Jump to main content
Jump to site search


Photoperiodic time measurement and photoentrainment of a circadian locomotor activity rhythm in subtropical tree sparrows

Author affiliations

Abstract

Experiments were performed on the subtropical tree sparrow (Passer montanus) to investigate the involvement of an endogenous circadian rhythm in photoperiodic time measurement during the initiation of gonadal growth and functions and also to study the photic entrainment of the circadian activity rhythm. Groups of photosensitive birds of both sexes were exposed to different “night-interruption” light–dark regimes of 24 h duration viz., G1 – 6L/5D/1L/12D, G2 – 6L/6D/1L/11D, G3 – 6L/7D/1L/10D, G4 – 6L/8D/1L/9D, G5 – 6L/10D/1L/7D, G6 – 6L/12D/1L/5D, G7 – 6L/14D/1L/3D and G8 – 6L/16D/1L/1D for 30 days in which 17 h long nights were interrupted by 1 h light pulse falling at different ZTs (i.e., 11, 12, 13, 14, 16, 18, 20 and 22). A control group, for each sex, was maintained under 7L/17D. The birds of all groups behaved as though they had been exposed to a stimulatory photoperiod except those of G1, G8 and the control. Furthermore, the serum levels of testosterone in males and estradiol-17β in females ran almost parallel to changes in the gonadal size. Birds, when exposed to 12L/12D, showed entrainment of their locomotor activity rhythm with the activity confined mainly during the light phase. However, various characteristics of the activity rhythm differed significantly upon transfer of birds to various night interruption regimes. These results suggest the involvement of the endogenous circadian rhythm in photoperiodic time measurement during the induction of gonadal growth and functions in the tree sparrow. Also, there is photic entrainment of the locomotor activity rhythm that shows variations in various circadian characteristics under different night interruption cycles suggesting that the photoinducible phase is differentially sensitive to light.

Graphical abstract: Photoperiodic time measurement and photoentrainment of a circadian locomotor activity rhythm in subtropical tree sparrows

Back to tab navigation

Publication details

The article was received on 24 Jul 2016, accepted on 28 May 2017 and first published on 30 May 2017


Article type: Paper
DOI: 10.1039/C6PP00271D
Citation: Photochem. Photobiol. Sci., 2017, Advance Article
  •   Request permissions

    Photoperiodic time measurement and photoentrainment of a circadian locomotor activity rhythm in subtropical tree sparrows

    A. S. Dixit, N. S. Singh and I. Bamon, Photochem. Photobiol. Sci., 2017, Advance Article , DOI: 10.1039/C6PP00271D

Search articles by author

Spotlight

Advertisements