Reader in Chronobiology and Integrative Physiology (from 2013)

Senior Lecturer in Neuroscience, University of Surrey (2010-2013)

Lecturer in Neuroscience, University of Surrey (2005-2010)

Postdoctoral Research Fellow, University of Aberdeen (2001-2005)

PhD, University of Manchester (1998-2001)

Biological Rhythms Life on Earth is profoundly affected by rhythmic changes in environmental conditions, including light, temperature and food availability, ultimately caused by planetary rotation and orbit. In order to adapt to these environmental changes, living organisms have evolved internal 'biological clocks' that influence many aspects of physiology (e.g. body temperature, sleep, hormone secretion and cell division).

Circadian Regulation of Adipose (Fat) Physiology Obesity and related metabolic disturbances (including type 2 diabetes mellitus) comprise one of the biggest healthcare problems in contemporary society. A clear link is now emerging between the biological clock and various aspects of metabolism and energy balance. We are developing model systems to study the causative relationships between clock function and metabolism in cultured fat cells (adipocytes) and also in tissue samples taken from human subjects.

A notable recent achievement has been our validation of human white fat as an accessible and metabolically relevant tissue that is suitable for studies of human daily rhythms. This finding will enable us to further understand the functional role of biological rhythms in human fat biology and also use white fat as a marker for studies into the fundamental properties of human biological rhythms.

Seasonal Rhythmicity and Melatonin Receptor Expression In mammals, an important biological rhythm is the nocturnal secretion of the hormone melatonin from the pineal gland, located in the brain. Changing day-length (photoperiod) varies the rhythm of melatonin secretion, and therefore melatonin signals both daily and seasonal time throughout the body. In many species, melatonin can help to reset daily rhythms and is used as a therapeutic agent in blindness, jet lag, and other human conditions where the biological clock becomes disrupted from the environment. Furthermore, most wild animals living in temperate regions use changes in the characteristics of the daily melatonin signal to control their seasonal changes in physiology, such as reproduction, fur quality and hibernation.

Current research focuses on 1) how changes in photoperiod and pineal melatonin secretion are decoded at the molecular and cellular level, and 2) the molecular mechanisms that drive developmental changes in melatonin receptor expression in the neuroendocrine system.

Laing EE, *Johnston JD, Möller-Levet CS, Bucca G, Smith CP, Dijk DJ, Archer SN. Exploiting human and mouse transcriptomic data: identification of circadian genes and pathways influencing health. (OPEN ACCESS) Bioessays 2015; 37: 544-556. Gee RH, Spinks JN, Malia JM, Johnston JD, Plant NJ, Plant KE. Inhibition of prenyltransferase activity by statins in both liver and muscle cell lines is not causative of cytotoxicity. Toxicology 2015; 329: 40-48. Johnston JD. Physiological links between circadian rhythms, metabolism and nutrition. Experimental Physiology 2014; 99: 1133-1137. Hampton SM, Johnston JD. Probing the diurnal regulation of glycemic control. (OPEN ACCESS) Journal of Diabetes and its Complications 2014; 28: 751-752. Frost G, Cai Z, Raven M, Otway DT, Mushtaq R, Johnston JD. Effect of short chain fatty acids on the expression of free fatty acid receptor 2 (Ffar2), Ffar3 and early-stage adipogenesis. (OPEN ACCESS) Nutrition and Diabetes 2014; 4: e128. Johnston JD. Physiological responses to food intake throughout the day. (OPEN ACCESS) Nutrition Research Reviews 2014; 27: 107-118.