Expression analysis of two types of transcripts from circadian output gene lark in Bombyx mori

We analyzed expression patterns of lark (Bmlark) in Bombyx mori. Southern blot analysis demonstrated that Bmlark was a single copy gene. Northern blot analyses revealed two types of Bmlark transcripts, one being of 1.38 kb (Bmlark-PA) and the other of 0.85 kb (Bmlark-PB). Both transcripts were detected in the eggs, larval and adult heads, testes, ovaries and flight muscles. Both types of transcripts are constitutively expressed with no clear rhythmicity in the adult heads under light:dark (LD) cycles but the amount of the Bmlark-PA transcript was twice as much as that of the Bmlark-PB transcript in the adult heads throughout a day. Real-Time PCR assays also indicated constant expressions of the two types of Bmlark in the pupal brains under LD12:12 and LD16:8.