Intracellular digestion

One consequence of the uptake of some contaminants is a reduction in the ability of lysosomes to retain the dye Neutral Red. As a consequence, the Neutral Red retention time has been developed as an index of lysosomal membrane fragility and thus of toxicity. The test has been used on the digestive cells involved with intracellular digestion of endocytosed food following administration of organic contaminants, such as polycyclic aromatic hydrocarbons [71]. The phenomenon has been reported many times after exposure to... 

In a review of feeding and digestion in the Bivalvia [37], it was proposed that the accumulation of metal-bound particulates in the digestive gland was a two-phase process reflecting extracellular and intracellular digestion, and Viarengo [87] has reached similar conclusions. In a pulse chase study of the uptake of radiolabelled metals (Ag, Cd, Cr, Hg, Se) by the zebra mussel Dreissena... 

An interesting outcome of the observed depuration patterns was that there could be a two- or three-phase process. This were interpreted as indicative of extracellular followed by intracellular digestion [95], A possible third phase might be due to metabolic loss of metals. 

Fankboner, P. V. (1971). Intracellular digestion of symbiotic zooxanthellae by host amoebocytes in giant clams (Bivalvia Tridacnidae) with a note on the nutritional role of the hypertrophied siphonal epidermis, Biol. Bull., 141, 222-234. 

Erlandsen, S. L., and Chase, D. G. (1972). Paneth cell function Phagocytosis and intracellular digestion of intestinal microorganisms. /. Ultrastruct. Res. 41, 296-318. 

Fig. 3.2. General mechanisms for the uptake and transport of macromolecules by an enterocyte. Intracellular uptake-, after absorption and endocytosis by the microvillous membrane, macromolecules are transported in small vesicles and larger phagosomes. Intracellular digestion occurs when lysosomes combine to form phagolysosomes. Intact molecules that remain after digestion are deposited in the intercellular space by exocytosis. Intercellular uptake-, alternatively, macromolecules may cross the tight junction barrier between cells and diffuse into the intercellular space. (After Walker, W. A. Isselbacher, K. J. Uptake and transport of macromolecules by the intestine possible role in clinical disorders. Gastroenterology, 6T. 531-50, by Williams Wilkins (1974).)...

Lysozome A membrane-bound organelle in the cytoplasm of most cells containing various hydrolytic enzymes that function in intracellular digestion... 

Extracellular digestion (GI tract) Intracellular digestion (lysosomes) Modification for food use... 

The importance of lysosomes in physiopathological autolysis, intracellular digestion and engulfing processes was pointed out by de Duve (D7, D8) and Novikoff (N5). Within recent years several studies have appeared in which the actions of purified lysosomal preparations on proteins, carbohydrates and lipids have been considered (A14, C5, M3, S2). 

A. functions in the intracellular digestion of materials entering the cell... 

Lysosomes are subcellular organelles in which a wide range of catabolic enzymes are stored in a closed, protective membrane system. They are major sites of intracellular digestion of complex macromolecules derived from both intracellular (autophagic) and extracellular (het-erophagic) sources. Lysosomal enzymes show optimal activity at acidic pH. The pattern of enzymes in lysosomes may depend upon the tissue of origin, as well as upon the physiological or developmental state of the cells. 

LOEL lowest-observed-effect level LOQ limit of quantification lyophilisate product of freeze drying lysosome cell organelle containing hydrolases (hydrolytic enzymes) it is active in phagocytosis, i.e. in intracellular digestion and destruction accompanied by release of the cell contents... 

Host cells on some plants that are infected with mycorrhizal fungi, especially endotrophic organisms, are able by intracellular digestion of the hyphae to keep the infection within bounds. This lends support to the view expressed by Garrett (1960) that the mycorrhizal association is much more a case of controlled parasitism than of symbiosis. Comprehensive generalizations are, however, not justified. 

Autolysis self digestion of dying cells, which occurs when cathepsins (see Proteolysis) are released from lysosomes and attack cytoplasmic proteins. In the living cell these proteases are sequestered inside the lysosomes, but at death the lysoscnnal membranes break down. See Intracellular digestion. 

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