Peter Beutelmann

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.

Biosynthesis of acetylenic fatty acids in the moss Ceratodon purpureus (Hedw.) Brid

Summary Protonema Cells Of The Moss Ceratodon Purpureus Accumulate Triacylglycerols With Two Acetylenic Acids, 9,12-Octadecadien-6-Ynoic Acid (18:2A) And 9,12,15-Octadecatrien-6-Ynoic Acid (18:3A), As Main Components. By Following The Incorporation Of The [ 14 C]-Precursors (Acetate, Linoleate, γ-Linolenate, α-Linolenate, Stearidonate And 18:2A) Into 18:3A In Triacylglycerol Accumulating Cells, The Pathway For Acetylenic Acids Could Be Established. 18:2A And 18:3A Could Be Synthesized By A Second Desaturation Of The Δ 6 Double Bond Of Linolenate And Stearidonate, Respectively. However The Major Pathway For 18: 3A synthesis was via a Δ 15 desaturation of 18:2A. Since 18:2A was found exclusively in the triacylglycerols of the cell, the triacylglycerols in Ceratodon purpureus can act either as a direct substrate for the Δ 15 desaturation or, alternatively, the 18:2A has to be detached, desaturated and reincorporated into triacylglycerols. These results, as well as recent results from developing sunflower seeds by Garces et al. (1994, in press), present evidence that, in contrast to the general believe, plant triacylglycerols are not metabolic inert molecules during the cell stage of triacylglycerol deposition.

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.

Untersuchungen zur Biosynthese eines Cytokinins in Calluszellen von Laubmoossporophyten

SummaryWhen callus cells derived from the sporogon of the hybrid Funaria hygrometrica x Physcomitrium piriforme are supplied with adenine-8-14C, they produce a labelled cytokinin which has the same chromatographic behavior as N6-γγ-(dimethylallyl)aminopurine. The cytokinin is the first radioactive product that can be detected in the culture medium. It is formed as long as labelled adenine is available. When callus cells are grown in an optimum culture medium containing amino acids, about 10% of the radioactivity supplied as adenine is found in the cytokinin. When the cells are grown in a medium without amino acids, the RNA-content of the cells and the total yield of cytokinin decrease, but about 18% of the radioactivity is taken up into RNA as adenine and guanine, which are both degraded to allantoin and urea but not converted to cytokinin. Free guanine is converted neither to adenine nor to cytokinin.Weak cytokinin activity can be detected in hydrolysates of sRNA, but no radioactive cytokinin can be isolated from sRNA of adenine-labelled callus cells. it is assumed that free cytokinin is not a degradation product of tRNA.When callus cells derived from the sporogon of the hybrid Funaria hygrometrica x Physcomitrium piriforme are supplied with adenine-8-(14)C, they produce a labelled cytokinin which has the same chromatographic behavior as N(6)-γγ-(dimethylallyl)aminopurine. The cytokinin is the first radioactive product that can be detected in the culture medium. It is formed as long as labelled adenine is available. When callus cells are grown in an optimum culture medium containing amino acids, about 10% of the radioactivity supplied as adenine is found in the cytokinin. When the cells are grown in a medium without amino acids, the RNA-content of the cells and the total yield of cytokinin decrease, but about 18% of the radioactivity is taken up into RNA as adenine and guanine, which are both degraded to allantoin and urea but not converted to cytokinin. Free guanine is converted neither to adenine nor to cytokinin.Weak cytokinin activity can be detected in hydrolysates of sRNA, but no radioactive cytokinin can be isolated from sRNA of adenine-labelled callus cells. it is assumed that free cytokinin is not a degradation product of tRNA.

An Uncommon Pathway in the Biosynthesis of Acetylenic Fatty Acids in Mosses

Although more than 600 acetylenic compounds of various structures have been found in plants [1], hardly anything is known about the formation of the triple bonds. The acetylenes so far known from Bryophytes, have been identified as long chain fatty acids with a characteristic arrangement of one triple bond and one to three double bonds.

Degradation of Acetylenic Triacylglyceroles and the Inactivation of Membrane Preparations from Moss Protonema Cells

Protonema cells of the moss Ceratodon purpureus accumulate triacylglycerols with two acetylenic fatty acids, 9,12-octadecadien-6-ynoic acid (18:2A) and 9,12,15-octadeca-trein-6-ynoic acid (18:3A), as main components. By following the incorporation of the [14C]-precursors acetate, linoleate, α-linolenate, γ-linolenate, stearidonate and 18:2A, into 18:3A in triacylglycerol accumulating cells, the pathway for acetylenic acids could be established. 18:2A and 18:3A could be synthesized by a second desaturation of the Δ6 double bond of γ-linolenate and stearidonate, respectively. However the major pathway for 18:3A synthesis was via a Δ15 desaturation of 18:2A. Since 18:2A was found exclusively in the triacylglycerols of the cell, there is evidence that the triacylglycerols in Ceratodon purpureus can act as a direct substrate for the Δ15 desaturation [1]. Our next goal is to confirm these in-vivo results by demonstrating the pathways in vitro with subcellular fractions of the moss cells. In the following we will report mainly on the obstacles we met on our way to successful in-vitro experiments. Cell fractionations, in-vitro measurements and analyses were carried out according to established methods [1], [3], [4].

Ligand requirement for LHC I reconstitution

Knowledge of the structure of photosynthetic light harvesting complexes is essential for understanding their function. Reconstitution of light harvesting complexes proved to be a very powerful tool for such structure analyses. In this way evidence was obtained for the central role of lutein and chlorophylls for LHCII structure (1) which was later confirmed by electron crystallographic analyses (2). Employing mutated, bacterial overexpressed LHCII apoproteins, amino acids could be identified which are involved in trimerization of LHCII and probably in binding of phosphatidylglycerol (3).

Untersuchungen zur Biosynthese eines Cytokinins in Calluszellen von Laubmoossporophyten@@@Studies on the biosynthesis of a cytokinin in callus cells of moss sporophytes

SummaryWhen callus cells derived from the sporogon of the hybrid Funaria hygrometrica x Physcomitrium piriforme are supplied with adenine-8-14C, they produce a labelled cytokinin which has the same chromatographic behavior as N6-γγ-(dimethylallyl)aminopurine. The cytokinin is the first radioactive product that can be detected in the culture medium. It is formed as long as labelled adenine is available. When callus cells are grown in an optimum culture medium containing amino acids, about 10% of the radioactivity supplied as adenine is found in the cytokinin. When the cells are grown in a medium without amino acids, the RNA-content of the cells and the total yield of cytokinin decrease, but about 18% of the radioactivity is taken up into RNA as adenine and guanine, which are both degraded to allantoin and urea but not converted to cytokinin. Free guanine is converted neither to adenine nor to cytokinin.Weak cytokinin activity can be detected in hydrolysates of sRNA, but no radioactive cytokinin can be isolated from sRNA of adenine-labelled callus cells. it is assumed that free cytokinin is not a degradation product of tRNA.When callus cells derived from the sporogon of the hybrid Funaria hygrometrica x Physcomitrium piriforme are supplied with adenine-8-(14)C, they produce a labelled cytokinin which has the same chromatographic behavior as N(6)-γγ-(dimethylallyl)aminopurine. The cytokinin is the first radioactive product that can be detected in the culture medium. It is formed as long as labelled adenine is available. When callus cells are grown in an optimum culture medium containing amino acids, about 10% of the radioactivity supplied as adenine is found in the cytokinin. When the cells are grown in a medium without amino acids, the RNA-content of the cells and the total yield of cytokinin decrease, but about 18% of the radioactivity is taken up into RNA as adenine and guanine, which are both degraded to allantoin and urea but not converted to cytokinin. Free guanine is converted neither to adenine nor to cytokinin.Weak cytokinin activity can be detected in hydrolysates of sRNA, but no radioactive cytokinin can be isolated from sRNA of adenine-labelled callus cells. it is assumed that free cytokinin is not a degradation product of tRNA.