Molecular cloning of the human gastrin gene.

A genomic clone that contains the human gastrin gene was isolated from a human gene library. Restriction endonuclease mapping and DNA sequencing analysis revealed that this gene is about 0.7 kb long, and has an intron. The intron is located at a position that separates the coding region into the peptide region essential for biological activities of gastrin and the non-essential, N-terminal peptide region.     

Production of L-proline by Kurthia catenaforma

A number of organisms were screened for their ability to produce l-proline. Kurthia catenaforma, which we recently isolated, was selected. A serine-requiring mutant, strain 45, produced about 1.5 times the amount of this amino acid that the parent strain did. In investigations of various media, it was found that approximately 30 ml of l-proline per ml was produced in shaken culture at 30 C in a medium containing glucose, urea, corn steep liquor, casein hydrolysate, l-aspartic acid, and inorganic salts. To study the effect of l-aspartic acid on the production of l-proline, various amino or organic acids were substituted for l-aspartic acid, and the changes during fermentation were investigated. l-Aspartic acid was not replaced by the compounds tested, and this acid appeared to increase growth during the later stages of fermentation with a concurrent increase in the production of l-proline.     

CHROMOSOME PULVERIZATION IN HUMAN BINUCLEATE CELLS FOLLOWING COLCEMID TREATMENT

Under the influence of Colcemid, a substantial number of binucleate human cells from a line infected with herpes-like virus was found to possess pulverized chromosomes. Although this abnormality was also detected in untreated binucleate cells, the increase in the number of pulverized cells after the addition of Colcemid was too striking to be explained by accumulation of spontaneously occurring cells in response to the mitotic inhibition by Colcemid. Furthermore, the induction of pulverization may be dependent upon Colcemid concentration. These findings imply an involvement of Colcemid in the mechanism of pulverization induction in the system studied. When tritiated thymidine was added to the culture medium simultaneously with Colcemid, the majority of binucleate cells with an intact and a pulverized chromosome set incorporated this isotope into the pulverized set only. This obviously suggests that the nuclei in the binucleate cell are asynchronous in DNA synthesis, and that this asynchrony is intimately related to the induction of the pulverization phenomenon. It seems very probable that the late S phase in the late synthesizing nuclei represents a critical stage at which damage to the chromosomes most readily occurs.