Aging alters properties of the circadian pacemaker controlling the locomotor activity rhythm in males of Drosophila nasuta.
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.
Joshi
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Zoology Department, Ahmednagar College, M.S., India. dsjoshi@pn3.vsnl.net.in
Barnabas
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Martin
E R
ER
Parihar
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V
Kanojiya
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M
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*