passages.id: split_4_validation_576_passage
passages.type: progene_text
passages.text: Fusion of a 1.5 - kb promoter fragment to the beta-glucuronidase ( gus ) reporter gene leads to circadian oscillations in the level of the gus transcript in transgenic Arabidopsis plants , with highest levels in the evening , indicating that transcription of the Atgrp7 gene is rhythmically activated by the endogenous circadian clock .