Comparison of white pock (h) mutants of monkeypox virus with parental monkeypox and with variola-like viruses isolated from animals

Monkeypox mutants arising spontaneously or after serial, high multiplicity passage were characterized phenotypically and by restriction endonuclease mapping. Some resemble "whitepox" and variola viruses in several of the markers tested but all are distinguishable phenotypically from these. None resembles "whitepox" viruses in genome structure although near-terminal deletions or symmetrical, terminal rearrangements, relative to parental monkeypox, occurred. "Whitepox" viruses isolated from animals closely resemble variola in both phenotype and genome structure.     

Shigella flexneri induces apoptosis in infected macrophages.

The Gram-negative bacterial pathogen Shigella flexneri causes dysentery by invading the human colonic mucosa. Bacteria are phagocytosed by enterocytes, escape from the phagosome into the cytoplasm and spread to adjacent cells. After crossing the epithelium, Shigella reaches the lamina propria of intestinal villi, the first line of defence. This tissue is densely populated with phagocytes that are killed in great numbers, resulting in abscesses. The genes required for cell invasion and macrophage killing are located on a 220-kilobase plasmid. We report here on the mechanism of cytotoxicity used by S. flexneri to kill macrophages. Each of four different strains was tested for its capacity to induce cell death. An invasive strain induced programmed cell death (apoptosis), whereas its non-invasive, plasmidcured isogenic strain was not toxic; neither was a mutant in ipa B (ref. 10) (invasion protein antigen), a gene necessary for entry. A non-invasive strain expressing the haemolysin operon of Escherichia coli induced accidental cell death (necrosis), demonstrating that other bacterial cytotoxic mechanisms do not lead to apoptosis. This is the first evidence that an invasive bacterial pathogen can induce suicide in its host cells.     

Einfluss von elektrischer Stimulation auf Phosphorylase-Aktivität und cAMP-Gehalt in Insektenflugmuskeln vonLocusta migratoria

Summary In half-thorax ofLocusta migratoria, the activity of phosphorylases and the level of cAMP was studied during electrical stimulation of flight muscles. Both phosphorylase activity and cAMP level increased during phasic and tetanic contractions but no exact correlation could be found.

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Der benutzte Szintillationszähler wurde aus Mitteln des Landesamtes für Forschung, Düsseldorf angeschafft.     

The chick ovomucoid gene contains at least six intervening sequences.

A 15-kilobase pair EcoRI chick DNA fragment, containing both the termination codon UGA and the 5'-portion of the structural ovomucoid gene, has been cloned in lambda phage Charon 4A by in vitro packaging. Restriction mapping and electron microscopic analyses of this cloned DNA have revealed that the structural ovomucoid gene sequences are separated by at least six intervening sequences.