Coon S L, Walch M, Fitt W K, Weiner R M, Bonar D B
Biol Bull. 1990 Dec;179(3):297-303. doi: 10.2307/1542321.
Oyster larvae exposed to solutions of NH4Cl exhibit stereotypical settlement behavior similar to that which normally precedes cementation and metamorphosis. Un-ionized ammonia is the active chemical species. At pH = 8.0, the threshold concentration of NH4Cl (pH = 8.0) for newly competent larvae is 2.5 mM; maximum activity is at 7.9 mM, corresponding to calculated NH3 concentrations of 100 {mu}M and 310 {mu}M, respectively. Induction of settlement behavior is rapid, with >90% of larvae exposed to 310 {mu}M NH3 responding within less than 5 min. After 15 to 30 min, larvae become habituated to NH3 and resume swimming so that the percent exhibiting settlement behavior after 30 min is <10%. Other weak bases, such as methylamine and trimethylamine, induce similar behavior suggesting that NH3 acts by increasing intracellular pH. Evidence that NH3 and L-3,4-dihyrodxyphenylalanine (L-DOPA) induce settlement behavior through different mechanisms is presented. Ammonia may be a natural environmental cue that promotes oyster settlement behavior and, ultimately, recruitment.
暴露于氯化铵溶液中的牡蛎幼虫表现出刻板的附着行为，类似于正常情况下在黏附及变态之前出现的行为。未电离的氨是活性化学物质。在pH = 8.0时，新具备附着能力的幼虫对氯化铵（pH = 8.0）的阈值浓度为2.5 mM；最大活性出现在7.9 mM时，分别对应计算得出的氨浓度为100 μM和310 μM。附着行为的诱导迅速，暴露于310 μM氨中的幼虫>90%在不到5分钟内做出反应。15至30分钟后，幼虫对氨产生适应性并恢复游动，因此30分钟后表现出附着行为的百分比<10%。其他弱碱，如甲胺和三甲胺，诱导出类似行为，表明氨通过提高细胞内pH起作用。本文提供了氨和L-3,4-二羟基苯丙氨酸（L-DOPA）通过不同机制诱导附着行为的证据。氨可能是一种促进牡蛎附着行为并最终促进补充群体形成的自然环境线索。
