A novel thermosensitive escape behavior in Drosophila larvae

We describe a novel thermosensitive escape behavior in Drosophila larvae and a simple assay to accurately define the response temperature. When a larva is placed in a droplet of water that is subsequently heated, a stereotypical escape response is robustly elicited at 29°C. Larvae defective for the painless TRP receptor, or blocked in the function of class IV multi-dendritic sensory dendrites respond to this stimulus at reproducibly higher temperature (34°C). The escape response has novel behavioral components and a lower temperature threshold in comparison with the responses to touch with a hot needle. Furthermore the assay minimizes operator bias that is present in current tests of thermosensitive nociception and generates a precise determination of temperature at the point of response. This response is highly reproducible and directly applicable to genetic and neural circuit analysis of a simple escape behavior.     

Identified taste bud cell proliferation in the perihatching chick [published erratum appears in Chem Senses 1998 Aug;23(4):459]

Developing taste buds in the anterior mandibular floor of perihatching chicks were studied by high voltage electron microscopic autoradiography in order to identify proliferating gemmal cell types. Montaged profiles of 29 taste buds in five cases euthanized between embryonic day 21 and posthatching day 2 were analyzed after a single [3H]thymidine injection administered on embryonic day 16, 17 or 18. Results showed that dark cells comprised 55% of identified (n = 900 cells) and 62% of labeled (n = 568 cells) gemmal cells as compared with light, intermediate, basal or perigemmal bud cells. Dark cells had both a greater (P < 0.05) number of labeled cells and a greater amount of label (grains/nucleus) than the other four bud cell types, irrespective of injection day. The nuclear area (micron 2) of dark cells was not significantly larger (P > 0.05) than that of the other gemmal cell types and therefore cannot account for the greater amount for label in the dark cells. Interestingly, only dark cells showed a positive correlation (P < 0.003) between amount of label and nuclear area. Results suggest that, during the perihatching period of robust cell proliferation, dividing dark cells may give rise primarily, but not exclusively, to dark cell progeny.