RAPID IDENTIFICATION OF NOVEL GENES EXPRESSED IN A CIRCADIAN MANNER IN RAT SUPRACHIASMATIC NUCLEI

THE circadian clock in mammals is located in the suprachiasmatic nucle i (SCN). There is evidence that changes in gene expression are central to its mechanism. We are engaged in identifying the genes involved. T he small size of the SCN, the large number of mammalian genes and the need to identify those differentially expressed over 24 h have require d novel experimental procedures. mRNA differential display and an impr oved tissue micropunching method have been used to examine temporal ch anges in gene expression in the SCN of rats maintained in constant dar kness. Several of the displayed cDNA species were found to be differen tially expressed; they show no homology with published sequences. Ribo probes of these cDNA species were used for in situ hybridization. Emul sion-dipped sections confirmed that at least two of these differential ly displayed mRNAs are expressed in a circadian manner.