Maroli Krishnayya Chandrashekaran earned his BSc, MSc and PhD (1963) degrees from the University of Madras and DSc (1985) from Madurai Kamaraj University. He did his PhD under the supervision of Professor CP Gnanamuthu, re-discovering the circadian and tidal rhythms in the swimming activity and oxygen consumption in the intertidal crab Emerita asiatica. He was invited as Alexander von Humboldt Scholar by Professor Erwin Bunning, the first chronicler of chronobiology, to the University of Tubingen, Germany. Here he switched over to work on the light relations of the biological clock in the fruitfully Drosophila pseudoobscura and performed the first two (Chase) light pulse experiments in chronobiology and additionally postulated in 1967 the Dawn and Dusk model to explain clock entrainment by light-dark cycles. This was the genesis of morning and evening oscillators much in vogue today.

Academic and Research Achievements: Chandrashekaran was the first Miller Invitation Fellow (1968-70) to work in Berkeley, UC independently and gave the first full account of the dependence of the phase shifts of the fly clock on the intensity of light of 1-10 lux. This important finding has implications in day length measurement (photoperiodism) regulating annual flowering of trees and bird migration. He returned to Tubingen and continued his work on Drosophila and demonstrated that the second half of the subjective night was ten-fold more sensitive to blue light of 480 nm and predicted that the several differences between early and late night phases may reflect deep seated differences in the kinetics as well as energy requirements of the oscillator. Chandrashekaran returned to India in 1975 and joined the Madurai Kamaraj University as Reader in Biology where he studied the biological clocks of insectivorous bats, working mainly with the cave-dwelling bat Hipposideros speoris. He discovered Social Synchronization of Circadian Rhymes in a colony of ca 600 bats living 40 m inside a cave, where bats told other bats time. He studied the light-sensitivity of the eyes of bats associated with dawn and dusk as well as colours and flashes. He built the first human isolation facility in the Third World and worked successfully on human circadian rhythms.

Awards and Honours: Professor Chandrashekaran was a National Fellow (UGC), National Lecturer (UGC) and National Lecturer (SERC-DST). He was awarded ASCOFF's Rule Prize of Germany (1991), SS Bhatnagar Prize (1979), JC Bose Prize (1986), Jawaharlal Nehru Birth Centenary Lectureship of INSA (1991), Professor Har Swarup Memorial Lecture of INSA (2005) and Millennium Plaque of Honour of Indian Science Congress Association (2007). He was a Fellow of the Indian Academy of Sciences, Bangalore (1983), National Academy of Sciences (India), Allahabad (1991), The Academy of Sciences for the Developing World (TWAS) (1995). Chandrashekaran served INSA as Editor of Publications (1998-99) and also as Vice-President (2000).