Effect of culture medium ions on chromate reduction by resting cells of Agrobacterium radiobacter

The influence of some ions in pre-growth culture medium on chromate reduction by resting cells of Agrobacterium radiobacter strain EPS-916 was investigated. The reduction was dependent on the Fe²⁺ content of the culture medium: the higher the iron content, the lower the reduction rate. The cells showed maximum chromate reduction when pre-grown in the presence of 0.243 m Mg²⁺, 20 m Ca²⁺ and 3.6 m Mn²⁺. Chromate reduction was not affected by the addition of MgCl₂, CdCl₂, ZnCl₂, MnCl₂, Na₂SO₄ (1000 m), and Na₂MoO₄ (100 m) to the activity assays. However, activity was inhibited by the presence of Na₂SO₄ (10 mm), Na₂MoO₄ (200 m) and ferric citrate.     

Changes in cell wall polysaccharides in developing barley (<Emphasis Type="Italic">Hordeum vulgare</Emphasis>) coleoptiles

Cell wall polysaccharides in developing barley coleoptiles were examined using acetic acid–nitric acid extraction, alditol acetate and methylation analyses and enzymatic digestion. The coleoptile cell wall from imbibed grain was rich in pectic polysaccharides (30 mol%), arabinoxylan (25 mol%), cellulose (25 mol%) and xyloglucan (6 mol%), but contained only low levels of (13,14)--D-glucan (1 mol%). During 5 days of coleoptile growth, pectic polysaccharides decreased steadily to about 9 mol%, while (13,14)--D-glucan increased to 10 mol%. Following the cessation of growth of the coleoptiles at about 5 days, (13,14)--D-glucan content rapidly decreased to 1 mol%. The cellulose content of the walls remained at about 35–40 mol% throughout coleoptile growth. Similarly, arabinoxylan content remained essentially constant at 25–30 mol% during growth, although the ratio of substituted to unsubstituted 4-linked xylosyl units decreased from about 4:1 to 1:1. Xyloglucan content ranged from 6 mol% to 10 mol% and the oligosaccharide profile determined using a xyloglucan-specific endoglucanase and MALDI-TOF mass spectrometry indicated that the oligosaccharides XXGG and XXGGG were the principal components, with one and two acetyl groups, respectively, Thus, dramatic changes in wall composition were detected during the growth of barley coleoptiles, both with respect to the relative abundance of individual wall constituents and to the fine structure of the arabinoxylans.     

Gibberellins play a role in the interaction between imidazole fungicides and cytokinins in Araceae

Imidazole fungicides such as imazalil, prochloraz, and triflurnizole and the triazole growth retardant paclobutrazol promote the shoot-inducing effect of exogenous cytokinins in Araceae, such as Spathiphyllum floribundum Schott and Anthurium andreanum Schott. The mechanism of their action could partially be based on the inhibition of gibberellic acid (GA) biosynthesis, because administration of GA₃ inhibits the phenomenon completely in S. floribundum. Not only is the suppression of GA biosynthesis involved, but also the metabolism of endogenous cytokinins is significantly altered. Although the balance between isopentenyladenine, zeatin, dihydrozeatin, and their derivatives was shifted to distinguished directions by administration of BA and/or imazalil and/or GA₃, no correlation between these changes in metabolic pathways and the number of shoots could be found. The metabolism of BA was not significantly altered by adding imazalil to the micropropagation medium of S. floribundum.Abbreviations 2,4-D 2,4-dichlorophenoxyacetic acid - [9R-5P]DHZ 9--d-ribofuranosyl-dihydrozeatin-monophosphate - [9R-5P]iP 6-isopentenyl-9--d-ribofuranosyladenine-monophosphate - [9R-5P]Z 9--d-ribofuranosyl-zeatin-monophosphate - [9G]BA 6-benzyl-9--d-glucopyranosyladenine - [9G]DHZ 9--d-glucopyranosyl-dihydrozeatin - [9G]iP 6-isopentenyl-9--d-glucopyranosyladenine - [9G]Z 9--d-glucopyranosyl-zeatin - [9R]BA 6-benzyl-9--d-ribofuranosyladenine - [9R]DHZ 9--d-ribofuranosyl-dihydrozeatin - [9R]iP 6-isopentenyl-9--d-ribofuranosyladenine - [9R]Z 9--d-ribofuranosyl-zeatin - BA 6-benzyladenine - DHZ dihydrozeatin - ES⁺ LC-MS/MS HPLC coupled Electrospray Tandem Mass Spectrometry - f.m. fresh mass - mT 6-(3-hydroxybenzyl)adenine - IMA imazalil - iP isopentenyladenine - NAA 1-naphthalene acetic acid - NFT Nutrient Film Technique - (OG)[9R]DHZ O--glucopyranosyl-9--d-ribofuranosyl-dihydrozeatin - (OG)[9R]Z O--d-glucopyranosyl-9--d-ribofuranosyl-zeatin - (OG)DHZ O--d-glucopyranosyl-dihydrozeatin - (OG)Z O--d-glucopyranosyl-zeatin - PAR Photosynthetic Active Radiation - PBZ paclobutrazol - PRO prochloraz - TDZ thidiazuron - TRI triflurnizole - Z zeatin     

Location by fluorescence microscopy of glycosidases and a xylanase in the anaerobic gut fungi Caecomyces communis,Neocallimastix frontalis,and Piromyces rhizinflata

-d-Glucosidase, -d-fucosidase -d-xylosidase, and -cellobiopyranosidase activities in Caecomyces communis, Neocallimastix frontalis, and Piromyces rhizinflata, located with fluorescent conjugates, occur throughout the whole thallus as from zoospore germination and disappear before sporulation. -d-Galactosidase and -l-arabinopyranosidase activities are low or nonexistent. A xylanase, detected by indirect immunofluorescence, was observed at the surface of the vegetative cells, vesicles, or rhizoids. Cross-reactions prove the existence of analogies in structure among the enzymes of these anaerobic gut fungi.     

Endogenous elemental sulfur production froml-cysteine in dormant α-spores ofPhomopsis viticola

The enzymatic production of sulfur froml-cysteine was studied in young dormant -spores ofPhomopsis viticola. Cysteine aminotransferase (CAT) and mercaptopyruvate sulfurtransferase (MST) activities could be responsible for the production of endogenous elemental sulfur (S⁰) in -spores.l-Cysteine was first deaminated, with production of -mercaptopyruvate, by the CAT. The -mercaptopyruvate produced is successively desulfurated by the MST with production of sulfur and pyruvate. Deaminase activity was recovered principally in the cytoplasmic fraction, whereas desulfurase activity was recovered mainly in the mitochondrial fraction.l-Cysteine and S⁰ sharply affected the respiratory activity, the ATP content, and suppressed germination of -spores. In contrast, reduced glutathione did not affect these metabolic parameters. Production of S⁰ by enzymatic degradation ofl-cysteine could be responsible for the inhibitory action of this amino acid. We suggest that CAT and MST, by their capacity to produce sulfur or S⁰, plays a key role in regulation of morphogenetic processes ofPhomopsis viticola.     

Photosynthese und Photomorphogenese bei Farnvorkeimen vonDryopteris filix-mas

Summary Under conditions of identical rate of photosynthesis (measured by dry weight increase under steady state conditions) growth and differentiation of the gametophytes of ferns (e.g.Dryopteris filix-mas) are completely different in red and blue light. In the blue light normal growth and morphogenesis take place and normal two or three-dimensional prothallia are formed (Fig. 3). In the red, however, the prothallia look very similar to those growing in complete darkness: they grow as one-dimensional filaments (Fig. 1).It has been shown in this paper that photosynthesis, which is important as a source of organic material and free energy, has no influence at all on morphogenesis. Morphogenesis, i.e. the formation of normal prothallia instead of filaments, is controlled by a photoreactive system which depends on blue light of suitable intensity and which is not related to photosynthesis as such. If no blue light is present no morphogenesis occurs in spite of high photosynthetic activity.In our opinion theprimary products of photosynthesis are the same in all wavelengths. But now the photomorphogenic light reaction which depends on blue light apparently directs the flow of metabolites. In this way even the same initial products of CO₂ fixation may lead subsequently to rather different photosynthetic products and consequently to the very great difference between prothallia growing with or without blue light.The addition of sucrose has practically no influence on growth and morphogenesis under our conditions. On the basis of our results we cannot agree with the general conclusions drawn byMiller andMiller (1961) who regard photosynthesis as a photomorphogenetic system in these gametophytes of ferns.Mit 6 Textabbildungen.Herrn Professor Dr.E. G. Pringsheim in Verehrung zum 80. Geburtstag.     

Hexagonally ordered “rosettes” of particles in the plasma membrane ofMicrasterias denticulata Bréb. and their significance for microfibril formation and orientation

Summary Cells ofMicrasterias denticulata Bréb. at the stage of secondary wall formation have been studied by freeze-etching. It was found that the plasma membrane exhibits oval areas in which arrays of membrane particles occur. These particles form rosettes which are arranged in a hexagonally ordered lattice with a center to center spacing of 25 nm. Nearly the same periodicities can be found between microfibrils. It is concluded that the rosettes probably together with the thickened area of the plasma membrane below them represent the apparatus for the production and orientation of microfibrils. The hypothesis suggesting the incorporation of membrane templates functional in microfibril formation, originally advanced byKiermayer andDobberstein (1973) has received further support.     

Enzymic synthesis of the trisaccharide core region of the carbohydrate chain ofN-glycoprotein

Transmannosylation from mannotriose (Man1-4Man1-4Man) to the 4-position at the nonreducing end N-acetylglucosaminyl residue ofN,N-diacetylchitobiose was regioselectively induced through the use of -d-mannanase fromAspergillus niger. The enzyme formed the trisaccharide Man1-4GlcNAc1-4GlcNAc (3.7% of the enzyme-catalysed net decrease ofN,N-diacetylchitobiose) from mannotriose as a donor andN,N-diacetylchitobiose as an acceptor. Mannobiose (Man1-4Man) was also shown to be useful as a donor substrate for the desired trisaccharide synthesis.Abbreviations Man d-mannose - (M _n) (n=1–5) -linkedn-mer of mannose - GlcNAc₂ 2-acetamido-2-deoxy--d-glucopyranosyl-(1–4)-2-acetamido-2-deoxy-d-glucose     

Synthesis of methyl α- and β-N-dansyl-d-galactosaminides,probes for the combining sites ofN-acetyl-d-galactosamine-specific lectins

The synthesis of the methyl - and -N-dansyl-d-galactosaminides is described using methyl ,-2-azido-2-deoxy-d-galactopyranoside as starting material. This was reduced to the corresponding methyl ,-2-amino-2-deoxy-d-galactopyranoside and then treated with dansyl chloride to yield a mixture of methyl ,-N-dansyl-d-galactosaminides which was separated into individual anomeric forms by flash chromatography on silica gel. Methyl -N-dansyl-d-galactosaminide was used as a fluorescent indicator ligand in continuous substitution titrations to determine the association constants of nonchromophoric carbohydrates with theN-acetyl-d-galactosamine specific lectin fromErythrina corallodendron.Abbreviations ECorL Erythrina corallodendron lectin - MeGalNDns methyl 2-deoxy-2-(5-dimethylamino-1-naphthalenesulfamido)--d-galactopyranoside - MeGalNDns methyl 2-deoxy-2-(5-dimethylamino-1-naphthalenesulfamido)--d-galactopyranoside Dedicated to Hilde De Boeck (1958–1991).     

Relation of nitrogen fertilizers and manure to vascular wilt of egyptian cotton caused by four fusaria species and strains

Summary Four different species and strains ofFusarium, namely,F. oxysporum f.vasinfectum (Atk.)Snyder &Hansen,F. solani (Mart.)App. &Wr.,F. vasinfectum (Atk.) f₁ Wr. strainFahmy, andF. vasinfectum Atk. are responsible for cotton wilt in U.A.R. Pathogenicity experiments have shown that the four experimentalFusaria possess varying degrees of pathogenicity towards two susceptible cotton varieties, namely, Karnak and Bahtim 190. On the other hand, Ashmouni cotton proved resistant to the fourFusaria. Variability of pathogenicity of the experimentalFusaria is not only related to host cotton plant or parasite, but also to nitrogenous fertilizer or manurial treatment of the soil. Resistance of Ashmouni cotton was not broken in presence of sodium nitrate, ammonium nitrate or stable manure added to soil inoculated with any of the fourFusaria. The application of nitrogen fertilizers or manure resulted on the whole, in increased wilt-disease incidence of the susceptible cotton varieties. Stable manure enhanced predisposition to vascular-wilt more than other nitrogen treatments, especially in presence of the virulentF. oxysporum f.vasinfectum or both strains ofF. vasinfectum Atk. Ammonium nitrate induced the sudden appearance of mottling characteristic of vascular-wilt of cotton when Bahtim 190 plants were raised in nitrogen-fertilized soil inoculated withF. solani (Mart.)App. &Wr. At the same time, the raised affected plants showed increased growth-vigour and enhanced maturity of their leaves.     

A fluorometric assay of ceramide glycanase with 4-methylumbelliferyl β-d-lactoside derivatives

4-Methylumbelliferyl 6-O-benzyl--d-lactoside (6Bn-MU-Lac) and some related compounds were synthesizedvia different selective reactions including phase-transfer glycosylation. Their suitability as substrates for a fluorometric assay of ceramide glycanase (CGase) was evaluated. Among others, the 6Bn-MU-Lac, which is resistant to exogalactosidase, was found to be a suitable substrate for routine assay of the CGase activity. For American leech CGase, theK _m value is 0.232 mM at pH 5. Abbreviations: CGase, ceramide glycanase; Gal, galactose; Glc, Glucose; Lac, lactose; MU, 4-methylumbelliferone; MU-Lac, 4-methylumbelliferyl -d-lactoside; bBn-Lac, 6-O-benzyl-lactose; 6Bn-MU-Lac, 4-methylumbelliferyl 6-Obenzyl--d-lactoside; 46Bd-MU-Lac, 4-methylumbelliferyl 4,6-O-benzylidene--d-lactoside; MU-Cel, 4-methylumbellifery -d-cellobioside; 46Bd-MU-Cel, 4-methylumbelliferyl 4,6-O-benzylidene--d-cellobioside; TLC, thin layer chromatography;¹H-NMR, proton nuclear magnetic resonance; GSL, glycosphingolipids; CSA, 10-camphorsulfonic acid. See Scheme 1 for chemical structures.     

Evolution alpiner Populationen vonEuphrasia (Scrophulariaceae): Die mittel- bis kleinblütigen,drüsenhaarigen Arten

A more precise taxonomic concept ofE. hirtella and its infraspecific synonymy is presented. Its diploid nature (2n = 22) is confirmed. Within the European area ofE. hirtella five different races may be recognised: typical, brandisii, capitulata, Rofan and Bretagne. Taxonomic rank is not yet attributed to these races. The heterogeneous taxonomic assembly E. drosocalyx is disentangled. The type refers to products of hybrid introgression ofE. rostkoviana-characters (long glandular hairs) intoE. minima.

Former contributions of this series areEhrendorfer & Vitek (1984) andGreilhuber & al. (1984).     

A stereologic electron microscope study of “tubular myelin figures” in alveolar fluids of rat lungs

Summary The three-dimensional structure of a composite material found in alveolar exudate of oxygen poisoned lungs but also present in normal lungs is stereologically analysed. It is composed of tubules of 450 Å diameter which are tightly packed in a quadratic lattice. The wall of the tub vile is formed by four-winged osmiophilic filaments which are located in the corners of the quadratic lattice; their interior is made up of a hydrophilic substance which contains either a tubule or a filament of moderate electron density. The osmiophilic substance of the walls is continuous with associated myelin figures which can be resolved into lamellae with a periodicity of 42 Å and can thus be considered to be water crystals of phospholipids. The nature of the content of the tubules, which presumably exerts the formative force on the phospholipid lamellae to form tubules, remains undetermined.Dedicated to Prof. W. Bargmann in honor of his 60th birthday.The research reported here has been sponsored by the Schweizerischer Nationalfonds zur Förderung der wissenschaftlichen Forschung (Nr. 2569); by the Stiftung für wissenschaftliche Forschung an der Universität Zürich; by the National Institutes of Health, USPHS, through grant RF-57; and the 6570th Aerospace Medical Research Laboratories under contract AF 61(052)-784 through the European Office of Aerospace Research (OAR), United States Air Force.     

The formation of the mesoderm in urodelean amphibians

Summary Experiments are described in which in early to late blastulae ofAmbystoma mexicanum (stages 7–8/9 Harrison) the animal, ectodermal half (zones I.II) was combined with the vegetative, endodermal yolk mass (zone IV) in various orientations, viz. in random orientation or with the dorso-ventral axes of the two components in identical, opposite or perpendicular orientation (0°, 180°, or 90° translocation respectively). The results demonstrate unequivocally that the dorso-ventral polarity of the induced mesoderm, and thus of the embryo, depends exclusively upon the inherent dorso-ventral polarity of the endoderm, whereas the grey crescent, a considerable part of which is located in the animal, ectodermal half, plays no causal role whatsoever.The results also show that the dorso-ventral polarity is inherent in the entire endodermal mass, but that the subsequent regional differentiation of the endoderm depends upon stimulating influences emanating from the surrounding mesoderm, the later nutritive yolk representing that part of the endoderm which normally does not come under the influence of the mesoderm, and therefore fails to receive the necessary stimulus for further differentiation.On the basis of these findings Schultze's Umkehrexperiment as studied byPenners andSchleip, Penners, andPasteels are reinterpreted, whileDalcq andPasteels' general developmental theory as well asCurtis' cortical grafting experiments are critically discussed.

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Zusammenfassung Es werden Experimente beschrieben, in denen in frühen bis späten Blastulae vonAmbystoma mexicanum (Stadien 7–8/9 Harrison) die animale, ektodermale Hälfte (Zonen I.II) mit der vegetativen, entodermalen Dottermasse (Zone IV) kombiniert wurde, und zwar in verschiedener Orientierung, d. h. in willkürlicher Orientierung oder mit den Dorsoventralachsen der beiden Komponenten identisch, entgegengesetzt oder senkrecht zueinander orientiert (0°, bzw. 180° oder 90° transloziert). Die Ergebnisse zeigen eindeutig, daß die Dorsoventralpolarität des induzierten Mesoderms, und damit die des Embryos, ausschließlich von der inhärenten Dorsoventralpolarität des Entoderms bestimmt wird, während der graue Halbmond, der zu einem beträchtlichen Teil in der animalen, ektodermalen Hälfte liegt, überhaupt keine kausale Rolle spielt.Außerdem zeigen die Ergebnisse, daß die Dorsoventralpolarität der ganzen Entodermmasse inhärent ist, daß aber die spätere regionale Differenzierung des Entoderms von stimulierenden Einflüssen seitens des umgebenden Mesoderms abhängig ist; der spätere Nährdotter ist derjenige Teil des Entoderms der normalerweise außerhalb des Wirkungsbereiches des Mesoderms liegt, und infolgedessen den für seine weitere Differenzierung benötigten Reiz nicht erhält.Angesichts dieser Befunde wird das Schultzesche Umkehrexperiment, welches vonPenners undSchleip, Penners, undPasteels näher untersucht worden ist, neu interpretiert, während die allgemeine Entwicklungstheorie vonDalcq u.Pasteels sowie die Cortextransplantationen vonCurtis kritisch diskutiert werden.

     

Effect of thidiazuron on somatic embryogenesis of Cayratia japonica

Unpollinated ovary explants of Cayratia japonica (Thump.) Gagnep, were cultured on the revised Murashige & Skoog's medium supplemented with different concentrations of 2,4-dichlorophenoxyacetic acid (2,4-d) alone, or in combination with 0.009 M thidiazuron (TDZ) or 0.23 M kinetin for induction of embryogenic callus. The best results were obtained on medium containing 2.3 – 4.6 M 2,4-d and TDZ. When the calluses were subcultured on the basal medium (BM), somatic embryogenesis took place spontaneously at surfaces of the calluses, but only about 5% of the somatic embryos could develop to cotyledonary stage and most of the rest remained at the globular stage of development. If the calluses were transferred onto medium containing TDZ or TDZ combined with 0.27 M -napthaleneacetic acid, the number of cotyledonary somatic embryos increased up to 25%. When the somatic embryos of different stages were transferred onto fresh BM, only the cotyledonary embryos could convert into the plantlets. The results revealed that for the induction of embryogenic callus and somatic embryogenesis of Cayratia japonica, both cytokinin and auxin are required in the medium and the cytokinin activity of TDZ is much stronger than that of kinetin even when the concentration of TDZ used was only 4% of kinetin.Abbreviations BA benzyladenine - 2,4-d 2,4-dichlorophenoxyacetic acid - IAA indole-3-acetic acid - NAA -naphthaleneacetic acid - PGR plant growth regulator - TDZ thidiazuron (N-phenyl-1,2,3,-thi-diazol-5-ylurea)     

Essentialistisches und evolution?res Denken in der systematischen Ornithologie des 19. und 20. Jahrhunderts

Zusammenfassung Die Ablösung des essentialistischen (typologischen) Denkens bei Vertretern der systematischen Ornithologie durch das darwinistische (evolutionäre) Populationsdenken um die letzte Jahrhundertwende bildete eine scharfe historische Diskontinuität. Die essentialistische Denkweise, die in Europa während des 19. Jahrhunderts dominierend war, erreichte ihr Ende im Werk vonOtto Kleinschmidt (1870–1954), dem letzten Vertreter derPallas-Schlegel Schule. In den ersten Jahrzehnten dieses Jahrhunderts wurde die evolutionäre Denkweise der Ornithologen der nordamerikanischenBaird-Coues Schule und der europäischenSeebohm-Harter Schule bestimmend. Die weite taxonomische Begrenzung von Arten durch die Ornithologen der essentialistischenPallas-Schlegel Schule und der evolutionären Mikrotaxonomie täuscht Gemeinsamkeiten dieser Schulen vor; im theoretischen Denken ihrer Vertreter bestanden fundamentale Unterschiede. Gegenwärtig ist eine Entwicklung innerhalb der evolutionären Mikrotaxonomie erkennbar, die möglicherweise in naher Zukunft zu einer Trennung in zwei Schulen mit verschiedenen Artkonzepten und unterschiedlicher Artabgrenzung führen wird: (a) Weite Artabgrenzung (mit relativ wenigen polytypischen Arten) und (b) enge Artabgrenzung (mit relativ vielen monotypischen Arten). Dazwischen vermitteln intermediäre Vorschläge. Der wissenschaftliche Naturschutz bezieht sich heute auf evolutionär signifikante Einheiten und ist unabhängig von den verschiedenen systematischen Konzeptionen über die Art.

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Essentialistic and evolutionary thinking in the field of systematic ornithology during the 19^th and 20^th century

Essentialistic thinking dominated systematic ornithology in North America during the first half of the 19^th century and in Europe until the beginning of this century, when evolutionary thinking superseded it marking a sharp historical discontinuity. Evolutionary thinking of the ornithologists of the North AmericanBaird-Coues school and of the EuropeanSeebohm-Hartert school prevailed increasingly from the late 19^th century and early 20^th century onward, respectively. The representatives of the essentialisticPallas-Schlegel school and of evolutionary microtaxonomy delimited species taxa broadly which common procedure concealed the fundamental differences in their theoretical thinking. Within the near future, evolutionary microtaxonomy may split into two different schools supporting different species concepts and a different delimitation of species taxa: (a) Wide species limits resulting in relatively few polytypic species taxa and (b) narrow species limits resulting in numerous monotypic species taxa; intermediate views connect these extremes. Conservation biology refers to evolutionarily significant units and is independent of the different views of systematists as to what constitutes a species.

     

Über die Malat-Dehydrogenase-und Lactat-Dehydrogenase-Aktivität L-Äpfelsäure-abbauender Bakterien

Zusammenfassung Bei 6 verschiedenen Arten L-Äpfelsäure-abbauender Bakterien werden Untersuchungen über die Malat-Dehydrogenase- und Lactat-Dehydrogenase-Aktivität vorgenommen. Die heterofermentativen Arten (Leuconostoc r, La Louvière, Pf-1) besitzen eine ausgeprägte Malat-Dehydrogenase-Aktivität, während die homofermentativen nur eine schwache (L. QT 1-6) bzw. keine meßbare Aktivität (L. casei, L. plantarum [arabinosus 17-5]) aufweisen. Alle Stämme sind in hohem Maße Lactat-Dehydrogenase-aktiv.Die Synthese der Malat-Dehydrogenase ist induktiv; L-Äpfelsäure als Substrat verstärkt eine vorhandene schwache Aktivität. Beweisend hierfür ist die starke Abnahme der Umsatzzahlen für die L-Äpfelsäure-Dehydrierung bzw. die Oxalessigsäure-Hydrierung nach erfolgter Entwöhnung der Bakterien von Äpfelsäure, sowie der größere Zahlenwert der Michaelis-Konstanten. Auch die Synthese der Lactat-Dehydrogenase wird von L-Äpfelsäure induziert. Insofern dürfte die Synthese dieses Enzyms mit derjenigen der Malat-Dehydrogenase gekoppelt sein.Die Lactat-Dehydrogenase von Leuconostoc r und La Louvière läßt sich wie die tierische Lactat-Dehydrogenase durch Sulfit hemmen; die Empfindlichkeit gegenüber Sulfit ist etwa doppelt so hoch wie beim tierischen Enzym. Die Enthemmung kann außer mit Lactat auch mit d(+)- und L(-)-Malat erfolgen; Malat ist jedoch nur in höherer Konzentration wirksam. Zur Hemmung der bakteriellen Malat-Dehydrogenase sind mehrfach höhere Sulfit-Konzentrationen nötig als beim tierischen Enzym. Außer d(+)-Malat hat auch Lactat enthemmende Wirkung.

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The malate dehydrogenase and lactate dehydrogenase activity of bacteria, decomposing L-malic acid

Summary The malate dehydrogenase and lactate dehydrogenase activities of six strains of bacteria, decomposing L-malic acid, were investigated. The heterofermentative strains (Leuconostoc r, La Louvière, Pf-1) possess a distinct malate dehydrogenase activity, while the homofermentative strains show only a weak (L. QT 1-6) respectively no measurable activity (L. casei, L. plantarum [arabinosus 17-5]). All strains possess a high lactate dehydrogenase activity.The synthesis of the malate dehydrogenase is inductive. The presence of L-malic acid intensifies a weak activity. This is shown by the strong decline of the turnover rates for the dehydrogenation of L-malic acid respectively the hydrogenation of oxaloacetic acid after deadaptation of the bacteria from malic acid, and by the greater values of the Michaelis' constants. Also the synthesis of the lactate dehydrogenase is induced by L-malic acid. Therefore the synthesis of this enzyme appears to be coupled with the synthesis of the malate dehydrogenase.The lactate dehydrogenase of Leuconostoc r and La Louvière can be inhibited by sulphite like the animal lactate dehydrogenase; the sensibility to sulphite is about the twofold of the animal enzyme. The reactivation can be achieved with lactate, or d(+)-and L(-)-malate; malate is effective only at higher concentrations. For the inhibition of the bacterial malate dehydrogenase manifold higher sulphiteion concentrations are needed than for the animal enzyme. Besides d(+)-malate also lactate has a reactivating effect.

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III. und letzte Mitteilung zum Problem des biologischen Säureabbaues. Über adaptive und konstitutive fermentchemische Eigenschaften L-Äpfelsäure-abbauender Bakterien.     

The appearance of a type of cortical vesicles subsequent to fertilization of the sea urchin egg,their character and possible function

Summary Three different types of vesicles present before fertilization in the sea urchin egg were examined. The a-type corresponds to rough endoplasmic vesicles; the vesicles of b-type are rather smooth but may have vestigial granules within their membranes; the c-type belongs to the multivesicular bodies. Upon fertilization, vesicles appear in the outer cortical zone (vesicles of d-type). The majority of them arises by budding from the vesicles ofb-type. The budding occurs mainly at the basis of or within ridges of the cell surface; they may also be present in broader microvilli. The distance between the ridges was varied by early transfer of the eggs to calcium-free sea water. An inducing effect of the ridges on location of theb-vesicles and on the formation ofd-vesicles by budding could thus be demonstrated.Thed-vesicles appearing upon fertilization resemble in size and structure Golgi vesicles formed by budding from Golgi bodies present in the interior cortex or below it. Also theb-vesicles have their counterpart in the Golgi bodies. Theb andd-vesicles are therefore regarded as a Golgi system in which theb-vesicles represent dispersed Golgi bodies and thed- vesicles Golgi vesicles. Thed-vesicles may be designated as cortical Golgi vesicles, (c.G.v.).In thec-vesicles i.e. the multivesicular bodies (m.v.b.), a nucleid was observed which may be subdivided. A compartmentation of m.v.b. was observed which may lead to a detachment of vesicles of about the same size as thed-vesicles (c.G.v.) but probably of a different character.The differentiation of the fertilization membrane of the sea urchin egg occurs in two stages: the assembly and the solidification stage. The tentative conclusion is drawn that a secretion from the c.G.v. functions as an agent in the solidification process. The c.G.v. may also act upon the hyaline layer, both in its early formation and its maintenance during the course of embryonic development.The material for the present investigation was collected at Kristineberg Zoological Station and at Stazione Zoologica, Naples. The writer is indebted to the authorities of these stations for generous helop. Financial support was received from the Swedish Natural Sciences Research Council and the Swedish Cancer Society for which I express my gratitude.I also express my gratitude to Dr.Björn Afzelius for surveying the electron microscopic part of the work, to Dr.Jane Baxandall for permission to study her original electron micrographs and to Dr.Elsa Wicklund and Dr. L.Contoli for contribution to the experiments on the effect of calcium-free sea water. I thank Mrs.Astri Runnwström and Mrs.AnneMarie Ede for their able assistance.This research was carried out in association with the Research group of embryology for the study of cellular differentiation of the Department of Zoology, University of Rome (Director Professor P.Pasquini).     

Substrate subsite recognition of the xyloglucan endo-transglycosylase or xyloglucan-specific endo-(1→4)-β-d-glucanase from the cotyledons of germinated nasturtium (Tropaeolum majus L.) seeds

We have investigated the substrate subsite recognition requirement of the xyloglucan endo-transglycosylase/xyloglucan-specific endo-(14)--d-glucanase (NXET) from the cotyledons of nasturtium seedlings. Seed xyloglucans are composed almost entirely of the Glc₄ subunits XXXG, XLXG, XXLG and XLLG, where G represents an unsubstituted glucose residue, X a xylose-substituted glucose residue and L a galactosyl-xylose-substituted glucose residue. Thus in the xyloglucan sequence shown below, the xylose (Xyl) residues at the backbone glucose (Glc) residues numbered — 3,— 2, + 2 and + 3 may be galactose-substituted, and NXET cleaves between the unsubstituted glucose at — 1 and the xylose-substituted glucose at + 1, which never carries a galactosyl substituent. We have isolated the xyloglucan oligosaccharides XXXGXXXG and XLLGXLLG from NXET digests of tamarind seed xyloglucan, have modified them enzymatically using a pure xyloglucan oligosaccharide-specific -xylosidase from nasturtium seeds to give GXXGXXXG and GLLGXLLG, and have identified and compared the products of NXET action on XXXGXXXG, GXXGXXXG, XLLGXLLG and GLLGXLLG. We have also compared the molar proportions of XXXG, XLXG, XXLG and XLLG in native tamarind and nasturtium seed xyloglucans with those in NXET digests of these polysaccharides. Using these and existing data we have demonstrated that NXET action does not require xylosesubstitution at glucose residues — 4, — 2, + 1 and + 3 and that xylose substitution at + 2, is a requirement. There may also be a requirement for xylose substitution at — 3. We have demonstrated also that galactosyl substitution of a xylose residue at + 1 prevents, and at — 2 modifies, chain-cleavage. A partial model for the minimum substrate binding requirement of NXET is proposed.Abbreviations G unsubstituted glucose residue - X xylose-substituted glucose residue - L galactosylxylose-substituted glucose residue - F fucosyl-galactosylxylose-substituted glucose residue - Gal galactose - Glc glucose - HPAE high-performance anion-exchange chromatography - NXET nasturtium xyloglucan endo-transglycosylase or xyloglucan-specific endo-(14)--d-glucanase - Xyl xylose This work was funded jointly by Unilever UK and the Department of Trade and Industry (UK) via the LINK initiative Agro-Food Quality.