INTERACTIONS OF MEMBRANE EXCITABILITY MUTATIONS AFFECTING POTASSIUM AND SODIUM CURRENTS IN THE FLIGHT AND GIANT FIBER ESCAPE SYSTEMS OF DROSOPHILA
INTERACTIONS OF MEMBRANE EXCITABILITY MUTATIONS AFFECTING POTASSIUM AND SODIUM CURRENTS IN THE FLIGHT AND GIANT FIBER ESCAPE SYSTEMS OF DROSOPHILA
复制标题
DOI：
10.1007/bf00195964
复制
发表时间：
1992-08-01
影响因子：
2.1
通讯作者：
WU, CF
中科院分区：
文献类型：
--
作者：
ENGEL, JE;WU, CF
我们研究了K+电流突变eag和Sh和Na+电流突变nap（ts）对果蝇飞行和逃避反应的两个明确的神经回路的影响，记录自背纵肌和背转子肌。Sh和eag基因突变影响跳跃和飞行逃避反应的不应期和跟随频率，但不影响潜伏期。nap（ts）突变改变了“跳跃”（TTM）的这3个生理参数，但不改变“飞行”（DLM）、分支，表明不同回路成分对突变的脆弱性存在差异。在eag Sh; nap三重突变体中，多个K+电流可能减少，飞行肌表现出与飞行无关的异常节律活动，一些果蝇还表现出异常的翼下姿势。低频峰电位可能起源于飞行肌运动神经元，但这种“非飞行活动”中肌纤维之间的协调与飞行不同。然而，尽管休息的Eag Sh果蝇存在这种非飞行活动，但那些具有正常翅膀姿势的动物也能够飞行，并且具有正常的肌肉活动模式。这表明，在这些突变体中，DLM运动神经元回路能够在两种输出模式之间切换，即非飞行活动和飞行。In eag Sh; nap三突变体，不飞行活动和异常的翅膀姿态是不存在的，表明Na+电流的减少抵消了该回路中K+电流突变的超兴奋影响。
We have studied the influence of the K+-current mutations eag and Sh and the Na+-current mutation nap(ts) upon two well-defined neural circuits that underlie flight and an escape response in Drosophila, recording from dorsal longitudinal and tergotrochanteral muscles. Mutations of Sh and eag affected refractory period and following frequency, but not latency, of the jump-and-flight escape response. The nap(ts) mutation altered these 3 physiological parameters of the "jump" (TTM), but not the "flight" (DLM), branch, suggesting differences in the vulnerability of different circuit components to the mutation. In contrast to their interaction in some other systems, nap(ts) did not counteract the effects of eag and Sh upon these physiological parameters in eag Sh; nap triple mutants.In eag Sh double mutants, in which multiple K+ currents may be diminished, flight muscles showed abnormal rhythmic activity not associated with flight, and some flies also had an abnormal wings-down posture. The low-frequency spikes probably originated in the flight muscle motoneurons, but the coordination between muscle fibers during this "non-flight activity" was distinct from flight. Nevertheless, in spite of the presence of this non-flight activity in resting eag Sh flies, those animals with normal wing posture were also able to fly, with a normal pattern of muscle activity. This suggests that in these mutants, the DLM motoneuron circuit is able to switch between two patterns of output, non-flight activity and flight. In eag Sh; nap triple mutants, the non-flight activity and abnormal wing posture were absent, indicating that a reduction of Na+ current counteracts the hyperexcitable influence of the K+-current mutations in this circuit.