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doi: 10.1111/j.1438-8677.1989.tb00062.xpmid: N/A
Photosensory adaptation (range adjustment) is of great importance in plants (including fungi and various microorganisms) that operate in large intensity ranges. The adaptation mechanisms of plants have some features in common with those of vertebrates and invertebrates. As with those systems, plants have biphasic exponential dark‐adaptation kinetics, that are much slower than the corresponding light adaptation kinetics. One needs to distinguish between sensor adaptation, which regulates range adjustment, and effector adaptation (habituation), which regulates the motor apparatus of the organism (flagellar movement or cell wall growth). In Phycomyces, and perhaps Stentor, sensor adaptation is mediated by the photoreceptor system. In contrast to vertebrates and invertebrates, dark adaptation can be controlled in some plants by special photoreceptors. In Phycomyces, these can be either photo‐products of the actinic photoreceptor(s) or not yet identified receptor pigments. In higher plants phytochrome can alter the state of adaptation.
Pollmann, Lutz; Wettern, Michael
doi: 10.1111/j.1438-8677.1989.tb00063.xpmid: N/A
The multiple biological functions of the small polypeptide ubiquitin are mirrored by its unparalleled conservation on the amino acid and gene organization level.
doi: 10.1111/j.1438-8677.1989.tb00064.xpmid: N/A
The changes of galactolipids (MGDG and DGDG, largely 18:3/18:3), free fatty acids (FFA), and phosphatidylcholine (PC) taking place during senescence of primary barley leaves were analysed employing HPLC and GLC. Upon induction of senescence MGDG and, with some delay, DGDG began to disappear and were largely broken down at the end of the senescence period. A concomitant appearance of a pool of FFA could not be observed. However, PC accumulated during the main period of galactolipid breakdown. This change was due to the marked increase of the 18:3/18:3 molecular species of PC. An inverse correlation between the changes of galactolipids and PC could be established. A hypothesis featuring the conversion of galactolipids via diacylglycerol to PC is presented as the principal route of galactolipid breakdown.
Lorenc‐Plucińska, Gabriela; Miszalski, Z.; Ziegler, H.
doi: 10.1111/j.1438-8677.1989.tb00065.xpmid: N/A
The mechanism of glucose and sucrose transport and the influence of various concentrations of sulfite on its activity was studied in mesophyll protoplasts (etioprotoplasts, semi‐etioprotoplasts and green protoplasts) isolated from oat (Avena sativa L.) seedlings.
Rhiel, E.; Kunz, J.; Wehrmeyer, W.
doi: 10.1111/j.1438-8677.1989.tb00066.xpmid: N/A
Antisera, raised against the subunits of phycoerythrin‐545 and total chlorophyll a/c light harvesting complex (chl a/c LHC) of Cryptomonas maculata, were tested for specificity by immunodiffusion and Western‐immunoblotting experiments. They were further used for immunogold‐labeling of Lowicryl sections of control and nitrogen deficient cells. In control cells (+ N) the antiserum against the chl a/c LHC labeled the thylakoid membranes uniformly. On the other hand, the label against the subunits of the water soluble phycoerythrin‐545 was almost completely restricted to the thylakoid lumen. Nitrogen deficient cells (–N) compared to control cells exhibited labels against the chl a/c LHC with very similar densities per unit area. For the subunits of phycoerythrin‐545 a three‐ to four‐fold weaker gold label per unit area was measured. These results confirm some of the earlier conclusions, e.g. the persistence of the chl a/c LHC even under conditions of nitrogen‐deficiency and the extensive degradation of the biliprotein (Rhiel et al., 1985, 1986, 1987).
Brown, R. C.; Lemmon, B. E.; Mullinax, J. B.
doi: 10.1111/j.1438-8677.1989.tb00067.xpmid: N/A
Methods for the indirect immunofluorescent staining of microtubules in embedded and sectioned plant tissues are described and compared. Root tips of Vicia faba, Saccharum officinale, Allium cepa, and root nodules of Glycine max were fixed using conventional methods, embedded in polyethylene glycol or Steedman's wax, sectioned with a glass knife on a rotary microtome, and dewaxed in water or alcohol. The addition of dithiothreitol (DTT), dehydrating at low temperatures and reducing the infiltrations times were found to reduce background fluorescence in Allium cepa. Steedman's wax yields a block that is similar to paraffin and is easier to section than PEG. Routine methods for indirect immunofluorescence were used to stain sections for tubulin/microtubules. The major microtubule arrays of mitotic cells are illustrated in this paper. The principal advantage of this technique is the preservation of cell‐to‐cell continuity in multicellular tissues. This method provides a much needed technique for the study of the cytoskeleton during growth and differentiation of plant tissues.
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