Y chromosomes are probably lost when cells divide, with some cells failing to divvy up their chromosomes equally.
Conversely, a palindrome on the
Y chromosome will be selected for because it provides a duplicate copy of the genes it contains, enabling them to be maintained.
The problem is to be sure that this is the personal
Y chromosome of Genghis Khan," adds Jaume Bertranpetit of the University of Pompeu Fabra in Barcelona.
The researchers used 167 chemical markers to probe alterations of nucleotide sequences in the
Y chromosomes in modern men.
Hammer of the University of Arizona in Tucson, who has used the
Y chromosome to investigate the origins of people in Japan (SN: 2/15/97, p.
After 22 generations, the males had even more impressive stalks, and the sex ratio had shifted to a surplus of males--suggesting a link between stalk length and more persistent
Y chromosomes.
Their indispensability may explain why they haven't degenerated like most other genes on the
Y chromosome.
Hammer, a researcher at the University of Arizona in Tucson, and Satoshi Horai, who works at the National Institute of Genetics in Mishima, Japan, addressed these theories with their study of the
Y chromosome.
Early in mammalian evolution, however, the
Y chromosome apparently began to degenerate rapidly.
In two recent reports, including one in the May 11 Lancet, Page's group has presented evidence that some cases of male infertility result from specific deletions within the
Y chromosome, a finding that suggests the deleted area contains a gene or genes crucial to the production of healthy sperm.
The product includes probes to identify cells containing fetal and adult forms of hemoglobin mRNA, providing a method of identifying fetal cells, as well as probes to identify the X and
Y chromosomes.
Twenty-two pairs of chromosomes, plus the X and
Y chromosomes, carry almost all of a person's genes.
