THE STRUCTURE OF THE Y CHROMOSOME - A COMPARATIVE MINIREVIEW OF DIFFERENT ORGANISMS
TEREZA DEKOVA, MEGLENA KITANOVA, DIMITRINA GEORGIEVA*
Department of Genetics, Faculty of Biology, Sofia University “St. Kliment Ohridski”, Sofia, Bulgaria
* Corresponding author: d.georgieva@biofac.uni-sofis.bg
Keywords: Y-chromosome, structure, evolution, mammalians, Drosophila, plants
Abstract: Y-chromosome is composed of large regions of non-recombinant sequences and transmitted only through the male sex. In 1959, when Patricia Jacob studied Klinefelter syndrome (XXY) and Charles Ford studied Turner syndrome (X0) concluded that Y-chromosome is determined by sexes. Y-chromosome originates from autosomes and its evolution has often been associated with large deletions and inversions. Recent studies of sex chromosomes in humans and other primates, as well as in plants and Drosophila, throw light on its structure and origin. Classical genetic studies have shown that the Y-chromosome contains an extremely small number of genes, some even disappeared in some species.
After sequencing the human genome, it is possible to study the molecular structure of the Y-chromosome. About 95 % of its length is not participating in recombination with X-chromosomes and is called NRY (nonrecombining region). The other part of the Y-chromosome is called MSY (male-specific region. Euchromatin sequences in MSY are separated into three regions: the X‐transposed region, the X‐degenerative region and the ampliconic region.
Recent studies suggested that the X and Y chromosomes are diverge 300 million years ago. Comparative analysis of Y chromosomes at different stages of differentiation in different organisms will give additional information on the structure and evolution of the sex chromosomes.