Monday, August 27, 2012

Sensation in a Single Neuron Pair Represses Male Behavior in Hermaphrodites

White, JQ. Jorgensen, EM. (2012) Sensation in a Single Neuron Pair Represses Male Behavior in Hermaphrodites. Neuron 75: 593-600.

Figure 1: Males are attracted to sex pheromones - daf-22-independent.WT herms avoid the pheromone. herms with daf-7 mutation are attracted to pheromones. Sensory neurons, ASK, AWA, AWC are needed (but they can compensate for each other).

Figure 2: ASI is only source of daf-7. Ablation of ASI shows attraction in herms. tax-4 expression in ASI is also needed for ASI to repress attraction. osm-3 mutation also cause herms to be attracted to pheromones. tax-4 is involved in ASI development and activity. osm-3 is involved in dendrite development of ASI.
For ASI to repress attraction, ASI must be:
1. present
2. active
3. capable of sensing environment

Expression of daf-7 in AWC and ASE neurons rescues pheromone avoidance in herms. ASI is not needed in the rescues to suppress attraction. Other manipulations show that ASI normally releases daf-7/tgf-beta and suppresses attraction. Can be bypassed by expressing daf-7 elsewhere or other manipulations.

Figure 3: expressing FEM-3 during development "masculinizes" the worms. herms become attracted to pheromones - doesnt happen if masculinized during adulthood.

Figure 4: can masculinize individual neurons. Can target sensory neurons (ASI/AWA/AWC/ASK) and different sets of interneurons (AIA, AIB, AIY, AIZ, RMG) with different promotors. To get attraction in herms, must masculinize both sensory and interneurons. Important to masculinize RMG.

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