Clock Gene Disruption (IMAGE) University of Pennsylvania School of Medicine Caption Daily variation in blood pressure in normal mice versus mice in which clock genes have been disrupted. In mice with normal clock protein (BMAL) function, blood pressure rises during the morning hours (left). In BMAL knockout mice, the daily variation in blood pressure vanishes (right). Credit Annie M. Curtis, Ph.D., and Garret A. FitzGerald, M.D., University of Pennsylvania School of Medicine; Proceedings of the National Academy of Sciences Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.