The chromosomes of metaphase II oocytes of the Chinese hamster were investigated at different intervals following 200R X-irradiation. The frequency of chromosome aberrations in the group exposed immediately before metaphase I was remarkably high. A significant increase of numerical aberrations also occurred in this group.
Karyotype analysis was made in a tumor (fibrosarcoma) developed in an Oceanian type black rat. The tumor was characterized by a hypo-pentaploid stemline. The chromosome constitution consists of varying elements such as pentasomic, tetrasomic, hexasomic, trisomic and disomic. Centromeric fission was especially noted in the large metacentric M2, playing an important role in the chromosome alteration.
Effect of aldosterone on T3-binding to the nuclear fraction of the tail of toad tadpoles was investigated in vitro. T3-binding was increased by adding aldosterone to the incubation medium. Scatchard analysis revealed that aldosterone (3.4×10-6M) increased the maximum binding capacity by 40% and that the steroid scarcely affected the value of dissociation constant. Elevation of thyroid hormone sensitivity in the presence of corticoids seems to be closely related to the corticoid-induced increase in nuclear binding capacity for thyroid hormones.
Triton WR-1339 was intraperitoneally injected into rats and its accumulation in hepatic lobule cells was observed under an electron microscope. In the lipid granules of fat-storing cells, much Triton accumulated during the first 30min to 3hr post-injection. Kupffer cells scarcely, and endothelial cells slightly, ingested Triton.