SPbU biologists are the first to decode a key element of the chicken genome sequence
An international group of scientists headed by SPbU Professor Elena Gaginskaya has decoded the ribosomal RNA gene cluster sequence of the domestic chicken — a highly important model object in biological research. The data obtained by the scientists are important for studying the evolution of cellular differentiation processes and changes in cellular energy balance, as well as causes and ways of healthy cells transformation into cancerous ones. The results of the study were reported in the research paper entitled “Chicken rRNA Gene Cluster Structure” published in PLoS ONE.
Chicken rRNA Gene Cluster Structure
In addition to unique genes, genomes of multicellular organisms also contain numerous regulatory and structural DNA sequences. Many of them are represented by a large number of successive short copies (tandem repeats). Such regions may constitute a substantial part of the genome, and their decoding is often an extremely complicated task that is sometimes impossible to accomplish using the methods available today.
Among the least investigated genetic elements are the so-called nucleolus organizer regions (NOR), which are formed by ribosomal RNA genes and intergenic spacers. These regions are the key elements in the genome of any living organism. Their structure and functioning affect the work of the cell protein-synthesizing machinery, and, therefore, all the ongoing cell metabolism processes in their entirety.
The structure of the rRNA gene cluster has been actively explored during the last 60 years; however, this area of research still remains one of the most complex problems facing the scientists around the world. Despite the development of highly efficient methods for decoding the genome, there are practically no data on the structure of the repeated ribosomal RNA gene clusters.
So far the GenBank genetic sequence database has contained information on the structure of complete rRNA gene cluster sequences for a limited number of vertebrate species only, namely, the Human, the Mouse, and two representatives of the Fish. By virtue of a joint project of scientists from SPbU, the Institute of Molecular Biology and Genetics at the Federal Almazov North-West Medical Research Centre, and Osaka University (Japan), a representative of the Birds is now added to this group.
Nowadays, the decoded rRNA gene cluster sequence of the chicken is already available in GenBank under accession number KT445934. The results of the study will increase the quality of decoding and assembly for other avian genomes, and will extend the use of the chicken as a model object, especially in investigations of NOR regulation in ontogenesis. Besides, the data obtained in the research could be useful for developing optimal solutions in the areas of population genetics and evolution of birds and reptiles.
“In the course of our work, we managed to determine and describe gene sequences and spacers separating them in the chicken genome, to define their boundaries and characteristics of their nucleotide composition. The results will enable us to achieve a deeper understanding of the principles behind the evolution of vitally important genetic structures in the vertebrates. In particular, this information will help us to conduct more detailed studies of cellular differentiation and malignant transformation of cells,” says the lead author of the article, SPbU post-doc Alexander Dyomin, Ph.D. in biology.