A Brief History of the Biological Stain Commission: its Founders,its Mission and the First 75 Years

The need for batch-to-batch consistency in available dyes and stains used for biological purposes posed a considerable problem for United States scientists following World War I. Prior to that time, most of the acceptable stains in this country were of German origin. In an attempt to standardize the performance of biological stains and dyes, the Society of American Bacteriologists in 1922 appointed Dr. Harold Conn to form the Committee on the Standardization of Biological Stains. To assist him, Dr. Conn recruited scientists from several major professional scientific societies. Mr. Holland Will, a Rochester, NY, vendor of stains, was also instrumental in the Committee's success. This article traces the origin, mission and accomplishments of the product of that Committee, the Biological Stain Commission, through the past 75 years, and focuses on some of the major events that influenced and shaped its development.     

A Brief History of the Biological Stain Commission: its Founders, its Mission and the First 75 Years

The need for batch-to-batch consistency in available dyes and stains used for biological purposes posed a considerable problem for United States scientists following World War I. Prior to that time, most of the acceptable stains in this country were of German origin. In an attempt to standardize the performance of biological stains and dyes, the Society of American Bacteriologists in 1922 appointed Dr. Harold Conn to form the Committee on the Standardization of Biological Stains. To assist him, Dr. Conn recruited scientists from several major professional scientific societies. Mr. Holland Will, a Rochester, NY, vendor of stains, was also instrumental in the Committee's success. This article traces the origin, mission and accomplishments of the product of that Committee, the Biological Stain Commission, through the past 75 years, and focuses on some of the major events that influenced and shaped its development.     

Phototropism: Some History,Some Puzzles,and a Look Ahead

After over a century of progress, phototropism research still presents some fascinating challenges.Though few and far between, phototropism studies through 1937 established a number of important principles. (1) Blue light is the active spectral region. (2) The phototropic stimulus is perceived by the coleoptile tip, and the consequences of the stimulation progress down into the growing region. (3) Lateral transport of auxin mediates the curvature response. (4) The reciprocity law holds for first positive curvature, whereas second positive curvature is time dependent. (5) Red light treatment had a major effect on phototropic sensitivity. Later studies established the following. (6) Seven blue light receptors (cryptochromes, phototropins, and three F-box proteins) were identified and characterized. (7) A flavin was established as the photoreceptor chromophore for all seven. (8) The chromophore domain, designated the LOV domain (for light, oxygen, or voltage), carries out a unique photochemistry. (9) LOV domains must be truly ancient chromophore domains. There remain some puzzles. The fluence-response threshold level for first positive curvature is far below that for phototropin photochemistry. Likewise, the fluence-response threshold level for the red light effect on coleoptile phototropism is far below those for phytochrome phototransformation. Cytological effects of red light are also very insensitive compared with the physiological effects of red light. What is the mechanism allowing for this extraordinary photosensitivity? How is phototropin specificity controlled? What are the functions of the phytochrome kinase substrate proteins in both phytochrome and phototropin responses? What mechanism leads to lateral auxin transport? Finally, are LOV domain proteins true photoreceptors in all of the bacteria in which they occur? If so, what is their biological function?Even in the ancient world, astute observers noted that plants could turn to face the sunlight. What was originally designated heliotropism for plants that followed the sun eventually became divided into two distinct response categories: solar tracking (the real heliotropism), a repetitive and completely reversible turgor-driven process; and phototropism, an irreversible directional growth response determined by light direction. Over the past 200 years, a large number of brilliant biologists, including Julius Sachs (1864), Charles Darwin (1881), Frits Went (1928), and Kenneth Thimann (Went and Thimann, 1937) have applied their talents to examining and elucidating the mechanisms accounting for both of these responses. The entire history of phototropism and solar tracking parallels and is intertwined with that for a number of other blue light responses, found not just in higher plants but in bryophytes, ferns, algae, fungi, and, most recently bacteria. For a detailed account of this history, see Briggs (2006).Progress in research on blue light-activated processes over the last half century was severely hampered by a lack of knowledge of the relevant blue light receptors. By contrast, the discovery and initial characterization of a red/far-red-reversible phytochrome (Butler et al., 1959) nurtured an enormous and sophisticated body of knowledge about these photoreceptors: their structure, their chromophores, their photophysics and photochemistry, and the extraordinary signal transduction networks that they rule. Meanwhile, although a huge and scattered body of knowledge on blue light responses in plants and fungi accumulated, there was scarcely a clue to what the photoreceptor(s) might be, and competing hypotheses abounded. Attention focused on the physical and physiological characterization of responses to blue light and, eventually, biochemical investigations of intriguing in vitro photochemistry. It was only with the advent of modern molecular genetics and its extraordinary capabilities that research on blue light photobiology finally began to catch up with phytochrome photobiology 20 years ago and the first blue light receptor, cryptochrome1 (cry1), became identified (Ahmad and Cashmore, 1993).This review will go back to some of the puzzles of earlier years, a few over 100 years old, and provide a glimpse of the status of these puzzles today. They arose from studies of response kinetics, action spectroscopy, interactions between blue and red regions of the visible spectrum, and discrepancies between in vivo and in vitro results. Although the focus will be on higher plant phototropism, several other blue light responses will contribute to the discussion. No effort will be made to be comprehensive. Any effort here would be redundant with that of three recent excellent reviews on phototropism (Sakai and Haga, 2012; Christie and Murphy, 2013; Hohm et al., 2013) and on LOV (for light, oxygen, or voltage) domain photochemistry (Losi and Gärtner, 2011, 2012). The article concludes with a look at the unexpected role of LOV domains in prokaryotes.