Isolation, structural studies and chemical synthesis of a 'palmitone lipid' from Corynebacterium diphtheriae.

The isolation of a 'palmitone lipid' from Corynebacterium diphtheriae is described. The use of a temporary hydrophobic protecting group allows the obtaining of the lipid in free and pure form. Structural studies by chemical degradation and mass spectrometry allow one to propose structure Ic for this compound, namely 6-(2-tetradecyl 3-keto octadecanoyl)-alpha-D-trehalose. This structure was confirmed by chemical synthesis.     

Metabolic cost of changes in diet and neutralization of allelochemics

Larvae ofPieris brassicae andMamestra brassicae use food on which they have been grown more efficiently than a novel food. This physiological adaptation to a certain food may be regarded as a functional reason underlying changes in food selection behaviour due to previous experiences (“preference induction”). Larvae ofManduca sexta show a reduced efficiency of digestion when the diet contains nicotine or atropine, alkaloids occurring in acceptable food plants. It is concluded that insects may spend a considerable amount of energy detoxifying host-plant specific allelochemics.

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Le Prix Métabolique du Changement de Diète et de la Neutralisaton de Produits Allélochimiques

Résumé Les chenilles dePieris brassicae et deMamestra brassicae digèrent la nourriture où elles ont poussé d'une manière plus efficace qu'un nouveau genre de nourriture. Cette adaption physiologique à la nourriture est probablement la raison fontionnelle qui est à la base de changements dans le comportement du choix alimentaire qui sont en rapport avec des expériences antérieures (“induction d'une préférence”). L'efficacité de la digestion dans les chenilles deManduca sexta subit une diminution, quand on ajoute à leur aliment artificiel de la nicotine ou de l'atropine, des alcalo?des qu'on trouve dans des plantes nutritives acceptables. Voilà pourquoi nous en venons à la conclusion que les insectes consacrent parfois une quantité considérable d'énergie à la détoxication de matières allélochimiques qui se trouvent dans leur plante-h?te.

     

Quantity of compentent cells in a population of Escherichia coli treated with Ca2+ cations]

An attempt was made to estimate the number of Escherichia coli K-12 cells rendered permeable to antibiotics under Ca2+ treatment. The effect of cold factor and Ca2+ alone as well as the cell age on the induction of permeability and the energy dependence of the latter were also investigated. About 70-75% and more exponentially growing cells as a result of Ca2+ treatment became sensitive to actinomycin, rubomycin and olivomycin. This number was somewhat lower (40-50%) in sationary phase culture. A fraction (20-30%) of stationary phase cells appeared to be sensitive to antibiotics even without Ca2+ pretreatment. Preincubation of the cells in cold in the absence of Ca2+ cations did not induce the cell permeability. The transport of antibiotics inside the cell was not prevented by an uncoupler of oxidative phosphorylation --carbonylcyanid-m-chlorophenylhydrazone (CCCP). It is suggested that the cells which are rendered permeable to tested antibiotics represent the "compentent" cells capable to uptake molecules of exogenous DNA as well.     

Light and electron microscopic histochemistry of the monoamines in the human foetal sympathetic ganglion in culture

Synopsis Sympathetic ganglia of 13 to 19-week-old human foetuses were cultured in small pieces with and without nerve growth factor for up to 5 weeksin vitro. The cultures were studied using phase-contrast, fluorescence and electron microscopy. Monoamines were demonstrated with the formaldehyde-induced fluorescence method, with and without pretreatment of the cultures with catecholamines or monoamine oxidase inhibitor.In the long-term cultures, primitive sympathetic cells, sympathicoblasts of types I and II, and young sympathetic neurons showed a fine structure identical to that described earlierin vivo. There were virtually no satellite or Schwann cells in the cultures. The neurons showed a considerable capacity to grow new nerve fibres in culture, even without nerve growth factor. Nerve terminals with accumulations of other nervous structures. Large granular vesicles were regularly found in the sympathicoblasts after glutaraldehyde-osmium tetroxide fixation. After permanganate fixation, dense-cored vesicles typical of adrenergic neurons were not seen, either in the perikarya, or in the processes, although it was possible to demonstrate specific fluorescence. No small intensely fluorescent (SIF) cells were observed.Variable formaldehyde-induced fluorescence was observed in the nerve cell perikarya and nerve fibres. The intensity of the fluorescence increased after treatment of the cultures with monoamine oxidase inhibitor and after incubation with catecholamines.     

Preparation and application of Nalpha-B1,Nepsilon-B29-bis (ter.-butyloxycarbonyl)insulin

Two methods are described for the preparation of NalphaB1,Nepsilon29-Boc2-insulin from Nalpha A1-trifluoroacetyl-insulin and Nalpha A1-citraconyl-insulin in 80 - 90% and 65% yields, respectively. Removal of the Boc protections afforded the fully active insulin. Application of this derivative was demonstrated by the preparations of des-GlyA1-insulin and [A1-guanidinoacetyl]insulin. The former compount exhibited 2% activity in the in vitro free fat cell assay and the latter 88 +/- 5% while NalphaB1-NepsilonB29-Boc2-insulin showed 45 +/- 3% activity only.     

Adenine nucleotides in cholinergic transmission: presynaptic aspects.

1. Isolated nerve terminals (T-sacs and synaptosomes) prepared from the purely cholinergic Torpedo electric organ have been studied for their ability to incorporate and metabolise [2-3H] adenosine and to degrade 5'-AMP to adenosine. 2. A temperature-dependent, saturable uptake system for adenosine was found with kinetic properties similar to nucleoside transport systems in other cells. The uptake system in Torpedo nerve terminals was inhibited by 2'-deoxyadenosine, a known inhibitor of adenosine transport. 3. Intraterminal adenosine is rapidly metabolised to a number of products including AMP, ADP and ATP. 4. Isolated nerve terminals contain considerable 5'-nucleotidase activity, most of which resides on the outer face of the external membrane. The Km of the enzyme is congruent to 5 micron and it is inhibited by a phosphonate analogue of ADP, alpha-beta-methylene-ADP. It is suggested that this 5'-nucleotidase plays an important role in the production of adenosine from a nucleotide pool in the synaptic cleft.