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Kumar V Rani S Malik S Trivedi AK Schwabl I Helm B Gwinner E 《Die Naturwissenschaften》2007,94(8):693-696
Daytime light intensity can affect the photoperiodic regulation of the reproductive cycle in birds. The actual way by which
light intensity information is transduced is, however, unknown. We postulate that transduction of the light intensity information
is mediated by changes in the pattern of melatonin secretion. This study, therefore, investigated the effects of high and
low daytime light intensities on the daily melatonin rhythm of Afro-tropical stonechats (Saxicola torquata axillaris) in which seasonal changes in daytime light intensity act as a zeitgeber of the circannual rhythms controlling annual reproduction
and molt. Stonechats were subjected to light conditions simulated as closely as possible to native conditions near the equator.
Photoperiod was held constant at 12.25 h of light and 11.75 h of darkness per day. At intervals of 2.5 to 3.5 weeks, daytime
light intensity was changed from bright (12,000 lux at one and 2,000 lux at the other perch) to dim (1,600 lux at one and
250 lux at the other perch) and back to the original bright light. Daily plasma melatonin profiles showed that they were linked
with changes in daytime light intensity: Nighttime peak and total nocturnal levels were altered when transitions between light
conditions were made, and these changes were significant when light intensity was changed from dim to bright. We suggest that
daytime light intensity could affect seasonal timing via changes in melatonin profiles.
Professor Dr. E. Gwinner died on 07 September 2004. 相似文献
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G. Hugh Sidaway 《The Environmentalist》2008,28(3):307-314
Exposure of small laboratory animals to power-frequency high-voltage electric fields was reported to have endocrinological
effects, including changes in pineal melatonin levels. It has been assumed that these results are directly attributable to
electric-field effects, but this article suggests that air ionization, produced by corona activity at the animals’ body surfaces,
may have been biologically active and could be relevant to the interpretation of some epidemiological and other studies. Although
presently a matter of dispute, there is evidence that atmospheric ionization may be biologically active and could provide
an alternative explanation for at least some apparent electromagnetic field interactions with biological subjects. Consideration
of the electricity utilization environment as a whole, rather than one selected component, could allow the introduction of
lower-cost, precautionary and putative hazard remediation measures. 相似文献
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