Abstract
The retention time of attenuated chemotactic response to continuous presentation of odorant diacetyl was investigated in the nematode Caenorhabditis elegans. The level of chemotactic response of nematodes pre‐exposed to diacetyl for 90 min was significantly smaller than that of nonexposed control nematodes. In this study, wild‐type (N2) nematodes were maintained at 15, 20 and 25°C after pre‐exposure to diacetyl. At 20°C, there was a decrease in response to diacetyl continuing for up to 6 hr after pre‐exposure to the chemical, but not up to 12 hr. Interestingly, the decrease in response to diacetyl did not continue up to 2 hr in nematodes bred at 15°C, although it continued beyond 12 hr in nematodes bred at 25°C. These results indicate that the retention time of attenuated chemotactic response to diacetyl is dependent on the environmental breeding temperature of nematodes. The breeding temperature correlated with aging speed of nematodes, suggesting that a short life span (higher aging speed) prolongs the retention time of attenuated chemotactic response to diacetyl after pre‐exposure to diacetyl. In the long‐lived daf‐2, age‐1, clk‐1 and isp‐1 mutants, the effect of diacetyl did not continue up to 2 hr. The short‐lived daf‐16, daf‐18, mev‐1 and gas‐1 mutants showed a longer duration of decrease in response to diacetyl, that is, the retention time of attenuated chemotactic response to diacetyl continued beyond 12 hr. There is a possibility that the duration of decrease in response to diacetyl after pre‐exposure to diacetyl was inversely related to the length of nematodes' life span. J. Exp. Zool. 311A:483–495, 2009. © 2009 Wiley‐Liss, Inc.