title: Aging alters properties of the circadian pacemaker controlling the locomotor activity rhythm in males of Drosophila nasuta.
abstract: Effects of aging on the circadian rhythm of locomotor activity in males of Drosophila nasuta were investigated. The adult life of males was divided in 1-3 stages according to spontaneous changes in free-running period tau in constant darkness (DD): stage 1, days 1-19; stage 2, days 20-36; stage 3, days 37-43. Stage 1 was characterized by a bimodal activity pattern with a short light-induced morning peak and a prolonged evening peak when the flies were entrained to light-dark cycles of 12 hours of light, 12 hours of darkness (LD 12:12). The morning peak had a phase angle difference psi m (psi, the time from lights on in LD 12:12 cycles to the onset of morning peak) of about 0.1 h, while psi e (psi of evening peak) was about 9 h at stage 1. The transient morning peak was curtailed at the end of stage 1. At stage 2, the psi e was about 10 h, and the activity end was delayed by an addition of about 3 h of activity in the scotophase. The changes in tau during DD free runs were determined in two groups of flies: flies reared in LD 12:12 and flies reared in DD. In both groups, tau increased from about 23 h at stage 1 to about 25 h at stage 2. Stage 3 was characterized by arrhythmicity associated with highest mean activity level (total number of passes/fly/day) in the entrained and both free-running groups. The mean activity level increased significantly from stage 1 to stage 3 in all three groups of flies.
authors.affiliation: Zoology Department, Ahmednagar College, M.S., India. dsjoshi@pn3.vsnl.net.in
authors.forename: D
authors.initials: D
authors.lastname: Joshi
authors.forename: R
authors.initials: R
authors.lastname: Barnabas
authors.forename: E R
authors.initials: ER
authors.lastname: Martin
authors.forename: V
authors.initials: V
authors.lastname: Parihar
authors.forename: M
authors.initials: M
authors.lastname: Kanojiya
mesh_terms: D000375:Aging; D000818:Animals; D001683:Biological Clocks; D002940:Circadian Rhythm; D003624:Darkness; D004330:Drosophila / Q000254:growth & development / Q000502:physiology*; D008027:Light; D008297:Male; D009043:Motor Activity / Q000502:physiology*