MethylTrans-monocyclofarnesate from the spongeHalichondria panicea

Riassunto L'estere metilico dell'acidotrans-monociclofarnesico (5) è stato ora isolato dalla spugnaHalichondria panicea. Il suo rinvenimento nello stesso organismo, dal quale erano state isolate precedentemente le paniceine. (1–3), supporta l'ipotesi che la parte sesquiterpenoidica di quest'ultime si origini biogeneticamente da un precursore monociclofarnesilico.     

Etude de l'agrégation plaquettaire par le Thrombofax

Summary Thrombofax Ortho is a stable, reproducible, ready-to-use reagent for the evaluation of the platelet release reaction.

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Recherches effectuées avec l'appui financier du Fonds voor Wetensschappelijik Geneeskundig Onderzoek, Brussel (contrat No. 1216).     

'Z-RNA'--a left-handed RNA double helix

In contrast to double-stranded DNA, there has so far been little evidence that double-stranded RNA can undergo major conformational transitions. We have investigated the conformation in different conditions of the double-stranded RNA molecule poly(G-C).poly(G-C), by NMR, circular dichroism and absorbance spectroscopy. We report here evidence obtained by these different spectroscopic techniques that poly(G-C).poly(G-C) undergoes a transition from the A-form to a left-handed Z-form in conditions of high ionic strength and at temperatures above 35 degrees C. This conformational transition may be of relevance to the biological situations in which double-stranded RNA occurs, such as in ribosomes and in some viruses.