Structure of an extracellular cross-reactive polysaccharide from Pseudomonas aeruginosa immunotype 4

A neutral small molecular mass (approximately 6.5 kDa) polysaccharide comprising a pentasaccharide repeat unit was isolated from culture supernatants of Pseudomonas aeruginosa immunotype 4. The polysaccharide had a pentasaccharide repeating unit as follows (formula; see text) where Rha is rhamnose. The structure was determined using acid hydrolysis, solvolysis with anhydrous hydrogen fluoride, methylation analysis, and 1H and 13C nuclear magnetic resonance spectroscopy including nuclear Overhauser enhancement experiments. The polysaccharide bound antibody raised to the lipopolysaccharide of the seven P. aeruginosa Fisher-Devlin immunotype strains. Inhibition assays demonstrated the presence of a serologically similar polysaccharide in supernatants of these strains. Affinity-purified antibody to the polysaccharide bound to lipopolysaccharide and whole cells of the immunotype strains of P. aeruginosa in a Western immunoblot and colony blot assay, respectively. This polysaccharide seems to contain an antigenic determinant present in the core of the P. aeruginosa lipopolysaccharide or may represent another minor polysaccharide substituent on the lipopolysaccharide in addition to the O side chain.     

Haemolysis of rabbit erythrocytes by a lectin from the seeds of<Emphasis Type="Italic">Croton tiglium</Emphasis>

The kinetics of haemolysis of rabbit erythrocytes byCroton tiglium lectin was studied as a function of concentration of the lectin and erythrocytes. The length of the prelytic period decreased with increasing lectin concentrations, indicating that the secondary events at the membrane which follow the binding of the lectin to cell surface carbohydrate receptors are accelerated at higher surface concentrations of the lectin. The rate or extent of haemolysis was not affected by the inclusion of ions like K⁺, Ca²⁺ and Mg²⁺ in the medium or by the substitution of ionic medium by a non-ionic medium. The inhibition of haemagglutination and haemolysis of rabbit red cells byCroton tiglium lectin by antilectin rabbit serum was observed. A possible mechanism of haemolysis by the lectin is discussed.     

Plant lectins specific for N-acetyl-β-D-galactosamine

N-Acetyl-D-galactosamine in β-linkage being ubiquitous in cell surface glycoproteins, their interaction with lectins specific for this sugar moiety may be a significant event in cell adhesion phenomena. This article discusses the common β-N-acetyl galactosamine-specific lectins, with particular stress on the lectin from winged beans (Psophocarpus tetragonolobus).     

“Pleiotypic Response”

A hypothesis has been developed to relate stringent control in bacteria to a set of interactions involved in the regulation of growth of transformed and untransformed mammalian cells.     

Inhibition of DNA Synthesis but not of Poly-dAT Synthesis by the Arabinose Analogue of Cytidine <Emphasis Type="Italic">in vitro</Emphasis>

Kimball and Wilson¹ reported that the arabinose analogue of cytidine (ara-C) inhibited DNA polymerase in a crude extract prepared from Ehrlich ascites cells. Furth and Cohen² observed cytosine arabinoside triphosphate (ara-CTP) inhibited DNA polymerase in extracts from either calf thymus or bovine lymphosarcoma tissue, although these investigators³ had already found no effect of ara-CTP on DNA polymerase from Escherichia coli. The inhibition in both of these cases could be substantially reversed by dCTP; but incorporation of the arabinose nucleotide (ara-CMP) into DNA could not be unequivocally demonstrated. Graham and Whitmore⁴ reported the incorporation of ara-C into DNA in vivo and the inhibition of a DNA polymerase from L cells by ara-CTP. They found that ara-CMP was initially incorporated into small DNA strands but subsequently appeared in long strands. Momparler⁵ has presented evidence that, in vitro, ara-C incorporation was limited to the 3′-hydroxyl end of DNA chains. Such incorporation might be expected to block further chain elongation but this expectation was not supported by the evidence presented by Graham and Whitmore.     

Endopeptidase Activity of Phage λ-Endolysin

JACOB and Fuerst^1,2 demonstrated the presence of a bacteriolytic enzyme (λ-endolysin) in the induced cultures of lysogenic Escherichia coli K12 (λ). The enzyme was later identified as the product of gene R; of phage λ³ which is involved in bacterial lysis at the end of a latent period. The enzyme is apt to form spheroplast-like structures in E. coli² and one would therefore expect its substrate to be murein.     

Toxigenic fungi associated with stored corn

A total of 246 fungal isolates were obtained from 25 moldy corn samples collected in central Iowa. Either water or ether extracts of all corn samples except one exhibited some degree of toxicity in mice and/or ducklings. At least one toxigenic isolate was obtained from each corn sample. Extracts of cultures of 99 of the fungal isolates, involving 13 genera, produced death in one or more of the assay animals. The majority of the toxigenic isolates belonged to the generaAspergillus andPenicillium. Three isolates ofTrichothecium roseum were highly toxic to ducklings and mice. The ducklings exhibited a flaccid paralysis shortly after receiving an oral dose of extracts of these three isolates. Death frequently occurred following a second oral dose given 24 hr later. Mice given intraperitoneal injections of extracts ofT. roseum first exhibited lethargy and intermittent tremors, then hyperemotivity, roughening of the hair coat, abdominal respirations, incoordination, dyspnea and clonic convulsions with death occurring usually within 10 to 20 min.

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Zusammenfassung Insgesamt sind 246 Pilzisolierungen von 25 verschimmelten Getreideproben, die in Zentral-Iowa gesammelt worden sind, erhalten worden. Sowohol Wasser- wie Aether-Extrakte von allen Getreideproben zeigten eine gewisse Toxizität in Mäusen als auch in Entchen außer einer einzigen Probe. Kulturextrakte von 99 der Pilzisolierungen, die 13 Gattungen umfaßten, verursachten den Tod in einem oder in mehreren Versuchstieren. Die Mehrheit der toxischen Isolierungen gehörte den GattungenAspergillus undPenicillium an. Drei Isolierungen vonTrichothecium roseum waren hoch toxisch für Entchen und Mäuse. Die Entchen zeigten eine schlaffe Paralyse kurz nachdem sie eine orale Dosis der Auszüge dieser drei Isolierungen erhalten hatten. Tod erfolgte häufig nach der zweiten oralen Dosis innerhalb 24 Stunden. Mäuse, die eine intraperitoneale Injektion der Auszüge vonT. roseum erhielten, zeigten erst eine Lethargie und einen intermittierenden Tremor, dann eine Hyperemotivität, aufgerauhte Haarbedeckung, abdominale Atmung, Inkoordination, Dyspnoe, klonische Zuckungen und Tod gewöhnlich innerhalb 10 bis 20 Minuten.