Abstract
There are five distinct memory phases in Drosophila, in terms of temporal sustains: Learning, short-term memory (STM), middle-term memory (MTM), (anesthesia resistant memory) ARM and (long-term memory) LTM. With time the memories can be transferred from labile into long-lasting form that are resistant to mental interruptions. ARM is the one that can resist the anesthesia agent -- cold shock. A point mutation fly, radish is the only reported case which has defective ARM. Little is known about the molecular, genetic, or cellular pathways underlying ARM. Here, we report another mutant, Mampus, involved in ARM formation. The Mampus mutant has a GAL4 insertion at upstream of escargot (esg). We have obtained or collected three Mampus alleles with similar expression patterns in two pairs of anterior lateral neurons since mid-pupa stage. Using genetic FLIP-out technique to visualize one neuron at a time, I found that both Mampus neurons project fibers first to the antennal lobe, and then extend proteriorly to the ipsilateral posterior superior protocerebrum (PSP) and finally terminate at contralateral PSP. The two neurons are however different in morphology. One has more fibers at the ipsilateral PSP while the other has more fibers at the contralateral PSP. Using specific polarity reporters, I found that Mampus fibers at antennal lobe are dendrites and at PSP are axons. The two pairs of Mampus neurons are likely cholinergic since their GAL4 expression is inhibited by the expression of Cha-GAL80. When blocking neurotransmitter release from Mampus neurons with shibirets, ARM is disrupted. An independent manipulation by the ablation of Mampus with reaper toxin also disrupts ARM. For a more thorough behavior assay in the future, I have also obtained two promoter-driven lines of engrailed (6356 and 8165) that also expresses in the Mampus neurons. These results together with previous study suggest that formation or retrieval of ARM requires neurons expressing genes disrupted in radish and Mampus mutants in the fly brain.