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Updated: Aug 6, 2026

Expression of Fluorescent Proteins in Branchiostoma lanceolatum by mRNA Injection into Unfertilized Oocytes
Published on: January 12, 2015
Specific sequences outside the E-box are required for proper per expression and behavioral rescue
L C Lyons1, T K Darlington, H Hao
1Department of Biology and Biochemistry, University of Houston, TX, USA.
Abstract:
A 69 bp circadian regulatory sequence (CRS) upstream of the per gene is sufficient to drive circadian transcription, mediate proper spatial expression, and rescue behavioral rhythmicity in per01 flies. Within the CRS, an E-box is required for transcriptional activation by two basic-helix-loop-helix (bHLH) PERARNT-SIM (PAS) transcription factors, dCLOCK (dCLK) and CYCLE (CYC). To define sequences within the CRS that are required for spatial expression, circadian expression, and behavioral rhythmicity, a series of mutants that alter blocks of 3 to 12 nucleotides across the entire CRS were used to drive lacZ or per expression in vivo. As expected, the E-box within the CRS is necessary for high-level expression and behavioral rhythmicity, but sequences outside the E-box are also required for transcriptional activation, proper spatial expression, and behavioral rhythmicity. These results indicate that the dCLK-CYC target site extends beyond the E-box and that factors other than dCLK and CYC modulate per transcription.
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