by Olga ANATSKAYA, Cand. Sc. (Biol.), Alexander VINOGRADOV, Cand. Sc. (Biol.), RAS Institute of Cytology (St. Petersburg)
A chicken will never outstrip an eagle and a pig will never run faster than a deer-their hearts will not tolerate the stress. On a more serious note-what determines the endurance (the "capacity") of that most vitally important organ? Why this capacity is reduced in animals and humans after certain ailments? Answers to these questions are provided by genetic research conducted at the Institute of Cytology of the Russian Academy of Sciences.
WHAT IS SOMATIC POLYPLOIDY?
To begin with, let us remember that body tissues of animals and plants consist of cells. Each cell usually has one nucleus with two genomes with recordings of hereditary information (obtained one from each parent). These are diploid cells that multiply by division, which is preceded by duplication of the parental genomes and division of the nucleus. But if this standard process is stopped due to some reasons at the latter stage, then instead of two cells only one is produced, with two nuclei. Also, a cell can be formed with a large undivided nucleus containing four genomes (tetraploid one). If the rounds of incomplete divisions repeat many times over, there appear cells with many diploid nuclei or a large polyploid one (containing dozens of genomes). The increase of genome number in cells of some tissues is called "somatic polyploidy".
This process was described back in the middle of the 19th century by the German biologist Theodor Swann.
He examined the epithelium of a frog under the microscope and noted that almost every second cell contained two nuclei. A little later, in 1865 his compatriot, the Foreign Member of St. Petersburg Academy, Rudolph Virkhoff demonstrated in his book "Cellular Pathology" the pictures of multi - and binuclear cells from normal and pathologically modified human tissues. Later on, many researchers noted prevalence of this phenomenon in animals and pl ... Read more