Ricerc@Sapienza

One of the most striking structural features of the male specific region of the human Y
chromosome (MSY) is the presence, within the ampliconic sequences, of eight massive
palindromes (P1-P8). Each palindrome is composed of two large inverted repeats (arms)
separated by a small “spacer” sequence at the centre. These elements, ranging from 30 kb
to 2.9 Mb, contain many testis-specific genes and typically exhibit > 99.9% intra-palindromic

Gene families underlie genetic innovation and phenotypic diversification. However, our understanding of the early genomic and functional evolution of tandemly arranged gene families remains incomplete as paralog sequence similarity hinders their accurate characterization. The D. melanogaster-specific gene family Sdic is tandemly repeated and impacts sperm competition.

The male-specific region of the human Y chromosome (MSY) is characterized by the lack of meiotic recombination and it has long been considered an evolutionary independent region of the human genome. In recent years, however, the idea that human MSY did not have an independent evolutionary history begun to emerge with the discovery that inter-chromosomal gene conversion (ICGC) can modulate the genetic diversity of some portions of this genomic region.

The presence of large and near-identical inverted repeat sequences (called palindromes) is a common feature of the constitutively haploid sex chromosomes of different species. Despite the fact palindromes originated in a non-recombining context, they have evolved a strong recombinational activity in the form of abundant arm-to-arm gene conversion. Their independent appearance in different species suggests they can have a profound biological significance that has yet to be fully clarified.