How is the production of paramecium caudatum can be increased
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Paramecium caudatum and Proteus-type amoeba (Kauschke and Mohrig, 1987). In our experiments, lysenin (0.2–10 μg⧸ml) had no toxic effects on laboratory strains of Tetrahymena thermophila, Chlorogonium elongatum, Amoeba proteus, Euglena gracilis, and Acanthamoeba castellanii and on a wild-type strain of Chlamydomonas reinhardtii, which had been collected in the wild (Kobayashi et al., 2000). Moreover, all of 42 species belonging to seven invertebrate phyla had no response to CF (0.4–1.2%; Table I). Kauschke and Mohrig (1987) observed that CF had no effects on the nematode Rhabditis oxycerca. Among vertebrates, 11 teleostean species and tadpoles of a toad, newt, frogs, and salamanders died in 0.2–2.4% CF within 2 hr. In whole-body experiments with aquatic animals, CF was used because of the limited availability of lysenin. Among tetrapods, the reptiles Japanula polygonata and Trionyx japonicus, the quail Coturnix coturnix japonica, and the mammals Mus musculus and Rattus norvegicus albus died after receiving an intravenous injection of CF (more than 20 μl⧸kg; Kobayashi et al., 2001) and the frog Rana catesbeiana (450 and 500 g) died upon injection (iv) of CF (100 μl⧸kg). The CF of P. communissma did not kill mice at 50 μl⧸kg (unpublished data). The toxicity of CF to these animals was probably due to the lysenin contained in the CF. Pure CF contains about 500 μg of lysenin⧸ml, as determined in an assay with rat aorta. Two species of fish and toad tadpoles died in solutions of lysenin (5–16 μg⧸ml) in the same manner as in CF. Moreover, CF and lysenin, after incubation at 60 °C for 15 min or after incubation with SM–liposomes at 25 °C for 30 min, were no longer toxic to fish. It seems likely that lysenin is responsible, for the most part, for the lethal effects of CF and it is also likely that the presence of SM in animals is a prerequisite for the lethal response of animals to lysenin and CF (Kobayashi et al., 2001). It appears, thus, that vertebrates synthesize SM, which is the target molecule of lysenin, while invertebrates do not produce SM or the SM in their plasma membranes is covered by some cell-surface substances that prevent access by lysenin to SM. The biological implications of these speculations remain to be clarified.
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