Variant forms ofα-2-l-fucosyltransferase in human submaxillary glands from blood group ABH “secretor” and “non-secretor” individuals

The properties of the -2-l-fucosyltransferases in submaxillary gland preparations from blood group ABH secrefors and non-secretors were compared. The level of activity in the non-secretor gland homogenates amounted to about 5% only of that found in the secretor gland preparations. The enzymes from the two sources differed in solubility properties, charge and affinities for donor and acceptor substrates. The enzyme from secretor glands showed a preference for acceptors with Type 1 [d-galactosyl(1–3)-N-acetyl-d-glucosamine] structures whereas the enzyme from non-secretor glands had a preference for Type 2 [d-galactosyl(1–4)-N-acetyl-d-glucosamine] structures.These results demonstrate that expression of the secretor gene (Se) is associated with a molecular form of the -2-l-fucosyltransferase that is different from the species present in the same tissue when theSe gene is not expressed.     

Die bursa- und schwanzstrukturen und ihre aberrationen bei den strongylina (Nematoda) morphologische studien zum problem der pluri-und paripotenzerscheinungen

Zusammenfassung In der Einleitung ist das Ziel der Arbeit in den wesentlichsten Punkten herausgestellt.Die Bursastrukturen (Bursavelum und Rippen bzw. Papillen) der parasitischen Strongylina lassen sich von den entsprechenden Bildungen der freilebenden Rhabditina, vor allem der Gattung Rhabditis, ableiten und in ihren Einzelgliedern homologisieren.Die im Laufe der Phylogenie bei den Strongylina auftretenden strukturellen Transformationen lassen sich auf einige wenige, relativ einfache morphogenetische Grundvorgänge zurückführen, die da sind: Wachstumsallometrien, Materialkompensationen, Organverschmelzungen und Spaltungen (Fissationen), Rudimentationen und ähnliche Vorgänge.Innerhalb der Strongylina Bursa ist ein Gefälle der Wachstumsgradienten feststellbar, das sich vom Zentrum der Bursa sowohl nach distal als auch proximalwärts abschwdcht. Zunehmende Förderung der zentral gelegenen Organe (Rippen) führt zu entsprechender Reduktion der peripheren Bursastrukturen, was vor allem im terminalen Schwanzabschnitt auffällt und zur Ausbildung des oft nur noch als Rudiment vorhandenen Dorsalrippenkomplexes führt. Letzterer entspricht in seiner Gesamtheit der Schwanzspitze der peloderen Rhabditiden mit den Papillen 9 und 10.Die bei Rhabditis moist getrennten Papillen 7 und 8 sind bei allen Strongylina zu einer Rippe (Externodorsal-Rippe) verschmolzen, die jedoch in manchen Aberrationen durch Abspaltung eines akzessorischen Astes ihre wahre Natur (als Verschmelzungsprodukt) zu erkennen gibt (Atavismus).Da dieselben Transformationsvorgänge innerhalb der Strongylina mehrfach unabhängig voneinander wirksam geworden sind, treten bestimmte Strukturformen als Parallelbildungen in verschiedenen phylogenetischen Union auf (polytope Entstehung).Zahlreich untersuchte Bildungsabweichungen (Aberrationen), deren Bedeutung für die Morphologie kurz umrissen wird, erschöpfen sich in den gleichen strukturellen Transformationstypen, die auch bei der Evolution der verschiedenen Union der Strongylina nachweisbar sind. Die Aberrationen führen daher häufig zu Atavismen oder zu Parallelvariationen (homologe Variationen").Die Zahl der Umwandlungsmbglichkeiten (Potenzen) der Bursastrukturen innerhalb der Strongylina ist beschränkt (Paripotenz im Sinne Haeckers). Bestimmte Arten (und Entwicklungshnien) haben jeweils nur bestimmte Potenzen realisiert. Andere können jedoch latent (virtuell) im Kryptotypus vorhanden sein, ohne normalerweise in Erscheinung. zu treten. In bestimmten Aberrationen können sie jedoch plötzlich realisiert werden, so ihr latentes Vorhandensein demonstrierend (Pluripotenz).Wie lange bestimmte Potenzen in einer Gruppe erhalten bleiben konnen, verdeutlichen auch die Schwanzhocker weiblicher Nematoden, als zum Bauplan der Nematoden gehbrende Bildungen. Die Potenz zur Ausbildung dieser Strukturen kommt offensichtlich sehr vielen Nematoden-Arten zu, wird jedoch nur in relativ wenigen Fällen, aber innerhalb der verschiedenen Gruppen bald hier, bald dort (disjunkte Verbreitung), realisiert. Es handelt sich bei den Schwanzhöckern um rudimentäre Organe, die bei keiner Nematoden-Art mehr voll ausgebildet erhalten sind. Ihre Rudimentation beruht zum Teil auf Materialentzug, als Folge von Unkonstruktionen der Schwanzregion, wobei die Adultstadien zuerst betroffen werden (Aphanisie nach Sewertzoff).Bei den in Chiropteren parasitierenden Strongylacanthinae haben sich Schwanzhöcker noch bei allen Arten erhalten, was ein offensichtlich archaisches Merkmal darstellt. Bei anderen Nematoden, denen sie nur im Larvalstadium zukommen, treten sie wohl durch Fötalisation in seltenen Fällen auch bei den adulten Stadien wieder auf.Alle speziellen Bursaformen der Strongylina lassen sich durch relativ wenige und einfache Transformationsvorgänge aus einem durch Abstraktion gewonnenen diagrammatischen Typus ableiten (Prinzip der variablen Proportionen" nach Troll).Die typisierten Umwandlungsvorgänge decken sich weitgehend mit den von Remane allgemein gefaßten strukturellen Typen der Realmutationen. Da sie bei den beobachteten Aberrationen, deren Entstehung auf dem Wege über Realmutationen sehr wahrscheinlich ist, in homologer Weise auftreten, kann das innerhalb der Strongylina zu beobachtende Evolutionsphänomen auf Realmutationen zurückgeführt warden.Obwohl sich die untersuchten strukturellen Transformationen in dem systematisch relativ wait gefaßten Rahmen einer Unterordnung abspielen (transspezifische Evolution nach Rensch), handelt es sich bei der von uns bevorzugten Terminologie (nach Woltereck und Remane), unter Berücksichtigung des Charakters der Umwandlungen, doch nur um Vorgänge, die in den Bereich der Mikroevolution fallen.     

Purification of the blood groupH gene associated α-2-l-fucosyltransferase from human plasma

The -2-l-fucosyltransferase in human plasma has been freed from -3-l-fucosyltransferase activity and purified approximately 200,000-fold by a series of steps involving ammonium sulphate precipitation, hydrophobic chromatography on Phenyl Sepharose 4B and affinity chromatography first on GDP-adipate-Sepharose and then on GDP-hexanolamine-Sepharose. The purified -2-l-fucosyltransferase had a M_r on gel filtration HPLC of 158,000 and showed optimal activity in the pH range 6.5–7.0. The enzyme transferred fucose equally well to Type 1 (Gal1-3GlcNAc) and Type 2 (Gal1-4GlcNAc) substrates but Type 3 (Gal1-3GalNAc) structures were less efficient acceptors. Competition experiments indicated that a single enzyme species in the purified preparation was responsible for reactivity with the Type 1 and Type 2 structures. Thus the differences in conformation between the Type 1 and Type 2 disaccharides do not appear to influence the capacities of their terminal non-reducing -d-galactosyl residues to function as acceptor substrates for the -2-l-fucosyltransferase expressed by the blood groupH gene in haemopoietic tissue.     

Über das Verhalten von Champignonstämmen in Mischkultur

Zusammenfassung Mischungen aus dem Mycel sweier weißer oder zweier brauner Stämme des Kulturchampignons hatten keinen Einfluß auf den Fruchtkörperetrag.Bei Mischungen aus einem weißen und einem braunen Stamm was dagegen der Ertrag immer niedriger als erwartet und das Mycel verschwand verhältnismäßig schnell. Der Ertragsausfall beruht in der Regel auf einer Unterdrückung des braunen Stammes.Herrn Prof. von Sengbusch zum 65. Geburtstag in Dankbarkeit und Verehrung gewidment.     

The frequency of the γ chain variant AγT in different populations,and its use in evaluating γ gene expression in association with thalassemia

Summary The occurrence of the ^AT chain (i.e. ^A75 Ile Thr) in different populations was evaluated through a study of 4250 cord blood samples and blood samples from more than 350 SS¹ patients. High frequencies were observed in Italy, Yugoslavia, Turkey, Holland, but also in Japan, Vietnam, and India. The chain is (nearly) absent in the Black population of Ghana and Kenya, and low frequencies were observed in China and Australian aborigines. Only a few adult SS patients (18 out of 357) were ^AT heterozygotes. The chromosomes with the ^AT globin gene were mapped through an evaluation of the presence of 10 different restriction sites. The ^AT chromosomes from different populations were closely related and had the same subhaplotypes of [--++-+] (Hinc II 5 to ; Xmn I 5 to ^G; Hind III in ^G and ^A; Hinc II in and 3 to ), quite different from the subhaplotypes seen for ^AT negative chromosomes.² This suggests a common ancestor which may have originated in Southern Europe. An evaluation of the chain production by both chromosomes in SS patients and -thalassemia heterozygotes was possible for subjects with an ^AT heterozygosity. It was concluded that in -thalassemia trait, the chain synthesis is directed for about two-thirds by the thalassemic chromosome and for about onethird by the normal chromosome; the contribution by the normal chromosome decreases with a decrease in total chain production.This is contribution #0890 of the Department of Cell and Molecular Biology, Medical College of Georgia, Augusta, GA 30912, USA     

Hydrogen isotope discrimination in higher plants: Correlations with photosynthetic pathway and environment

Summary The ratio of deuterium to hydrogen (expressed as D) in hydrogen released as water during the combustion of dried plant material was examined. The D value (metabolic hydrogen) determined on plant materials grown under controlled conditions is correlated with pathways of photosynthetic carbon metabolism. C₃ plants show mean D values of-132 for shoots and -117 for roots; C₄ plants show mean D values of -91 for shoots and-77 for roots and CAM plants a D value of-75 for roots and shoots. The difference between the D value of shoot material from C₃ and C₄ plants was confirmed in species growing under a range of glasshouse conditions. This difference in D value between C₃ and C₄ species does not appear to be due to differences in the D value (tissue water) in the plants as a result of physical fractionation of hydrogen isotopes during transpiration. In C₃ and C₄ plants the hydrogen isotope discrimination is in the same direction as the carbon isotope discrimination and factors contributing to the difference in D values are discussed. In CAM plants grown in the laboratory or collected from the field D values range from-75 to +50 and are correlated with ¹³C values. When deprived of water, the D value (metabolic hydrogen) in both soluble and insoluble material in leaves of Kalanchoe daigremontiana Hamet et Perr., becomes less negative. These changes may reflect the deuterium enrichment of tissue water during transpiration, or in field conditions, may reflect the different D value of available water in areas of increasing aridity. Whatever the origin of the variable D value in CAM plants, this parameter may be a useful index of the water relations of these plants under natural conditions.     

The energy transmission in ATP synthase: From the γ-c rotor to the α3β3 oligomer fixed by OSCP-b stator via the βDELSEED sequence

ATP synthase (F₀F₁) is driven by an electrochemical potential of H⁺ (H⁺). F₀F₁ is composed of an ion-conducting portion (F₀) and a catalytic portion (F₁). The subunit composition of F₁ is ₃₃. The active ₃₃ oligomer, characterized by X-ray crystallography, has been obtained only from thermnophilic F₁ (TF₁). We proposed in 1984 that ATP is released from the catalytic site (C site) by a conformational change induced by the DELSEED sequence via -F₀. In fact, cross-linking of DELSEED to stopped the ATP-driven rotation of in the center of ₃₃. The torque of the rotation is estimated to be 420 pN·å from the H⁺ and H⁺-current through F₀F₁. The angular velocity () of is the rate-limiting step, because H⁺ increased theV _max of H⁺ current through F₀, but not theK _m (ATP). The rotational unit of F₀ (=ab₂c₁₀) is /5, while that in ₃₃ is 2/3. This difference is overcome by an analog-digital conversion via elasticity around DELSEED with a threshold to release ATP. The distance at the C site is about 9.6 å (2,8-diN₃-ATP), and tight Mg-ATP binding in ₃₃ was shown by ESR. The rotational relaxation of TF₁ is too rapid (=100 nsec), but the rate of AT(D)P-induced conformational change of ₃₃ measured with a synchrotron is close to . The ATP bound between the P-loop and E188 is released by the shift of DELSEED from RGL. Considering the viscosity resistance and inertia of the free rotor (-c), there may be a stator containing OSCP (= of TF₁) and F₀-d to hold free rotation of ₃₃.     

Stimulation of proliferation and immunoglobulin production of human-human hybridoma by various types of caseins and their protease digests

We have studied the effect of such milk proteins as caseins, lactalbumin, and lactoglobulin, on proliferation and immunoglobulin production of human-human hybridoma HB4C5 cells. It was found that -, -, and -caseins stimulated both proliferation and IgM product ion of human-human hybridoma HB4C5 cells, while the activities of -lactalbumin and -lactoglobulin were negligible. To localize the active sites of these caseins, effect of protease treatments on the activities were examined. When caseins were digested with trypsin, casein digests stimulated proliferation of the hybridoma, but not their IgM production. When -casein was digested with chymosin and fractionated top--casein and glycomacropeptide, both fragments stimulated proliferation of the cells, but onlyp--casein fragment stimulated IgM production. These results indicate that -casein has at least two proliferation stimulating sites and an IgM production stimulating site in thep--casein region.     

Callus proliferation from the protoplasts of embryogenic cells of Quercus serrata

Embryogenic culture was induced from the immature embryos of Quercus serrata using Marashige and Skoog's medium (MS) containing 0.1 M each of 2,4-d and BAP, and subcultured for seven months before isolation of protoplasts by using 1% Cellulase RS in 0.6 M mannitol solution. Efficient colony formation was obtained when protoplasts were cultured in a liquid MS medium containing 0.6 M mannitol, 3% sucrose and combination of 0.1 M or 1 M each of 2,4-d and BAP. Excluding ammonium nitrate from the MS medium resulted in the decrease of the percentage of colony formation. From colonies, both agar culture and liquid culture were sustained in the MS media without mannitol containing no plant growth regulator, or containing 0.1 M of BAP in combination with 0.1 M or 1 M of 2,4-d.Abbreviations BAP 6-benzylaminopurine - 2,4-d 2,4-dichlorophenoxyacetic acid - MS medium after Murashige & Skoog (1962).     

Modeling the acquisition of counting with an associative network

In the acquision of counting by children, there are three interesting phenomena (Fuson et al. 1982): (1) the number word sequence produced by children can be divided into three distinct portions, called the conventional, stable nonconventional, and unstable portions; (2) irregular number words such as fifteen are omitted more often than regular ones such as fourteen, sixteen, and seventeen; and (3) initially the number word sequence is in a recitation form, rather than in the form of an associative chain of separable serial elements. Our paper at first analyzes these phenomena from the viewpoint of associative memory by assuming the number word sequences are made up of many associative relationships between the number words. This assumption is not contradictory to the third phenomenon described above, because the associative relationships are not confined only to those between the serial number words. On the basis of these anaylses, an associative network model, HAPS proposed by one of the authors (Hirai 1983), is extended so that it can mimic some aspects of the learning of sequence which involves the above three phenomena. The learning and production of sequence by the network are simulated on a digital computer, and the results show that the three phenomena can be observed in the performance of the network.     

Purification and properties of recombinant β-glucosidase of the hyperthermophilic bacterium Thermotoga maritima

A -glucosidase of the hyperthermophilic bacterium Thermotoga maritima has been purified from a recombinant Escherichia coli clone expressing the corresponding gene. The enzyme was found to be a dimer with an apparent molecular mass of approximately 95 kDa as determined by size exclusion chromatography. It was composed of two apparently identical subunits of about 47 kDa (determined by sodium dodecyl sulphate-polyacrylamide gel electrophoresis). The enzyme had a bbroadsubstrate specificity and attacked -glucoside, -galactoside, -fucoside, and, to a very small extent, also -xyloside substrates. -Glycosidic bonds were not hydrolysed. Kinetic measurement of the hydrolysis of o-nitrophenyl--d-glucopyranoside (oNPGlc) and o-nitrophenyl--d-galactopyranoside (oNPGal) in the concentration ranges 0.05–20 mm and 0.1–10 mm, respectively, at 75°C resulted in non-linear Lineweaver-Burk and Eadie-Hofstee 3lots whereas cellobiose and lactose did not induce this type of effect. Lactose caused substrate inhibition above 350 mm. The enzyme was optimally active at about pH 6.1. The T. maritima -glucosidase represents the most thermostable -glucosidase described to date. In 50 mm sodium phosphate buffer, pH 6.2, at an enzyme concentration of 50 g/ml, the pure enzyme without additives retained more than 60% of its initial activity after a 6-h incubation at 95°C. Correspondence to: W. Liebl     

Electrogenic properties of the sodium-alanine cotransporter in pancreatic acinar cells: II. Comparison with transport models

Summary In this paper, the results of the preceding electrophysiological study of sodium-alanine cotransport in pancreatic acinar cells are compared with kinetic models. Two different types of transport mechanisms are considered. In the simultaneous mechanism the cotransporterC forms a ternary complexNCS with Na⁺ and the substrateS; coupled transport of Na⁺ andS involves a conformational transition between statesNCS andNCS with inward- and outward-facing binding sites. In the consecutive (or ping-pong) mechanism, formation of a ternary complex is not required; coupled transport occurs by an alternating sequence of association-dissociation steps and conformational transitions. It is shown that the experimentally observed alanine- and sodium-concentration dependence of transport rates is consistent with the predictions of the simultaneous model, but incompatible with the consecutive mechanism. Assuming that the association-dissociation reactions are not rate-limiting, a number of kinetic parameters of the simultaneous model can be estimated from the experimental results. The equilibrium dissociation constants of Na⁺ and alanine at the extracellular side are determined to beK _N <-64mm andK _S <-18mm. Furthermore, the ratioK _N /K _N ^S of the dissociation constants of Na⁺ from the binary (NC) and the ternary complex (NCS) at the extracellular side is estimated to be <-6. This indicates that the binding sequence of Na⁺ andS to the transporter is not ordered. The current-voltage behavior of the transporter is analyzed in terms of charge translocations associated with the single-reaction steps. The observed voltage-dependence of the half-saturation concentration of sodium is consistent with the assumption that a Na⁺ ion that migrates from the extracellular medium to the binding site has to traverse part of the transmembrane voltage.     

Problems in estimating growth rates of marine phytoplankton from short-term14C assays

Growth rate estimates () of phytoplankton populations that were sampled from nitrogen-limited continuous cultures and then incubated for short durations in batch culture with added¹⁴C-HCO₃ ^– were significantly different than steady-state growth rates () for 3 of 5 marine phytoplankton species. Two diatoms,Thalassiosira weissflogii andChaetoceros simplex, displayed virtually identical growth rates (=) over a wide range of, whereas for a third diatom,Phaeodactylum tricornutum, was overestimated by an average of 40% compared to. In contrast, was underestimated by the¹⁴C technique for the two remaining species: up to 40% at a steady-state of 1.0 day^–1 for the chlorophyteDunaliella tertiolecta and up to 100% at of 1.4 day^–1 for the haptophytePavlova lutheri. For the latter two species the divergence between and appeared to increase with increasing steady-state. A simple model of labeled and total carbon flow between the aqueous phase and cellular biomass was constructed to demonstrate that respiration was negligible when=, but was significant when>. In the cases in which<, a rapid physiological alteration presumably took place once the steady state was disturbed and cells were placed in the incubation chambers, which perhaps was related to the nutritional state of the cultures at the time of sampling. Questions thus are raised regarding our ability to measure accurately primary productivity from shipboard experiments with confined samples of phytoplankton from nutrient-impoverished waters that probably are less hardy than the laboratory cultures used in these studies.     

UDP-GlcNAc: Galβ3GalNAc-Mucin: (GlcNAc → GalNAc) β6-N-Acetylglucosaminyltransferase and UDP-GlcNAc: Galβ3(GlcNAcβ6) GalNAc-Mucin (GlcNAc → Gal)β3-N-Acetylglucosaminyltransferase from Swine Trachea Epithelium

Summary Two specific -N-acetylglucosaminyltransferases involved in the branching and elongation of mucin oligosaccharide chains, namely, a 1,6 N-acetylglucosaminylsaminyltransferase that transfers N-acetylglucosamine from UDP-N-acetylglucosamine to Gal3GalNAc-Mucin to yield Gal3(GlcNAc6)GalNAc-Mucin and a 3-N-acetylglucosaminyl transferase that transfers N-acetylglucosamine from UDP-N-acetylglucosamine to Gal3(GlcNAC6)GalNAc-mucin to yield GlcNAc3Gal3 (GlcNAc6)GalNAc-Mucin were purified from the microsomal fraction of swine trachea epithelium. The 1,6-N-acetylglucosaminyltransferase was purified about 21,800-fold by procedures which included affinity chromatography on DEAE columns containing bound asialo Cowper's gland mucin glycoprotein with Gal1,3GalNAc side chains. The apparent molecular weight estimated by gel filtration was found to be about 60 Kd. The purified enzyme showed a high specificity for Gal1,3GalNAc chains and the most active substrates were mucin glycoproteins containing these chains. The apparent Km of the 6-glucosaminyltrans-ferase for Cowper's gland mucin glycoprotein containing Gal1,3GalNAc chains was 0.53 µM; for UDP-N-acetylglucosamine, 12 µM; and for Gal 1,3GalNAc NO₂ø, 4 mM. The activity of the 6-glucosaminyltransferase was dependent on the extent of glycosylation of the Gal3GalNAc chains in Cowper's gland mucin glycoprotein.The best substrate for the partially purified 3-Glucosaminyltransferase was Cowper's gland mucin glycoprotein containing Gal1,3(GlcNAc6)GalNAc side chains. This enzyme showed little or no activity with intact sialylated Cowper's gland mucin glycoprotein or derivatives of this glycoprotein containing GalNAc or Gal1,3GalNAc side chains.The radioactive oligosaccharides formed by these enzymes in large scale reaction mixtures were released from the mucin glycoproteins by treatment with alkaline borohydride, isolated by gel filtration on Bio-Gel P-6 and characterized by methylation analysis and sequential digestion with exoglycosidases. The oligosaccharide products formed by the 6- and 3-glucosaminyltransferases were shown to be Gal3(GlcNAC6) GalNAc and GlcNAc3 Gal3(GlcNAC6)GalNAc respectively.Taken collectively, these results demonstrate that swine trachea epithelium contains two specific N-acetylglucosaminyltransferases which catalyze the initial branching and elongation reactions involved in the synthesis of O-linked oligosaccharide chains in respiratory mucin glycoproteins. The first enzyme a 6-glucosaminyltransferase converts Gal3GalNAc chains in mucin glycoproteins to Gal3(GlcNAc6)GalNAc chains. This product is the substrate for a second 3-glucosaminyltransferase which converts the Gal3(GlcNAc6)GalNAc chains to GlcNAc3Gal(GlcNAc6)GalNAc chains in the glycoprotein. The 3-glucosaminyltransferase did not utilize Gal3GalNAc chains as a substrate and this results in an ordered sequence of addition of N-acetylglucosamine residues to growing oligosaccharide chains in tracheal mucin glycoproteins.Abbreviations NeuNAc N-acetylneuraminic acid - GalNAcol N-acetylgalactosaminitol - CGMG Cowper's gland mucin glycoprotein - GalNAc-CGMG Cowper's gland mucin glycoprotein containing GalNAc side chains O-glycosidically linked to serine or threonine - Gal3GalNAc-CGMC Cowper's gland mucin glycoprotein containing Gal3GalNAc side chains - MES 2-(N-morpholino) Ethane Sulfonic acid - PBS Phosphate Buffered Saline     

Cellobiose phosphorylase (EC 2.4.1.20) of Cellulomonas: occurrence,induction, and its role in cellobiose metabolism

The occurrence of cellobiose cleavage by phosphorolysis and by hydrolysis was investigated in Cellulomonas spec., C. uda, C. flavigena, and C. cartalyticum. Cellobiose phosphorylase (EC 2.4.1.20) was shown to be produced by Cellulomonas spec. when cellobiose or cellulose was used as sole source of energy and carbon but not with glycerol or glucose. Using inhibitors of protein synthesis as well as double labelling techniques it was shown that cellobiose phosphorylase is synthesized de novo in Cellulomonas spec. Aryl--D-glucosidase which was shown to be present in crude extracts of this microorganism as well is not involved in cellobiose cleavage.Abbreviations oNPGluc ortho-nitrophenyl--D-glucopyranoside - oNPGlucase ortho-nitrophenyl--D-glucopyranoside hydrolase (aryl--D-glucosidase) - CMC carboxymethyl-cellulose - CMCase carboxymethyl-cellulase - PAGE polyacrylamde disc gel electrophoresis Parts of this work were presented on the Herbsttagung der Gesellschaft für Biologische Chemie (Schimz et al. 1979) and on the 14th FEBS Meeting (Schimz et al. 1981)     

Uptake of sewage derived nitrogen by<Emphasis Type="Italic"> Ulva rigida</Emphasis> (Chlorophyceae) in Bahía Nueva (Golfo Nuevo,Patagonia, Argentine)

Uptake kinetics of nitrogen derived from sewage–seawater mixtures (2.5–20% v/v effluent) were determined in the laboratory for Ulva rigida (Chlorophyceae) native from Bahía Nueva (Golfo Nuevo, Patagonia, Argentine). In terms of nitrogen concentration, experimental enrichment levels varied between 53.7 and 362.3M of ammonium and between 0.77 and 6.21M of nitrate+nitrite. Uptake rates were fitted to the Michaelis–Menten equation, with the following kinetic parameters: ammonium: V_max = 591.2molg^–1h^–1, K _s=262.3M, nitrate+nitrite: V _max=12.9molg^–1h^–1, K _s=3.5M). Both nutrients were taken up simultaneously, but ammonium incorporation was faster in all cases. The results show a high capability of Ulva rigida to remove sewage-derived nitrogen from culture media. In the field, most of the nitrogen provided by the effluent would be tied up in algal biomass, supporting low nitrogen levels found at a short distance away from the source.     

Methodological problems in evolutionary biology VIII. Biology and culture

Biology cannot accommodate all aspects of culture. Aspects of culture that a biological approach can take into account can be covered by the biological categories of phenotype and environment. There is no need to treat culture as a separate category. Attempts to elaborate biological explanations of cultural variation will meet with success only if biologists expand theories of development, and integrate them in evolutionary biology. The alternative — elaborating the idea of so-called cultural inheritance — makes little sense from a biological point of view.     

Immobilized Lotus tetragonolobus agglutinin binds oligosaccharides containing the Lex determinant

A defined set of oligosaccharides and glycopeptides containing -linked fucose were used to examine the specificity of the immobilized fucose-binding lectin Lotus tetragonolobus agglutinin (LTA1), also known as lotus lectin. Glycans containing the Lewis x determinant (Lex) Gal1-4[Fuc1-3]GlcNAc1-3-R were significantly retarded in elution from high density LTA-Emphaze columns. The lectin also bound the fucosylated lacdiNAc trisaccharide GalNAc1-4[Fuc1-3]GlcNAc. The lectin did not bind glycans containing either sialylLex or VIM-2 determinants, nor did it bind the isomeric Lea, Gal1-3[Fuc1-4]GlcNAc-R. Although 2-fucosyllactose Fuc1-2Gal1-4Glc) was retarded in elution from the columns, larger glycans containing the H-antigen Fuc1-2Gal1-3(4)GlcNAc-R interacted poorly with immobilized LTA. Our results demonstrate that immobilized LTA is effective in isolating glycans containing the Lex antigen and is useful in analyzing specific fucosylation of glycoconjugates. Abbreviations: LTA, Lotus tetragonolobus agglutinin; UEA-1, Ulex europaeus agglutinin-I; LNT, AAL, Aleuria aurantia agglutinin; Gal1-3GlcNAc1-3Gal1-3Glc; LNnT, Gal1-4GlcNAc1-3Gal1-3Glc; Lex, Lewis x antigen; Lea, Lewis a antigen; GDPFuc, guanosine 5-diphosphate--L-fucose     

The rapid switch-off of nitrogenase activity in obligate methane-oxidizing bacteria

Nitrogenase activity in the obligate methaneoxidizing bacterium Methylococcus capsulatus (Bath) was added ammonia. This observation was extended to include other ammonia. This observation was extended to include other representative N₂-fixing species of methanotrophs. The ammonia switch-off of nitrogenase in M. capsulatus (Bath) was reversed on washing cells to remove excess ammonia, in the presence of chloramphenicol, suggesting that a form of covalent modification of nitrogenase may occur. Replacing the oxidizable substrate methanol with formaldehyde, formate, ethanol or hydrogen had no effect on nitrogenase switch-off. A number of potential nitrogen sources or intermediates of nitrogen metabolism such as glutamine, asparagine, glutamate and alanine when tested, did not effect switch-off. However, the rapid inhibition of nitrogenase activity of M. capsulatus (Bath) could be achieved by adding the uncoupler carbonylcyanide m-chlorophenylhydrazone or nitrite. The glutamine synthetase inhibitor methionine sulphoximine blocked the switch-off effect of ammonia, indicating that the metabolism of ammonia may be essential for switch-off to occur. Inhibitors of glutamate synthase did not alleviate the ammonia switch-off response. Methionine sulphoximine did not alleviate the rapid inhibition of nitrogenase by carbonylcyanide m-chlorophenylhydrazone indicating that the shortterm regulation of nitrogenase by uncouplers and ammonia proceed via different mechanisms.Abbreviations MSX methionine-DL-sulphoximine - DON 6-diazo-5-oxo-L-norleucine - GS glutamine synthetase - GOGAT glutamine 2-oxoglutarate aminotransferase (glutamate synthase) - CCCP carbonylcyanide m-chlorophenyl hydrazone