Prediction of the three-dimensional structure of aflatoxin of Aspergillus flavus by homology modelling

Aflatoxins are polyketide-derived secondary metabolites produced by Aspergillus spp. The toxic effects of aflatoxins have adverse consequences for human health and agricultural economics. The aflR gene, a regulatory gene for aflatoxin biosynthesis, encodes a protein containing a zinc-finger DNA-binding motif. AFLR-Protein three-dimensional model was generated using Robetta server. The modeled AFLR-Protein was further optimization and validation using Rampage. In the simulations, we monitored the backbone atoms and the C-α-helix of the modeled protein. The low RMSD and the simulation time indicate that, as expected, the 3D structural model of AFLR-protein represents a stable folding conformation. This study paves the way for generating computer molecular models for proteins whose crystal structures are not available and which would aid in detailed molecular mechanism of inhibition of aflatoxin.     

Mapping the amino acid properties of constituent nucleoporins onto the yeast nuclear pore complex

Visualization of molecular structures aids in the understanding of structural and functional roles of biological macromolecules. Macromolecular transport between the cell nucleus and cytoplasm is facilitated by the nuclear pore complex (NPC). The ring structure of the NPC is large and contains several distinct proteins (nucleoporins) which function as a selective gate for the passage of certain molecules into and out of the nucleus. In this note we demonstrate the utility of a python code that allows direct mapping of the physiochemical properties of the constituent nucleoporins on the scaffold of the yeast NPC׳s cytoplasmic view. We expect this tool to be useful for researchers to visualize the NPC based on their physiochemical properties and how it alters when specific mutations are introduced in one or more of the nucleoporins. The code developed using Python is available freely from the authors.     

Interconnection of parameters of regulation system of lipid peroxidation and of morphophysiological parameters of mouse liver

A complex analysis of seasonal fluctuations of the mean group parameters of the system of regulation of lipid peroxidation has been performed in liver of Balb/c mice. Association of lipid characteristics and morphophysiological parameters is studied in the Balb/c mouse liver. An inter-connection is revealed between the liver index and the amount of lysoforms of phospholipids, the scale and character of the interconnection differing essentially depending on proportion of phos-phatidylcholine in mouse liver phospholipids.     

Effect of chemical toxicants in a wide range of concentrations on the characteristics of lipids of mouse blood erythrocytes

The lipid composition of blood erythrocytes of mice at days 7 and 31 after a single per os administration of oily hexane-ester extracts with different contents of benzapyrene and polychlorobiphenyls in a wide concentration range was analyzed. It was shown that the parameters of the lipid metabolism in mouse blood erythrocytes depend on the dose of the extract in a nonlinear manner. The administration of extract 3 with a higher content of polychlorobiphenyls at a dose of 5.3 mg/kg and of extract M with a higher content of benzapyrene at the lowest dose of 5.3 x 10(-5) mg/kg had a more pronounced effect on the phospholipid composition of blood erythrocytes. It was shown that the magnitude and direction of changes in the structural state of erythrocyte membranes and the capacity of lipids for oxidation depend on the time elapsed after exposure, the chemical nature of the toxicants, and the dose of the extract.     

Influence of the antioxidant status on the characteristics of lipids in tissues of animals after acute irradiation with sublethal doses

The effect of the acute exposure to sublethal doses of X-rays on the interrelation between parameters of the lipid peroxidation regulatory system (lipid antioxidative activity, AOA; peroxide amount, lipid composition) was studied in liver, spleen and blood erythrocytes of CBA and SHK mice and rats within 1 month after irradiation. The reverse correlation between the lipid AOA values and the initial peroxide amount in lipids of the CBA mice spleen was found. The coefficient of the linear regression of this correlation for the exposed mice was 1.8-fold higher as compared with control. The correlative dependence between the ratio of the sums of the more readily to more poorly oxidizable phospholipid and the ratio of phosphatidyl choline to phosphatidyl ethanolamine content in phospholipids of liver and blood erythrocytes was revealed. The direction (the phospholipids of the rat liver) or the value of the linear regression coefficient of that correlation were different for groups of the exposed and control animals, especially in the blood erythrocytes. Thus, the different sensitivity of examined characteristics of lipids and the possibility of their normalization in the dependence on the lipid AOA value cause the conversion of the lipid peroxidation regulatory system in organs and blood erythrocytes of the exposed animals to the other scale of the functioning.     

Comparative analysis of the antioxidant system of mouse liver and blood during exposure to toxins, extracted from drinking water

A comparative analysis of the antioxidant system of mouse liver and blood was done during one month after a single per os administration of oil solutions of hexane--ether extracts from the drinking water sources with different proportions of benz(o)pyrene and polychlorbiphenyls. The absence of a linear dependence dose-effect on the extract concentration and a change in the scale and direction of interrelations between the parameters examined (the antioxidant activity of lipids, the content of peroxides, and the content of products interacting with 2-thiobarbituric acid) were revealed, indicating a high sensitivity and the absence of normalization of the antioxidant status in animal tissues.     

Influence of the characteristics of lipids on the regulation of biochemical processes in animal liver and blood

It has been established experimentally that the character and the scale of interrelations between various parameters of the phospholipid composition and their group-average values depend significantly on the characteristics of lipids (the antioxidative activity, quantity of peroxides, and antiperoxide activity) of animal liver and blood erythrocytes. It was shown that a single injection of low-toxicity Tween 80 and acetone at low doses modifies the intensity of lipid peroxidation in the liver and changes the physicochemical properties of lipids, and the interrelations between the parameters that are coordinated in norm, thereby causing the disturbance of biochemical functions of the liver.     

Effect of Low Doses of Chemical Toxicants on Phospholipid Composition in Animal Liver

The composition of phospholipids in the liver was studied 7, 14, and 31 days after single oral administration of oil solutions of hexane–ether extracts from potable water sources with different contents of benzo[a]pyrene and polychlorinated biphenyls. Neither linear effect–dose relationship nor directional correlations between individual phospholipid fractions and integrated indices of their composition were revealed, providing evidence for a high sensitivity of phospholipid composition to toxic agents and the absence of its normalization in the mouse liver one month after administration of these agents.     

The treatment of isolated genera

Problems presented by genera, or small groups of genera, which have been given family rank are reviewed, and the genera are divided into a number of categories according to the closeness of their affinity to other genera or families. Satellite genera that stand in close relation to families should be united with them. Binary families, that have been divided into two (or more) related families, should be re–united. Families connected by linking genera, should, logically, be united but practical considerations usually prevent this. Clusters of diverse but more or less distantly related genera present unusual problems, being treated either as several, often monogeneric families or as a loosely structured family. Truly isolated genera must be given family and often ordinal rank.