Dr. Tyler J. Stevenson has made major research contributions to a central question in regulatory biology, specifically the timing of biological functions to match environmental and seasonal conditions. His contributions include an examination of the role of one of the most important regulators of reproductive and sexual processes, gonadotropin-releasing hormone (GnRH). He conducted some seminal work on a newly-discovered form of this neurohormone in birds (GnRH-II), outlining its role in seasonality and reproduction, was the first to clone the gene for this hormone, and then used this genetic information to study the ways in which social and seasonal processes affected gene expression in the brain. More recent work in a mammalian system has shown how epigenetic regulation of genes in the brain and periphery can coordinate annual rhythms and cycles.
An exceptionally novel set of experiments revealed that melatonin can exert opposite epigenetic effects on gene expression at the same time, depending upon the target tissue. In short days (simulating winter conditions), a timing signal from the brain can epigenetically suppress gene expression that helps regulate gonadal function (since reproduction is not critical in winter months for a rodent) while at the same time enhancing gene expression in the immune system, which is critical for surviving harsh winter conditions. Stevenson’s current work addresses similar questions on biological timing using another innovative technique, transcriptomics, to further identify the ways in which biological clocks exert their effects on seasonality in different physiological systems. Thus, Stevenson has made major contributions to an exceptionally important scientific question: how are annual cycles coordinated by the brain? Notably he has explored these questions using techniques that are innovative, cutting-edge, and sophisticated.
Dr. Stevenson has communicated his work to the general public through a variety of articles in the popular science press. The links between photoperiod and immunology are particularly relevant for humans, given the universal exposure of people to artificial illumination. Further, he was recently the lead author on a paper that is likely to have high societal impacts as it links disrupted seasonal timing of biological functions with human health, food security, and broader ecosystems health (PMID: 26468242).
Dr. Stevenson is Senior Lecturer, School of Biological Sciences, University of Aberdeen, United Kingdom and received his doctorate in Psychological and Brain Sciences from Johns Hopkins University in 2011.
