The Y chromosome that marks male genes has an additional role in the body, apart from selecting for male mammals, including humans. These structures also contain genes needed for the general operation of the genome. This is the entire genetic mechanism of DNA, including both genes and noncoding sequences of the genetic structure.
Men possess both an X and Y chromosome in each cell of their bodies, while women have a pair of X structures. Over time, the Y chromosome has lost hundreds of genes, making it much shorter than its corresponding partner. Some biologists became concerned that if Y chromosomes were still losing genes, the whole chromosome might soon become extinct.
Two research teams investigated whether the disappearance of genes could signal the eventual end of the chromosome. Diego Cortez and Henrik Kaessmann of the University of Lausanne in Switzerland led one of the groups of investigators, while the other was headed by Daniel Bellott and David Page of the Whitehead Institute.
"The human X and Y chromosomes evolved from an ordinary pair of autosomes, but millions of years ago genetic decay ravaged the Y chromosome, and only 3 percent of its ancestral genes survived," researchers wrote in one of a pair of studies published on the findings.
Page and Bellott mapped the DNA of eight species of mammals, including human beings and rhesus monkeys. Other animals examined included chimpanzees, rat, mouse, bull, possums and marmosets.
Rhesus monkeys were found to possess the same number of genes in their Y chromosomes as humans. The two species diverged from each other 25 million years ago. This suggests the chromosome has not lost any genetic material since that time, and the structure is stable.
These genes may cause the bodies of men and women to read genomes differently. This could explain differences in the way diseases affect people of each gender. Researchers believe the genes which survive on the Y chromosome may prevent a wide variety of disorders.
"This paper tells us that not only is the Y chromosome here to stay, but that we need to take it seriously, and not just in the reproductive tract," David Page, director of the Whitehead Institute, said in a press release announcing the findings.
The Y chromosome is so challenging to analyze that many early versions of human genome maps ignored the structure altogether. Kaessmann and his group developed a way to quickly sequence the genes making up the chromosome.
Both studies of the various roles of the Y chromosome were detailed in the journal Nature.
