Informational Content of Polytene Chromosome Bands and Puffs

Abstract

Three widely documented mechanisms of chloride transport across plasma membranes are anion-coupled antiport, sodium-coupled symport, and an electrochemical coupling process. No direct genetic evidence has yet been provided for primary active chloride transport despite numerous reports of cellular Cl-stimulated adenosine triphos-phate (ATP)ases coexisting in the same tissue with uphill chloride transport that could not be accounted for by the three common chloride transport processes. Ch-stimulated ATPases are a common property of practically all biological cells, with the major location being of mitochondrial origin. It also appears that plasma membranes are sites of Cl–stimulated ATPase activity. Recent studies of Cl'-stimulated ATPase activity and chloride transport in the same membrane system, including liposomes, suggest a mediation by the ATPase in net movement of chloride up its electrochemical gradient across plasma membranes. Further studies, especially from a molecular biological perspective, are required to confirm a direct transport role to plasma membrane-localized Ch-stimulated ATPases.     

External forcing factor reflected in the common signals of δ18O-tree-ring series of Larix sibirica Ledeb. in the Lake Baikal region

A set of δ¹⁸O-tree-ring series obtained from larch trees growing in three different ecotopes near Lake Baikal are analysed together with the relevant meteorological data. It has recently been proposed that the external forcing factor, as a characteristic of the total investigated territory, must cause a certain similarity of the essential properties of the simple processes induced by this forcing. The similarity is the main point of this investigation and is the basis for a constructive definition of the intersection of the sets of these induced processes as data sets. We specify the elements of the intersection of the sets as the “common signals” for each process (set). The common signals are computed by a new algorithm of “co-filtering”, which is based on the trigonometric Fourier transform. We call the output of this algorithm the “co-filtered common signals” (CCS).We discovered that the CCS gave substantial contributions to the variances of the initial isotope series, which are more weakly correlated than their CCS. Next, we found that synchronous variations of the CCS of the temperature and precipitation for April–May and June–August induce synchronous variations in the CCS of the δ¹⁸O-tree-ring series. Furthermore, the characteristics of such synchronism vary with time.We concluded that the CCS of the δ¹⁸O-tree-ring series clearly express the external forcing factor even when there are significant differences in the vegetation conditions.     

Isolation and characteristics of compound transposons Tn1000::Tn5

Two types of compound transposons were derived. In the first case, transposon Tn5 is inserted into the gene responsible for Tn1000 transposase synthesis. In the other, Tn5 is inserted into the region near the left end of Tn1000, where no functionally significant genes were found. It is known that translocation of the compound transposons does not depend on their size and takes place with the efficiency close to that characteristic of the intact Tn1000. Insertion of Tn5 into the gene coding for Tn1000 transposase results in sharp decrease in the efficiency of Tn1000 translocations. This effect, however, may be eliminated by introduction into the cell of the intact Tn1000.     

The study of structure-antiarrhythmic activity relationship of N-phenylacetamide derivatives and aromatic carbonic acid amides

Using the SARD-21 (Structure Activity Relationship & Design) computer system, structural features of high- and low-effective antiarrhythmic agents have been recognized and the influence of these features on the antiarrhythmic properties has been evaluated. This information has been used for generation of the model to predict antiarrhythmic effectiveness of pharmaceutical preparations at the recognition level of 82% by means of two different approaches. The recognized structural parameters may be successfully used to design new highly effective antiarrhythmic drugs, and also to modify structures of the already-existing anti-arrhythmic drugs in order to increase the effectiveness of their antiarrhythmic action.     

Molecular modeling of immersion optical clearing of biological tissues

The interaction of six low-molecular tissue-clearing agents (1,2 and 1,3-propanediol, ethylene glycol, glycerol, xylitol, sorbitol) with the collagen mimetic peptide (GPH)₃ was studied by applying the methods of classical molecular dynamics (GROMACS), molecular docking (AutoDock Vina) and quantum chemistry (PM6 and B3LYP). The spatial configurations of intermolecular complexes were determined and interaction energies calculated. The dependence of the volume occupied by the collagen peptide on the clearing agent concentration in an aqueous solution was calculated. This dependence is not linear, and has a maximum for almost all the agents in the study. The correlations between the optical clearing potential and intermolecular interactions parameters, such as the time of an agent being in a hydrogen-bonded state, and the relative probability of formation of double hydrogen bonds and interaction energies, were determined. Using the correlations determined, we predicted the numeric value of the optical clearing potential of dextrose molecules in rat skin, which correlates with experimental data. A molecular mechanism of tissue optical clearing within the post-diffusion stage is suggested.

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Graphical abstract The molecular modeling of the interaction between clearing agents and collagen

     

Skeletal muscle dispersion (400‐1000 nm) and kinetics at optical clearing

Skeletal muscle dispersion and optical clearing (OC) kinetics were studied experimentally to prove the existence of the refractive index (RI) matching mechanism of OC. Sample thickness and collimated transmittance spectra were measured during treatments with glucose (40%) and ethylene glycol (EG; 99%) solutions and used to obtain the time dependence of the RI of tissue fluids based on the proposed theoretical model. Calculated results demonstrated an increase of RI of tissue fluids and consequently proved the occurrence of the RI matching mechanism. The RI increase was observed for the wavelength range between 400 and 1000 nm and for the 2 probing molecules explored. We found that for 30 min treatment with 40% glucose and 99% EG, RI of sarcoplasm plus interstitial fluid was increased at 800 nm from 1.328 to 1.348 and from 1.328 to 1.369, respectively.      

When things don't add up: quantifying impacts of multiple stressors from individual metabolism to ecosystem processing

Ecosystems are exposed to multiple stressors which can compromise functioning and service delivery. These stressors often co‐occur and interact in different ways which are not yet fully understood. Here, we applied a population model representing a freshwater amphipod feeding on leaf litter in forested streams. We simulated impacts of hypothetical stressors, individually and in pairwise combinations that target the individuals' feeding, maintenance, growth and reproduction. Impacts were quantified by examining responses at three levels of biological organisation: individual‐level body sizes and cumulative reproduction, population‐level abundance and biomass and ecosystem‐level leaf litter decomposition. Interactive effects of multiple stressors at the individual level were mostly antagonistic, that is, less negative than expected. Most population‐ and ecosystem‐level responses to multiple stressors were stronger than expected from an additive model, that is, synergistic. Our results suggest that across levels of biological organisation responses to multiple stressors are rarely only additive. We suggest methods for efficiently quantifying impacts of multiple stressors at different levels of biological organisation.