Investigation of surface properties of rat spinal ganglion neuron by microelectrophoresis

The surface charge of isolated neurons in rat spinal ganglia was studied by microelectrophoresis. The surface potential of these neurons was shown to be caused by anionic groups which form complexes with calcium ions with a binding constant of between 10 and 50 liters/mole, and to titrate with hydrogen ions in accordance with pK=3.8. After treatment with trypsin under "mild" conditions many of these groups are removed from the surface. Tosyl chloride (a reagent for amino groups) leads to a small increase, and N-bromosuccinimide (a reagent for carboxyl groups) leads to a marked decrease in surface charge. It is suggested that the surface charge of neurons in rat spinal ganglia, determined by microelectrophoresis, is due to carboxyl groups of peripheral proteins. These groups are evidently located in the glycoprotein layer covering the outer side of the membrane. According to estimates the distance between the groups is about 2 nm and the thickness of the glycoprotein layer is 10 nm.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSSR, Kiev. Translated from Neirofiziologiya, Vol. 16, No. 2, pp. 176–182, March–April, 1984.     

Stellate cells of aortic intima: I. Human and rabbit.

Stellate cells hitherto accounted exclusively in the innermost elastic-hyperplastic layer were already reported to inhabit human aortic intima. The present paper shows that most of these cells are situated just beneath the endothelium. Stellate cells also appear in the deendothelialization-induced myointimal thickening of rabbit aorta. In the myointimal thickening these cells were revealed in the direct proximity to the endothelium. A conclusion is available that the previously demonstrated polymorphism of human aortic intimal cells may be reproduced in a simple experimental model, which gives new possibilities for the study of the cellular polymorphism in the vessel wall.     

Aspects of petroleum hydrocarbon metabolism in marine animals

Studies on hydrocarbon composition of Black Sea musselsMytilus galloprovincialis sampled from different habitats indicate that the quantity and composition of hydrocarbons distributed in the molluscs depend on season and sea-water quality. The data obtained under experimental conditions testify to the possibility of hydrocarbon concentration in mussel tissues after death. During filtration in sea water containing oil and oil products, these pollutants are bound into faeces and pseudofaeces which contain a greater percentage of aromatic compounds than the oil initially present in sea water. Quantitative data are presented on hydrocarbon changes in mussel excretory products during transfer from oil-polluted to clean sea water. When Black Sea crabsEriphia verrucosa are fed with mussels containing fuel-oil components accumulated from sea water, the pollutants concentrate in the whole body of the crab. This is in contrast to parenteral oil uptake, which leads to a concentration of most of the hydrocarbon in the muscles.     

Transposition of the deo operon structural genes in Escherichia coli K-12 to plasmid RP4 using bacteriophage mu]

Transposition of the structural genes of the deo operon of Escherichia coli K-12 into plasmid RP4 by means of temperate bacteriophage Mu was carried out. Some variants of composite RP4-deo-Mu plasmids were obtained and the expression of the deo genes integrated into the RP4 plasmid genome was studied. It was shown that the expression of these genes remains under the control of the chromosomal regulatory genes (deoR and cytR); although the activity of thymidine phosphorilase in the strain E. coli which contains hybrid plasmid is 4-6 fold greater than that in strains of E. coli with chromosomal localization of the deo operon.     

COPII collar defines the boundary between ER and ER exit site and does not coat cargo containers

COPII and COPI mediate the formation of membrane vesicles translocating in opposite directions within the secretory pathway. Live-cell and electron microscopy revealed a novel mode of function for COPII during cargo export from the ER. COPII is recruited to membranes defining the boundary between the ER and ER exit sites, facilitating selective cargo concentration. Using direct observation of living cells, we monitored cargo selection processes, accumulation, and fission of COPII-free ERES membranes. CRISPR/Cas12a tagging, the RUSH system, and pharmaceutical and genetic perturbations of ER-Golgi transport demonstrated that the COPII coat remains bound to the ER–ERES boundary during protein export. Manipulation of the cargo-binding domain in COPII Sec24B prohibits cargo accumulation in ERES. These findings suggest a role for COPII in selecting and concentrating exported cargo rather than coating Golgi-bound carriers. These findings transform our understanding of coat proteins’ role in ER-to-Golgi transport.     

Biotechnological Potential of the Bacillus subtilis 20 Strain

Molecular Biology - Bacillus subtilis bacteria play an important role in veterinary medicine, medicine, and biotechnology, and the permanently growing demand for biotechnological products fuels the...     

Regulatory role of membrane fluidity in gene expression and physiological functions

Plants, algae, and photosynthetic bacteria experience frequent changes in environment. The ability to survive depends on their capacity to acclimate to such changes. In particular, fluctuations in temperature affect the fluidity of cytoplasmic and thylakoid membranes. The molecular mechanisms responsible for the perception of changes in membrane fluidity have not been fully characterized. However, the understanding of the functions of the individual genes for fatty acid desaturases in cyanobacteria and plants led to the directed mutagenesis of such genes that altered the membrane fluidity of cytoplasmic and thylakoid membranes. Characterization of the photosynthetic properties of the transformed cyanobacteria and higher plants revealed that lipid unsaturation is essential for protection of the photosynthetic machinery against environmental stresses, such as strong light, salt stress, and high and low temperatures. The unsaturation of fatty acids enhances the repair of the damaged photosystem II complex under stress conditions. In this review, we summarize the knowledge on the mechanisms that regulate membrane fluidity, on putative sensors that perceive changes in membrane fluidity, on genes that are involved in acclimation to new sets of environmental conditions, and on the influence of membrane properties on photosynthetic functions.     

Base-Calling Algorithm with Vocabulary (BCV) Method for Analyzing Population Sequencing Chromatograms

Sanger sequencing is a common method of reading DNA sequences. It is less expensive than high-throughput methods, and it is appropriate for numerous applications including molecular diagnostics. However, sequencing mixtures of similar DNA of pathogens with this method is challenging. This is important because most clinical samples contain such mixtures, rather than pure single strains. The traditional solution is to sequence selected clones of PCR products, a complicated, time-consuming, and expensive procedure. Here, we propose the base-calling with vocabulary (BCV) method that computationally deciphers Sanger chromatograms obtained from mixed DNA samples. The inputs to the BCV algorithm are a chromatogram and a dictionary of sequences that are similar to those we expect to obtain. We apply the base-calling function on a test dataset of chromatograms without ambiguous positions, as well as one with 3–14% sequence degeneracy. Furthermore, we use BCV to assemble a consensus sequence for an HIV genome fragment in a sample containing a mixture of viral DNA variants and to determine the positions of the indels. Finally, we detect drug-resistant Mycobacterium tuberculosis strains carrying frameshift mutations mixed with wild-type bacteria in the pncA gene, and roughly characterize bacterial communities in clinical samples by direct 16S rRNA sequencing.