“…Detection of Ca 2ϩ transients in individual cilia is of particular interest with respect to the mechanisms of sensory adaptation in ORNs. Elevated [Ca 2ϩ ] i governed by the activity of CNG channels plays important roles in feedback control of the sensitivity of olfactory transduction and is involved in a variety of specific regulatory functions such as desensitization during sustained stimulation (Kurahashi and Shibuya, 1990;Zufall et al, 1991b), rapid termination and recovery of the primary odor response (Kurahashi, 1989), and initiation of long-term adaptation (Zufall and Leinders-Zufall, 1997). Although many of the specific mechanisms and consequences triggered by Ca 2ϩ entry remain to be investigated, it is clear from previous work that elevated [Ca 2ϩ ] i can influence the activity of several molecular components of the cAMP pathway, including adenylyl cyclase (Sklar et al, 1986;Anholt and Rivers, 1990;Jaworski et al, 1995), CNG channels Kramer and Siegelbaum, 1992;Chen and Yau, 1994;Lynch and Lindemann, 1994), calmodulin-dependent phosphodiesterase (Borisy et al, 1992;Yan et al, 1995), Ca 2ϩ -activated Cl Ϫ channels (Kleene, 1993;Kurahashi and Yau, 1993;Lowe and Gold, 1993b;Zhainazarov and Ache, 1995), and Ca 2ϩ -activated K ϩ channels (Morales et al, 1995).…”