Spermatocytes of the crane-fly, Nephrotoma suturalis, were attached to electron microscope grids and then sheared by applying centrifugal force. Transmission electron microscopy of exposed regions of the cell cortex revealed networks containing arrays of filamentous structures. Networks were present in sheared spermatocytes at all stages of meiosis. The networks of dividing spermatocytes (meta-...

Chromosome fragmentation is a hallmark of apoptosis, conserved in diverse organisms. In mammals, caspases activate apoptotic chromosome fragmentation by cleaving and inactivating an apoptotic nuclease inhibitor. We report that inactivation of the Caenorhabditis elegans dcr-1 gene, which encodes the Dicer ribonuclease important for processing of small RNAs, compromises apoptosis and blocks apopt...

Mercuric ions, as well as organomercuric ions and cadmium ions, can inhibit deoxyribonucleic acid-mediated transformation in Bacillus subtilis 168 without decreasing the viability of the total population. Differences in the inhibition of transformation by mercuric ions are identifiable on a temporal and concentration dependence basis. Sensitivity to low concentrations (9.2 x 10(-8) M) appears e...

Streitfeld, Murray M. (University of Miami, Coral Gables, Fla.), Edward M. Hoffmann, and Herbert M. Janklow. Evaluation of extracellular deoxyribonuclease activity in Pseudomonas. J. Bacteriol. 84:77-80. 1962.-Of 23 strains of P. aeruginosa isolated from pathological processes, 22 strains, representative of at least nine different somatic antigen types, were found to elaborate extracellular deo...

A Swedish bovine and a Dutch human phage set for coagulase-negative staphylococci were used to phage type coagulase-negative staphylococci isolated from bovine milk from Minnesota dairy herds. A comparison was also made of the deoxyribonuclease activity of coagulase-negative staphylococci isolated from bovine milk in Sweden and Minnesota. Of 133 Minnesota isolates, only one could be typed with ...

Mouse mammary tumor virus (MTV) was isolated from the milk of RIII mice by density-gradient centrifugation in Ficoll. The homogeneity of the preparation was demonstrated in electron micrographs. The nucleic acid was extracted with phenol in the presence of Pronase. Its viral origin was attested by failure of ribo-nuclease and deoxyribonuclease treatment of the virus preparation to destroy the f...

A deoxyribonuclease distinct from the previously isolated asparagus ribosome-inactivating proteins, possessing a molecular weight of 30 kDa and requiring a pH of 7.5 for optimum hydrolytic activity toward herring sperm DNA, was isolated from Asparagus officinalis seeds. The isolation procedure involved extraction with saline, (NH(4))(2)SO(4) precipitation, ion-exchange chromatography on DEAE-ce...