Regulation of seed germination and polarity in seedling development inOrobanche aegyptiaca by growth substances

InOrobanche aegyptiaca PEES. (Orobanchaceae) the mature seed is tiny and contains a subglobose embryo which is not differentiated into radicle, hypocotyl, plumule, and cotyledons. In aseptic seed cultures on medium TB supplemented with yeast extract or coconut milk, both roots and shoot originated from the morphological radicular pole of the embryo (monopolar pattern). The bipolar mode of seedling formation, that is a shoot originating from the plumular pole and roots from the radicular pole, ensued on the basal medium THS and on TB supplemented with certain concentrations of IAA, kinetin, GA3, or strigol.     

Heteroxanthin in Euglena gracilis

Summary 1. From a large scale preparation of Euglena gracilis, strain Z, besides the acetylenic pigments diatoxanthin and diadinoxanthin and the allene neoxanthin, an additional acetylenic xanthophyll has been isolated. 2. Mass and IR spectra and chemical reactions showed typical patterns of heteroxanthin from Vaucheria. 3. The pigment was transformed into diadinochrome-isomers with acidified acetone. 4. A partial synthesis of heteroxanthin from diadinoxanthin by LiAlH₄-reduction is described, confirming the structure proposed by Strain. 5. The identity of heteroxanthin with the trollein—like pigment described for Euglena is discussed.     

Proteolysis in Euglena gracilis

Endoproteolytic activities (EC 3.4.22. and 23.) of cell-free extracts of Euglena gracilis, measured by autolysis and azocaseinolysis, vary considerably during the culture growth cycle. They are high in the lag phase, drop sharply up to the mid-logarithmic phase, and then rise again reaching the initial high levels in the stationary phase. This pattern has been observed for both the soluble and the particulate proteolytic activities of four cell types differing with regard to the developmental state of the chloroplast: dark-grown, light-induced, and light-grown wild-type cells, as well as light-grown apoplastic W₃BUL mutant cells, all on a glucose-based medium. Therefore, the activity of the main intracellular proteinases is neither directly nor indirectly light-regulated, but seems to be controlled by the availability of nutrients. Endogenous inhibitors of proteinases could not be detected. Cysteine proteinase activity has been found in the soluble and the particulate fractions, but aspartic proteinase activity in the latter ones only. Different cysteine proteinases may be present in the two fractions, during the different growth phases, and in the four cell types studied.Abbreviations CBB Coomassie Brilliant Blue G-250 - DFP diisopropyl fluorophosphate - EDTA disodium ethylendiaminetetraacetic acid - E-64 l-transepoxysuccinyl-leucyl-amido(4-guanidino)butane - Iog phase logarithmic growth phase - MET 2-mercaptoethanol - PMSF phenylmethylsulfonyl fluoride - Z benzyloxycarbonyl Paper I of this series is Krauspe and Scheer (1986). A preliminary publication appeared (Krauspe et al. 1982)     

迷果芹根化学成分的研究

利用普通硅胶柱色谱技术和多种现代波谱技术,从迷果芹(Sphallerocarpus gracilis)的根中分离并鉴定了11个化合物,通过波谱学方法鉴定为:falcarinol(1)、(3R,8S)-falcarindiol(2)、diplaniol(3)、5-hydroxy-8-methoxy-2H-1-benzopyran-2-one(4)、esculetin(5)、东莨菪内酯(6)、xanthalin(7)、isoimperatorin(8)、胡萝卜苷(9)、β-谷甾醇(10)和豆甾醇(11),其中化合物1～6为首次从该植物中分离得到。     

Protoplasten der Hefe Rhodotorula gracilis

Zusammenfassung Die Protoplasten der obligat aeroben Hefe Rhodotorula gracilis wurden hinsichtlich ihrer charakteristischen physiologischen und Transporteigenschaften mit intakten Zellen verglichen. Folgende Ergebnisse wurden gewonnen: 1. Endogene und durch d-Glucose stimulierte Atmung entsprach den Werten von intakten Hefezellen. 2. d-Glucose wurde von Protoplasten aus dem Medium aufgenommen und abgebaut. 3. Die Aufnahme von d-Xylose führte zu vielfacher Akkumulation der Pentose im Zellinnern. Nach 50 min wurde ein für den Xyloseabbau induziertes System wirksam. 4. Bei Zugabe im Gemisch wurde die Aufnahme von d-Xylose durch d-Glucose unterbunden. 5. Akkumulierte d-Xylose wurde bei Zugabe von d-Glucose im Austauschtransport durch den mobilen Träger aus der Zelle heraus befördert. 6. Der Zuckertransport, gemessen an der d-Xyloseaufnahme, war streng stoffwechselenergieabhängig und wurde durch Entkoppler vollständig gehemmt.Diese Ergebnisse zeigen, daß die Stoffwechsel- und Transportfunktionen der intakten Hefezellen in ihren Protoplasten vollstädig erhalten bleiben. Die Anwendung von R. gracilis-Protoplasten zur Klärung spezieller Fragestellungen ergab: 1. Der Transport von d-Trehalose erfolgte nach extracellulärer Spaltung des Disaccharides durch Aufnahme der entstandenen Glucose. 2. Densitometrische Messungen an Protoplastensuspensionen zeigten sich geeignet zur kontinuierlichen Aufzeichnung von Zuckeraufnahmevorgängen.

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Protoplasts from the yeast Rhodotorula gracilisII. Physiological and transport properties

The protoplasts of the obligatory aerobic yeast Rhodotorula gracilis (5/Fres/Harrison) were compared with the intact yeast cells with respect to the identity of their physiological and transport properties. It was found: 1. The rates of endogenous and glucose-stimulated respiration of protoplasts were similar to those of the whole cells. 2. d-glucose was taken up from the medium with constant velocity; no free glucose could be detected inside the protoplasts. 3. The uptake of d-xylose led to manifold accumulation of the pentose intracellularly. Within 50 min incubation an enzyme system for the degradation of d-xylose became effective. 4. In a mixture of d-xylose and d-glucose the latter blocked the uptake of the pentose. 5. d-xylose once accumulated was exchanged by the mobile membrane carrier for d-glucose after its addition to the protoplast suspension. 6. Addition of NaN₃ or CCCP resulted in an inhibition of d-xylose uptake. The transport process is tightly coupled to cell metabolism.It is concluded that the metabolic and transport functions of R. gracilis protoplasts equal those of the intact yeast cells. The application of the protoplasts to study some special transport problems revealed: 1. In the course of d-trehalose uptake the disaccharide was cleaved to glucose, which was actually transported across the cell membrane. 2. Densitometry of protoplasts suspensions was found suitable for the continuous recording of sugar uptake processes. This observation is of special importance for further investigations of the oscillations in sugar transport observed earlier (Heller and Höfer, 1973).

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Herrn Professor Dr. Maximilian Steiner zum 70. Geburtstag gewidmet.     

Triterpene glycosides from Agrostemma gracilis

Four triterpene saponins, agrostemmosides A–D were isolated from the methanol extract of Agrostemma gracilis. The structures of the compounds were determined as 3-O-β-d-xylopyranosyloleanolic acid 28-O-β-d-glucopyranosyl-(1 → 2)-[β-d-xylopyranosyl-(1 → 6)]-β-d-glucopyranosyl-(1 → 6)-β-d-glucopyranosyl ester, 3-O-α-l-rhamnopyranosyl-(1 → 2)-β-d-xylopyranosyloleanolic acid 28-O-β-d-glucopyranosyl-(1 → 2)-[β-d-xylopyranosyl-(1 → 6)]-β-d-glucopyranosyl-(1 → 6)-β-d-glucopyranosyl ester, 3-O-β-d-xylopyranosylechinocystic acid 28-O-β-d-glucopyranosyl-(1 → 2)-β-d-glucopyranosyl-(1 → 6)-β-d-glucopyranosyl ester, 3-O-β-d-xylopyranosylechinocystic acid 28-O-β-d-glucopyranosyl-(1 → 2)-[β-d-xylopyranosyl-(1 → 6)]-β-d-glucopyranosyl-(1 → 6)-β-d-glucopyranosyl ester by a combination of one- and two-dimensional NMR techniques, and mass spectrometry. To the best of our knowledge this is the first phytochemical report on A. gracilis, and echinocystic acid saponins were encountered for the first time in Caryophyllaceae family.     

Thiamin uptake in Euglena gracilis

Thiamin uptake has been investigated in Euglena gracilis Z. This protozoon possessed an active transport system for thiamin with a Km value of 17 nM and a Vmax value of 7.8 pmol per 10(6) cells per min. Thiamin uptake was dependent on pH and temperature, but not on exogenous glucose as an energy source. Oxythiamin and pyrithiamin were competitive inhibitors with Ki values of 33 nM and 15 nM, respectively. Thiamin monophosphate, thiamin pyrophosphate, thiamin triphosphate, heteropyrithiamin, quinolinothiamin, thiamin chloride and amprolium inhibited uptake. Inhibition of thiamin uptake by various metabolic inhibitors and anaerobiosis suggest that thiamin uptake requires an energy source generated by respiration and glycolysis.     

Isolation of dictyosomes fromEuglena gracilis

Summary A method for the isolation of dictyosomes fromEuglena gracilis Klebs strain Z (Pringsheim) is described. An extensive Golgi system, with the individual dictyosomes commonly containing ten to twenty cisternae is present. Log phase cells are broken in a French pressure cell at 105 to 120 kg/cm₂ in a breaking mix containing sucrose, sorbitol and ficoll. Addition of 0.3% of glutaraldehyde or formaldehyde to the breaking mix increases the number of stacked cisternae present in the final preparation. In addition to membrane stacks, the fractions contain numerous smooth vesicles. Swollen cisternae, which are also present, may account for these vesicles. Three dictyosome-enriched fractions are obtained by centrifugation in a discontinuous sucrose gradient. Fractions differ morphologically in the degree of stacking of cisternae. Further identification of the membrane fractions was accomplished by measuring IDPase activities in each of the fractions. Inosine diphosphatase activity is enriched 8–10-fold relative to the initial homogenate. The highest IDPase activity was present in the fraction containing the greatest number of stacked cisternae.     

Dark-induced chloroplast dedifferentiation in Euglena gracilis

Transfer of light-grown autotrophic Euglena gracilis cells to darkness and carbon (glucose) containing heterotrophic media causes structural and functional decomposition of the photosynthetic apparatus. The process can be ascribed to a strict diluting-out mechanism of stroma constituents among the progeny, as shown for ribulose-1,5-bisphosphate carboxylase (RuBPCase, EC 4.1.1.39), and aminoacyl-tRNA synthetases (Aa-RS; especially Leu-RS, EC 6.1.1.4) activities. The diluting-out effect of thylakoid membranes and chlorophyll seems to be superimposed by additional degradations, beginning soon after the transfer of cells to darkness. Cultivation of cells in darkness in 0.03 M KCl or without utilizable organic carbon (resting media) preserves chloroplast structure and function over a long period, indicating negligible turnover in these cells. Thus, under both growing and resting conditions, darkness induces the arrest of synthesis of plastid constituents. Experiments with the inhibitors cycloheximide, chloramphenicol, and nalidixic acid demonstrate that chloroplast dedifferentiation does not require organelle gene expression, but it is more strictly dependent on biosynthetic events in the nucleo-cytoplasmic compartment than the reverse process, light-induced chloroplast formation. Since cycloheximide at low concentrations in growth medium causes a marked suppression of precursor uptake or re-utilization similar to that in cells of resting media, intracellular precursor deficiency is suggested to control the observed blockade in cytoplasmic synthesis of plastid proteins. On the other hand, darkness might signalize the stop of gene expression in the organelles.Abbreviations Aa aminoacid - CH cycloheximide - CM chloramphenicol - Leu-RS leucyl-tRNA synthetase - RuBP ribulose-1,5-bisphosphate - TCA trichloroacetic acid