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In the present study, the effects of Euglena and paramylon on hyperglycemia were examined in Otsuka Long-Evans Tokushima fatty (OLETF; type 2 diabetes mellitus model) rats. OLETF rats were fed an AIN-93 M diet containing cellulose, Euglena, or paramylon for 10 weeks. Long-Evans Tokushima Otsuka (LETO) rats were used as nondiabetic controls. An oral glucose-tolerance test (OGTT) was performed at 0 and 10 weeks. OLETF control rats were obese because of bulimia and showed abdominal fat accumulation and hyperglycemia. Euglena supplementation improved hyperglycemia and decreased food intake, body weight gain, and abdominal fat. However, there were no changes in the paramylon-supplemented group compared to the OLETF control group. Triglyceride concentrations in the serum and liver were lower in Euglena-supplemented rats than in OLETF control rats. There was a correlation between hepatic triglyceride concentration and the area under the curve (AUC) of OGTT at 10 weeks. This suggests that the improvement in glycemic control in the Euglena-supplemented group may depend on substances other than paramylon present in Euglena.

The gram-negative bacterium Holospora obtusa is a macronucleus-specific symbiont of the ciliate Paramecium caudatum, which invades the host cell via a food vacuole, infects its macronucleus and grows exclusively in the nucleus. From infection experiments, we showed that a property of the macronucleus that is necessary for it to be recognized and infected by H. obtusa is commonly provided by P. caudatum, P. multimicronucleatum and 14 species of the P. aurelia complex, but not by P. jenningsi, P. bursaria, P. trichium, P. duboscqui, Didinium nasutum, Blepharisma japonicum, Pseudourostyla levis, seven species of Euplotes or Tetrahymena thermophila. Furthermore, it was also shown that the bacteria that infect the macronuclei of P. multimicronucleatum and the P. aurelia species complex always disappear from the nuclei within 5 days and the infected bacteria are maintained stably in the host nuclei in only 13 out of 22 strains of P. caudatum. The results indicate that the species specificity of the habitat of H. obtusa is not simply a matter of its ability to penetrate the host nuclear membrane but depends on unknown factors that exist only in certain strains of P. caudatum.

Our results provide initial evidence that scallop shell extract reduces scopolamine-induced memory impairment and suppresses MK-801-induced hyperlocomotion.

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