A fly pheromone receptor
Tal Soo Ha and Dean P. Smith
Insects use pheromone signaling for all sorts of interesting behaviors, yet only a single volatile pheromone has been identified in Drosophila, the lipid 11-cis-vaccenyl acetate (VA). Upon release by males, VA induces aggregation behavior in both sexes. This week, Ha and Smith identify VA's molecular target on trichoid sensilla, located on the ventrallateral surface of the antenna. VA activates olfactory neurons on T1-type sensilla. The authors screened the Drosophila odorant receptor (Or) gene family in flies lacking functional T1 sensilla. One gene, Or67d was reduced or absent in the mutants. Misexpression of Or67d in olfactory neurons of non-T1 sensilla conferred sensitivity to VA. LUSH, an extracellular protein expressed by sensillar lymph cells, is required for T1 sensitivity to VA and is also expressed in non-T1 sensilla. The lush1 mutation eradicated VA sensitivity in transgenic flies misexpressing Or67d. Thus, VA sensitivity requires both Or67d and LUSH.
Visualizing a netrin gradient
Timothy E. Kennedy, Hao Wang, Wallace Marshall, and Marc Tessier-Lavigne
Chemotropic guidance cues can act through gradients formed by graded expression levels or graded distribution. This week, Kennedy et al. visualized the netrin-1 gradient that guides commissural axons within the developing spinal cord. The authors generated antibodies to visualize netrin-1 and netrin-2 in the developing chick spinal cord. At the time when commissural axons began to extend, netrin-1 immunoreactivity was found not only in the floor plate where it is expressed by floor plate cells, but also in the ventral neural epithelium and dorsal spinal cord. Netrin-2 in contrast had a much more restricted pattern limited to neural epithelial cells that express it in the ventral spinal cord, and it was expressed at much lower lev
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Society for Neuroscience