Protistology 6 (2) 98–102 (2009)
Suppression effects of nutrients on Ca2+-induced encystment of Colpoda cucullus
Akemi Kida, Takahiko Akematsu, Hitomi Hayakawa and Tatsuomi Matsuoka
Institute of Biological Science, Faculty of Science, Kochi University, Kochi, Japan
‘Starvation’ is known to be a common factor for encystment induction among a number of protozoans. This may involve that the encystment is suppressed by nutrient molecules contained in a surrounding medium or by incorporated ones. In the present study, what kinds of the nutrients suppress Ca2+-mediated encystment of Colpoda cucullus was examined. Among the tested substances (sugars, vitamins, protein, peptides, amino acids), only a bovine serum albumin (BSA) and its digested products (peptides) markedly suppressed encystment, but free amino acids did not show a marked encystment-suppression effect. The suppression of encystment by BSA was not affected when the endocytic internalization of BSA was blocked. The results suggest that the suppression of Ca2+-mediated encystment by BSA may not be correlated with certain receptors on the cell surface stimulated by some partial conformations of the peptides or proteins.
Key words: Colpoda, encystment suppression, endocytosis, nutrients, starvation
Address for correspondence. Tatsuomi Matsuoka.Institute of Biological Science, Faculty of Science, Kochi University, Kochi 780-8520, Japan, e-mail: email@example.com
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