caa a22 4500 463175859 CHVBK 20180406164825.0 cr unu---uuuuu 170326e20071201xx s 000 0 eng 10.1007/s10336-007-0236-z doi (NATIONALLICENCE)springer-10.1007/s10336-007-0236-z Photoperiodism, pineal clock and seasonal reproduction in the Indian Weaver Bird ( Ploceus philippinus ) [Elektronische Daten] [Sangeeta Rani, Sudhi Singh, Vinod Kumar] Previous studies show that, in birds, pineal melatonin is important for circadian rhythmicity, and circadian rhythms mediate photoperiodic effects. The effect of pinealectomy or melatonin administration in photoperiodic induction of testicular growth is not found in many bird species. This is inconsistent with the fact that avian pineal is a self-sustained circadian biological clock and decodes both the daily and annual photoperiodic information. Does this mean that the pineal clock in birds regulates circadian rhythms, but not the one that is involved in the photoperiodic induction of the seasonal response? We have examined this in experiments on the subtropical Indian Weaver Bird (Ploceus philippinus). We investigated the effects of the absence of the pineal gland or exogenous melatonin administration on circadian rhythmicity in activity, and on photoperiodic induction of testicular growth, androgen-dependent beak pigmentation and luteinizing hormone-specific plumage coloration. Weaver birds were subjected for several weeks to short day length (8h light: 16h darkness, 8L:16D), long day length (16L:8D) and to light-dark cycles that tested the involvement of circadian rhythmicity in photoperiodic time measurement. The results show that circadian pineal clock may regulate the circadian rhythm in activity, but is not essential for the expression of photoperiodism associated with the photoperiodic induction of testicular growth. This suggests that the circadian activity and photosensitivity rhythms are outputs of different circadian oscillators or of the same set of circadian oscillators, but that they are not closely coupled. Dt. Ornithologen-Gesellschaft e.V., 2007 Circadian rhythm nationallicence Melatonin nationallicence Photoperiod nationallicence Pineal nationallicence Ploceus philippinus nationallicence Rani Sangeeta DST-IRHPA Unit on Biological Rhythm Research, Department of Zoology, University of Lucknow, 226 007, Lucknow, India aut Singh Sudhi DST-IRHPA Unit on Biological Rhythm Research, Department of Zoology, University of Lucknow, 226 007, Lucknow, India aut Kumar Vinod DST-IRHPA Unit on Biological Rhythm Research, Department of Zoology, University of Lucknow, 226 007, Lucknow, India aut Journal of Ornithology Springer-Verlag 148(2007-12-01), 601-610 0021-8375 148<601 2007 148 10336 https://doi.org/10.1007/s10336-007-0236-z text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10336-007-0236-z text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Rani Sangeeta DST-IRHPA Unit on Biological Rhythm Research, Department of Zoology, University of Lucknow, 226 007, Lucknow, India aut NATIONALLICENCE 700 1- Singh Sudhi DST-IRHPA Unit on Biological Rhythm Research, Department of Zoology, University of Lucknow, 226 007, Lucknow, India aut NATIONALLICENCE 700 1- Kumar Vinod DST-IRHPA Unit on Biological Rhythm Research, Department of Zoology, University of Lucknow, 226 007, Lucknow, India aut NATIONALLICENCE 773 0- Journal of Ornithology Springer-Verlag 148(2007-12-01), 601-610 0021-8375 148<601 2007 148 10336 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer