New tandem array in chicken genome: SPbU
The SPbU’s researchers have developed a unique method to study the tandem arrays and discovered a new tandem array in the chicken genome. It helps scientists get a deeper insight into how the mechanisms to identify sex work. The research outcomes are published in Chromosoma.
Apart from the unique genes, the genomes of the vertebrates, and the humans are vertebrate as well, have a great number of DNA sequences. Some of them are tandem arrayed genes: gene cluster created by tandem duplications,[1] a process in which one gene is duplicated and the copy is found adjacent to the original. Changes in DNA sequences can cause various diseases: Martin-Bell syndrome, Steinert's disease, Huntington's disease, and others.
However, little is known what the tandem arrays are for. It is hardly possible to decode them, and information is highly difficult to process. So this information is simply ignored at the final stage of the sequencing. Much is still to be discovered even on the well-studied species.
The recent discovery made by our scientist Aleksei Komissarov, Theodosius Dobzhansky Center for Genome BioInformatics, is a real breakthrough in DNA research. The young scientist has developed a new approach to identify and describe little studied tandem arrays and perform a quantitative analysis. The method, based on the highly-productive sequencing, opens ample opportunities to get insight into the tandem arrays in various species, including humans.
The new method was probated on the domestic chicken that are the most popular species in biological research. The group of scientists headed by the Director of the SPbU’s Resource Centre Chromos Alsu Saifitdinova carried out a research to enlarge a cytogenetic map of the W sex chromosomes of the chicken that determine the female sex.
Males are the homogametic sex (ZZ), while females are the heterogametic sex (ZW), with an unpaired chromosome prone to degradation and accumulation of DNA tandem. An incredibly small size of the chromosome makes it hardly possible to study it using ordinary substances. However, SPbU’s cytogenetics has a unique high-resolution sequence mapping using the substances of the decondensed chromosomes from the nucleus of the growing oocytes. It make possible to be precise in identifying the localization of the new tandem array. Still, the function of the accumulation of the DNA tandem is little, if any, studied problem.
The key aspect in sex determination system and sex chromosome evolution, as some scientists say, is when one of the chromosomes acquire the sex determination functions.
Director of the Resource Centre Chromos of the SpBu’s Research Park Alsu Saifitdinova
“Regardless our efforts, we have failed to identified the gene in the chicken DNA that would have a sex determination function. However, we are gaining more and more data that the tandem arrays can perform regulatory functions and have influence on how other genes are active”, — said Alsu Saifitdinova.
The new tandem arrays described by SPbU’s scientists occur in some chicken DNA sequences that are responsible for protein production in the ovaries, development of the organs, systems, parts of the body, and behavior of the animals. Moreover, this fragment of DNA, as the scientists say, repose to stress. In other words, this breakthrough will make it possible to know why some diseases occur, how the sex is determined, and how stress and other conditions influence these processes.