R. Brandstatter et al., Initial demonstration of rhythmic Per gene expression in the hypothalamus of a non-mammalian vertebrate, the house sparrow, NEUROREPORT, 12(6), 2001, pp. 1167-1170
In mammals, the major pacemaker controlling circadian rhythmicity is locate
d in the hypothalamic suprachiasmatic nuclei which are characterized by spe
cific molecular features including the expression of three homologues of th
e Drosophila clock gene period (per). Until now, no comparable structure ha
s been unambiguously described in the brain of any nonmammalian vertebrate.
We cloned the PAS-domain of the Per2 gene in the house sparrow (Passer dom
esticus), a model organism in circadian research. Hypothalamic expression o
f posserPer2 (pPer2) showed a marked diurnal rhythm in the suprachiasmatic
nucleus, a cell group located in the anterior hypothalamus directly above t
he optic chiasm and adjacent to the third ventricle. Additionally, pPer2 wa
s diurnally expressed in the lateral hypothalamus. This first demonstration
of rhythmic clock gene expression in the hypothalamus of a nonmammalian ve
rtebrate provides basic information for future research on the evolution of
circadian pacemaking systems. NeuroReport 12:1167-1170 (C) 2001 Lippincott
Williams & Wilkins.