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In this study, Okano-Uchida et al. describe the physiological role of ORC1 in mice by generating knock-in mice with LoxP sites flanking exons encoding the critical ATPase domain of ORC1. They show that ORC1 ablation in extraembryonic trophoblasts and hepatocytes failed to impede genome endoreduplication and organ development and function and conclude that ORC1 in mice is essential for mitotic cell divisions but dispensable for endoreduplication.

The Broward County (Fla.) Utilities Department was faced with the problem of reducing color in water from the Biscayne Aquifer and simultaneously controlling the potential for the formation of excessive trihalomethanes (THMs). The solution was to provide a short coagulation period, using ferric chloride, followed by softening to remove color plus providing a chloramine residual by adding ammonia. The improved treatment processes resulted in color control and THM levels of less than half the maximum contaminant level.

1Total diet samples collected in 1961 from 10 to 25 major cities were analyzed for radionuclides arising from nuclear debris (Sr90, Cs137, Ce144, Pu239, Zn65), for natural radioactivity (Ra226, Pb210, K40), and for the stable nuclides of Ca and K. The variability arising from collection of samples was not greater than that due to analytical procedures.2Levels of Sr90in the total diet ranged from 2 to 15 µµc/gm of Ca. Values in the West, with the exception of the Far Northwest, tended to be lower, but no marked differences were observed among other geographical regions. The Sr90/gm Ca values for adult diets, presumably because of their lower milk content, were higher than for infant and teenage diets.3The values of Sr90/ gm of Ca for the total diet were about 1.6 times those for the milk contained in the diet. It was calculated that 54% of the total Sr90intake came from dairy products, on the assumption that 75% of the Ca originated from this source.4The daily intake of Ra226was estimated to be about 2 µµc in teenage and adult diets, and about 1 µµc in infant diets.5Average daily intakes of the various radionuclides expressed in micromicrocuries, were as follows: K40, 4,000; Cs137, 50; Sr90, 10; Ce144, 4; Pb210, 4; Ra226, 2; Pu239, 0.1.