‐Weiler, I.
doi: 10.1111/j.1438-8677.1988.tb00049.xpmid: N/A
The xanthophycean alga Pleurochloris meiringensis was homocontinuously cultured under high light (16 W/m2) and low light (2 W/m2) conditions. In low light cells, the chlorophyll a content and the dry weight on per cell basis is increased, the maximal photosynthetic capacity per chlorophyll is decreased. The content of chlorophyll c, vaucheriaxanthin‐ester and heteroxanthin is similar in both cultures, whereas the content of diadinoxanthin and ß‐carotene is twice as high in high light cultures. High light cells contain more photosystem I and cytochrome f per chlorophyll than low light cells, whereas the QB content is found to be unchanged. Therefore, the ratio reaction center II/reaction center I is twofold higher in low light cells than in high light ones. The regulation of energy distribution between the photosystems is examined by fluorescence emission spectra at 77 K scanned after different preillumination of the cells. No wavelength dependent state I/state II transition can be detected. However, P. meiringensis regulates the energy distribution in response to light intensity: The higher the irradiance of preillumination, the higher the energy transfer to photosystem I. The sensitivity of the regulation to light intensity is increased in low light cells.
Rother, Th.; Acker, G.; Scheibe, PD Dr. R.
doi: 10.1111/j.1438-8677.1988.tb00050.xpmid: N/A
Immunogold labelling on ultrathin sections of Lowicryl K4M embedded lower epidermis of spinach (Spinacia oleracea L.) with adhering mesophyll cells has been applied to localize five proteins, namely ribulose‐1,5‐bisphosphate carbocylase/oxygenase (EC 4.1.1.39), chloroplast coupling factor (EC 3.6.1.34), NADP‐malate dehydrogenase (EC 1.1.1.82), chloroplast fructose‐1,6‐bisphosphatase (EC 3.1.3.11) and thioredoxin m by electron microscopy in stomata. Comparative data of labelling densities of the localized proteins in chloroplasts of spongy parenchyma, epidermis and guard cells are presented. All five proteins could be detected in guard cell chloroplasts at levels little different from those found in chloroplasts of spongy parenchyma and of epidermis cells. The two light‐activated enzymes NADP‐malate dehydrogenase and fructose‐1,6‐bisphosphatase are reduced in stomata to about one third of the mesophyll concentration. Aldehyde‐sensitivity of the inspected enzymes and suitability of cryosections for immunolocalization studies on plant tissues, in comparison with resin‐embedded specimens, was investigated. Fixation with 2% glutaraldehyde resulted in no detectable decrease of antigenicity. Cryosections were found to be less suitable for immunogold labelling, since labelling densities were lower than on resin. Only labelling of the thylakoid‐bound coupling factor was comparable using both techniques.
Komor, E.; Cho, B.‐H.; Kraus, M.
doi: 10.1111/j.1438-8677.1988.tb00051.xpmid: N/A
Incubation of the green alga Chlorella vulgaris (strain K, Tanner and Kandler, 1967) with glucose leads to the induction of a glucose transport system and of two amino acid transport systems. Because it was not clear whether the regulation of 3 different transport systems by glucose is specific to our strain of Chlorella or whether it is a general property of the genus Chlorella, 11 other free living and symbiotic Chlorella species and strains were tested for glucose‐inducible glucose, arginine and proline transport. It was found that nearly all Chlorella species possess glucose and amino acid uptake systems. Often they were constitutive, although in some species they were induced or stimulated by glucose. According to the transport activities of the different Chlorella species and strains, a physiological classification of Chlorella was constructed, resulting in 3 groups: the C. fusca vacuolata, the C. vulgaris and the symbiotic Chlorella group. Our Chlorella (strain K) obviously belongs to the C. vulgaris group and forms a link to symbiotic Chlorella strains. This suggests that the possession of the glucose‐regulated transport systems is of advantage for Chlorella in symbiotic situations, whereas the constitutive systems are useful for free living Chlorella.
Eschrich, W.; Fromm, J.; Evert, R. F.
doi: 10.1111/j.1438-8677.1988.tb00052.xpmid: N/A
Membrane potentials of −;160 to −210 mV were recorded with microelectrodes inserted into meta‐phloem sieve tubes of intact zucchini plants (Cucurbita pepo L. var. medullosa Alef.). The effects of darkness, white light and colored light on membrane potential were studied. Reference electrodes were in contact with the apoplast via fluid‐filled cavities or “drinks”. Electrolyte solutions (100 mM) in the cavities could be quickly replaced by flushing with 100 mM solutions of sucrose, KCl, sorbitol, or EDTA without altering osmolarity. KCl and EDTA caused depolarization of the sieve tube membrane potential, while sucrose caused depolarization or hyperpolarization of the sieve tube membrane potential in mature or growing plant parts respectively. Recovery of the original voltage was recorded when rapid (sucrose) or slow (sorbitol) transients occurred. When two measuring circuits were installed, one in a growing fruit and the other in the petiole of the subtending mature leaf, the alteration of the sieve tube membrane potential at one site was accompanied by an alteration of the potential at the other site after a few seconds. The responses were opposite in the exporting leaf and importing fruit when sucrose was applied. The signal, transmitted via the sieve tubes, reached maximum velocities of 10 cm per second.
doi: 10.1111/j.1438-8677.1988.tb00053.xpmid: N/A
Uptake experiments and efflux compartmental analyses of abscisic acid (ABA) with acid treated epidermal peels of Valerianella locusta were performed to elucidate the mechanisms of transport of ABA across the plasmalemma and tonoplast of guard cells.
Le, Silva; Le, W.; Wollgiehn, R.; Parthier, B.
doi: 10.1111/j.1438-8677.1988.tb00054.xpmid: N/A
Cotyledons detached from pumpkin seedlings of different stages of development were either illuminated or treated with 4.10−5 M cytokinin (benzyladenine, BA) in darkness. Comparison of the abilities to incorporate 14C‐leucine into proteins in vivo as well as 35S‐methionine in vitro by means of an RNA‐programmed cell‐free wheat germ system demonstrates that the patterns of the two‐dimensionally separated in vivo labelled soluble proteins are very similar in differently developed or treated cotyledons. Although the translatable mRNA patterns were almost identical in qualitative respect, our data do not exclude the appearance of a few minor polypeptides altered by either illumination or BA treatment. The steady‐state levels of the mRNAs in cotyledons from 12 days old seedlings were remarkably similar irrespective of cotyledon treatment (water, BA, light) and resemble those levels obtained with illuminated or BA‐treated cotyledons of earlier seedlings stages. Our results suggest that the amount of abundant (soluble) proteins in pumpkin cotyledons is developmentally regulated mainly at the transcript level. Extrinsic factors such as cytokinins (BA) or light are equally able to accelerate the developmental program of gene expression in early‐detached cotyledons, which are probably deficient in endogenous hormone.
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