Filamentous Marine Fungi as Producers of <Emphasis Type="Italic">O</Emphasis>-Glycosylhydrolases: β-1,3-Glucanase from <Emphasis Type="Italic">Chaetomium indicum</Emphasis>

Ninety fungal strains (42 species) isolated from marine habitats were studied for their ability to produce extracellular enzymes. Cultural filtrates of these strains were shown to contain a series of glycosidases (-glucosidases, N-acetyl--glucosaminidases, -galactosidases -mannosidases) and glucanases (1,3--glucanases, amylases) which varied with habitat. The level of activity depended on the species of fungi. Several promising strains capable of producing both individual enzymes and a set of enzymes for splitting carbohydrate-containing compound have been isolated. Optimal conditions for growth of Chaetomium indicum and for biosynthesis of -1,3-glucanase were determined. -1,3-Glucanase was isolated using ion-exchange chromatography, ultrafiltration, and gel filtration. The presence of 2 enzyme forms was shown; both forms were exo--1,3-glucanases.     

Purification,and characterization of a β-mannanase of Trichoderma reesei C-30

Trichoderma reesei was studied for its ability to produce -mannanase activity on a variety of carbon sources. The highest -mannanase activity was produced on cellulose, whereas -mannan-containing carbon sources (such as kojac powder or locust bean gum) gave lower enzyme titres. The enzyme responsible for the major -mannanolytic activity from T. reesei was purified to physical homogeneity by preparative chromatofocusing and anion exchange fast protein liquid chromatography. This -mannanase is a glycoprotein, with a molecular mass of 46 (±2) kDa and an isoelectric point of 5.2. It has an optimal pH at 5.0 and broad pH stability (2.5–7.0). It is stable for 60 min at 55° C, and has an optimal temperature for activity at 75° C. During incubation with locust bean gum, the enzyme releases mainly tri- and disaccharides. Correspondence to: C. P. Kubicek     

Distance-constraint approach to protein folding. I. Statistical analysis of protein conformations in terms of distances between residues

A statistical analysis of protein conformations in terms of the distance between residues, represented by their C atoms, is presented. We consider four factors that contribute to the determination of the distanced _i,i+k between a given pair ofith and(i+k)th residues in the native conformation of a globular protein: (1) the distancek along the chain, (2) the size of the protein, (3) the conformational states of theith to(i+k)th residues, and (4) the amino acid types of the and(i+k)th residues. In order to account for the dependence on the distancek along the chain, the statistics are taken for three ranges, viz., short, medium, and long ranges (k8; 9k20; andk21; respectively). In the statistics of short-range distances, a mean distanceD _k and its standard deviationS _k are calculated for each value ofk, with and without taking into account the conformational states of all residues fromi toi+k (factors 1 and 3). As an Appendix, the relations for converting from the distances between residues into other conformational parameters are discussed. In the statistics of long-range distances, a reduced distanced* _ij (the actual distance divided by the radius of gyration) is used to scale the data so that they become independent of protein size, and then a mean reduced distanceD _l (a, a) and its standard deviation _l (a, a) are calculated for each amino acid pair (a, a) (factors 2 and 4). The effect of the neighboring residues along the chain on the value of the distanced* _ij is explored by a linear regression analysis between the actual reduced distanced* _ij and the mean value over theD _l for all possible pairs of residues in the two segments of the (i–2)th to the (i+2)th and the (j–2)th to the (j+2)th residues. The effect is assessed in terms of the tangentA _l (a, a) of the calculated regression line for each amino acid pair (a, a). In the statistics of medium-range distances, only factors 1 and 4 are considered, to simplify the analysis. The scaled distanced _i,i+k =(d _i,i+k -D _k )/S _k is used to eliminate the dependence onk, the distance along the chain. The propertiesD _m (a, a), _m (a, a) andA _m (a, a) corresponding toD _l (a, a), _l (a, a), andA _l (a, a), and also calculated for each amino acid pair (a, a). The results are interpreted as follows: the smaller values ofD _l (a, a) andD _m (a, a) indicate a preference of the pair (a, a) for a contact (e.g., pairs between hydrophobic amino acids, and pairs of Cys with aromatic amino acids), and the larger values of these quantities indicate a preference for distant mutual location (e.g., pairs between strong hydrophilic amino acids); the smaller values of _l (a, a) and _m (a, a) indicate a strong preference for either contact or noncontact (e.g., pairs between hydrophobic amino acids, and pairs between strong hydrophobic and hydrophilic amino acids, respectively), and the larger values of these quantities indicate the ambivalent/neutral nature of the preference for contact and noncontact (e.g., pairs containing Ser or Thr); the smaller values ofA _l (a, a) andA _m (a, a) indicate that the distance of an (a, a) pair is determined independently of the amino acid character of the neighboring residues along the chain (e.g., some pairs of Cys or Met with other amino acids) and the larger values of these quantities indicare that such amino acid character contributes strongly to the determination of the distance (e.g., pairs containing Ser or Thr, and pairs between amino acids with small side chains). The difference between the statistics for the long- and medium-range distances is also discussed; the former reflect the difference between the hydrophobic and hydrophilic character of the residues, but the latter cannot be easily interpretable only in terms of hydrophobicity and hydrophilicity. The data analyzed here are used in the optimization of an object function to compute protein conformation in a subsequent paper.     

Zentrale versus periphere Kontrolle des Gesanges von Grillen (Gryllus campestris)

Zusammenfassung Bei Gryllus campestris werden Singbewegung und Aktivität einiger mesothorakaler Singmuskeln untersucht. Aus operativen Eingriffen in das Bewegungssystem, die Muskeln und ihre Nerven sowie in die Konnektive des thorakalen Bauchmarks wird gefolgert: Die Gesänge der Grillen sind überwiegend zentral programmiert; eine periphere Kontrolle verändert sie nur in engen Grenzen. Lautmuster und zugeordnete Muskelaktivität werden kaum geändert, nachdem die Tegmina oder die Mittelbeine einseitig oder beidseitig amputiert sind, ebenso wenig nach Belasten der Vorderflügel mit Gewichten bis zu 120 mg. Grillen mit kurzen Vorderflügeln forme néoténique und mit langen Hinterflügeln forme makroptère zeigen ebenfalls ein normales Aktivitätsmuster der Muskeln. Tegmina, die in der Ruhelage festgelegt sind, beeinflussen lediglich die Entladungshäufigkeit der fast-Einheiten im Subalar- und 2. Basalarmuskel, und zwar links mehr als rechts. Es wird nach solchen Eingriffen eine Asymmetrie im motorischen System der Grillen aufgedeckt. Auch eine Belastung der Tegmina, nicht aber die Amputation, erhöht die Muskelaktivität, allerdings nur in Pleuralmuskeln der linken Seite.Muskeln, deren ventrale Ansatzstellen am Sekelet durchtrennt sind, degenerieren nicht, solange Sauerstoffversorgung und Innervation gewährleistet sind. Im Gesang, der auch noch nach solchen Eingriffen auftritt, arbeiten sie wie beim normalen Tier. Grillen können noch zirpen, wenn die Pro- und Remotoren und die Subalar- und Basalarmuskeln an einer Ansatzstelle abgelöst sind; ja selbst nach Denervierung dieser Muskeln kann man von den Einheiten der intakt gebliebenen dorsalen Längsmuskeln die gesangsspezifische Aktivität ableiten.Nur nach der Durchtrennung des linken Konnektivs zwischen dem 1. und 2. Brustganglion findet man eine Assymmetrie in der Muskelaktivität, wobei nur die linke Seite betroffen ist. Dabei können Subalar- und 2. Basalarmuskel ihre Entladung erhöhen, ggf. tonisch feuern.

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Central versus peripheral control in cricket stridulation

Summary Behavioural studies and recordings from single fast motor units of several mesothoracic muscles of Gryllus campestris before and after operations at the stridulatory apparatus, the corresponding muscles, the motor nerves, and the thoracic connectives gave strong evidence that song patterns in crickets mainly depend upon centrally programmed phasing mechanisms with very limited modulation by peripheral control.Muscular activity during sound production is not significantly changed after the removal of tegmina or middle legs from one or both sides or after loading the tegmina with weights up to 120 mg. No differences occur in the modifications forme néoténique and forme makroptère. Tegmina fixed at resting position do not cause a change in discharge patterns of pro- and remotor-muscles. However, the activity of the fast motor units of the 2nd basalar and the subalar muscle shows a slight increase due to repetitive firing. This increase is more pronounced on the left than on the right side and demonstrates an asymmetry within the cricket's neuronal system not known before. Tegmina loaded give rise to a slight increase in activity but only in units of the left subalar muscle, whereas amputation does not affect the motor activity at all. Muscles cut close to one point of their insertion at the skeleton do not degenerate, as long as oxygen supply and innervation remain intact. They act during sound production as do those in intact males and several crickets have been observed singing normally after the pro- and remotor as well as the subalar and 2nd basalar muscles have been cut. Even males which have the motor nerves to these muscles severed do stridulate, as is shown by recordings from units of the dorsal longitudinal muscles; however the tegmina are only slightly moved.After severing only the left connective between the pro- and mesothoracic ganglion, an asymmetry in the muscular activity can be demonstrated. This leads to an increase in firing activity of only the left pleural muscles (M 98,99); cutting the right connective does not give a similar effect.

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Mit dankenswerter Unterstützung durch die Stiftung Volkswagenwerk.     

Extracellular amylolytic system of the yeast Lipomyces kononenkoae

Summary A strain of the yeast Lipomyces kononenkoae which converted starch into SCP with a high yield, produced three extracellular amylases which were purified from the culture fluid by Ficoll concentration, dialysis, isopropanol precipitation and DE-cellulose chromatography: an -amylase, a glucoamylase and a debranching transferase. The latter transferred -1,6-glucosyl units from panose to glucose forming maltose and appeared to have some debranching activity on amylopectin. The -amylase had the following properties: MW 38000 daltons; no effect of added calcium ions on activity; optimum temperature and pH for activity around 40°C and pH 5.5; H and S of heat inactivation 24360 cal mol^–1 and 29.2 cal deg^–1 mol^–1; range of pH stability pH 4–6.5; pI=7.1; final low molecular weight products of starch hydrolysis, maltose and glucose; K_m (40°C, pH 5.5) for starch 2.7 gl^–1, for maltotriose 109 gl^–1; uncompetitive inhibition by maltose with K_i (40°C, pH 5.5) 29.5 gl^–1. The glucoamylase had the following properties: MW 81500 daltons; optimum temperature and pH for activity around 50°C and pH 4.5: H and S of heat inactivation 20400 cal mol^–1 and 17.7 cal deg^–1 mol^–1; range of pH stability pH 4–6.5; pI=6.1; K_m (30°C, pH 4.5) for soluble starch 16.2 gl^–1, for maltose 0.36 gl^–1, for p-nitrophenyl--D-glucoside 0.35 gl^–1; competitive inhibition by glucose with K_i (30°C, pH 4.5) 4.7 gl^–1.     

The carotenoids of Flavobacterium strain R1560

The main carotenoid of Flavobacterium strain R1560 has been identified as (3R,3R)-zeaxanthin. Also present were small amounts of 15-cis-phytoene, phytofluene, -carotene (7,8,7,8-tetrahydro-, -carotene plus 7,8,11,12-tetrahydro-, -carotene), neurosporene, lycopene, -zeacarotene, -carotene, -carotene, -cryptoxanthin, rubixanthin, 3-hydroxy--zeacarotene and several apo-carotenals. Zeaxanthin production was inhibited by nicotine (10 mM), and lycopene and rubixanthin accumulated. The biosynthesis of zeaxanthin is discussed in terms of pathways and also of half-molecule reaction sequences. The presence of zeaxanthin may be a characteristic of a group of Flavobacterium species, and may thus be useful in the taxonomic classification of these organisms.     

cDNA Sequence, Protein Structure, and Evolution of the Single Hemocyanin from Aplysia californica, an Opisthobranch Gastropod

By protein immunobiochemistry and cDNA sequencing, we have found only a single hemocyanin polypeptide in an opisthobranch gastropod, the sea hare Aplysia californica, which contrasts with previously studied prosobranch gastropods, which express two distinct isoforms of this extracellular respiratory protein. We have cloned and sequenced the cDNA encoding the complete polypeptide of Aplysia californica hemocyanin (AcH). The cDNA comprises 11,433 bp, encompassing a 5UTR of 77 bp, a 3UTR of 1057 bp, and an open reading frame for a signal peptide of 20 amino acids plus a polypeptide of 3412 amino acids (M_r ca. 387 kDa). This polypeptide is the subunit of the cylindrical native hemocyanin (M_r ca. 8 MDa). It comprises eight different functional units (FUs: a, b, c, d, e, f, g, h) that have been identified immunobiochemically after limited proteolysis of AcH purified from the hemolymph. Each FU shows a highly conserved copper-A and copper-B site for reversible oxygen binding. FU AcH-h carries a specific C-terminal extension of ca. 100 amino acids that include two cysteines that may be utilized for disulfide bridge formation. Potential N-glycosylation sites are present in six FUs but lacking in AcH-b and AcH-c. On the basis of multiple sequence alignments, phylogenetic trees and a statistically firm molecular clock were calculated. The latter suggests that the last common ancestor of Haliotis and Aplysia lived 373±47 million years ago, in convincing agreement with fossil records from the early Devonian. However, the gene duplication yielding the two distinct hemocyanin isoforms found today in Haliotis tuberculata occurred 343±43 million years ago.[Reviewing Editor: Dr. Axel Meyer]The sequence reported in this paper has been deposited in the GenBank database under accession number AJ556169.     

Modeling of Alternative Pathways of Electron Transport to Photosystem I in Isolated Thylakoids

Kinetics of dark decay of absorbance changes at 830 nm (₈₃₀) was examined in thylakoids isolated from leaves of pea seedlings at various concentrations of exogenous NADPH or NADH. Absorbance changes were induced by far-red light to avoid electron donation from photosystem II. In the presence of either biological reductant, the kinetics of ₈₃₀ decay reflecting dark reduction of 700⁺, the primary electron donor of photosystem I, was fitted by a single exponential term. The rate of 700⁺ reduction increased with the rise in the concentration of both NADPH and NADH. The values of K _M and V _max for 700⁺ reduction estimated from concentration dependences were 105 ± 21 M and 0.32/s for NADPH or 21 ± 8 M and 0.12/s for NADH. The rate of P700⁺ reduction by either NADPH or NADH significantly increased in the presence of rotenone, a specific inhibitor of chloroplast reductase. The value of V _max was changed only in the presence of rotenone, whereas K _m was practically unaffected. Unlike the chloroplasts of intact leaves, the only enzyme mediating the input of reducing equivalents from NADPH or NADH to the electron transport chain was concluded to be present in thylakoids.     

Relation between trace element levels in plasma and myocardium during coxsackievirus B3 myocarditis in the mouse

During most infections the plasma levels of trace elements change, but it is not clear if this reflects changes in the infected tissues. Coxsackievirus B3 (CB3) infection may result in viral replication, subsequent inflammation and changed trace element levels in the myocardium. In the present study, the trace element levels in the plasma and heart of adult male A/J mice were determined during the pre-inflammatory stage (day 4) of CB3 myocarditis for the following trace elements: aluminium (Al), arsenic (As), calcium (Ca), cobalt (Co), copper (Cu), iron (Fe), magnesium (Mg), manganese (Mn), selenium (Se), silver (Ag), vanadium (V) and zinc (Zn). The severity of the infection was assessed through clinical signs of disease and trace element levels were measured through inductively-coupled plasma mass-spectrometry (ICP-MS). In the heart, the levels decreased for V (59%; p<0.01), Co (38%; p<0.01), Al (81%; p< 0.01), As (66%; p<0.01) and Se (16%; p<0.01). Increased levels were detected for Mn (13%; p<0.05), Fe (48%; p<0.01), Cu (34%; p<0.01) and Ag (46%; p< 0.01). In the plasma, decreases were detected in the level of Zn (32%; p<0.05), whereas increases were seen in Mn (362%; p<0.05), Fe (272%; p<0.01), Co (71%; p<0.05), Cu (25%; n.s.) and Mg (43%; p<0.01) levels. A correlation was found between the levels in plasma and myocardium for Co (r _s=–0.636; p<0.05), Fe (r _s=0.764; p<0.05), Mn (r _s=0.682; p<0.05) and Mg (r _s=–0.791; p<0.05). Thus, determination of some of these trace elements in the plasma may be useful to indicate target tissue involvement in the early pre- inflammatory stage of an infectious disease. Some of these elements are important nutrients for the immune system, while others may be associated with the development of disease complications, such as cardiac arrhythmias.     

Expression of the β-subunit of β-conglycinin in seeds of transgenic plants

Soybean (Glycine max (L.) Merr.) seeds contain the storage protein -conglycinin, encoded by a multigene family. -Conglycinin consists of three subunits; , , and . A genomic clone for a -subunit of -conglycinin has been characterized by restriction-enzyme mapping and hybrid selected in-vitro translation followed by immunoprecipitation. In order to determine the developmental regulation of this -subunit gene, its expression was studied in seeds of transgenic petunia (Petunia hybrida) and tobacco (Nicotiana tabacum L.) plants. The -subunit expressed in seeds of petunia and tobacco was recognized by anti--conglycinin serum at a relative molecular mass of 53 000, equivalent to that of the native protein. Separation of the petunia-seed proteins by isoelectric focusing followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblot analysis showed that multiple isoelectric forms of the -subunit were produced. There was approximately a twofold variation in the accumulation of the -subunit protein in the mature seeds of transgenic petunia plants, each containing a single -subunit gene. However, the level of protein accumulation in mature seeds and the amount of -subunit mRNA in developing seeds was not correlated. Accumulation of the -subunit protein in transgenic seeds was less than the -subunit protein that accumulated in transgenic petunia seeds containing a single -subunit gene and less than the amount of the -subunit in mature soybean seeds which contain 8–13 -subunit genes. In transgenic tobacco plants, the accumulation of the -subunit protein in seeds was generally well correlated with the number of genes that were incorporated in the different transformants.Abbreviations kb kilobase - kDa kilodalton - M_r relative molecular mass - SDS-PAGE sodium dodecyl sulfate polyacrylamide gel electrophoresis     

β-Glucuronidase activity in human T and B lymphocytes and the Tμ and Tγ subpopulations

Summary The -glucuronidase staining characteristics of isolated T cell populations and the T and T enriched fractions derived of them were studied. T lymphocytes were obtained from purified T lymphocytes by ox-IgG rosette sedimentation. The rosette-forming cells in the pellet were referred to as T lymphocytes, whereas the lymphocytes in the interface were referred to as T depleted or T lymphocytes. B cells were studied on rosetted mononuclear cells with either mouse erythrocytes or with Staphylococcus Aureus (Cowan I) bacteria, after a preceeding polyvalent anti-human Ig treatment of the cells. While B cells showed mostly no reactivity, T and T cells were respectively characterised by a dot-like and granular pattern of reactivity. These findings are in agreement with those observed by others after -naphthyl-acetate esterase or acid phosphatase staining. Within the T lymphocyte fraction, the T non-, non lymphocytes seemed to have a granular pattern of reactivity. The same staining pattern was found in non-B, non-T lymphocytes.     

Characterization of the la antigens involved in suppressor T cell generation in the rat

The WRC rat, an intra-class II recombinant strain (RT1.B ⁿ B ^a D _, ^a ), was used to study the relative roles of the two class II loci in mixed lymphocyte reaction (MLR) proliferation and suppressor T cell (Ts) generation. Both MLR proliferation and Ts generation were noted in cultures of WRC with DA (RTI ^{a) stimulator cells. In contrast, cultures of WRC with BN (RT1sun} ) stimulator cells proliferate but do not generate significant amounts of Ts. The data suggest that RT1.B incompatibility is important in the generation of Ts in the WRC rat. Suppressor cells generated in cultures of WF (RT1 ^u ) with WRC stimulator cells potently suppressed a WF+WRC_x test MLR, with less suppression when tested against either the WF+DA_x or WF+BN_x MLRs. The latter experiments suggest that Ts clones may be produced to either class II subregion, and therefore that MLR proliferation and Ts induction are not necessarily linked, but vary with particular genotypes. The current lack of other rat intra-class II recombinant strains precludes assignment of suppressor induction/activation to a single locus.     

Bacteriophage phi 1 as a gene-cloning vector in Bacillus subtilis

Summary We attempted to use Bacillus subtilis phage 1 as a gene-cloning vector since the 1 genome was found to have few cleavage sites upon digestion with several kinds of restriction endonucleases. A 1 stock supplied by J. Ito (University of Arizona, Tucson, USA) consisted of two phages, 1E1 and 1E2, having one and two EcoRI-cleavage sites in their genomes respectively. From the latter isolate a deletion mutant 1E21 was induced to increase the size range of DNA segments to be cloned. It was demonstrated, by in vitro recombination experiments with phage 11 DNA, that 1E21 can be used for cloning EcoRI fragments of various sizes. We analyzed the DNAs of ten 1 clones isolated from independent transfectants and found that six of them carried 11 DNA fragments inserted at either of the two EcoRI-cleavage sites. Some of the hybrid phage DNAs were found to be cleaved with BamHI and HaeIII endonucleases at the 11 DNA portion, whereas the parental 1E21 DNA was insensitive to any of these enzymes. These hybrid phages would therefore be useful vectors for cloning foreign DNA fragments generated by cleavage with BamHI or HaeIII endonucleases.     

β-Alanine metabolism and high salinity stress in the sea anemone,Bunodosoma cavernata

Summary During high salinity stress, -alanine accumulates to high levels in the sea anemone,Bunodosoma cavernata. Following a salinity increase from 26 to 40 -alanine increased 28-fold from 1.5 to 41.9 moles/g dry weight. Both whole animal studies and experiments with cell free homogenates indicate that under high salinity conditions an increase in the rate of -alanine synthesis from aspartic acid as well as a decrease in the rate of -alanine oxidation are responsible for the observed accumulation of -alanine. The rate of aspartic acid decarboxylation to -alanine is about 3 times greater in anemones acclimated to 40 than for those in normal salinity water (26). -alanine oxidation to CO₂ and acetyl-CoA proceeds 2.5 to 3 times slower in high salinity adaptedB. cavernata than in those acclimated to normal salinity. There is always a rapid degradation of uracil to -alanine, but this does not change with salinity.Abbreviations CASF cold acid soluble fraction - FAA free amino acids - MES 2(N-morpholino) ethane sulfonic acid - NPS ninhydrin positive substances - PCA perchloric acid - TCA trichloroacetic acid     

Synthetic substrate analogues for UDP-GlcNAc: Manα1-6R β(1-2)-N-acetylglucosaminyltransferase II. Substrate specificity and inhibitors for the enzyme

UDP-GlcNAc: Man1-6R (1-2)-N-acetylglucosaminyltransferase II (GlcNAc-T II; EC 2.4.1.143) is a key enzyme in the synthesis of complexN-glycans. We have tested a series of synthetic analogues of the substrate Man1-6(GlcNAc1-2Man1-3)Man-O-octyl as substrates and inhibitors for rat liver GlcNAc-T II. The enzyme attachesN-acetylglucosamine in 1-2 linkage to the 2-OH of the Man1-6 residue. The 2-deoxy analogue is a competitive inhibitor (K _i=0.13mm). The 2-O-methyl compound does not bind to the enzyme presumably due to steric hindrance. The 3-, 4- and 6-OH groups are not essential for binding or catalysis since the 3-, 4- and 6-deoxy and -O-methyl derivatives are all good substrates. Increasing the size of the substituent at the 3-position to pentyl and substituted pentyl groups causes competitive inhibition (K _i=1.0–2.5mm). We have taken advantage of this effect to synthesize two potentially irreversible GlcNAc-T II inhibitors containing a photolabile 3-O-(4,4-azo)pentyl group and a 3-O-(5-iodoacetamido)pentyl group respectively. The data indicate that none of the hydroxyls of the Man1-6 residue are essential for binding although the 2- and 3-OH face the catalytic site of the enzyme. The 4-OH group of the Man-O-octyl residue is not essential for binding or catalysis since the 4-deoxy derivative is a good substrate; the 4-O-methyl derivative does not bind. This contrasts with GlcNAc-T I which cannot bind to the 4-deoxy-Man- substrate analogue. The data are compatible with our previous observations that a bisectingN-acetylglucosamine at the 4-OH position prevents both GlcNAc-T I and GlcNAc-T II catalysis. However, in the case of GlcNAc-T II, the bisectingN-acetylglucosamine prevents binding due to steric hindrance rather than to removal of an essential OH group. The 3-OH of the Man1-3 is an essential group for GlcNAc-T II since the 3-deoxy derivative does not bind to the enzyme. The trisaccharide GlcNAc1-2Man1-3Man-O-octyl is a good inhibitor (K _i=0.9mm). The above data together with previous studies indicate that binding of the GlcNAc1-2Man1-3Man- arm of the branched substrate to the enzyme is essential for catalysis. Abbreviations: GlcNAc-T I, UDP-GlcNAc:Man1-3R (1-2)-N-acetylglucosaminyltransferase I (EC 2.4.1.101); GlcNAc-T II, UDP-GlcNAc:Man1-6R (1-2)-N-acetylglucosaminyltransferase II (EC 2.4.1.143); MES, 2-(N-morpholino)ethane sulfonic acid monohydrate.     

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.     

Subtle behavioral variation in wild chimpanzees, with special reference to Imanishi’s concept of kaluchua

Here we consider the concept of kaluchua (a word adopted from the English culture) in group-living animals developed by Imanishi in the 1950s. He distinguished it from bunka (the Japanese equivalent to the English culture) because he thought that bunka had strong connotations of noble and intellectual human-like activities. Although he did not rigidly define kaluchua, his original concept of kaluchua was much broader than bunka and represented non-hereditary, acquired behavior that was acknowledged socially. However, instead of social life, complex feeding skills have often formed the central topic in the current studies of animal culture. In order to provide evidence that more subtle behavioral variations exist among wild chimpanzee (Pan troglodytes) populations, we directly compared the behaviors of two well-habituated chimpanzee groups, at Bossou and Mahale. During a 2-month stay at Bossou, M.N. (the first author) saw several behavioral patterns that were absent or rare at Mahale. Two of them, mutual genital touch and heel tap were probably customary for mature females and for mature males, respectively. Index to palm and sputter are still open to question. These subtle patterns occurred more often than tool use during the study period, suggesting that rarity is not the main reason for their being ignored. Unlike tool use, some cultural behavioral patterns do not seem to require complex skills or intellectual processes, and sometimes it is hard to explain the existence of such behaviors only in terms of function.     

Existence and uniqueness of a sharp travelling wave in degenerate non-linear diffusion Fisher-KPP equations

In this paper we use a dynamical systems approach to prove the existence of a unique critical value c ^* of the speed c for which the degenerate density-dependent diffusion equation u _ct = [D(u)u _x ] _x + g(u) has: 1. no travelling wave solutions for 0 < c < c ^*, 2. a travelling wave solution u(x, t) = (x - c ^* t) of sharp type satisfying (– ) = 1, () = 0 ^*; '(^*–) = – c ^*/D'(0), '(^*+) = 0 and 3. a continuum of travelling wave solutions of monotone decreasing front type for each c > c ^*. These fronts satisfy the boundary conditions (– ) = 1, '(– ) = (+ ) = '(+ ) = 0. We illustrate our analytical results with some numerical solutions.     

Fromβ-lactams toα- andβ-amino acid derived peptides

Summary The potential of-lactams as intermediates for the access to- and-amino acid-derived peptides is shortly reviewed, with major focus on the technologies developed in our group. The two general strategies lie, on one side, in the oxidative ring expansion of 3-hydroxy-lactams toN-carboxy-amino acid anhydrides or Leuch's anhydrides and subsequent coupling with-amino acid esters and, on the other side, in the nucleophilic ring opening ofN-Boc--lactams. Both approaches have been successfully applied to the synthesis of,-diamino acid,-amino--hydroxy acid, polyhydroxylated-amino acid,,-disubstituted-amino acid,-amino acid,-amino--hydroxy acid and,-disubstituted-amino acid derived peptides. Because of the mild reaction conditions needed for the above transformations and the highly stereoselective procedures employed for the construction of the starting-lactam ring, the whole process allows the production of optically pure final products.     

The human genes for the α and γ subunits of the mast cell receptor for immunoglobulin E are located on human chromosome band 1823

The receptor with high affinity for immunoglobulin E (FcERI) is a key molecule in triggering the allergic reaction. It is tetrameric complex of one subunit, one subunit, and two disulfide-linked subunits. This receptor is present exclusively on mast cells and basophils. Molecules identical to the subunit of FcRI also form cell surface complex with other Fc receptors such as mouse FcRIIa in macrophages and most probably with human FcRIII (CD16) in natural killer (NK) cells. Here we show by in situ hybridization that the human genes for the (FCER1A) and subunits (FCER1 G) of FcERI and the gene for FcRIII (FCGR3, CD16) are located on human chromosome band 1823.