Biological effects of D2O administration to Coturnix japonica

Levels of 7.8, 18.5 and 26 mole % deuterium oxide were administered sequentially to $\text{Coturnix japonica}$ (Japanese quail) via the drinking water. The primary effect observed was on egg frequency, which decreased from a normal level of 0.89 for 7.8 mole % D₂O to a low of 0.38 during the administration of 26 mole % D₂O. Adverse symptoms, such as hyperexcitability, convulsions, skin ulcerations, comatosity, weight loss, or death, which have been associated with deuterium toxicity in other animals, were not observed in these experiments. The amount of deuterium deposited in the water of the egg was 6.9, 13.98, and 19.83 mole % when 7.8, 18.5 and 26 mole % deuterium respectively was administered. For each period, the deuterium content of egg water rapidly reached a maximum concentration after which the concentration decreased slightly. This dilution effect has not been noted previously in body fluids from other animals.     

Mitochondrial DNA in Xenopus laevis oocytes. I. Displacement loop occurrence

Displacement loops are found in mitochondrial DNA isolated from the ovaries of mature female Xenopus laevis. These displacement loops subtend some 7% of the contour length of a mitochondrial circular DNA. When mature oocytes are shed as unfertilized eggs at least 76% of the mitochondrial DNA in these eggs contains displacement loops. The implications of these findings are discussed with respect to displacement loop occurrence in other mitochondrial DNAs and especially with respect to mitochondrial DNA replication.