Specificity of sterol-glucosylating enzymes from Sinapis alba and Physarum polycephalum.

1. Sinapis alba L. seedlings contain glycosyltransferase catalyzing the synthesis of sterol glucosides in the presence of UDPglucose as sugar donor. The major activity occurs in the membranous fraction sedimenting at 300--9000 x g. Successive treatment of the particulate enzyme fraction with acetone and Triton X-100 affords a soluble glucosyltransferase preparation which can be partly purified by gel filtration on Sephadex G-150. Molecular weight of the glucosyltransferase is 1.4 . 10(5). Apparent Km values for UDPglucose and sitosterol are 8.0 . 10(-5) M and 5.0 . 10(-6) M, respectively. 2. Comparison was made of the S. alba glucosyltransferase with a similar sterol-glucosylating enzyme isolated from non-photosynthesizing organism Physarum polycephalum (Myxomycetes). UDPglucose was the most efficient glucose donor in both cases but the enzyme from Ph. polycephalum can also utilize CDPglucose and TDPglucose. Glucose acceptors are, in case of both enzymes, sterols containing a beta-OH group at C-3 and a planar ring system (5 alpha-H or double bond at C-5). The number and position of double bonds in the ring system and in the side chain, as well as the presence of additional alkyl groups in the side chain at C-24 are of secondary importance. 3. The present results indicate that both enzymes can be regarded as specific UDPglucose:sterol glucosyltransferases. Certain differences in their specificity towards donors and acceptors of the glucosyl moiety suggest, however, a different structure of the active sites in both enzymes.     

Magnetic Alignment in Carps: Evidence from the Czech Christmas Fish Market

While magnetoreception in birds has been studied intensively, the literature on magnetoreception in bony fish, and particularly in non-migratory fish, is quite scarce. We examined alignment of common carps (Cyprinus carpio) at traditional Christmas sale in the Czech Republic. The sample comprised measurements of the directional bearings in 14,537 individual fish, distributed among 80 large circular plastic tubs, at 25 localities in the Czech Republic, during 817 sampling sessions, on seven subsequent days in December 2011. We found that carps displayed a statistically highly significant spontaneous preference to align their bodies along the North-South axis. In the absence of any other common orientation cues which could explain this directional preference, we attribute the alignment of the fish to the geomagnetic field lines. It is apparent that the display of magnetic alignment is a simple experimental paradigm of great heuristic potential.     

Differential expression of genes participating in cardiomyocyte electrophysiological remodeling via membrane ionic mechanisms and Ca2+-handling in human heart failure

Molecular and Cellular Biochemistry - Excitation–contraction coupling in normal cardiac function is performed with well balanced and coordinated functioning but with complex dynamic...     

Virucidal Nanofiber Textiles Based on Photosensitized Production of Singlet Oxygen

Novel biomaterials based on hydrophilic polycaprolactone and polyurethane (Tecophilic®) nanofibers with an encapsulated 5,10,5,20-tetraphenylporphyrin photosensitizer were prepared by electrospinning. The doped nanofiber textiles efficiently photo-generate O₂(¹Δ_g), which oxidize external chemical and biological substrates/targets. Strong photo-virucidal effects toward non-enveloped polyomaviruses and enveloped baculoviruses were observed on the surface of these textiles. The photo-virucidal effect was confirmed by a decrease in virus infectivity. In contrast, no virucidal effect was detected in the absence of light and/or the encapsulated photosensitizer.     

Epigenetic and Conventional Regulation Is Distributed among Activators of FLO11 Allowing Tuning of Population-Level Heterogeneity in Its Expression

Epigenetic switches encode their state information either locally, often via covalent modification of DNA or histones, or globally, usually in the level of a trans-regulatory factor. Here we examine how the regulation of cis-encoded epigenetic switches controls the extent of heterogeneity in gene expression, which is ultimately tied to phenotypic diversity in a population. We show that two copies of the FLO11 locus in Saccharomyces cerevisiae switch between a silenced and competent promoter state in a random and independent fashion, implying that the molecular event leading to the transition occurs locally at the promoter, in cis. We further quantify the effect of trans regulators both on the slow epigenetic transitions between a silenced and competent promoter state and on the fast promoter transitions associated with conventional regulation of FLO11. We find different classes of regulators affect epigenetic, conventional, or both forms of regulation. Distributing kinetic control of epigenetic silencing and conventional gene activation offers cells flexibility in shaping the distribution of gene expression and phenotype within a population.     

Nearest Neighbor Classification Rule for Mixtures of Discrete and Continuous Random Variables

In this paper very simple nonparametric classification rule for mixtures of discrete and continuous random variables is described. It is based on the method of nearest neighbor proposed by Cover and Hart (1967). The bounds on the limit of the nearest neighbor rule risks are given. Both lower and upper bound depend on the Bayes risk and the loss function. Finally the method is compared with other existing methods on some practical data set.     

Pollen allergies in czechoslovakia

The article discusses the possible utilisation of the palynological and geobotanical observations in immunotherapy of children with pollinosis in Czechoslovakia. Three approaches to this problem exist: 1. Use of the individual pollen mixtures (prepared by the Institute of Sera and Vaccines (USOL), Prague), according to the clinical history and the results of diagnostic tests of each patient. 2. Use of the available standard pollen mixtures. 3. Improvement of the specificity of these mixtures by eliminating the redundant pollen types (i.e. pollen of the species not spread in the area). Intentions for the future, including the establishment of a pollen forecasting service, are mentioned.