Serotonin (5-hydroxytryptamine) turnover in adult female Ascaris suum tissue

1. The 5-hydroxytryptamine (5-HT, serotonin) turnover was examined in the tissues of adult female Ascaris suum. The 5-HT turnover was highest in the intestine at 34.7 ng 5-HT produced/mg protein/hr and 13.8 ng 5-HT produced/mg protein/hr in muscle tissue. 2. The levels of 5-HT metabolites namely tryptophan, 5-hydroxytryptophan, 5-hydroxytryptamine, 5-hydroxyindole acetic acid and 5-hydroxytryptophol were measured in muscle and intestinal tissue of adult A. suum. 3. Parachlorophenylalanine inhibited 5-HT production in muscle and intestinal tissue providing in situ evidence for the presence of tryptophan hydroxylase in this tissue. 4. Pargyline increased 5-HT production in muscle and intestinal tissue providing in situ evidence for the presence of monoamine oxidase in this tissue.     

Subcellular distribution of digestive enzymes in Ascaris suum intestine

Van den Bossche H. and Borgers M. 1973. Subcellular distribution of digestive enzymes in Ascaris intestine. International Journal for Parasitology3: 59–65. The microvilli of the intestinal cells of Ascaris suum resemble the microvilli of the mammalian intestine in respect to their morphologic structure; their behaviour to homogenization in the presence of a chelating agent; the presence of the disaccharide hydrolases, maltase, sucrase and trehalase and the presence of an enzyme which hydrolyses 5′-AMP at neutral pH. The microvilli of the Ascaris intestinal cells differ completely from those present in mammalian intestine in respect to the presence of non-specific phosphatases. The brush border fraction contains the bulk of acid phosphatase present in the intestinal cells. Although some pinocytotic vesicles have been observed only low endocytotic activity was found. We therefore suggest that the acid hydrolases found on the brush border membrane may be functionally related to extracellular digestion of macromolecules.     

Factors in the movement of hexose across the intestine of Ascaris suum

Trichloroacetic acid extractable carbohydrate of the intestine of Ascaris suum decreases rapidly when ribbons of the tissue are incubated in a basal salt solution. After 10 min incubation endogenous carbohydrate is 32% and after 80 min it is 19% of the "zero" time control value. In contrast, there is approximately a 2-fold increase in the endogenous carbohydrate of tissue that is incubated in saline with glucose. The increase occurs within the first 5 min and is maintained throughout an 80-min incubation period. Sac preparations of the intestine that are preincubated with glucose and incubated without glucose move 3-0-methylglucose from the luminal to the pseudocoelomic fluid at a rate that is comparable initially to the rate of movement measured for sac preparations that are incubated in saline with glucose. After 10 min the rate decreases. The addition of glycogen or trehalose to the saline bathing the pseudocoelomic side of sac preparations does not facilitated the movement of 3-0-methylglucose. Collectively, the results support the suggestion that the limited movement of 3-0-methylglucose across intestinal sac preparations that are incubated without glucose is due to the tissue's limited carbohydrate reserve and its rapid depletion in vitro.     

Permeability characteristics of the basement membrane (basal lamella) of the intestine of Ascaris suum

Permeability characteristics have been determined for isolated ribbons of the basement membrane of the intestine ofAscaris suum. The solute permeability coefficient (P_c) was measured for a series of hydrophobic, nonionic molecules of graded molecular size. The geometric pore area per unit path length (A_o/Δx) was estimated to be 24.0 cm from the diffusion rates for the various solute molecules. A filtration coefficient (L_p) of 18.1×10^?12 cm⁵/dyne-sec was determined by a method that employs osmotic pressure. The preceding values were used to calculate an average pore radius of 24.0 A for the membrane. The unstirred layer was estimated to be 30μm thick from measurements of the change in the rate of diffusion of water across the membrane with change in the rate of perfusion. The preceding values were used to calculate a reflection coefficien (σ), effective permeability coefficient (ω′), and a permeability coefficient (ω). The results support the view that this basement membrane functions as a filter and selective barrier to diffusion of constituents of the worm's body fluid.     

Tissue and ultrastructural localization of 5-hydroxytryptamine (serotonin) in the tissues of Ascaris suum with energy dispersive X-ray spectrometry of immunoreactive structures

Muscle, hypodermis and gastrointestinal epithelial cells from adult female Ascaris lumbricoides var. suum were found to contain serotonin based upon glyoxylic acid induced histofluorescence and indirect immunolabeling with an antiserotonin monoclonal antibody conjugated to protein A-colloidal gold. Histofluorescence indicated that muscle-hypodermis and intestinal epithelial cells contained significant concentrations of 5-hydroxytryptamine while fluorescence was absent in the nerve cord and cuticle. Immunolabeling at the ultrastructural level indicated that serotonin was sequestered in electron-opaque patches, dense vesicles and mitochondria of the muscle-hypodermis and intestinal tissue. Perfusion of whole worms and isolated tissues with 10(4) M-serotonin further indicated: (1) immunolabeled patches and dense vesicles were often associated with cytoskeletal elements, (2) serotonin did not appear to enter the intestinal or muscle cells by endocytosis, (3) immunolabeled patches examined with energy dispersive X-ray spectrometry (X-ray microanalysis) were found to contain iron at concentrations approximately double that of the surrounding cytoplasm.