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Clusters of argon, krypton, and xenon are grown in a free jet and ionized by electron impact. The size of these clusters, (Rg)+n, extends up to n[bar_over_tilde:_approx._equal_to]1000. Individual cluster sizes are mass resolved up to n[bar_over_tilde:_approx._equal_to]570 in the case of Ar+n. The well known, but puzzling differences in the size distributions of Kr and Xe clusters disappear beyond n[bar_over_tilde:_approx._equal_to]130, while those between Ar and Xe disappear beyond n[bar_over_tilde:_approx._equal_to]220. The most pronounced ‘‘magic numbers’’ in the distributions of large cluster ions occur at n=147 (148 for Ar), 309, and 561, in striking agreement with the number of atoms required to build icosahedral clusters with 3, 4, and 5 complete coordination shells, respectively. Closure of the 6th icosahedral coordination shell is indicated by another strong intensity drop at n[bar_over_tilde:_approx._equal_to]923 in the unresolved part of the spectra. Several additional intensity extrema are observed between major shell closures. A simple structural model, assuming an icosahedral core decorated by the additional atoms, accounts for these anomalies reasonably well up to n=561. [ABSTRACT FROM AUTHOR]

No fumarase activity could be found in whole cells or in cell-free crude extracts from Leuconostoc mesenteroides or Lactobacillus curvatus. The degradation of l-malate-4-C by these organisms yielded more than 95% of the label as CO. It is therefore recommended that these organisms, rather than Lactobacillus plantarum, should be used in the determination of isotope distribution in l-malate-C, since L. plantarum exhibits a significant fumarase activity and thus randomizes malate prior to the decarboxylation of this substance by the malolactic enzyme. [ABSTRACT FROM AUTHOR]

In extracts from Phaseolus vulgaris seeds an enzyme has been found which transfers the galactosyl moiety of galactinol to raffinose giving rise to stachyose and myo-inositol. Two tests to measure the enzyme activity are described. The reaction is reversible. An equilibrium constant of approximately 4 has been determined for [stachyose][myo-inositol]⁄[raffmose][galactinol]. The enzyme catalyzes exchange reactions between galactinol and myo-[14C]inositol and between stachyose and [14C]raffinose. Specifically labeled galactinol and stachyose can be prepared in this way. The Km values for galactinol and for the two best galactosyl acceptors, raffmose and melibiose, have been measured. Besides the galactinol: raffinose-6-galactosyl transferase the extract of the seeds also contains an &alph;-galactosidase, which separates from the transferase during the purification. The transferase is strongly inhibited by p-chloromercuribenzoate. Ripening seeds contain an enzyme which catalyzes the reaction UDP-galactose + myo-inositol → galactinol + UDP. However, no direct transfer of galactose from UDP-galactose to raffinose has been observed. The physiological importance of the results is discussed. [ABSTRACT FROM AUTHOR]

The cell wall polymer of Natronococcus occultus (DSM 3396) consists of L-glutamate, N-acetyl-D-glucosamine, N-acetyl-D-galactosamine, D-galacturonic acid, D-glucuronic acid and D-glucose in a molar ratio of 5:7:1:8:0.5:0.3. Partial acid hydrolysis of the cell wall polymer produced soluble fragments that could be separated by HPLC. A gamma-glutamyl dipeptide was isolated. In the intact cell wall polymer, the glutamate residues form a poly-(gamma-glutamine) chain with a length of about 60 monomers, which corresponds to a relative molecular mass of approximately 7700 Da. Two other soluble dimeric fragments, composed of glutamate and either glucosamine or galactosamine in a molar ratio of 1:1, were purified from the hydrolysate, suggesting the presence of two different oligosaccharides linked to the poly-(gamma-glutamine) chain of the intact polymer. The analysis of additional fragments, which were composed of an amino sugar and galacturonic acid or glucose indicated that one oligosaccharide consisted of a glucosamine pentamer in an alpha-1,3 linkage at the reducing end and an oligomer with at least five beta-1,4-linked galacturonic acid residues at the non-reducing end. The second oligosaccharide was comprised of a galactosamine dimer in a beta-1,3 linkage at the reducing end and a maltose unit at the non-reducing end. Both oligosaccharides were linked to the alpha-amide group of the glutamine residues of the poly-(gamma-glutamine) chain. The whole cell wall polymer, which represents a novel type of natural glycoconjugate, has a relative molecular mass of 54 kDa.

The term 'Waldsterben' was introduced in the early 1980s to describe the progressive death of forests that was believed to be occurring in Central Europe as a result of air pollution. Subsequent surveys and investigations have failed to confirm that forests are dying or are even declining over large areas of Central Europe, defined here as consisting of Germany, Switzerland, southeastern France (Alsace), the Czech Republic, northern Italy and Austria. Foliar injury by air pollutants, together with mortality, has occurred, but is generally restricted to specific locations in the Czech Republic and in eastern Germany, such as the Fichtelgebirge. Where foliar damage has been recorded, it can often be attributed to high concentrations of sulphur dioxide, often acting in combination with other stresses (e.g. frost or insects). Outside areas affected by local sources of pollution, there is little, if any, evidence that the crown condition of trees has been adversely affected by pollution over large areas. Instead, climate appears to have a major effect on the crown condition and growth of trees. Measurements and surveys have revealed a very different picture to that forecasted in the mid-1980s. Growth rates of trees and stands in Central Europe are currently higher than have been recorded at any time in the past; the reasons for this are uncertain, although increases in forest area have not substantially contributed to the observed trends. Although declines in individual species in specific areas have been recorded, past records indicate that these do not represent a new phenomenon. Consequently, the terms 'Waldsterben' (forest deaths) and 'neuartige Waldschäden' (novel type of forest damages) should not be used in the context of the phenomenon reported in Central Europe in the 1980s. Instead, different problems should be described separately and the term forest decline used only when there is clear evidence of a general deterioration in the condition of all tree species within a forest.

The following putative precursors of the pseudomurein were isolated from trichloroacetic acid extracts of Methanobacterium thermoautotrophicum: a uridine diphosphate activated derivative of glutamic acid and the uridine diphosphate activated peptides (see text). The activated glutamic acid residue and the three activated pepetides lack the glycan components N-acetylglucosamine and N-acetyltalosaminuronic acid present in the intact pseudomurein. In this case uridine diphosphate should be directly linked to the amino group of a glutamic acid residue, which represents a new mode of amino acid and peptide activation.

Molecular structures and sequences are generally more revealing of evolutionary relationships than are classical phenotypes (particularly so among microorganisms). Consequently, the basis for the definition of taxa has progressively shifted from the organismal to the cellular to the molecular level. Molecular comparisons show that life on this planet divides into three primary groupings, commonly known as the eubacteria, the archaebacteria, and the eukaryotes. The three are very dissimilar, the differences that separate them being of a more profound nature than the differences that separate typical kingdoms, such as animals and plants. Unfortunately, neither of the conventionally accepted views of the natural relationships among living systems--i.e., the five-kingdom taxonomy or the eukaryote-prokaryote dichotomy--reflects this primary tripartite division of the living world. To remedy this situation we propose that a formal system of organisms be established in which above the level of kingdom there exists a new taxon called a "domain." Life on this planet would then be seen as comprising three domains, the Bacteria, the Archaea, and the Eucarya, each containing two or more kingdoms. (The Eucarya, for example, contain Animalia, Plantae, Fungi, and a number of others yet to be defined). Although taxonomic structure within the Bacteria and Eucarya is not treated herein, Archaea is formally subdivided into the two kingdoms Euryarchaeota (encompassing the methanogens and their phenotypically diverse relatives) and Crenarchaeota (comprising the relatively tight clustering of extremely thermophilic archaebacteria, whose general phenotype appears to resemble most the ancestral phenotype of the Archaea.

The immunogenicity and antigenic characteristics of the unique surface layer (S layer) of Methanococcus vanielii was studied with a panel of six monoclonal antibodies. Six surface determinants were identified for the first time, each recognized by one antibody exclusively. The determinants are proteins, located in the S layer, and accessible to antibody in whole, unfixed, as well as formalinized bacteria. Hence the six antigens and antibodies reported here should be useful for rapid identification of new isolates and for taxonomy of methanogens, notably Methanococcaceae. In this connection two novel applications of the slide immunoenzymatic assay were developed for analyses of monoclonal antibodies and their complementary sites in the bacterial envelope.

The mechanism of glycine action in growth inhibition was studied on eight different species of bacteria of various genera representing the four most common peptidoglycan types. To inhibit the growth of the different organisms to 80%, glycine concentrations from 0.05 to 1.33 M had to be applied. The inhibited cells showed morphological aberrations. It has been demonstrated that glycine is incorporated into the nucleotide-activated peptidoglycan precursors. The amount of incorporated glycine was equivalent to the decrease in the amount of alanine. With one exception glycine is also incorporated into the peptidoglycan. Studies on the primary structure of both the peptidoglycan precursors and the corresponding peptidoglycan have revealed that glycine can replace l-alanine in position 1 and d-alanine residues in positions 4 and 5 of the peptide subunit. Replacement of l-alanine in position 1 of the peptide subunit together with an accumulation of uridine diphosphate-muramic acid (UDP-MurNAc), indicating an inhibition of the UDP-MurNAc:l-Ala ligase, has been found in three bacteria (Staphylococcus aureus, Lactobacillus cellobiosus and L. plantarum). However, discrimination against precursors with glycine in position 1 in peptidoglycan synthesis has been observed only in S. aureus. Replacement of d-alanine residues was most common. It occurred in the peptidoglycan with one exception in all strains studied. In Corynebacterium sp., C. callunae, L. plantarum, and L. cellobiosus most of the d-alanine replacing glycine occurs C-terminal in position 4, and in C. insidiosum and S. aureus glycine is found C-terminal in position 5. It is suggested that the modified peptidoglycan precursors are accumulated by being poor substrates for some of the enzymes involved in peptidoglycan synthesis. Two mechanisms leading to a more loosely cross-linked peptidoglycan and to morphological changes of the cells are considered. First, the accumulation of glycine-containing precursors may lead to a disrupture of the normal balance between peptidoglycan synthesis and controlled enzymatic hydrolysis during growth. Second, the modified glycine-containing precursors may be incorporated. Since these are poor substrates in the transpeptidation reaction, a high percentage of muropeptides remains uncross-linked. The second mechanism may be the more significant in most cases.

The antigenic mosaic of the Archaebacterium Methanobacterium thermoautotrophicum, strain delta H, was analyzed with a panel of six monoclonal antibodies. Five antigenic determinants were identified. One contains N-acetyl-D-glucosamine, another contains N-acetyl-D-galactosamine, and a third contains gamma-glutamylalanine (gamma-Glu-Ala). These residues are not involved, at least as immunodominant epitopes, in the other two determinants, one of which contains L-talosaminuronic acid, a component of pseudomurein found only in Methanobacteriaceae. Each of the five determinants was recognized by one monoclonal antibody exclusively. A sixth antibody recognized a structure containing gamma-Glu-Ala that could be either a sixth determinant or a subdeterminant within the site already recognized as containing gamma-Glu-Ala. We postulate that two of the determinants are strain specific, three are species specific, and one is a common antigen.

The allosteric L-lactate dehydrogenases of Lactobacillus curvatus and Lactobacillus casei exist in the tetrameric from (molecular weight about 145 000) at pH 5.0--5.5 even in the absence of the effectors Mn2+ and Fru(1,6)P2 (fructose 1,6-bisphosphate), but undergo reversible dissociation to monomers (molecular weight about 35 000) at higher pH values or in the presence of urea. In the range between pH 5.5 (tetrameric state) and pH 7.4 (monomeric state) the L. curvatus L-lactate dehydrogenase exists in a dissociation-association equilibrium comprising tetramers, dimers and monomers as indicated by the Sc20,w values and the results of hybridization experiments. The simultaneous addition of both effectors [Mn2+ and Fru(1,6)P2] at pH 7.4, however, resulted in the stabilization of the tetrameric form. The addition of Fru(1,6)P2 alone at pH 7.4 had almost no influence on the quarternary structure, whereas the addition of Mn2+, as well as that of NADH, largely prevented dissociation. The L-lactate dehydrogenase of L. casei showed similar properties, although the enzyme dissociates only at about pH greater than or equal to 7.8. As in the case of the L. curvatus enzyme, Fru(1,6)P2 has no influence on the pH-dependent dissociation of the L. casei enzyme, whereas Mn2+ stabilizes the tetrameric structure. Reconstitution of a mixture of the two dissociated enzymes results in the formation of all statistically possible, enzymatically active hybrids. No hybridization between the allosteric enzymes from L. casei and L. curvatus and the non-allosteric ones of Lactobacillus plantarum and Lactobacillus acidophilus was observed.