Recherches sur l'utilisation deVagoiavirus melolonthae pour la lutte microbiologique contre les vers blancs

Résumé Les résultats des infections au laboratoire des larves deM. melolontha par le virus de la ≪sphéro?dose≫ ont fait l'objet d'essais sur le terrain dans la Sarthe. Cette expérimentation, en parcelles, préliminaire à des applications à une échelle plus agricole, a mis en évidence la possibilité d'implantation de la maladie dans un sol non contaminé naturellement et le développement de cell-ci avec le temps. D'après cet exemple les possibilités d'emploi de ce type de virus en lutte microbiologique contre les insectes sont discutées.

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Summary The results of laboratory infections ofMelolontha melolontha larvae by the virus of ≪sphero?dosis≫ have been tested in the field in Sarthe. These plot experiments were made preliminary to applications on a larger agricultural scale, and have shown the possibility to implant the disease in a naturally non-infected soil, and the further development of this disease. By this example, the possibilities to use this type of virus in microbial control against insects are discussed.

     

Concentration and Purification of Herpesviruses (Simplex, Cytomegalo, and EB) in a Zonal Ultracentrifuge

By using the BXIV zonal ultracentrifuge rotor, it was possible to efficiently concentrate and partially purify members of the herpesvirus group by pelleting the virus onto a double sucrose cushion.     

Effect of Endotoxin on Serum Zinc Concentrations in the Rat

Serum zinc concentrations decreased significantly in a dose-dependent response after endotoxin administration in the rat. The reproducibility and sensitivity of the biological response offer a potential bioassay of endotoxin.     

Identification of the Mima-Herellea Group of Organisms and Selected Members of the Genus Neisseria

To determine a rapid and reliable protocol for the differentiation of Mima polymorpha, M. polymorpha var. oxidans, Herellea, Bacterium antitratum, Neisseria gonorrheae, and other related members of the genus Neisseria, reference cultures were examined on a variety of microbiological media. The media were selected because of the typical morphological and biochemical characteristics exhibited by the test organisms and were those media which would be readily available in a microbiology facility. After compiling data obtained from 21,714 observations, an inclusive protocol is presented which has proven to be quite adequate for the identification of these particular gram-negative bacteria.     

Rapid Fluorescent-Antibody Staining Technique

The rapid fluorescent-antibody staining technique described by Kellogg and Deacon for staining Neisseria gonorrhoeae and Treponema pallidum was applied to fluorescent-antibody tests for group A streptococci and enteropathogenic Escherichia coli. Results obtained with this staining technique were compared with results using the conventional staining procedure; excellent correlation was obtained. Considerable time and materials were saved by using the rapid method; it was also found completely satisfactory.     

Enteric Pathogens in Monkeys

From 1964 to 1967, 6,646 monkeys, representing 10 primate species, were examined for Shigella and Salmonella infections upon arrival at the National Center for Primate Biology. Of these animals, 12% were infected with Shigella, and 75% of the Shigella isolates were S. flexneri 4. The incidence of Salmonella infections decreased from 12 to 3% during the period of study. Epidemiological studies of animals in the colony for 90 days or more indicated no seasonal variation in the occurrence of Shigella and Salmonella. Many of the isolates from incoming monkeys as well as from laboratory-conditioned animals were resistant to chloramphenicol, dihydrostreptomycin, and tetracycline. The possible operation of drug-resistance factors in these infections is discussed.     

Kinetics of Induction of the Lactose Operon on an Episome in Salmonella typhimurium

A kinetic study of induction of the enzymes of the lactose operon was carried out under conditions known to affect the kinetics of derepression of the enzymes of the histidine operon. The results show that the lactose system is similar to the histidine system in its responsiveness to conditions thought to affect the formylating capacity of the cell. This was demonstrated in the following ways: (i) trimethoprim, which is known to reduce the formylating capacity of the cell, gives rise to a relatively long interval between the times of induction of beta-galactosidase and transacetylase; (ii) under conditions in which the histidine operon is derepressed, chloramphenicol causes a prolongation of the interval between the times of induction of the two enzymes, and this prolongation is reversed by adenine, methionine, and serine, compounds known to enrich the one-carbon pool of the cell; and (iii) 4-amino-5-imidazolcarboxamide ribonucleoside, a compound which may act as a drain for formyl groups, reverses the effect of the latter compounds. The finding that the interval between the times of induction of the two enzymes is shortened under conditions expected to maintain a relatively high intracellular fo rmylating capacity suggests that under certain conditions translation of the polycistronic messenger ribonucleic acid of the lactose operon may be initiated at more than one site or may proceed more rapidly from the operator end.