Washington, May 6: <\/p>\n
Scientists have found that fragile sites that can be a breeding ground for human cancers appear in specific areas of the genome where the DNA-copying machinery is slowed or stalled. <\/p>\n
Each time a human cell divides, it must first make a copy of its 46 chromosomes to serve as an instruction manual for the new cell. Normally, this process goes off without a hitch. <\/p>\n
But from time to time, the information isnt copied and collated properly, leaving gaps or breaks that the cell has to carefully combine back together. <\/p>\n
Researchers have long recognised that some regions of the chromosome, called fragile sites, are more prone to breakage and can be a breeding ground for human cancers. But they have struggled to understand why these weak spots in the genetic code occur in the first place. <\/p>\n
A comprehensive mapping of the fragile sites in yeast by a team of researchers from Duke University showed that fragile sites appear in specific areas of the genome where the DNA-copying machinery is slowed or stalled, either by certain sequences of DNA or by structural elements. <\/p>\n
The study, which appears in Proceedings of the National Academy of Sciences, could give insight into the origins of many of the genetic abnormalities seen in solid tumours. <\/p>\n
Other studies have been limited to looking at fragile sites on specific genes or chromosomes, said Thomas D Petes, the Minnie Geller professor of molecular genetics and microbiology at Duke University School of Medicine. <\/p>\n
Ours is the first to examine thousands of these sites across the entire genome and ask what they might have in common, Petes said. <\/p>\n
The term fragile sites was first coined in the 1980s to describe the chromosome breaks that appeared whenever a molecule called DNA polymerase responsible for copying DNA was blocked in mammalian cells. <\/p>\n
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\nFaulty DNA copying may lead to cancer: study<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"