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).     

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.     

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.     

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     

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.     

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     

Changes with age in the absorption spectrum of chlorophyll α in a diatom

Summary Absorption spectra of a young and an old culture of the diatom Pheodactylum tricornutum were measured in thin layers between two opal glass sheets. The spectra at 24° and at -196°C were replotted to give equal areas from 730–625 m to allow direct comparison. At 24°C the spectrum for the difference between the two cultures had a negative component of 18 m half width centered at 675 m and a positive region of W_0.5=26 m near 700 m.The spectra at -196°C may be somewhat distorted by clumping of the cells during freezing but nevertheless the 16 day culture clearly showed a smaller proportion of Ca 670 to Ca 680. This older culture has a shoulder due to a 707 m component. The difference curve at -196°C shows the decrease of an unsymmetrical band peaking at 669 m and an increase at 695 m in addition to the 707 m component. Due to the possibility of distortion, the presence of an actual component at 695 is doubtful in these particular cultures.The room temperature spectrum in the chloropyhll a region for the 5 day culture can be closely fitted by a single probability curve at 675 m having a half-width of 31 m. The sum of two components, with widths more reasonable for chlorophylls, also matched the data well enough. These two probability curves, of 22 m half width, centered on 669 and 683.2 m and had a height ratio, h₆₆₉/h₆₈₃ of 1.18. In the 16 day culture the ratio for these bands changed to 1.11 and there was extra absorption around 700 m.Dedicated to Professor C. B. van Niel on the occasion of his 70th birthday     

Properties of β-glucosidase purified from Aspergillus niger mutants USDB 0827 and USDB 0828

Summary Two extracellular -glucosidases (EC 3.2.1.21) were isolated from Aspergillus niger USDB 0827 and A. niger USDB 0828, and their physical and kinetic properties studied. Both enzymes were very similar in terms of molecular size (230000 Da), pH optimum (pH 4.6), temperature optimum (65° C), stability at high temperatures and substrate preferences. They were capable of hydrolysing -linked disaccharides, phenyl -d-glucoside, p-nitrophenyl -d-glucoside (PNPG), o-nitrophenyl -d-glucoside, salicin and methyl -d-glucoside but lacked activity towards -linked disaccharides, a range of p-nitrophenyl monoglycosides and p-nitrophenyl diglycosides. Both -glucosidases were better at hydrolysing cellobiose than cellotriose, cellotetraose or cellopentaose. For both enzymes, glucose showed competitive inhibition with PNPG as substrate but had no effect with cellobiose. However, the two -glucosidases differed in inhibition by glucono-1,5-lactone and affinity for cellobiose. -Glucosidase from A. niger USDB 0827 also gave lower specific activity, and was more susceptible to metal ions (Ag⁺, Fe²⁺ and Fe³⁺) inhibition than that of A. niger USDB 0828. Correspondence to: Y. K. Hoh     

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.     

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.     

Tubular and filamentous structures in pollen tubes: Possible involvement as guide elements in protoplasmic streaming and vectorial migration of secretory vesicles

Summary An ultrastructural study of the pollen tubes of Lilium and Clivia has demonstrated three different classes of longitudinal structures which could influence patterns of protoplasmic streaming and/or serve as guide elements in the vectorial migration of secretory vesicles: (a), cortical and noncortical microtubules; (b), microfilaments; and (c), subcortical tubules and cisternae of the endoplasmic reticulum (subsurface cisternae). Morphological details of these structures are described. Colchicine concentrations which lead to the complete disappearance of the microtubules affect neither germination of the pollen nor cytoplasmic streaming and tip growth of the elongating pollen tubes. Tip growth is initially uninhibited by cycloheximide, and cytoplasmic streaming is insensitive to this inhibitor. However, both of these processes are sensitive to cytochalasin B and vinblastine. Our results suggest that neither microtubules nor subsurface cisternae are essential for cytoplasmic streaming and directional secretion of cell surface materials in the pollen tube but would be consistent with an involvement of microfilamentous structures in these processes. Additionally, the possible importance of the lateral cross-link elements interconnecting all three types of structures is discussed.     

Fine structure of boar spermatozoa

Summary The fine structure of epididymal spermatozoa of boars was studied, with special regard to the head cytoplasm, the neck, and the axial filament. Epon embedding and staining with heavy metals was used.The acrosome consists of a moderately opaque, homogeneous substance bounded by a single membrane. Within the distinct equatorial segment, the acrosome is very thin and separated from the nuclear membrane by a narrow rim of moderately dense material, which may be related to the perforatorium of rat spermatozoa.The postnuclear cap consists of a dense, homogenous substance inside the cell membrane and is stainable with phosphotungstic acid.The fibre structures of the neck are surrounded by folded extensions of the nuclear membrane. Two short, dark rods appear in the centre of the neck. The light segments of the coarse, peripheral fibres are merely deep notches in the fibre substance. The coarse peripheral fibres reach their maximal thickness at the anterior end of the middle piece. They taper rapidly anteriorly from this point and more gradually posteriorly. Irregular bridges connect them with each other in the anterior middle piece.The central 9+2 fibrils of the axial filament have distinct arms and spokes in the middle piece and main piece. The subfibrils connected with the arms and spokes appear to be solid, except in the neck and end pieces. The two central fibrils run through the neck to the wall of the proximal centriole. Acknowledgements. We wish to express our sincere gratitude to Dr. B. Afzelius, the Wenner-Gren Institute, Stockholm, for helpful discussions regarding tail fine structure, and to Dr. J. Luft, Department of Anatomy, University of Washington, Seattle, Wash., U.S.A., for the generous supply of ingredients for the Epon embedding procedure.     

Comparative structural analysis of snail galactans by a radioimmunoassay to elucidate species-specific determinants

Summary Galactans, the storage polysaccharides in the perivitelline fluid of many snails showed a high degree of species-specificity as revealed by quantitative precipitin formations with lectins, polyclonal antisera, myeloma proteins as well as by the reactivity with the enzyme galactose oxidase. However, their chemical compositions were remarkably similar since thed-Gal residues were all linked 13 and 16 glycosidically.The specificity seemed to be related to the different degrees of branching in the various galactans but could also be due to some other minor constituents in some galactans such asl-galactose or phosphate.In this study a Radioimmunoassay was developed using the galactan of the snailLymnaea stagnalis to elucidate those differences which were only related to a unique distribution of the 13 and 16 linkages, since this galactan was composed exclusively ofd-galactose residues. The galactan was labeled by sequential oxidation with galactose oxidase and reduction with tritiated sodium borohydride. Inhibition of the binding of the labeled galactan to insolubilized antibodies was investigated by galactans of different species, their chemically modified products, andd-galactose-composed oligosaccharides of unambiguously identified structures.Inhibition byLymnaea stagnalis galactan was about 45 000 times that ofHelix pomatia galactan. The most complementary oligosaccharide found was -d-Gal13[-d-Gal16]-d-Gal11l-Gro, being about 200 times more effective thand-Gal. However, a fraction with molecular weights between 700 and 1000 isolated from the partially hydrolized galactan was still seven times more effective. From the reactivity of the antiserum with the different oligosaccharides tested the following structure was inferred which most likely represented the complete determinant recognized by the antiserum: -d-Gal13[-d-Gal16]-d-Gal16[-d-Gal13]-d-Gal1. This determinant seemed to be most common inLymnaea stagnalis galactan and its frequency of occurrence appears to correspond to the inhibitory potency of other snail galactans.     

Tissue culture and micropropagation of Cuphea ericoides,a potential source of medium-chain fatty acids

Plant rgeneration occurred on leaf-and stem-derived callus of Cuphea ericoides Cham. & Schlechtd obtained in Murashige and Skoog medium supplemented with auxins [indole-3-acetic acid (IAA), -naphthaleneacetic acid (NAA) or 2,4-dichlorophenoxyacetic acid (2,4-d)] plus cytokinins [6-benzyladenine (BA) or kinetin]. These calluses were subcultured and showed vigorous growth. When subcultured on medium containing 2.22 or 4.44 M BA, the calluses showed profuse regeneration of shoots whereas those subcultured on medium supplemented with 2.69 M NAA or 0.226 M 2,4-d produced numerous roots. Isolated shoots rooted on Murashige and Skoog medium lacking growth regulators or containing 0.54 M NAA or 0.49 M indole-3-butyric acid (IBA). Plantlets were acclimatized to greenhouse conditions.Abbreviations BA 6-benzyladenine - 2,4-d 2,4-dichlorophenoxyacetic acid - IAA indole-3-acetic acid - IBA indole-3-butyric acid - MS Murashige & Skoog medium - NAA 1--naphthaleneacetic acid     

Bewegungsstudien an Anatinen

Zusammenfassung Vorliegende Arbeit ist eine Weiterführung derLorenz'schen Bewegungsstudien an Anatinen aus dem Jahre 1941, fortgesetzt an Mischlingen zwischen den dort beschriebenen Arten. Die sich dabei ergebenden Befunde machten eine erneute Untersuchung der Elternarten notwendig. Außerdem wurden einige Arten beobachtet, deren Verhalten noch nicht untersucht worden war. Fragestellung und Begründung werden in der Einleitung gegeben.Im zweiten Abschnitt werden einige der vonLorenz gemachten Beobachtungen berichtigt. So zeigten einige der Kreuzungen mitbahamensis, daß die vonLorenz bei eben dieser Art als Kurzhoch-werden bezeichnete Bewegungsweise dem Ab-auf anderer Schwimmenten homolog ist. Ebenso ist die eine der beiden vonLorenz als Kurzhoch-werden bezeichneten Verhaltensweisen des Krickerpels als Ab-auf zu deuten. Der Gruß desflavirostre-Erpels wurde auch bei weiblichen Tieren gesehen. BeiAnas acuta wurde ein Kinnheben festgestellt, das sich in der Form stark vom Kinnheben beiplatyrhynchos unterscheidet. Als neue Verhaltensweisen wurden u. a. das Haltungannehmen und das Tendieren beimflavirostre-Erpel beschrieben.Im dritten Abschnitt werden einige Verhaltensweisen und ihre Funktion diskutiert und der Versuch gemacht, eine Motivationsanalyse zu geben.(Zeichnungen vonHermann Kacher)     

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.     

The presence of an endogenous lectin in early embryos ofXenopus laevis

Summary Xenopus laevis embryos were examined for the presence of endogenous carbohydrate binding proteins. Soluble extracts of cleavage, gastrula and neurula embryos are able to agglutinate trypsinized rabbit erythrocytes. Unlike other embryonic lectins this agglutination activity requires the presence of calcium ions but not of sulphydryl reducing agents. It is specifically inhibited by galactose and galactose containing derivatives. Thiodigalactoside is the most potent disaccharide inhibitor followed by lactose and melibiose respectively. Methyl -d-galactopyranoside is a more effective inhibitor than its anomer. N-acetyl-d-galactosamine, N-acetyl-d-glucosamine, methyl -d-mannopyranoside andl-fucose do not inhibit activity at concentrations at or above 25 mM. EDTA and EGTA are also strong inhibitors of this activity. -d-galactoside binding lectins present in the early chick embryo have been implicated in cell to cell and cell to substrate adhesiveness of extraembryonic chick endoderm cells. Since cells of the blastula inXenopus laevis possess surface receptors bearing terminal -d-galactoside groups it is possible that this -d-galactoside binding lectin may play a role in the control of cell surface mediated events during development.     

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).     

Über die Herkunft „synaptischer“ Bläschen in neurosekretorischen Axonen

Zusammenfassung In der Neurohypophyse fetaler und neugeborener Ratten entsteht die Mehrzahl der synaptischen Bläschen aus Erweiterungen der Neurotubuli. Ferner können pinocytotische Bläschen als synaptische Vesikel imponieren. Die Bläschenbildung aus Membranen von Elementargranula (vgl. Herlant, 1967) tritt dagegen in den Hintergrund. Ein Auftreten von Vesikeln im Innern von Elementargranula wurde nicht beobachtet.

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The origin of synaptic vesicles in neurosecretory axons

Summary In the neurohypophysis of fetal and newborn rats the majority of synaptic vesicles originate from dilatations of neurotubuli. Moreover, pinocytotic invaginations give rise to synaptic vesicles. Evaginations of elementary granule membranes, as described by Herlant (1967), are seldom to be found and do not seem to play an important role in the formation of synaptic vesicles. The occurrence of vesicles within elementary granules was not observed.

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Mit Unterstützung durch die Deutsche Forschungsgemeinschaft.