Uridylate kinase activity: effect of isoproterenol

Isoproterenol stimulates cell proliferation in mouse salivary glands. Prior to the stimulation of DNA synthesis, (3)H-uridine incorporation into RNA is decreased. This decreased incorporation results from a depression of uridylate kinase activity.

Isolation from a salivary gland of granules containing renin and kallikrein

Granules of the submaxillary gland of the white mouse contain both kallikrein and renin. The granules were separated and concentrated in sequential centrifugation procedures. They were more stable at room temperature and in hypertonic sucrose solutions than in the cold or in isotonic solution. The amylase, acid phosphatase, renin, kallikrein, and benzoyl-L-arginine ethyl ester esterase contents of the granules were determined. Kallikrein and renin showed a similar distribution pattern after fractionation. Granular renin released the equivalent of 9.6 µg angiotensin II amide/mg enzyme protein/min from swine serum angiotensinogen. Granular kallikrein liberated from human kininogen the equivalent of 8.4 µg bradykinin/mg enzyme protein/min.

Electron micrographs of the isolated granules showed various forms; some were spherical and symmetrical, and others were amorphous.

Assay systems for the study of gene function. 2 assay systems, the syntheses of RNA and protein, are described; their virtues and drawbacks are discussed

The study of genetic regulatory mechanisms operating in plants and animals is of paramount importance in contemporary biology. A precise understanding of the mechanisms that underlie normal cellular differentiation is a prerequisite for understanding neoplastic transformation and genetic disease. At present, we are not aware of a single assay system that can give answers to all questions we are already able to pose. Studies of RNA synthesis are valuable because they provide a direct measurement of transcriptional activity. But these studies remain incomplete until we succeed in unraveling the metabolic roles of the molecules whose synthesis we study. In this respect, the study of enzyme synthesis represents a better defined assay system, although the interpretation of observed fluctuations in synthetic rates is made difficult by the many steps that intervene between the genes and their finished protein products. We propose that a combination of protein biosynthetic and cytogenetic analysis is a promising assay system for further investigation.

The physiological division of labour in the salivary glands of Oncopeltus fasciatus (Dall.) (Heteroptera: Lygaeidae)

The physical and chemical characteristics of the contents of the different lobes of the salivary glands of O. fasciatu8 are compared with the characteristics of the two types of salivary secretion: namely the solid "stylet sheath" and the liquid "watery saliva". It is concluded that the anterior lobe contributes most of the sulphydryl groups that form the disulphide bonds in the sheath material, but that the lateral lobe provides most of the bulk of the sheath; that the posterior lobe contributes the digestive enzymes found in the watery saliva; that the accessory gland secretes water that can dilute the watery saliva; and that the accessory gland also provides the polyphenol oxidase that is sometimes found in the watery saliva and is always secreted along with the sheath material. Surgical isolation of the accessory gland gave no positive information on the function of the polyphenol oxidase.