Hemoglobin Yoshizuka (G10(108)beta asparagine--aspartic acid): a new variant with a reduced oxygen affinity from a Japanese family

During the course of a survey, a new hemoglobin, designated hemoglobin Yoshizuka, has been encountered in a Japanese family. Clinically, mild anemia was noted in five of six heterozygous individuals but no other significant abnormalities were found. Hemoglobin Yoshizuka is characterized by the substitution of aspartic acid for asparagine at the tenth residue of the G helix in the beta-chain. Reduced oxygen affinity with almost normal heme-heme interaction was found to be a property of this abnormal hemoglobin. The asparagine residue G10(108)beta lies in the internal cavity of the tetrameric molecule and its main chain carbonyl is thought to be hydrogen bonded to histidine G10(103)alpha at the region of contact between alpha- and beta-chains. It would appear likely that the introduction of a carboxyl group into the central cavity might result in interactions between the polar groups and the substituted side chain, disrupting the system of hydrogen bonds which contribute to the stability of the contacts between unlike subunits.

Addition of carbethoxynitrene to trans- and cis-propenylbenzene and the ring-opening of the resulting aziridines

Carbethoxynitrene (1) generated thermally from ethyl azidoformate adds stereospecifically to trans- and cis-propenylbenzene. Ring-opening of the aziridines thus produced, proceeds with inversion at the phenyl-substituted carbon in dry acetic acid, while the reaction in aqueous acetic acid occurs with no stereospecificity.

Quantitative analysis of cell proliferation and differentiation in the cortex of the postnatal mouse cerebellum

The generation cycle of germinative cells (external matrix cells) in the external granular layer of the cerebellar cortex of the 10-to 11-day-old mouse was studied by radioautography following repeated injections of H(3)-thymidine. The generation time is 19 hr, presynthetic time 8.5 hr, DNA-synthetic time 8 hr, postsynthetic time 2 hr, and mitotic time 0.5 hr. These proliferating cells occupy the outer half of the external granular layer and make up the external matrix layer. Neuroblasts are differentiated from the external matrix cell, migrate out from the layer and accumulate in the inner half of the external granular layer to form the external mantle layer. The transit time of the neuroblasts in the external mantle layer is 28 hr. Thereafter, they migrate farther into the molecular layer and the internal granular layer. By means of long-term cumulative labeling, the rate of daily production of neuroblasts from the external matrix cell is studied in quantitative terms. It becomes clear that the entire population of the inner granule neurons arises postnatally in the external granular layer between 1 and 18 days of age and that 95% of them is produced between postnatal days 4 and 15. Finally, the fate of the cells in the external granular layer at its terminal stage was studied by marking the cells with H(3)-thymidine during 15-16 days of life and following their subsequent migration and developmental changes up to 21 days of life. Comparison of radioautographs taken before and after the migration disclosed that the external matrix cells give rise to a small number of neuroglia cells. This finding revealed their multipotential nature.