| Budget Amount *help |
¥6,700,000 (Direct Cost: ¥6,700,000)
Fiscal Year 2001: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 2000: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 1999: ¥2,600,000 (Direct Cost: ¥2,600,000)
Fiscal Year 1998: ¥1,900,000 (Direct Cost: ¥1,900,000)
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| Research Abstract |
Asterina pectinifera flees from the predator asteroid Solaster dawsoni before contact. This response is called an avoidance reaction. A. pectinifera is the only asteroid among marine fauna, which show the avoidance reaction. Several asteroids, such as Asterias rubens, show an escape response, which refer to the physical contact by the opponent to reject the predation.
We have elucidated that the avoidance response in A. pectinifera is induced by biomolecules of S. dawsoni, and in the present research project, we aimed to develop a quantitative bioassay and isolation and purification of bioactive compounds responsible to the avoidance reaction.
The bioactivity was quantified by measuring the following items : "lag time before avoidance response", "average speed of evasion", and "distance from the origin". Each item was evaluated by five grades, and the sum of grades of three items were categorized into four intensities of bioactivity (+++, ++, +, and -). A liquid (drip) obtained from S. dawsoni by freeze-thaw procedure elicited the strongest response (+++). The bioactivity of the drip was eliminated by Pronase E treatment. Bioactive substances were remained in the inner solution by the ultra filtration of 30,000. Separation by ammonium sulfate fractionation, gel filtration chromatography, and HPLC revealed that the avoidance response in A. pectinifera elicited by several proteinaceous compounds with molecular weight of around 100,000. As far as we can tell that this is the first report of allelochemicals having such larger molecular weights.
In the course of the above study, we found that the aquarium water of A. pectinifera showed remedial and preventive effects on scaly area of human hands. Two polyhydroxysteroids and three steroidal saponins (pectiniosides A, B and C) were isolated as bioactive substances from the water extract of A. pectinifera.
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