Biological responses to environmental contamination. How can metal pollution impact signal honesty in avian species?

Environmental pollution, for example with metals, can significantly affect the ecosystem balance leading to severe changes. Biologically active pigments are relevant for the appearance and condition of birds. Melanin and carotenoid particles are the most frequently deposited pigments in avian integument. They are responsible for the majority of colors of bird plumage. The phenotypic expression can be affected by metal contamination. It can be manifested as color bleaching or differences in the size of plumage badges. In this study, we performed a comprehensive review of related studies in order to estimate the underlying population effect of this potential dependency. The study is based on the review of the literature regarding several avian species. It was designed to identify an area where the effect of the exposure is still poorly known. The analysis was specifically conducted to investigate the correlation between trace element concentration and eumelanin deposition. Moreover, we searched for factors that could affect spectral properties of feathers with carotenoid-based pigmentation. As a result, we found carotenoid-based pigmentation to be of a good use in terms of visual condition assessment. Changes in melanin-based pattern should be analyzed separately for eu- and pheomelanin as well as for a range of essential and toxic elements. Comprehensive studies on the subject are still scarce. Therefore, the issue requires further investigation

Self-assembly of the anti-fungal polyene amphotericin B into giant helically-twisted nanotapes

The amphiphilic polyene amphotericin B, a powerful treatment for systemic fungal infections, is shown to exhibit a critical aggregation concentration, and to form giant helically-twisted nanostructures via self-assembly in basic aqueous solution

Prediction of binding affinities for DNA intercalators by molecular dynamics simulations

The computer modelling and simulation methods are widely used in rational drug design to obtain information necessary for understanding interactions between a ligand (drug molecule) and its cellular macromolecular target on molecular level. The determination of free energies of binding for ligand-target complexes is one of the crucial points in those studies. In recent years several methods have been proposed to solve this problem. The majority of them use molecular dynamics (MD) simulations. Two, most popular methods: (i) a free energy perturbation method (FEP), and (ii) a linear response (LR) method, are shortly presented in this paper together with their limitations and advantages. In this work I presented the first attempt to use LR approach to 10 anti-tumour agents able to intercalate into DNA. The LR relationship obtained in the present study indicated that in the system studied the electrostatic term has no influence on the free energy of binding. The relationship is now successfully used in our research group in further molecular modelling studies concerning DNA intercalators with similar structure

QUARTERLY The intercalation of imidazoacridinones into DNA induces conformational changes in their side chain ��

molecular dynamics simulations, C-1311 Imidazoacridinones (IAs) are a new group of highly active antitumor compounds. The intercalation of the IA molecule into DNA is the preliminary step in the mode of action of these compounds. There are no experimental data about the structure of an intercalation complex formed by imidazoacridinones. Therefore the design of new potentially better compounds of this group should employ the molecular modelling techniques. The results of molecular dynamics simulations performed for four IA analogues are presented. Each of the compounds was studied in two systems: i) in water, and ii) in the intercalation complex with dodecamer duplex d(GCGCGCGCGCGC) 2. Significant differences in the conformation of the side chain in the two environments were observed for all studied IAs. These changes were induced by electrostatic as well as van der Waals interactions between the intercalator and DNA. Moreover, the results showed that the geometry of the intercalation complex depends on: i) the chemical constitution of the side chain, and ii) the substituent in position 8 of the ring system. Imidazoacridinones (IAs) are a new group o

Molecular modelling in the rational design of some anti-tumor and antifungal agents

In this paper we present our approaches and results concerning application of molecular modelling techniques in the design of new chemotherapeutic agents for the control of eukariotic systems, comprising compounds for the treatment of systemic fungal infections and tumor deseases. In the case of anti-tumor agents we focused our attention on molecular properties of natural and synthetic anthraquinones. In the area of antifungal compounds we adopted two approaches. In one of them we examine molecular nature of undesirable properties of polyene macrolide antifungal antibiotic - amphotericin B using molecular modelling techniques. Another approach was aimed at the development of selective inactivator of glucosamine synthase, a novel target for antifungal compounds. In this problem we have used computational chemistry methods to identify structural features responsible for the selective inactivation of the target enzyme