Identification of putative rat ribonuclease III by differential display: a novel rat mRNA expressed in a circadian manner in the rat suprachiasmatic nucleus

The suprachiasmatic nucleus (SCN) of the hypothalamus constitutes the principal site responsible for the generation and entrainment of circadian rhythms in mammals. The mechanisms of the circadian clock involve periodic gene expression. Here we report the use of differential display reverse transcriptase polymerase chain reaction to identify a novel rat mRNA sequence which is highly homologous to human ribonuclease III. Analysis of its expression in the rat brain by in situ hybridization histochemistry showed this transcript to be expressed at differing intensities at various sites. Temporal variation in expression was observed in the SCN, with a peak at circadian time (CT) 2 and a nadir at CT14. No significant changes in its expression were detected across the cycle within the supraoptic nucleus, cingulate cortex or caudate putamen. (C) 2004 Elsevier B.V. All rights reserved.