Influence of water temperature on acetylcholinesterase activity in the Pacific tree frog (Hyla regilla)

This investigation evaluated whether acetylcholinesterase (AChE) in Pacific tree frogs (Hyla regilla) from different geographical locations was influenced by different temperatures during early aquatic life stages, independent of pesticide exposure. Tadpoles were collected from both a California coastal pond and a Sierra Nevada mountain range pond, USA. Groups of frogs from each location were raised in temperatures representative of either the Sierra Nevada (8 degrees C) or the coastal (19 degrees C) location. Metamorphs from both locations raised as tadpoles at 19 degrees C had AChE activities of 42.3 and 38.7 nm/min/mg protein, while those raised as tadpoles at 8 degrees C had activities of 26.9 and 28.2 nm/min/mg protein. A two-way analysis of variance revealed temperature to be the significant factor in determining AChE activity (F = 22.3, p < 0.001), although origin was not important (F = 0.09, p = 0.75). Interpretations regarding the influence of pesticides upon AChE activity in Pacific tree frogs must consider the influence of environmental temperature to enable cross-population comparisons.