In this report we review alpha-satellite DNA (AS) sequence data to support the following proposed scenario of AS evolution. Centromeric regions of lower primate chromosomes have solely "old" AS based on type A monomeric units. Type A AS is efficiently homogenized throughout the whole genome and is nearly identical in all chromosomes. In the ancestors of great apes, a divergent variant of the type A monomer acquired the ability to bind CENP-B protein and expanded in the old arrays, mixing irregularly with type A. As a result, a new class of monomers, called type B, was formed. The "new" AS families were established by amplification of divergent segments of irregular A-B arrays and spread to many chromosomes before the human-chimpanzee-gorilla split. The new arrays contain regularly alternating monomers of types A and B. New AS is homogenized within an array with little or no homogenization between chromosomes. Most human chromosomes contain only one new array and one or a few old arrays. However, as a rule only new arrays are efficiently homogenized. Apparently, in evolution, after the establishment of the new arrays homogenization in the old arrays stopped. Notably, kinetochore structures marking functional centromeres are also usually formed on the new arrays. We propose that homogenization of AS may be limited to arrays participating in centromeric function.

RegTransBase is a manually curated database of regulatory interactions in prokaryotes that captures the knowledge in public scientific literature using a controlled vocabulary. Although several databases describing interactions between regulatory proteins and their binding sites are already being maintained, they either focus mostly on the model organisms Escherichia coli and Bacillus subtilis or are entirely computationally derived. RegTransBase describes a large number of regulatory interactions reported in many organisms and contains the following types of experimental data: the activation or repression of transcription by an identified direct regulator, determining the transcriptional regulatory function of a protein (or RNA) directly binding to DNA (RNA), mapping or prediction of a binding site for a regulatory protein and characterization of regulatory mutations. Currently, RegTransBase content is derived from about 3000 relevant articles describing over 7000 experiments in relation to 128 microbes. It contains data on the regulation of about 7500 genes and evidence for 6500 interactions with 650 regulators. RegTransBase also contains manually created position weight matrices (PWM) that can be used to identify candidate regulatory sites in over 60 species. RegTransBase is available at .

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