Ovulation in rabbits following intravenous and intracerebral administration of copper sulphate

The present authors (1965) previously reported that the site of action of copper sulphate in the induction of ovulation might be in the vicinity of the posterior median eminence (PME) in the hypothalamus. The authors have now injected a solution of copper sulphate intravenously into adult female Japanese mongrel rabbits and also infused the solution directly into the PME of the hypothalamus. The 50% effective dose for inducing ovulation in some of the rabbits of the tested group was 0.76 μg/kg of copper sulphate in the PME infusion or 3.0 mg/kg in the intravenous injection. This means that the 50% effective dose of copper sulphate required for infusion into the PME is 1/4000 of the 50% effective dose required by intravenous injection.

Drug resistance of enteric bacteria. V. High frequency of transduction of R factors with bacteriophage epsilon

Kameda, Mitsuo (Gunma University, Maebashi, Japan), Kenji Harada, Mitsue Suzuki, and Susumu Mitsuhashi. Drug resistance of enteric bacteria. V. High frequency of transduction of R factors with bacteriophage epsilon. J. Bacteriol. 90:1174-1181. 1965.-In the transduction of R factors with phage epsilon(15), a lysate capable of transducing the markers for (TC) or (CM.SM.SA) resistance at high frequency was obtained. The transducing agent is a defective element called epsilon(15)dR(23) which lacks certain functions of phage epsilon(15). After lysogenization with normal epsilon(15) phage and ultraviolet (UV) induction, strains carrying the epsilon(15)dR(23) element produce lysates which have a high frequency of transduction (HFT) on group E(1)Salmonella. Lytic lysates prepared on phage epsilon(15) sensitive strain with the epsilon(15)dR(23) element have a low frequency of transduction (LFT). Lytic growth of phage epsilon(34) on an epsilon(15)dR(23) strain or UV induction of an epsilon(34) lysogenic strain containing epsilon(15)dR(23) results in LFT lysates on group E(2)Salmonella. On UV induction, group E(2)Salmonella (epsilon(15) lysogens) with the epsilon(15)dR(23) element give lysates which are HFT on group E(1)Salmonella but are LFT when tested on group E(2)Salmonella. In all instances, the production of drug-resistant transductants requires infection of the cell with only a single epsilon(15)dR(23) element. It appears that the resistance region of the R factor has replaced that portion of phage genome which is essential for vegetative replication and superinfection immunity. The epsilon(15)dR(23) element does not contain the genetic determinants of the R factor responsible for transmissibility, inhibition of F mating, and interference between two R factors.