|Budget Amount *help
¥2,000,000 (Direct Cost : ¥2,000,000)
Fiscal Year 1996 : ¥400,000 (Direct Cost : ¥400,000)
Fiscal Year 1995 : ¥1,600,000 (Direct Cost : ¥1,600,000)
We have established a unique bioassay for screening attachment attractants and repellents using the blue mussel Mytilus edulis galloprovincialis. The effects of various physical factors such as, size, mechanical agitation, exposure to air, salinity, calcium and/or magnesium and temperature on byssal thread formation have been studied. We examined the effects of chemicals on byssal thread formation. Fe (III) EDTA, kojic acid, L- ascorbic acid, sodium benzoate and phenol, each at 100 mumol/l, showed an increase of 49,44,19,16, and 4% over control (number of threads 8+1 ; 100%) on byssal thread formation in M.edulis galloprovinciales. For Fe (III) EDTA,the number of threads doubled at 200mumol/l. No significant change of activity was observed for kojic acid over a concentration range of 50 to 200mumol/l. Slight inhibitory effect of 6 and 24% was observed for MgCl_2 and CaCl_2, whereas CuSO_4 and nicotinamide completely inhibited the formation of threads even at a concentration as low as 10 and 5mumol/l. Significantly, Fe (III) EDTA showed a significant dose-dependent effect against the blue mussel. The new assay uses a free mussel instead of a fixed mussel, as used in previous assay where it couldn't show its natural behavior. The mussel selected the zones of preference by its sensory receptacle, moved toward preferred zones and fixed there by production of byssus filaments. If the mussel moved toward sample zone, the compound was determined to be attractant, if it moved toward blank zone, the compound was determined to be repellent. By the new assay method, curcumin, indigo carmine, alpha-tocopherol and iron powder at 1.0mumol/cm^2 promoted attachment while 18-crown-6 and BHT were effective at 20 and 28 mumol/l, respectively. Nonylphenol showed the repellent activity at 0.1mumol/l. The amount of samples required is almost same for both the assay methods.