Intermolecular histone H4 interactions in core nucleosomes

Chicken histone H4, labeled at methionine-84 with 1-N-pyrenyliodoacetamide, has been incorporated into a nucleosome-like particle with core length DNA and unmodified histones H2A, H2B, and H3. These synthetic nucleosomes exhibit properties very similar to those displayed by native particles and those labeled with other fluors. The emission spectrum of the pyrene-labeled nucleosome was characteristic of excited dimer (excimer) fluorescence, indicating that the single pyrene groups on the two H4 molecules are in close proximity in the reconstituted particle. Histone H4 was also labeled randomly at lysines with a group that contains two pyrene moieties separated by 12 A at most. Incorporation of this histone into nucleosome-like particles provides an excimer standard which does not depend on intermolecular interactions. The properties of the pyrene-containing nucleosome were examined as a function of ionic strength. It was found that the H4-H4 pyrene excimer fluorescence exhibited a cooperative disruption centered at 0.1 M NaCl which preceded increases in accessibility and environment polarity revealed by other fluors attached at the same site.     

Effect of platelet-activating factor on airway vascular permeability: possible mechanisms

We studied the effects of the potent inflammatory mediator, platelet-activating factor (PAF), on vascular permeability in airways (and other tissues) of guinea pigs by measuring extravasation of circulating Evans blue dye. PAF caused a dose-dependent increase in vascular permeability. At 1 ng/kg iv, PAF caused an increase in Evans blue extravasation of 220% (P less than 0.05) in the trachea, with the greatest effect at a dose of 100 ng/kg (858%; P less than 0.01). Histamine (150 micrograms/kg iv) caused a 320% increase over base line in the trachea and 200% in main bronchi; this effect was equivalent to that induced by 10 ng/kg PAF in the trachea and 1 ng/kg in main bronchi. The duration of effect of PAF was greatest in main bronchi (less than 10 min). Platelet depletion with a cytotoxic antibody, or the cyclooxygenase inhibitor, indomethacin, or the cyclooxygenase-lipoxygenase inhibitor, BW 7556, did not affect the vascular permeability response to PAF. The PAF-receptor antagonist, BN 52063, inhibited Evans blue extravasation in the airways in a dose-dependent manner, with complete inhibition at 5 mg/kg. Thus PAF-induced airway vascular leakage is mediated by specific receptors but not by products of arachidonic acid metabolism or by platelets. Increased airway microvascular leakage induced by PAF may lead to plasma extravasation and airway edema, factors that may contribute to the airway narrowing and hyperresponsiveness induced by PAF.     

Nitrospira marina gen. nov. sp. nov.: a chemolithotrophic nitrite-oxidizing bacterium

A new chemolithotrophic nitrite-oxidizing bacterium, for which the name Nitrospira marina is proposed, was isolated from the Gulf of Maine. N. marina is a Gramnegative curved rod which may form spirals with 1 to 12 turns. Cells have a unique periplasmic space and lack intracytoplasmic membranes and carboxysomes. N. marina is an obligate chemolithotroph, but best growth is obtained in a mixotrophic medium. N. marina may be one of the most prevalent nitrite-oxidizing bacteria in some oceanic environments. Type strain is field with American Type Culture Collection (ATCC 43039).     

The conformational analysis of oligosaccharides by H-NMR and HSEA calculation

The application of 1H-nuclear Overhauser enhancement, 1H-spin-lattice-relaxation-time and 1H-chemical shift measurements for the assessment of the conformational preferences of oligosaccharides are briefly reviewed. It is demonstrated that additivity rules, for the correlation of the chemical shifts of similar hydrogen atoms in different oligosaccharides, can be useful in the conformational analysis of oligosaccharides when the differential chemical shifts are greater than 0.1 ppm. These often can be attributed to specific interunit deshielding of a hydrogen atom by an oxygen atom with which it is in strong nonbonded interaction. HSEA calculations are used to demonstrate that differential chemical shifts of less than 0.1 ppm can have origins that are not significant to the overall conformational preferences of the oligosaccharides which are being compared. Both shielding and deshielding effects can arise from a change in the orientation of a substituent group as the result of the introduction of a sugar on a neighboring unit. It is demonstrated that substituent groups, such as hydroxymethyl and acetamido groups, on occasions, should be treated in HSEA calculations as freely rotating about their linkage to a pyranose ring.     

Beiträge zur funktionellen Morphologie der Neurohypophyse

Zusammenfassung Beidseitige Adrenalektomie und Hypophysektomie führen bei der Ratte zu gleichartigen histologischen Veränderungen in der Zona externa infundibuli. In beiden Fällen treten in der normalerweise weitgehend goniorinegativen Zona externa infundibuli große Mengen gomoripositiver Granula auf. Sie scheinen Fasern anzugehören, die senkrecht zur Längsachse des Infundibulum verlaufen.Die Befunde werden als weiterer Hinweis dafür betrachtet, daß die gomoripositiven Substanzen der Zona externa infundibuli eine Bedeutung für die Steuerung der Nebennierenrindenfunktion haben.

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Studies on the functional morphology of the neurohypophysisII. Comparison of histological changes in the median eminence of the rat after bilateral adrenalectomy and hypophysectomy

Summary Bilateral adrenalectomy and hypophysectomy in the rat produce similar histological changes in the outer layer of the median eminence. In both cases, abundant gomoripositive granules are observed in the outer layer, which normally reacts gomorinegative. The gomoripositive granules seem to belong to fibres running vertically through the infundibulum.These findings are regarded as a further indication, that the gomoripositive substances of the outer layer of the median eminence play a significant role in controlling adrenocortical function.

     

The Complex Carbohydrate Structure Database

The Complex Carbohydrate Structure Database (CCSD) and CarbBank, an IBM PC/AT (or compatible) database management system, were created to provide an information system to meet the needs of people interested in carbohydrate science. The CCSD, which presently contains more than 2000 citations, is expected to double in size in the next two years and to include, soon thereafter, all of the published structures of carbohydrates larger than disaccharides.     

Growth inhibition of selected food-borne bacteria, particularly Listeria monocytogenes, by plant extracts

C hung , K.-T., T homasson , W.R. & W u -Y uan , C.D. 1990. Growth inhibition of selected food-borne bacteria, particularly Listeria monocytogenes , by plant extracts. Journal of Applied Bacteriology 69 , 498–503.
Six extracts from Chinese medicinal plants: Tin Men Chu, Sey Lau Pai, Siu Mao Heung, Bak Tao Yung, Kam Chin Chiu and Liao Ya, were tested for their inhibitory effect on selected food-borne bacteria by the well assay technique. Among them, Tin Men Chu, Siu Mao Heung and Sey Lau Pai inhibited the growth of Staphylococcus aureus, Klebsiella pneumonia, Escherichia coli, Shigella flexneri, Streptococcus faecalis, Salmonella paratyphi, Salm. enteritidis, Enterobacter aero-genes, Pseudomonas fluorescens, Proteus vulgaris, Alcaligenes faecalis , and three strains of Listeria monocytogenes . Two of these three extracts, Tin Men Chu and Siu Mao Heung, suppressed the growth of L. monocytogenes Scott A in cabbage juice. This inhibition was prevented by the addition of protein but not sodium chloride. Plant extracts show potential to control the growth of food-borne bacteria.