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Phage D10, a Vibrio cholerae O-1 El Tor group X phage, is one of the five newly isolated phages used in the phage typing scheme developed for V. cholerae O-1 biotype El Tor and belongs to the Myoviridae family. From electron microscopic studies it is shown that phage D10 has a DNA genome of 32 +/- 0.2 kb. This is the first report where it has been shown by the construction of a partial denaturation map that this vibriophage genome is nonpermuted and has cohesive ends. The location of the ends of the DNA in the phage head has also been inferred.

The conventional phage typing scheme proposed by S. Basu and S. Mukerjee (Experientia 24:299-300, 1968) has been used routinely for identification of the strains at the Vibrio Phage Reference Laboratory since 1968. However, because of limitations of this scheme, a new phage typing scheme using five newly isolated phages was incorporated into the conventional scheme. A different definition of routine test dilution (almost confluent lysis) was found to be more useful than the one previously used (confluent lysis). The 1,000 strains tested could be clustered into 27 types with the five new phages. With the new scheme of 10 phages (5 new phages and 5 phages of Basu and Mukerjee), the 1,000 strains could be grouped into 146 types. The new phages were different from each other and also from those of Basu and Mukerjee, as revealed by lytic pattern, electron microscopy, restriction endonuclease digestion, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and antiphage antiserum studies. With the new typing scheme, 99.6% of the strains were typeable. Phage type 115 was the most common and includes 119 (11.9%) of the 1,000 strains tested. Next most common were phage types 142 (9.4%), 143 (7.0%), 104 and 116 (both 5.4%), 3 (5.3%), 5 (4.1%), 4 (3.9%), 24 (2.1%), and 100 (1.7%). The larger number of types would be useful for further classification of the strains for epidemiological purposes. This newly developed scheme is highly applicable to, and could be widely adopted for, phage typing of Vibrio cholerae O1 biotype El Tor strains.

Addition of silver greatly accelerated the rate and extent of copper dissolution from chalcopyrite ores in the process of leaching with acidic ferric sulfate solution. The solubility of copper depended on silver- and ferric ion concentrations, pulp density, pH and temperature. The mineralogy of ores was probably the most important factor since the extent of copper extraction in the presence of Ag + from different samples varied under identical conditions. It was thought that the presence of other metal ions in the ores might have influenced extraction rates catalysed by silver. This was confirmed by pretreatment of ore particles with other metal ions, which exhibited either a positive or no effect on subsequent leaching of copper with solutions containing Ag + .

Prolonged exposure to carbon monoxide accelerates the development of atheroma in rabbits owing to intimal accretion of platelets and fibrin and intramural lipid accumulation (Wanstrup, Kjeldsen, and Astrup, 1967; Birnstingl, Hawkins, and McEwen, 1970). A group of 7 rabbits was exposed in a closed chamber to an atmosphere containing 400 p.p.m. CO for 6-14 hours on several occasions. Platelet stickiness was estimated by a modified Hellem's glass-bead method immediately after exposure and on the following day, for comparison with values in the resting period prior to exposure. There was a highly significant increase in platelet stickiness immediately after exposure to CO, followed the next day by a significant fall below the pre-exposure value. The increase in platelet stickiness after CO exposure may provide a link between tobacco smoking and peripheral vascular disease.