YORK (Reuters Health) - As part of the Human Genome Project, scientists
have constructed the map of the Y chromosome--the stocky chunk
of DNA that makes men look and act like men--and it's not what
they expected. In fact, it is more interesting than once thought,
according to one of the researchers involved in the mapping, Dr.
David C. Page.
In an interview
with Reuters Health, Page, of the Whitehead Institute at the Massachusetts
Institute of Technology (MIT) in Cambridge, said that for many
years the Y chromosome was considered to be a ``genomic junkyard''
that contained few, if any, genes. Besides determining a person's
sex, scientists generally thought the chromosome was a bit of
a wasteland, he said.
on the recently constructed map, a better label for the Y chromosome
is ``the genome's national park,'' according to Page, who said
that the male chromosome contains ``quite amazing features.''
The findings are published in the February 15th issue of the journal
Nature, a special issue of the journal with scientists' first
look at the completed sequence of the human genome.
constructed map ``provides the foundation for sequencing the chromosome
that has historically been very (poorly) understood,'' Page said.
The MIT scientist
explained that the Y chromosome differs from other chromosomes
in two ways. First, it is only present in one sex (women have
two X chromosomes while men have an X and a Y). Second, the chromosome
is the only one that does not participate in a process called
recombination--a shuffling of the genetic deck that occurs in
the making of an embryo.
of the chromosome is not involved in recombination, the chromosome
has evolved differently than the others over the course of the
last 300 million years, Page noted.
One of the
interesting features that the mapping of the chromosome revealed
was the repetition of large chunks of the chromosome, he said.
At first glance, these segments may appear to be ``abandoned debris''
that does not serve any function, but these repeated segments
actually carry many genes involved in the production of sperm,
which is the chromosome's ``specialty,'' Page pointed out.
out that the part of maleness that the Y chromosome really has
to do with is sperm production,'' he said. He noted that defects
in the Y chromosome have been linked to some types of male infertility.
that the map is only a glimpse of what is contained in the Y chromosome.
Later in the year, he and his colleagues expect to publish the
results of the sequencing of the chromosome, he said.
Reference Source 99