Submandibular glands

High amounts of somatostatin are found in the CNS, the peripheral nervous system, the gut and the endocrine pancreas whereas the kidneys, adrenals, thyroid, submandibular glands, prostate and placenta produce rather low amounts. In particular, the hypothalamus, all limbic structures, the deeper layers of the cerebral cortex, the striatum, the periaqueductal central grey and all levels of the major sensoty pathway are brain areas that are especially rich in somatostatin. Eighty percent of the somatostatin immunoreactivity in the hypothalamus is found in cells of the anterior periventricular nucleus (Fig. 1, [1]). The gut 5 cells of the mucosa and neurons, which are intrinsic to the submucous and... 

Thavathiru E., Jana N. and De P.K. (1999). Abundant secretory lipocalins displaying male and lactation-specific expression in adult hamster submandibular gland cDNA cloning and sex hormone-regulated repression. Eur J Biochem 266, 467-476. 

FIGURE 3.3 Glands in salamanders, [a) Genial glands on the side of the head of Notophthalmus viridescens (6) diffuse submandibular glands of Taricha torosa ... 

Neu7Ae5Gc in sialic acid mixtures from bovine, submandibular glands, based on analysis by g.l.c.-m.s.82... 

There is some evidence for the occurrence of a glycolyl group at 0-4 of Neu5Ac in serum and submandibular-gland glycoproteins from the horse, based on biosynthetic studies with radioactive precursors,33 and chemical and t.l.c. analysis of the sialic acid ester groups.74... 

Histochemical demonstration of most of the O-acetylated sialic acids is possible because substituents on the side chain of Neu hinder periodate oxidation of this part of the molecule to an extent dependent on the number and position of the O-acetyl groups already mentioned. Correspondingly, removal of these ester groups by alkaline treatment (0.5% KOH in 70% ethanol91) may increase the staining reaction of a sialic acid. For example, the presence of O-acylated sialic acids has been demonstrated in colonic, epithelial mucin of man and various mammals (summarized in Ref. 91), in healthy and diseased, human small-intestine,188-190 in bovine submandibular gland,182 in mouse and rat erythrocyte-membranes,191 and in human lymphocytes.192... 

The group of 7- and 8-mono-O-acetylated, 7,9- or 8,9-di-O-acetylated, and 7,8,9-tri-O-acetylated sialic acids (the existence of which in bovine, submandibular glands is well established82) is specifically stained in the following way. Tissue slices are treated with 0.5 M periodate for 120 min at 25°, causing complete oxidation of the side chain to the C7 aldehyde of the unsubstitutecl and 9-mono-O-acetylated sialic acids. 

The mode, and subeellular site, of biosynthesis of Neu5Gc is similar in bovine, submandibular glands, although the activity is less pronounced.216 Neu5Ac-mono-oxygenase activity has also been determined in liver and serum of the pig.216 Because of the wide occurrence of Neu5Gc in Nature, the mono-oxygenase is, presumably, also widespread. 

N-Acylneuraminate-9(7)-0-acetyltransferase seems to be widespread in Nature, as sialic acids O-acetylated in the side chain are found in many animal species, including man (see Section II). However, enzyme activity has thus far been measured only in bovine, submandibular gland and in bovine serum. The 4-O-acetyltransferase appears... 

In contrast to the behavior of submandibular-gland sialyltrans-ferases, reports exist in the literature describing marked differences in the rate of transfer of different sialic acids to glycoconjugates. For instance, in embryonic chicken-brain, the occurrence of at least four si-... 

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