Per1^tm1Saco

A region encompassing sequence from exons 4 through 10 was replaced with a neomycin selection cassette. The deleted region encoded the entire PAS domain and a downstream portion of the PAC domain that is involved in dimerization and regulatory functions. RT-PCR analysis showed the presence of two truncated transcripts in homozygous mutant mice. Sequence analysis of the transcripts showed that the inserted neomycin transgene had been excised and in-frame stop codons had been introduced. The presence of two transcripts was the result of different splice patterns, one which included the remaining 5' portion of exon 4 and one that did not. Western blot analysis of protein extracts showed an absence of encoded protein in homozyous mutant mice. (J:70850)