Erwin Bueunning (1906-1990): A centennial homage

摘要

The study of biological rhythms, now called chronobiology, has had a hoary past in Europe and is replete with big names. It drew into its fold many brilliant scientists in the 18th, 19th and 20th centuries and continues to draw outstanding talent in the 21st century. The first record of a cir-cadian rhythm was by the Greek philosopher Androsthenes describing the sleep movements of the leaves of the tamarind tree, when he joined Alexander of Macedon in his march on India in the fourth century BC. Carl von Linne (1707-1778) constructed a floral clock based on his knowledge of the opening of flowers at different hours of the day. The experimental demonstration of an endogenous component was first performed by the French astronomer de Mairan in 1729: he took potted Mimosa pudica plants into the perpetual darkness of a deep cave and reported that the nightly 'sleep' movements of the leaves persisted. Wilhelm Pfeffer (1845-1920) had built a laboratory for research on bean leaf movement rhythms at the University of Leipzig over a hundred years ago with temperature control and automatic switching of lights on and off for desired light: darkness cycles complete with built-in dawn and dusk simulations (Buenning and Chandrashekaran 1975). Jagadish Chandra Bose (1858-1937) wrote landmark papers on his findings on diurnal movements in plants. In the monograph Life Movements in Plants (in three volumes), written in 1918, 1919 and 1923, Bose had investigated with consummate care, all environmental factors that could modulate and interact with diurnal rhythms. Bose described the entrainment of plant movements to light: dark cycles and observed free-running periods in continuous light and continuous darkness as early as 1919 (Chandrashekaran and Subbaraj 1996). This work of Bose was cited by Buenning (1958) in his classic first monograph The Physiological Clock. In 1930 Buenning and Stem stressed that the periods of rhythms under constant conditions deviated from 24 h thus justifying the use of the expressive term circadian coined by Halberg in 1959. In 1932 Buenning did crossing experiments with bean plants having different periods and demonstrated that the F-1 generation had periods of intermediate durations clearly demonstrating the heritability of circadian rhythms. Buenning truly bridged the tradition of experimental chrono-biology started by stalwarts like Pfeffer and Bose and the traditions of molecular and genetic studies of circadian rhythms.