Dr Dave Hazlerigg
I am interested in the mechanisms animals use to deal with predictable environmental changes based on geophysical cycles (Earth's rotation and orbit of the Sun, and the Moon's orbit of the Earth). Organisms have evolved biological clocks to synchronise to these cycles, and hence to predict temporal sequences of environmental change.
Intense research in this area has defined the mechanisms through which organisms generate endogenous "circadian" (= of approximately 24-h period length) rhythms in behaviour and physiology. The prevailing view is that cells throughout the organism can behave as autonomous circadian oscillators, but require synchronisation by a pacemaker in order that they coordinate their activities effectively.
This view of biological clock organisation invites questions about the differences between "pacemaker" structures (for example the suprachiasmatic nucleus within the brain of mammals) and those tissues enslaved to them, and about the pathways through which such communication is mediated.
We are exploring these issues by focussing on one particular facet of pacemaker output in mammals: the rhythmic production of melatonin. This neuroendocrine output is strongly coupled to the light-dark cycle, and has a particular involvement in seasonal responses. We are using multi-methodological approaches to investigate the ways in which melatonin synchronises oscillators in melatonin receptor expressing cells, and the impact of this on their functionality.
Hazlerigg DG, Wagner GC. Seasonal photoperiodism in vertebrates: from coincidence to amplitude. Trends Endocrinol Metab. 2006 Apr;17(3):83-91. Epub 2006 Mar 2.
Johnston JD, Tournier BB, Andersson H, Masson-Pevet M, Lincoln GA, Hazlerigg DG. Multiple effects of melatonin on rhythmic clock gene expression in the mammalian pars tuberalis. Endocrinology. 2006 Feb;147(2):959-65. Epub 2005 Nov 3.
Johnston JD, Ebling FJ, Hazlerigg DG. Photoperiod regulates multiple gene expression in the suprachiasmatic nuclei and pars tuberalis of the Siberian hamster (Phodopus sungorus). Eur J Neurosci. 2005 Jun;21(11):2967-74.