Analysis of ethanol–glucose mixtures by two microbial sensors: application of chemometrics and artificial neural networks for data processing

Although biosensors based on whole microbial cells have many advantages in terms of convenience, cost and durability, a major limitation of these sensors is often their inability to distinguish between different substrates of interest. This paper demonstrates that it is possible to use sensors entirely based upon whole microbial cells to selectively measure ethanol and glucose in mixtures. Amperometric sensors were constructed using immobilized cells of either Gluconobacter oxydans or Pichia methanolica. The bacterial cells of G. oxydans were sensitive to both substrates, while the yeast cells of P. methanolica oxidized only ethanol. Using chemometric principles of polynomial approximation, data from both of these sensors were processed to provide accurate estimates of glucose and ethanol over a concentration range of 1.0–8.0 mM (coefficients of determination, R²=0.99 for ethanol and 0.98 for glucose). When data were processed using an artificial neural network, glucose and ethanol were accurately estimated over a range of 1.0–10.0 mM (R²=0.99 for both substrates). The described methodology extends the sphere of utility for microbial sensors.     

Analysis of EEG Structural Synchrony in Adolescents with Schizophrenic Disorders

A total of 39 healthy adolescents and 45 adolescents with schizophrenic disorders (mean age 12.3 years) were examined to study the EEG structural synchrony as reflecting temporal synchronization of the operational activity of neuronal networks. A significant decrease in the EEG structural synchrony was observed in the adolescents with schizophrenic disorders as compared to the healthy adolescents. The decrease was detected predominantly in the interhemispheric pairs of EEG derivations, as well as in the pairs related to the frontal, temporal (predominantly on the left), and right parietocentral regions. The findings provide evidence in favor of Friston’s hypothesis of disintegration of cortical electrical activity in schizophrenia and extend the hypothesis in that it is the operational synchrony of cortical activity that might suffer first in schizophrenia.__________Translated from Fiziologiya Cheloveka, Vol. 31, No. 3, 2005, pp. 16–23.Original Russian Text Copyright © 2005 by Borisov, Kaplan, Gorbachevskaya, Kozlova.     

Recapitulatory significance of coeloblastulas

The problem is discussed whether in Metasoa evolution there was a blastea stage, or else they were of parenchymal structure from the very beginning. The author favours the colonal theory in Metasoa origin and, as their progressive form, he considers spherical colonies where the cells are not united by intracellular substance but have immediate contact with each other. There are two ways of flagellar cells union: by their lateral surfaces or by basal ends. With the first way of union, a rather large colony acquires inevitably the form of blastea. With the second way of union, the number of cells increases, the colony becomes either a homogenous parenchimella or a blastea. The possibility of both ways of evolutionary development were studied experimentally. The results of artificial mutant selection of zootrophic colonial Euglena, Anthophysa vegetans are represented. The author comes to the following conclusions from the results obtained: 1. In Metosoa phylogenesis a blastea-like stage should be present. 2. Recapitulatory significance of the coeloblastulas is evident.     

Shigella toxicity in immunological tolerance

The toxic effect of killed and live Shigella sonnei cultures on normal mice and on mice, tolerant to Shigella O-antigen and to human erythrocytes of different blood groups (in the ABO system) was under study. The toxicity of shigellae, introduced intraperitoneally, has been found to depend on their viability, on their capacity for penetration into the blood, and on the split character of immunological tolerance to Shigella antigens.     

Synthesis,molecular docking,and biological activity of 2-vinyl chromones: Toward selective butyrylcholinesterase inhibitors for potential Alzheimer's disease therapeutics

We investigated the biological activity of a series of substituted chromeno[3,2-c]pyridines, including compounds previously synthesized by our group and novel compounds whose syntheses are reported here. Tandem transformation of their tetrahydropyridine ring under the action of activated alkynes yielding 2-vinylsubstituted chromones was used to prepare nitrogen-containing derivatives of a biologically active chromone system. The inhibitory activity of these chromone derivatives against acetylcholinesterase (AChE), butyrylcholinesterase (BChE) and carboxylesterase (CaE) was investigated using the methods of enzyme kinetics and molecular docking. Antioxidant (antiradical) activity of the compounds was assessed in the ABTS assay. The results demonstrated that a subset of the studied chromone derivatives selectively inhibit BChE but do not exhibit antiradical activity. In addition, the results of molecular docking effectively explained the observed features in the efficacy, selectivity, and mechanism of BChE inhibition by the chromone derivatives.     

Ontogeny of light response in the early life history of the red king crab Paralithodes camtschaticus (Anomura: Lithodidae)

Phototactic responses of light-adapted zoeae IV, glaucothoe, and first stage juveniles of the red king crab to three intensities of white light were quantitatively measured under laboratory conditions. All stages observed were photopositive to all light intensities tested, except for late glaucothoe (10 days since moulting) which did not respond to light stimuli. Phototactic response changed in the early life history of the red king crab. The extent of photopositive movement decreased after each metamorphosis. Peak phototactic response in zoea IV were observed at a light intensity of 1.9 × 10¹³ q cm^-2 s^-1, in early glaucothoe at 1.1 × 10¹⁰ q cm^-2 s^-1 and in juveniles at 1.3 × 10⁹ q cm^-2 s^-1. The data on behavioural responses to light may provide a better understanding of the early life history, survival and recruitment of the red king crab and assist the development of feasible methods and techniques for aquaculture of this species.     

Cytochrome bd from Azotobacter vinelandii: evidence for high-affinity oxygen binding

Cytochrome bd from Azotobacter vinelandii is a respiratory quinol oxidase that is highly efficient in reducing intracellular oxygen concentration, thus enabling nitrogen fixation under ambient aerobic conditions. Equilibrium measurements of O2 binding to ferrous heme d in the one-electron-reduced form of the A. vinelandii enzyme give Kd(O2) = 0.5 microM, close to the value for the Escherichia coli cytochrome bd (ca. 0.3 microM); thus, both enzymes have similar, high affinity for oxygen. The reaction of the A. vinelandii cytochrome bd in the one-electron-reduced and fully reduced states with O2 is extremely fast approaching the diffusion-controlled limit in water. In the fully reduced state, the rate of O2 binding depends linearly on the oxygen concentration consistently with a simple, single-step process. In contrast, in the one-electron-reduced state the rate of oxygen binding is hyperbolic, implying a more complex binding pattern. Two possible explanations for the saturation kinetics are considered: (A) There is a spectroscopically silent prebinding of oxygen to an unidentified low-affinity saturatable site followed by the oxygen transfer to heme d. (B) Oxygen binding to heme d requires an "activated" state of the enzyme in which an oxygen channel connecting heme d to the bulk is open. This channel is permanently open in the fully reduced enzyme (hence no saturation behavior) but flickers between the open and closed states in the one-electron-reduced enzyme.     

Identification of DNA amplification fingerprinting (DAF) markers close to the symbiosis-ineffective sym31 mutation of pea (Pisum sativum L.)

 We demonstrate efficient genome mapping through a combination of bulked segregant analysis (BSA) with DNA amplification fingerprinting (DAF). Two sets of 64 octamer DAF primers, along with two PCR programs of low- and high-annealing temperatures (30°C and 55°C, respectively), appeared to be enough to locate molecular markers within 2–5 cM of a gene of interest. This approach allowed the rapid identification of four BSA markers linked to the pea (Pisum sativum L.) Sym31 gene, which is responsible for bacteroid and symbiosome differentiation. Three of these markers are shown to be tightly linked to the sym31 mutation. Two markers flanking the Sym31 gene, A21-310 and B1-277, cover a 4–5 cM interval of pea linkage group 3. Both markers were converted to sequence-characterized amplified regions (SCARs). The flanking markers may be potential tools for marker-assisted selection or for positional cloning of the Sym31 gene. Received: 2 July 1998 / Accepted: 8 October 1998