The circadian clock is a self-sustaining oscillator system controlling many physiological and behavioural processes. The underlying rhythms are generated by a set of clock genes, which are expressed in an oscillating manner on transcriptional and translational levels. To investigate the avian circadian system, homologues of mammalian clock genes have been cloned in the house sparrow, a model organism in circadian research. Expression levels were investigated in the brain and in peripheral tissues, including the gastro-intestinal tract. Pronounced rhythmic mRNA expression was found in all tissues investigated. .Tissue-specific differences in temporal distribution, peak expression and amplitude suggest that the molecular composition of the avian circadian clock is distinct from that in mammals. A novel cryptochrome gene in birds is described and subsequent molecular analysis reveals that functionally diverse cryptochromes are present in the house sparrow. A comparison of clock gene expression normalised to different house-keeping genes. demonstrates results on phasing and amplitude are strongly influenced by the selection of house-keeping genes for normalisation. This study has therefore improved our understanding of the circadian system in birds and provides new insights into the molecular basis of a complex circadian organisation in birds.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:487496 |
| Date | January 2007 |
| Creators | Gisela, Helfer |
| Publisher | University of Birmingham |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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