Photoperiod and its effects on seasonal changes in the song control system of the house sparrow, Passer domesticus /
The house sparrow is a well studied species for
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
1995.
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| Summary: | The house sparrow is a well studied species for photoperiodism. Song control nuclei have been shown to exhibit seasonal morphological changes in several avian species, with breeding season coinciding with large robust nuclei. In the following study three separate experiments were run to determine whether seasonal changes in song control nuclei of the house sparrow were regulated by photoperiod, gonadal steroids or a combination of both. All three experiments used adult male house sparrows housed in one of three separate light dark cycles (Id) for 20 weeks. Each Id cycle represented a different reproductive state. Birds housed in an extended short day (Id 6:18) photoperiod for 20 weeks were the photosensitive group (SD). This group had small regressed gonads. Birds housed in a long day (Id 18:6) for the last 8 weeks of the experiment were the photostimulated group (LD). This group had large recrudesced gonads. Birds housed in extended long days (Id 18:6) for the last 14 weeks of the experiment were the photorefractory group (LDLD). This group had small spontaneously regressed gonads. Morphometric seasonal fluctuations occurred in the song control nuclei in all three experiments. In Experiment 1, these changes were linked to photoperiodic control, perhaps independent of gonadal steroids. In Experiment 2, these changes were linked to gonadal steroid control. In Experiment 3, which compared castrated and sham operated animals, these changes were linked to both gonadal steroid and photoperiodic control. Therefore, together these experiments suggested a parallel role of gonadal steroid and photoperiodic regulation of seasonal morphological changes in the house sparrow song control system. To determine the mechanism of these seasonal changes 2-[125I] iodomelatonin (IMEL) binding was measured, as was cytochrome oxidase (CO) activity. IMEL binding and CO activity were found in all song control nuclei measured. However, no clear patterns emerged linking IMEL binding or CO activity to either photoperiodic or gonadal steroid regulation. In spite of this, both IMEL binding and CO activity were photoperiodic, indicating a need for further study of their role in the regulation of the song control system of the house sparrow. |
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| Item Description: | Vita. "Major subject: Zoology". |
| Physical Description: | xii, 120 leaves : illustrations ; 28 cm. Issued also on microfiche from Lange Micrographics. |
| Bibliography: | Includes bibliographical references. |