Inhibition of DNA synthesis in relation to enhanced survival of UV-damaged herpes virus in monkey cells treated by a variety of 2-nitronaphthofurans

Various 2-nitronaphthofuran derivatives (related to each other by simple structural modifications) were tested for 2 different effects in CV-1 monkey kidney cell cultures: the immediate inhibition of normal DNA synthesis and the capacity of pretreated cultures (40 h of contact) to support the replication of UV-damaged Herpes simplex virus (HSV). For all compounds tested, a fair correlation was found between their efficiencies to inhibit cellular DNA synthesis and to provoke an increase in UV-HSV production (virus reactivation). Virus reactivation was due to an increase in both the number of virus-producing cells and the amount of infectious particles produced per cell. The most efficient 2-nitronaphthofurans (particularly 2-nitro-7-methoxy-naphtho[2,1-b]furan-R 7000) were at least as potent as aflatoxin B1 in inducing virus reactivation.     

A new species of land planarian preying on termites in Kenya (Platyhelminthes: Turbellaria: Tricladida: Terricola)

A new species of land planarian is described from Kenya. Microplana rermirophaga sp. nov. preys on termites by capturing them at the openings to their nest. The pharynx is unusually far forwards for a land planarian and this is probably related to the active nature of the prey. There is an anterior depression caused by the termination of parenchymal longitudinal muscle bundles which might act as a sucker. All specimens are immature which leads to some difficulty in assigning the species to a genus.     

Les supports morphologiques de l'intégration dans la colonie de Veretillum cynomorium Pall. (Cnidaria,Penntularia)

The morphological supports of integration, including the nervous system, are to be found.After a morphological observation, ecto and endoderms and their intercellular junctions are presented.The regionally different mesogleal synaptic nerve nets are surrounded by ecto and endodermal nervous structures.The presence of behavioural activity centers is also discussed.

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Liste des abréviations des figures AS autozoïde sectionné - AU autozoïde - CAL canal longitudinal - CAV cavité gastrique - CC corps compact - CGL cellule globuleuse myo-épitheliale MESlame mésentériale MF microfilament - CGR cellule granuleuse myo-épithéliale - CLC cloison commune à deux autozoïdes - CLR cloison radiale - CLT cloison transversale - CM corps myélinique - CME cellule mesenchymateuse - CNE cellule nerveuse ectodermique - CNEN cellule nerveuse endodermique - CNM cellule nerveuse mésogléenne - COL colonne - CSP cellule spumeuse - CSPH cellule sphéruleuse - CU cellule urticante - D dépot de matériel intercellulaire (zonula adhaerens) - DS desmosome septé - ECT ectoderme - EE empilement d'ergastoplasme rappelant un corps de Nissl - FF fibres fasciculées h structure - G glycogène - GA granule aréolé - IC inclusion crênelée - M mitochondrie - MB membrane basale - ME mésoglée - MES lame mésentériale - MF microfilament - MT figure interprétée on terme de microtubule - MV microvilli - N noyau - E neurite - NO nodosité - P pédoncule - PC paroi des canaux - PE perforation - R rachis - SF siphonozoïde fendu - SIPH siphonozoïde - SM sipment musculaire d'une cellule myoépithéliale - T travé ous-siphonozoïdale - TME travée mésogléenne - VC vésicule claire - VME vésicule mésenchymateuse - ZI zône intermédiaire - I synapse polarisée - 2 synapse réciproque - 3 figure ressemblant à un desmosome septé - 4 contact par apposition Cc travail correspond à la première partie d'une thèse de Doctorat d'Etat, consacrée aux «Structures et aux mécanismes de l'intégration dans la colonie de Veretillum cynomoriurra» — Il a été effectué au sein de l'Equipe de Recherche Associée au C.N.R.S., n°183 (Directeur Al. Pavans de Ceccatty) avec le concours du Laboratoire Arago à Banyuls sur Mer (France) et la collaboration technique de Madame J. Villeneuve.     

Photo-induced protein-RNA cross-linking in mammalian 60-S ribosomal subunits.

Rat liver 60-S ribosomal subunits were submitted to increasing doses of radiation (253.7 nm), at 4 degrees C and 25 degrees C, as previously reported fro 40-S subunits. The existence of protein-RNA cross-linking was demonstrated by two methods. The first consisted in the separation of protein-RNA complex; the second was indirect, and took into account alteration either in the electrophoretic mobility of cross-linked proteins or the separability of 28-S RNA in a 4 M urea/3 M LiCl buffer. The peptide synthetase activity and the sedimentation characteristics of the particles irradiated at 4 degrees C were well preserved, but at 25 degrees C the large subunits were progressively inactivated and unfolded for doses higher than 2 x 10(18) quanta. The dose-dependent variations of protein cross-linkage determined by two-dimensional gel electrophoresis allowed us to distinguish those proteins which reacted at the lowest doses with a first-order reaction from those which cross-linked to RNA after a subtle modification of the subunit structure. At 25 degrees C, all proteins became low-dose reactive. The curve obtained for 28-S RNA cross-linkage was similar to that of the total protein moiety, while those obtained fro the 5-S and 5.8-S RNA (which were parallel) suggest a lower reactivity of these RNAs. As a general rule, proteins from the large subunits were more reactive to RNA than those from the small subunits. This could indicate differences in the organisation of the two subunits.     

Application of silica aerogel encapsulated lipases in the synthesis of biodiesel by transesterification reactions

Two types of commercial lipases preparations, one from Burkholderia cepacia, the other one from Candida antartica, were encapsulated in silica aerogels reinforced with silica quartz fibre felt and dried by the CO₂ supercritical technique. These immobilized biocatalysts were applied in biodiesel synthesis by transesterification of sunflower seed oil with methyl acetate. They were found to be efficient even with mixtures of both substrates without any solvent addition. The aerogel encapsulation technique made it possible to maintain the enzymes in a dispersion state similar to the dispersion prevailing in an aqueous solution, even for further use in organic hydrophobic media. In transesterification in excess iso-octane, the two lipases encapsulated in aerogels made from 40% MTMS, were found to have activities relatively close to each other and comparable with commercial Novozyme 435. On the other in transesterification with mixture of oil and methyl acetate without any solvent, the kinetics were severely limited by substrate diffusion inside the aerogels. This was particularly true with the C. antartica, so that the corresponding aerogel encapsulated enzyme was much less active than commercial Novozyme 435, although it improved after a few tests.     

Detection of chitinase activity by 2-aminobenzoic acid labeling of chito-oligosaccharides

Chitinases are hydrolases capable of hydrolyzing the abundant natural polysaccharide chitin. Next to artificial fluorescent substrates, more physiological chito-oligomers are commonly used in chitinase assays. Analysis of chito-oligosaccharides products is generally accomplished by UV detection. However, the relatively poor sensitivity poses a serious limitation. Here we report on a novel, much more sensitive assay for the detection of chito-oligosaccharide reaction products released by chitinases, based on fluorescent detection, following chemical labeling by 2-aminobenzoic acid. Comparison with existing UV-based assays, shows that the novel assay offers the same advantages yet allows detection of chito-oligosaccharides in the low picomolar range.