Immunohistochemical localization of lactoperoxidase in bovine tissues

Distribution of lactoperoxidase in bovine tissues was investigated by using fluorescent antibody techniques, and immunochemical properties of the enzyme were also examined. As a result of immunodiffusion, two antigenic components were found, but no cross-reactivity between lactoperoxidase and hemoproteins such as catalase, cytochrome c, hemoglobin or ferritin was observed. Lactoperoxidase was found mainly in the cytoplasm of alveolar cells of the mammary gland; in those acinar cells, which were morphologically identical to serous cells, of the sublingual gland; in acinar cells of the lacrimal gland; and also in some peripheral leukocytes and in a small number of splenic cells in the red pulp. Lactoperoxidase in the alveolar and ductal spaces and in some of the ductal epithelia of those glands was observed after ethanol or acidified ethanol fixation but not after formalin fixation. It has been demonstrated by both the present and previous work (Morikawa and Harada (1969)) that lactoperoxidase and liver-catalase were distinguishable in bovine tissues when fluorescent antibody techniques were utilized.

Lingual lipase and its role in the digestion of dietary lipid

The serous glands of rat tongue were found to contain a potent lipolytic enzyme which hydrolyzed triglyceride to mostly diglyceride and free fatty acids (FFA) at pH 4.5-5.4. Homogenates of lingual serous glands from adult rats hydrolyzed 40-70 mmol of triglyceride/g per h. The soft palate, anterior oral pharyngeal wall, and lateral oral pharyngeal glands also contained the activity, but at a much lower level. The lipolytic activity was also found in saliva collected through an esophageal cannula and in stomach contents of rats fed a fat-rich meal. The stomach contained very little activity, however, when saliva was excluded. Lipolytic activity was not found in the stomach wall or in the parotid, submandibular, and sublingual glands. The findings suggest that the lingual serous glands secrete a lipase which catalyzes in the stomach the conversion of triglyceride to partial glycerides and FFA. It is proposed that this reaction is the first step in the digestion of dietary lipid.

The effect of changes in the respiratory metabolism upon genome activity. A correlation between induced gene activity and an increase in activity of a respiratory enzyme

The in vitro regression of experimentally induced chromosome puffs was investigated in explanted salivary gland chromosomes of Drosophila hydei. It was observed that the regression of the puffs 2-32A, 2-36A, 2-48C, and 4-81B is accelerated if substrates for the respiratory metabolism are supplied to the cells. A similar effect can be produced by addition of KCN or oligomycin to medium in which intact salivary glands are incubated. The acceleration of puff regression by these substances occurs not only if the puff-inducing stimulus is removed but as well under conditions in which the stimulus is maintained. Regression of the puffs 2-32A, 2-36A, and 4-81B is inhibited if cycloheximide is present in the incubation medium. Chloramphenicol has no effect on puff regression. Measurements on nicotinamide adenine dinucleotide-dehydrogenase activity in homogenates of salivary glands revealed an increase in enzyme activity of 41 %. Maximum increase is attained at 30 min after the induced puffs have reached their maximum size. The increase in enzyme activity does not occur if the glands are kept in a medium containing either actinomycin D or cycloheximide. Chloramphenicol does not inhibit the increase in enzyme activity. The possible relationship between puff activity and its control as a result of changes in the respiratory metabolism is discussed.