Brighter than the sun: Rajni Govindjee at 80 and her fifty years in photobiology.

We celebrate distinguished photobiologist Rajni Govindjee for her pioneering research in photosynthesis and retinal proteins on the occasion of her 80th birthday.

Victor Henri: 111 years of his equation.

Victor Henri's great contribution to the understanding of enzyme kinetics and mechanism is not always given the credit that it deserves. In addition, his earlier work in experimental psychology is totally unknown to biochemists, and his later work in spectroscopy and photobiology almost equally so. Applying great rigour to his analysis he succeeded in obtaining a model of enzyme action that explained all of the observations available to him, and he showed why the considerable amount of work done in the preceding decade had not led to understanding. His view was that only physical chemistry could explain the behaviour of enzymes, and that models should be judged in accordance with their capacity not only to explain previously known facts but also to predict new observations against which they could be tested. The kinetic equation usually attributed to Michaelis and Menten was in reality due to him. His thesis of 1903 is now available in English.

Of ion pumps, sensors and channels - perspectives on microbial rhodopsins between science and history.

We present a historical overview of research on microbial rhodopsins ranging from the 1960s to the present date. Bacteriorhodopsin (BR), the first identified microbial rhodopsin, was discovered in the context of cell and membrane biology and shown to be an outward directed proton transporter. In the 1970s, BR had a big impact on membrane structural research and bioenergetics, that made it to a model for membrane proteins and established it as a probe for the introduction of various biophysical techniques that are widely used today. Halorhodopsin (HR), which supports BR physiologically by transporting negatively charged Cl⁻ into the cell, is researched within the microbial rhodopsin community since the late 1970s. A few years earlier, the observation of phototactic responses in halobacteria initiated research on what are known today as sensory rhodopsins (SR). The discovery of the light-driven ion channel, channelrhodopsin (ChR), serving as photoreceptors for behavioral responses in green alga has complemented inquiries into this photoreceptor family. Comparing the discovery stories, we show that these followed quite different patterns, albeit the objects of research being very similar. The stories of microbial rhodopsins present a comprehensive perspective on what can nowadays be considered one of nature's paradigms for interactions between organisms and light. Moreover, they illustrate the unfolding of this paradigm within the broader conceptual and instrumental framework of the molecular life sciences. This article is part of a Special Issue entitled: Retinal Proteins - You can teach an old dog new tricks.

A tribute to Hemming Virgin (1918-2005), a Swedish pioneer in plant photobiology.

We present here a tribute to Hemming Ivar Virgin (October 19, 1918-October 19, 2005), a pioneer in Swedish plant photobiology, developer of a University, and an outstanding educator.

A tribute to Per Halldal (1922-1986), a Norwegian photobiologist in Sweden.

We present here a tribute to Per Halldal (February 2, 1922-March 26, 1986), a leader, an instrumentalist, an expert on phototaxis in algae, and one whom we remember, even after 20 years of his death, as a person who spread joy, enthusiasm and knowledge wherever he went.

My early days in photobiology with Philip Hanawalt.

Phil and I started our careers on somewhat similar scientific paths. I had an undergraduate degree in physics from Swarthmore College and a Ph.D. degree in physics from Yale for research in the field for ultraviolet spectroscopy. Phil received an undergraduate degree in Physics from Oberlin College, joined the Yale Physics Department in 1954, and transferred to the new Biophysics Department in 1955. We began our interactions then by virtue of the fact that Phil had to take a Laboratory Course in Experimental Physics, one part of which was spectroscopy in which I was the instructor. One of my principal interests was in the effects of different wavelengths of ultraviolet (UV) radiation on proteins, viruses and bacterial cells. So what was more natural than for Phil to dream up a Ph.D. research project to investigate the effects of different wavelengths of UV on macromolecular synthesis in Escherichia coli. I became his mentor with expertise in UV, whereas he did most of the microbiological/biochemical work. Thus began a collaboration and a communicating friendship, the latter going on for 50 years. That communication was essential in elucidating some of the important steps in nucleotide excision repair-a field in which Phil is a pre-eminent scholar and investigator.