化学物质对硬壳蛤幼虫变态的诱导

Induction of metamorphosis of the hard clam Mercenaria mercenaria larvae by chemical cues

用KCl、肾上腺素(EPI)、去甲肾上腺素(NE)、L-DOPA和GABA(γ-氨基丁酸)进行了不同浓度不同处理时间对硬壳蛤(Mercenaria mercenaria L.)幼虫变态诱导实验.结果表明,KCl、肾上腺素、去甲肾上腺素和L-DOPA对硬壳蛤幼虫的变态均有诱导作用,而GABA的诱导作用不显著.KCl的最佳诱导浓度随处理时间不同而有所不同.处理时间为1～24,48,72 h时KCl的最佳诱导浓度分别为33.56,20.13～26.85,13.42 mmol/L.肾上腺素和去甲肾上腺素的诱导作用与浓度和处理时间均有关.肾上腺素的最佳处理浓度为100 μmol/L,最佳处理时间均为8 h,此时幼虫变态率提高最大,为36.97个百分点.当去甲肾上腺素的诱导浓度为100 μmol/L,处理时间为8～16 h时,幼虫变态率提高也较大,均大于18个百分点,死亡率增加,但均低于30个百分点,当去甲肾上腺素诱导浓度为500 μmol/L时,虽然在8～16 h的处理时间范围内,幼虫变态提高率也较大,均大于18个百分点,但当处理时间超过8 h,在16～48 h范围内,幼虫死亡率提高明显增大,均大于50个百分点.L-DOPA的适宜诱导浓度为10～50 μmol/L,适宜处理时间为8～24 h,此时幼虫变态率均提高30个百分点以上,最高可提高79.43个百分点.GABA的诱导作用较弱,最佳诱导浓度随处理时间的不同而有所不同,处理时间为24 h和48 h时,最佳诱导浓度为0.1 μmol/L;处理时间为0.5～16 h时,最佳诱导浓度为100 μmol/L.

The abilities of KCI, epinephrine （EPI）, norepinephrine （NE）, L-DOPA, and GABA （γ-aminobutyric acid） to induce metamorphosis of Mercenaria mercenaria L. larvae were studied. Results suggested that KCI, EPI, NE, L-DOPA were active inducers of metamorphosis, whilst GABA was less effective. Optimum concentration of KCI varied with different exposure time, and was 33.56 mmol/L when the exposure time was 1-24h, with metamorphosis rate increments all 〉24 percentage. The optimum concentrations of KCI were 20.13-26.85 mmol/L and 13.42 mmol/L when the exposure time lasted 48h and 72 h, respectively. The inductive effects of EPI and NE were dose- and time-dependent. The optimum concentration of EPI was 100 μmol/L at 8h exposure time, with the highest metamorphosis rate increment being 36.97 percentage. The metamorphosis rate increment was〉18 percentage when the larvae were exposed to 100 μtmol/L NE for 8-16h, with the mortality rate increment all〈30 percentage. Exposure to 500μmol/L NE for 8-16 h was also sufficient for the larvae to increase metamorphosis rate〉18 percentage, but prolonged exposure time （16-48 h） caused toxic effect, with the mortality rate increasing significantly, all〉50 percentage. The better inductive effects of L-DOPA were archived when the larvae were exposed in 10μmol/L and 50/,mol/L for 8-24 h, with the metamorphosis rate increment〉30 percentage.