SYNOPSIS Some carbohydrates inhibited glucose and fructose transport in Trypanosoma gambiense. Glucose transport was inhibited by glycerol, mannose, 2‐deoxy‐D‐glucose, glucosamine and N‐acetylglucosamine. Fructose transport was inhibited by glucose, glycerol, mannose, glucosamine and N‐acetylglucosamine. Glucosamine transport appeared to be a mediated process and had a Km of 1.20 mM and a Vmax of 28.5 μM glucosamine/g dry wt/2 min. Glucosamine absorption was competitively inhibited by glucose, fructose and N‐acetylglycosamine. N‐Acetylglucosamine appeared to enter by passive diffusion. Reciprocal inhibition experiments suggested that glucosamine entered entirely via the “fructose site.” Specificity of sugar transport in T. gambiense differs from that of other organisms.
JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. The American Society of Parasitologists is collaborating with JSTOR to digitize, preserve and extend access to The Journal of Parasitology.Several workers have observed that in a cestode infection the size of the worms is, roughly speaking, inversely proportional to the number of worms in the given infection. This has been called the "crowding effect." Woodland (1924), Shorb (1933), and Hunninen (1935) demonstrated this phenomenon in rats and mice infected with Hymenolepis nana. Chandler (1939) and Hager (1941) reported this effect in studies on Hymenolepis diminuta. Reid (1942) obtained similar results with Raillietina cesticillus. Reid's data may be somewhat more accurate from a quantitative standpoint since he used weight as a measure of size, whereas previous workers relied on linear measurements as criteria. Wardle and Green (1941), studying the rate of growth of Diphyllobothrium latum, used the weight-length ratio as an index of average cross sectional area. This seems to be a valid approach to problems of this type.In connection with other studies on the metabolism of Hymenolepis diminuta the writer has gathered considerable data on the mean wet weights of worms from infections varying in size from one to one hundred worms. In selecting data for study particular care was taken to be certain that the worms were of similar age (38 to 44 days after infection) and that the host rats were males of similar size (190 to 208 grams). The wet weights of 1694 worms were available for consideration after imposing the restrictions indicated above.In studying the data it was obvious not only that the worms become smaller in infections with increasing numbers of worms, but with decreasing size the surface area per unit of weight of the individual worm rapidly becomes larger. Since the relationship Area (cm2) = Weight (grams)2/3 or Area = (k) (Weight)2/3 has been demonstrated in the case of other animals (Brody, 1945), it seems reasonable that for practical purposes when comparing worms of the same species we may arbitrarily assume k = 1 and obtain the relation, Area = Weight2/3. Actually, in the case of cestodes, there is reason to believe that k = 1 (approximately). T'ie mathematicians will agree that this relation holds true in determining the area of a cylinder of material having a specific gravity of 1.00, and we may think of a cestode as essentially a compressed cylinder. In other animals (e.g., nematodes) the presence of a gut presents additional complications, but the gutless tapeworm does not offer difficulty in this particular respect. Applying this to the data at hand we may obtain the relative area in each case and, on dividing the "area" by the original weight we derive a com...
The uptake of purines and pyrimidines by adults of Schistosoma mansoni was studied. Cytosine, thymine, and uracil entered the worms entirely by diffusion. Adenine, guanine, hypoxanthine, and the nucleosides adenosine and uridine were absorbed in part by mediated systems. The results of inhibitor studies suggest the presence of 5 distinct transport sites for these latter compounds. The interaction of adenosine monophosphate with these sites was also studied.
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