Transduction of Pseudomonas aeruginosa streptomycin resistance by a generalized transducing phage, F116, was shown to occur during a 10-day incubation in a flow-through environmental test chamber suspended in a freshwater reservoir. Mean F116 transduction frequencies ranged from 1.4 x 10-5 to 8.3 x 10-2 transductants per recipient during the in situ incubation. These transduction frequencies were comparable to transduction frequencies determined in preliminary laboratory transduction experiments. The results demonstrate the potential for naturally occurring transduction in aquatic environments and concurrent environmental and ecological ramifications.

a hog-growing facility. Can. J. Anim. Sci. 7I: 2'71-2'77.In order to assess the effects of ventilation rate, temperature, relative humidity and source of air on bioaerosol levels and dust with particle size < l0 pm, a total of 120 pigs housed in 12 pens in two separate rooms were used. Pigs averaged 30 kg initially and the trials were discontinued when2O% of the pigs were marketed. A six-stage Andersen sampler and a light scattering particle counter were used to determine bioaerosols and respirable dust (0.1-10 pm), respectively. Total bioaerosols were assessed using Trypticase Soy Agar. Potato Dex-

The chemotherapeutic agent cis-platinum(II)diamminedichloride (cis-PDD) has been shown to be mutagenic, teratogenic, and carcinogenic. We determined the cytogenetic effects of cis-PDD on human and rabbit lymphocytes in vitro and on rabbit marrow cells, lymph node cells, and lymphocytes in vivo. Lymphocyte cultures from two humans and one rabbit were treated in vitro with cis-PDD. For in vivo studies, five New Zealand white rabbits were given iv injections of cis-PDD. Posttreatment blood samples were withdrawn for analysis and rabbits were sacrificed at either 6 or 24 hr for cytogenetic analysis of marrow and node cells. Sister chromatid exchange (SCE) analysis of human and rabbit metaphases from lymphocytes treated in vitro showed that rabbit lymphocytes are more sensitive to SCE induction by cis-PDD. Significant increases in SCE were observed in lymphocyte cultures obtained as early as 1 hr post treatment from injected rabbits. Analysis of node, marrow, and lymphocyte metaphases from injected rabbits showed a high number of chromosome aberrations in these cells with bone marrow showing a delayed response to treatment. These results indicate that cis-PDD is clastogenic in hematopoietic tissues in vivo and that SCE methodology may be useful in monitoring patients receiving cis-PDD therapy.

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