Romanowsky staining,the Romanowsky effect and thoughts on the question of scientific priority

I give an historical account and analysis of the scientific priority of the discovery of the polychrome staining of microscopic biological preparations provided by mixtures of eosin plus methylene blue and its derivatives, especially azure B. I maintain that both the formal priority for the discovery of the polychrome staining phenomenon and credit for initiating the development of a technique of polychrome staining properly belong to D. L. Romanowsky. His scientific work demonstrated the possibility of using a simple technique to stain hematological preparations selectively to give good contrast, high resolution and the ability to identify malaria parasites. Romanowsky’s approach constituted the starting point for the development of a family of polychrome stains for microscopic investigation of hematological preparations by a number of his contemporaries.     

Microfluidics Approaches in Modern Developmental Biology

Modern automated microsystems based on microhydrodynamic (microfluidic) technologies— labs on chips—make it possible to solve various basic and applied research problems. In the last 15 years, the development of these approaches in application to the problems of modern quantitative (systems) development biology has been observed. In this field, high-throughput experiments aimed at accumulating ample quantitative data for their subsequent computer analysis are important. In this review, the main directions in the development and application of microfluidics approaches for solving problems of modern developmental biology using the classical model object, Drosophila embryo, as an example is discussed. Microfluidic systems provide an opportunity to perform experiments that can hardly be performed using other approaches. These systems allow automated, rapid, reliable, and proper placing of many live embryos on a substrate for their simultaneous confocal scanning, sorting them, or injecting them with various agents. Such systems make it possible, in particular, to create controlled gradients of microenvironmental parameters along a series of developing embryos or even to introduce discontinuity in parameters within the microenvironment of one embryo, so that the head half is under other conditions compared to the tail half (at continuous scanning). These approaches are used both in basic research of the functions of gene ensembles that control early development, including the problems of resistance of early patterns to disturbances, and in test systems for screening chemical agents on developing embryos. The problems of integration of microfluidic devices in systems for automated performance of experiments simultaneously on many developing embryos under conditions of their continuous scanning using modern fluorescence microscopy instruments will be discussed. The methods and approaches developed for Drosophila are also applicable to other model objects, even mammalian embryos.     

Energetic aspects of CO oxidation in desulfovibrio desulfuricans

In cell suspension of Desulfovibrio desulfuricans B-1388, oxidation of CO as the only energy source is associated with reduction of SO42-. After a 2-h incubation of cells in 8% CO, 81% of the gas is converted. Oxidation of 1 mole CO results in formation of 0.23 mole H2S. Intracellular ATP content increases from 2.5 (control) to 8.3 nmoles/mg (during CO conversion). Dinitrophenol inhibits sulfate reduction and CO oxidation. CO dehydrogenase was detected in cytoplasmic and membrane cell fractions (59 and 34%, respectively).     

Characterization of the Drosophila segment determination morphome

Here we characterize the expression of the full system of genes which control the segmentation morphogenetic field of Drosophila at the protein level in one dimension. The data used for this characterization are quantitative with cellular resolution in space and about 6 min in time. We present the full quantitative profiles of all 14 segmentation genes which act before the onset of gastrulation. The expression patterns of these genes are first characterized in terms of their average or typical behavior. At this level, the expression of all of the genes has been integrated into a single atlas of gene expression in which the expression levels of all genes in each cell are specified. We show that expression domains do not arise synchronously, but rather each domain has its own specific dynamics of formation. Moreover, we show that the expression domains shift position in the direction of the cephalic furrow, such that domains in the anlage of the segmented germ band shift anteriorly while those in the presumptive head shift posteriorly. The expression atlas of integrated data is very close to the expression profiles of individual embryos during the latter part of the blastoderm stage. At earlier times gap gene domains show considerable variation in amplitude, and significant positional variability. Nevertheless, an average early gap domain is close to that of a median individual. In contrast, we show that there is a diversity of developmental trajectories among pair-rule genes at a variety of levels, including the order of domain formation and positional accuracy. We further show that this variation is dynamically reduced, or canalized, over time. As the first quantitatively characterized morphogenetic field, this system and its behavior constitute an extraordinarily rich set of materials for the study of canalization and embryonic regulation at the molecular level.     

Feedback equilibrium control during human standing

Equilibrium maintenance during standing in humans was investigated with a 3-joint (ankle, knee and hip) sagittal model of body movement. The experimental paradigm consisted of sudden perturbations of humans in quiet stance by backward displacements of the support platform. Data analysis was performed using eigenvectors of motion equation. The results supported three conclusions. First, independent feedback control of movements along eigenvectors (eigenmovements) can adequately describe human postural responses to stance perturbations. This conclusion is consistent with previous observations (Alexandrov et al., 2001b) that these same eigenmovements are also independently controlled in a feed-forward manner during voluntary upper-trunk bending. Second, independent feedback control of each eigenmovement is sufficient to provide its stability. Third, the feedback loop in each eigenmovement can be modeled as a linear visco-elastic spring with delay. Visco-elastic parameters and time-delay values result from the combined contribution of passive visco-elastic mechanisms and sensory systems of different modalities