Elmar Hartmann

Isopentenyladenine from mutants of the moss, Physcomitrella patens

Abstract The culture media from gametophore over-producing mutants of the moss Physcomitrella patens have been examined for their cytokinin content. Two cytokinins have been detected, one of which has been identified as N6-(Δ2-isopentenyl) adenine (2iP).

Moss cell cultures as sources of arachidonic and eicosapentaenoic acids

Lipid classes from tissue cultures of the moss Leptobryum pyriforme (Hedw.) Wils. were analyzed. In the total lipid fraction, this species contained 20% arachidonic acid and about 7% eicosapentaenoic acid. The distribution of these fatty acids showed a preference for the phospholipid fraction. In particular, the phosphatidylethanolamine fraction was enriched in arachidonic acid. The arachidonic acid content of Leptobryum could be altered by transferring the cultures to different culture conditions. Mosses show high organic mass production in tissue cultures in relatively simple media. The great potential of using mosses as sources for the production of polyunsaturated fatty acids is evident.

Fatty acid composition of mutants of the moss Physcomitrella patens

Abstract The fatty acid composition of various mutant strains of the moss Physcomitrella patens has been compared to the wild-type. These included strains defective in their responses to auxins and/or cytokinins, one which releases much more cytokinin into the medium than the wild-type, and two aphototropic strains. The lipids of the aphototropic mutants were also studied after culture in different light regimes. Although some differences in fatty acid composition have been found between strains, these alone are probably not responsible for their physiological differences. Considerable changes occur in many fatty acids in senescent or dark-grown material, including changes in the proportion of C 20 polyenoic fatty acids.

Distribution and chemotaxonomic significance of acetylenic fatty acids in mosses of the dicranales

Abstract Thirty-eight moss species from four families of the order Dicranales were analysed for the fatty acid composition of their acyl lipids. In the Ditrichaceae and the Dicranaceae numerous species were found to contain acetylenic fatty acids in their triglycerides, 9,12,15-Octadecatrien-6-ynoic acid was the major component, often accounting for more than 80 mol%, whereas 9,12-octadecadien-6-ynoic acid was found in small amounts of less than 5 mol%. In some genera, all the species examined contained acetylenic fatty acids, e.g. Dicranella and Dicranum , whereas in the genus Campylopus all five species tested were free of acetylenic compounds. Two genera, Ditrichum and Dicranoweisia , were found to have a non-homogeous distribution of acetylenic fatty acids. The chemotaxonomic significance of the fatty acid composition in relation to morphological characters is discussed.

Acetylenic fatty acids in the ricciaceae (hepaticae)

Abstract Twelve species of the liverwort genus Riccia were analysed for their fatty acid composition and in all species acetylenic fatty acids were detected. In the species of the subgenus Ricciella , 9-octadecen-6-ynoic acid, and in the subgenus Euriccia , 9,12,15-octadeatrien-6-ynoic acid were the most abundant components. 9,12-octadecadien-6-ynoic acid was present in low amounts in both subgenera. In other genera, for example, Marchantia , Corsinia , Oximitra and Ricciocarpos , which are related to Riccia , no acetylenic fatty acids could be detected.

Partial purification and initial characterization of phytochrome from the mossAtrichum undulatum P. Beauv. grown in the light.

The extraction and partial purification of phytochrome from light-grownAtrichum undulatum P. Beauv., a chlorophyllous moss, is described. Polyethyleneimine and salt fractionation followed by hydroxyapatite and Affi-gel-blue chromatography were used to separate phytochrome from chlorophyll, and to purify the pigment. All steps were performed in the presence of Triton X-100 which improved the yield by a factor of about three. The protein has a molecular weight some-what larger than that ofAvena phytochrome (124 kDa), as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblot analysis. It cross-reacts with a monoclonal antibody against phytochrome from etiolated corn (Zea) and a polyclonal antibody against phytochrome from etiolated oat (Avena), and its photoreversibility is similar to that of phytochrome from greenAvena.

Über den Nachweis eines Neurohormones beim Laubmooscallus und seine Beeinflussung durch das Phytochrom

SummaryThe presence of a neurohormone in moss callus could be demonstrated by means of pharmacological experiments on the heart of the frog (Rana temporaria L.) and by chromatography.The hearts react in the same manner as they do to application of acetylcholine and the substance resembles acetylcholine in its Rf-value. Therefore it is suggested that this hormone is identical with acetylcholine. The concentration of the hormone in the callus cells is mediated by the phytochrome. Moss callus cultivated under red and far-red illumination contain less substance than moss callus grown in red light.The presence of a neurohormone in moss callus could be demonstrated by means of pharmacological experiments on the heart of the frog (Rana temporaria L.) and by chromatography.The hearts react in the same manner as they do to application of acetylcholine and the substance resembles acetylcholine in its Rf-value. Therefore it is suggested that this hormone is identical with acetylcholine. The concentration of the hormone in the callus cells is mediated by the phytochrome. Moss callus cultivated under red and far-red illumination contain less substance than moss callus grown in red light.

Über die wirkung des phytochroms beim laubmooskallus II. Sauerstoffmetabolismus und acetylcholinwirkung

Summary The oxygen metabolism is a good parameter for the determination of rapid responses of green moss callus to light. We measured the oxygen uptake with the Warburg method and polarographically with a Clark electrode and the YSI-oxygen monitor. The exposure of dark grown moss callus to red light (5–20 min) induced a rapid increase in O2-uptake after switching off the light. The respiration change depends on the exposure duration and the light intensity. During the first 2 or 3 h after irradiation with red light and with red-far red light, the rates of the O2-uptake show no differences but after this lag-phase the 2 curves are splitting. The respiration of the red irradiated cells remained higher over a period of 23 h compared to the red — far red irradiated cells. In the latter case the respiration reached the value of the dark control after 20 h. We could reverse the red effect of the rapid respiration change immediately with far red, using an irradiation apparatus with a rhythm of 0.45 s red — far red without a dark-phase. The acetylcholine (ACh) interactions with these light qualities were very complex. ACh was only physiologically active when the cofactor ascorbic acid was present. ATP is an additional cofactor for the ACh action with red — far red induced processes. There are great differences between ACh effects in long time experiments (like our Warburg tests) and in short time ones. ACh had no effect on the oxygen output or uptake when the cells were irradiated with red light, in contrast to the effect occuring with quick alternating red — far red illumination. In this case ACh promotes the oxygen output. This effect is inhibited by eserine. The complex manner of ACh effects is indicated by the results which we got from Warburg experiments. The application of ACh together with the onset of red irradiation has no effect independent of the ATP content of the substrate. We got the opposite results in experiments were we applied the hormone after the red illumination. In this case ACh mimicked a far red effect. ATP in the substrate nullified the ACh-action. We got exactly antagonistic ACh-effects with red — far red light treatments. In this case we had to apply the hormone with the onset of the irradiation. Then ACh mimicked a red light effect but only with ATP as cofactor. The physiological effects of red irradiations in moss callus grown in darkness or in continuous far red light cannot be mimicked by ACh. ACh becomes active after or during the irradiation. Light is necessary for ACh effects. Therefore, we think one cannot consider this hormone as being a special phytochrome hormone.

Isolierung und charakterisierung einer cholinkinase aus Phaseolus vulgaris L.-Keimlingen

Summary The enzyme choline kinase (ATP: Choline phosphotransferase E.C. 2.7.1.32) was extracted and partially purified from hypocotyl hooks of Phaseolus vulgaris L. seedlings. K m -value and pH-dependence of the activity were determined. The amount of enzyme activity in extracts depended on light conditions used for plant growth. Etiolated seedlings showed much lower enzyme levels than those grown in white light. Blue and red light conditions decreased enzyme levels below dark values. The in vitro enzyme activity was influenced by inhibitors and growth regulators. The enzyme activity was stimulated by Atropine, 2-Chloroethylammoniumchloride (Cycocel) and Gibberellic acid and was inhibited by Physostigmine. Neostigmine had no effects.

The Influence of Acetylcholine and Choline on the Incorporation of Phosphate into Phospholipids of Etiolated Bean Hypocotyl Hooks

Summary Acetylcholine influenced the radiolabelling of phospholipids in vivo in etiolated hypocotyl tissue of dwarf beans in darkness. Under aerobic conditions the specific activity of the phospholipids was decreased and under anaerobic conditions increased. The biosynthesis of phospholipids was strongly increased by the bivalent cations calcium and manganese and decreased by 2,4-dinitrophenol, anaerobiosis, atropine and ascorbic acid. Magnesium stimulated the uptake of the radioactive phosphate but not the specific activity of the phospholipids. The results are discussed in comparison with the «phospholipid-effect» of acetylcholine in animal tissues.