Role of cAMP, cGMP and Ca++ in chemotaxis of Schistosome Miracidia

2001 Fiscal Year Final Research Report Summary

• Project/Area Number: 11670244
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: 寄生虫学(含医用動物学)
• Research Institution: Nagasaki University
• Principal Investigator: AOKI Yoshiki Nagasaki University, Institute of Tropical Medicine, Professor, 熱帯医学研究所, 教授 (90039925)
• Co-Investigator(Kenkyū-buntansha): FUJIMAKI Yasunori Nagasaki University, Institute of Tropical Medicine, Lecturer, 熱帯医学研究所, 講師 (10209083) ; KATSUMATA Tatsuya Nagasaki University, Institute of Tropical Medicine, Research Asscociate, 熱帯医学研究所, 助手 (10284712) ; NIWA Masami Nagasaki University, School of Medicine, Professor, 医学部, 教授 (20136641) ; WATANABE Kanji Nagasaki University, Institute of Tropical Medicine, Research Associate, 熱帯医学研究所, 助手 (70325679)
• Project Period (FY): 1999 – 2000
• Keywords: schistosome / miracidia / chemotaxis / signal transduction / cAMP / muscle contraction / behavior change / secretion of snails

Research Abstract

Schistosoma miracidia show chemotaxis, exactly speaking klinokinesis, towards the excretion/secretion of the intermediate snails. The present study was attempted to examine the signal transduction of miradial behavior changes caused by the excretion/secretion of the snails and examine the demographic character of snails which secrete the attractant for miracidia.
1. Signal transduction of chemotaxis of miradicia towards the secretion of snails.
The method was developed to observe qualitatively and quantitatively the chemotactic activity of miracidia. Miracidia were allowed to swim free in a rectangular glass tube. An aliquot of 0.5 ul of secretion of snails was syringe inoculated at the end of tube, then the behavior changes of miracidia was recorded on the video tape. The experiments were attempted to examine pharmacologically the factors which are involved in the behavior changes of miracidia caused by the secretion of snails. The membrane permeable |cAMP and IBMX induced the behavior changes which mimic those caused by the secretion of snails. Non-membrane permeable CAMP and CGMP did not cause any change. Serotonin induced the behavior changes. Miracidia exposed to eserine did not show the chemotaxis towards the secretion of snails. These results suggest that CAMP is involved in the chemotaxis of miracidia towards the snails and the behavior changes are induced by the contraction of muscles.
2. Demographic character of snails which secrete thp attractant for miracidia.
The experiment was attempted to examine the aciivity of secretion of snails with different ages or with/without infection, and of different species of snailak Schistosome intermediate hosts secrete the attractant for miracidia regardless of age and infection by schistosome. Out of the snails which are not intermediate hosts, some snails secrete powerful attractant for schistosojoie.