Gene Expression in the Three-Spined Stickleback (Gasterosteus aculeatus) of Marine and Freshwater Ecotypes.

Three-spine stickleback (Gasterosteus aculeatus) is a well-known model organism that is routinely used to explore microevolution processes and speciation, and the number of studies related to this fish has been growing recently. The main reason for the increased interest is the processes of freshwater adaptation taking place in natural populations of this species. Freshwater three-spined stickleback populations form when marine water three-spined sticklebacks fish start spending their entire lifecycle in freshwater lakes and streams. To boot, these freshwater populations acquire novel biological traits during their adaptation to a freshwater environment. The processes taking place in these populations are of great interest to evolutionary biologists. Here, we present differential gene expression profiling in G. aculeatus gills, which was performed in marine and freshwater populations of sticklebacks. In total, 2,982 differentially expressed genes between marine and freshwater populations were discovered. We assumed that differentially expressed genes were distributed not randomly along stickleback chromosomes and that they are regularly observed in the "divergence islands" that are responsible for stickleback freshwater adaptation.

SITECON: a tool for detecting conservative conformational and physicochemical properties in transcription factor binding site alignments and for site recognition.

The local DNA conformation in the region of transcription factor binding sites, determined by context, is one of the factors underlying the specificity of DNA-protein interactions. Analysis of the local conformation of a set of functional DNA sequences may allow for determination of the conservative conformational and physicochemical parameters reflecting molecular mechanisms of interaction. The web resource SITECON is designed to detect conservative conformational and physicochemical properties in transcription factor binding sites, contains a knowledge base of conservative properties for >100 high-quality sample sites and allows for recognition of potential transcription factor binding sites based on conservative properties from both the knowledge base and the results of analysis of a sample proposed by a user. The resource SITECON is available at http://wwwmgs.bionet.nsc.ru/mgs/programs/sitecon/.

Detection of conserved physico-chemical characteristics of proteins by analyzing clusters of positions with co-ordinated substitutions.

MOTIVATION: It is known that the physico-chemical characteristics of proteins underlying specific folding of the polypeptide chain and the protein function are evolutionary conserved. Detection of such characteristics while analyzing homologous sequences would expand essentially the knowledge on protein function, structure, and evolution. These characteristics are maintained constant, in particular, by co-ordinated substitutions. In this process, the destabilizing effect of a substitution may be compensated by another substitution at a different position within the same protein, making the overall change in this protein characteristic insignificant. Consequently, the patterns of co-ordinated substitutions contain important information on conserved physico-chemical properties of proteins, requiring their investigation and development of the corresponding methods and software for correlation analysis of protein sequences available to a wide range of users. RESULTS: A software package for analyzing correlated amino acid substitutions at different positions within aligned protein sequences was developed. The approach implies searching for evolutionary conserved physico-chemical characteristics of proteins based on the information on the pairwise correlations of amino acid substitutions at different protein positions. The software was applied to analyze DNA-binding domains of the homeodomain class. As a result, two conservative physico-chemical characteristics preserved due to the co-ordinated substitutions at certain groups of positions in the protein sequence. Possible functional roles of these characteristics are discussed. AVAILABILITY: The program package is available at http://wwwmgs.bionet.nsc.ru/programs/CRASP/.