Distribution of glucose-6-phosphatase and 5-nucleotidase in the digestive system of two teleost fishes

Lipid digestion in turbot (Scophthalmus maximus). I: Lipid class and fatty acid composition of digesta from different segments of the digestive tract

“…Esterase has also been reported to be present from stomach to rectum in turbot (Munilla- Moran and Stark 1990). It is possible that in the turbot a lipase produced in the intestinal mucosa (Sastry 1974) and more active at higher pH accumulates in the hindgut and rectum with the digesta and exhibits increased activity as a consequence of the alkaline pH found there (Buddington and Doroshov 1986;Borlongan 1990;Munilla-Moran and Stark 1990). The principle products available for absorption following lipolysis of TAGs, namely FFA and MAG, are thought to be fundamentally the same in both mammals and fish (Fange and Grove 1979;Sire et al 1981).…”

“…Consequently, lipase activity that are subsequently absorbed in the intestinal wall has been detected in the digestive tract of various of the jejunum (Gurr and Harwood 1991). Almarine fish species (Chesley 1934;Kitamikado and though the teleost pancreas is generally diffuse, fish Tachino 1961 ;Brockerhoff 1966;Sastry 1974; digestive lipases were assumed to be similar to Mukhopadhyay 1977; Olatunde and Ogunbiyi mammalian lipases (Brockerhoff 1966) and this was demonstrated in several species (Brockerhoff and Hoyle 1965;Brockerhoff 1966;Tocher and Sargent 1984). It followed that lipid digestion and absorption were shown to take place primarily in the anterior intestine (Mukhopadhyay 1977;Fange and Grove 1979;Buddington and Doroshov 1986;Das et al 1987;Borlongan 1990).…”

“…However, the PUFA of marine lipids are not readily hydrolysed, irrespective of position, by mammalian 1,3 specific pancreatic lipase in vitro (Bottino et al 1967;Chen et al 1990) suggesting that a lipase other than pancreatic lipase is the major lipolytic enzyme in fish . In fact, some teleosts can secrete intestinal mucosal lipase (Sastry 1974;Kapoor et al 1975) that can be active throughout the digestive tract (Munilla-Moran and Stark 1990). Fish lipases can vary in their lipolytic activity showing a combination of positional and fatty acid specificity.…”

Functional units in rainbow trout (Salmo gairdneri) liver: I. Arrangement and histochemical properties of hepatocytes

“…However, the accentuation associated with the periportal hepatocytes of the trout G-6-Pase was slight when we compared it to that of identically reacted rat liver (Teutsch, 1978(Teutsch, , 1981(Teutsch, , 1984; this study). Sastry et al (1976) reported studies of G-6-Pase localization in livers of a herbivorous fish, Barbus sophore, and an omnivorous fish, Heteropneustes fossilis. In both they stated that G-6-Pase activity was localized in the centrolobular area surrounding the biliary canaliculi and sinusoids.…”

“…Hepatocytes, endothelial cells, bile ductular epithelial cells, fat-storing cells, macrophages, circulating blood cells, and exocrine pancreatic cells all occur in teleost liver (Hinton et al, 1984b), but we do not know whether there are subpopulations of hepatocytes based on histochemistry (Novikoff, 1959;Teutsch, 1981), ultrastructure (Schmucker et al, 1978;Kanamura et al, 19841, andor response to specific xenobiotics (Jones and Fawcett, 1966;Baron et al, 1981). Literature on liver of teleosts in general (Hinton and Pool, 1976;Hinton et al, 1984b;Welsch and Storch, 1973;Sastry, 1975;Sastry et al, 1976) and trout in particular (Gingerich et al, 1978;Chapman, 1981;Anderson and Mitchum, 1974) contains @ 1985 ALAN K. LISS, INC numerous instances in which terms derived from the mammalian liver lobule are used. Such usage, without scientific basis in a tubular liver, underscored the need for analysis of functional units in teleost liver.…”