化学物质诱导泥蚶幼虫附着变态的研究

Inducement of settlement and metamorphosis by chemical cues in Tegillarca granosa larvae

1996年8～9月间在室内用8种化学诱导物对泥蚶变态前期幼虫进行附着变态诱导实验。结果表明,8种药物对泥蚶幼虫的变态均有一定的诱导作用。其中,3-HT、EPI和NE对幼虫变态的诱导作用极显著,有效浓度范围较广;KCl和Ala的诱导作用较显著,有效浓度范围较窄;而Try、CABA和Ach只有某些浓度组的诱导效果明显,诱导效率对浓度的信赖性较强。从诱导物浓度来看,10-4mol/L的Ala、GABA和10-5mol/L的EPI诱导效果最好,与对照组相比,变态率均提高12%以上。不同处理时间试验表明,处理时间的长短与幼虫的变态率无一致的相关性关系,因药而异;总的来看,处理时间不超过8h的诱导效果较好,时间过长诱导率降低(GABA除外)。其中,用10-5mol/L的Ala处理1～4h或10-5mol/L的EPI处理4h效果最好,与对照组相比,变态率均提高25%以上。8种药物中,只有Try表现出对幼虫明显的毒性影响,Try的浓度越高,处理时间越长,幼虫的死亡率越高,用10-4mol/L的Try处理幼虫3h,死亡率达89%。

The competent Tegillarca granosa larvae were induced to metamorphose by 8 different kinds of chemical cues including DL-a-alanine (Ala), Dl-tryptophan (Try), g-aminobutyric acid (GABA), 3-hydroxytyramine (3-HT,or Dopamine), epinephrine (EPI), L-noradrenalin (NE), acetylcholine chloride (Ach), potssium chloride (KCl). Effects of these chemical cues on the metamorphoses and survival of T. granosa larvae at different concentrations and exposure times were tested during August and September,1996. Results show that all these chemical cues induce larval metamorphosis to some extent. In general, 3-HT, EPI and NE can induce larval metamorphosis very significantly, and the metamorphosis rates are increased in all the treatments; KCl and Ala can induce larval metamorphosis significantly, and metamorphosis rates are increased in most of the treatments; Try,GABA and Ach can induce larval metamorphosis at very strict concentration. From single concentration treatment, 10 -4 mol/L of Ala, GABA and 10 -5 mol/L of EPI can induce larval metamporphosis most effectively, and the metamorphosis rate increases by over 12%. Results also show that the relationship between exposure time and metamorphosis rate varied with different chemical cues. In general, exposure time less than 8 h, the treaments can induce larval metamorphosis more effectively than a longer time .Treated with Ala(10 -5 mol/L) for 1～4 h or EPI(10 -5 mol/L) for 4 h, the larvae have the most effective metamorphosis, of which both the percentages increase by more than 25%. Among these 8 kinds of chemical cues, only Try has negative effects on the larvae that the higher the concentration and the longer the exposure time of Try are, the higher the larval mortality is. Treated with Try at a concentration of 10 -4 mol/L and exposure time of 3 h, the larvae have a mortality of 89%.