Researchers at St. Petersburg University have discovered how chicken genes transmit information.

The research findings have been published in Nucleic Acids Research. Scientists from the Laboratory of Structure and Dynamics of the Cell Nucleus conducted a significant study that has shed light on how genes function on the chromosomes of domestic chickens. The research was supported by the Russian Science Foundation (RSF), and the complex data analysis was carried out by a specialist from the Skoltech Genomics Center.

The chicken genome, being one of the most studied genomes of animals worldwide, is well understood. The lampbrush-type chromosomes are unique structures that form in the oocytes (egg cells) of all vertebrates, except for mammals. They are named for their characteristic shape, which resembles the brushes used for cleaning kerosene lamp glasses or test tubes, where a central axis is surrounded by numerous loops called lateral loops. These structures produce RNA at a very high rate, making them an excellent subject for studying how gene activity is activated and how information is transmitted within cells.

“We undertook a comprehensive, multi-component study of the giant lampbrush chromosomes of chickens. We collected chicken oocytes at various developmental stages and carefully extracted their nuclei using specialized tools. We then isolated RNA from the oocyte nuclei and the remaining cytoplasm. This allowed us to see for the first time how specific genes on the lampbrush chromosomes of birds operate,” said Alla Krasikova, an associate professor in the Department of Cytology at St. Petersburg State University.

They discovered that the genes functioning on lampbrush chromosomes are essential for normal cellular activity. Additionally, this high gene activity is crucial for transmitting a large amount of information (maternal RNA) to the new organism. Another intriguing finding was that the active functioning of genes influences the very structure of the chromosomes. Most remarkably, the processes of gene activation in chickens were found to be similar to those occurring in other cells. However, due to their large size, lampbrush chromosomes are perfectly suited for studying these mechanisms.

Moreover, scientists have compiled detailed information for the first time on the activity of small gene regulators (miRNAs) in chicken oocytes. These small gene regulators, such as miRNAs (microRNAs), play a vital role in managing gene activity. They act as “switches,” helping to control which genes will be active at any given moment and in what quantities. Additionally, it was discovered that other short regulatory RNAs (piRNAs) regulate specific regions of DNA in the chicken genome where repeating fragments exist.

These discoveries aid scientists in better understanding how hereditary information is passed from one generation to the next. This represents a significant advancement in the fields of genetics and molecular biology.

The work was conducted in the Laboratory of Structure and Dynamics of the Cell Nucleus at St. Petersburg State University with the participation of the Skoltech Collective Use Center in Genomics, supported by an RSF grant.