Researchers have zoomed in on mouse chromosomes to map hotspots of genetic recombination sites where DNA breaks and reforms to shuffle genes. The findings of the scientists at the National Institutes of Health and Uniformed Services University of Health Sciences (USU) have the potential to improve the detection of genes linked to disease and to help understand the root causes of genetic abnormalities. The research, published online April 3 in Nature, moves scientists one step closer to understanding how mammals evolve and respond to their environments.
In this image, hundredfold magnification of a single sperm precursor cell shows the chromosomes in green and the places where these chromosomes are most likely to break apart and re-form, called genetic recombination hotspots in red. Genetic rearrangements at these hotspots have the potential to shuffle maternal and paternal chromosomes, the end results of which ensure that the genetic information in every sperm cell is unique. Source: Fatima Smagulova, Ph.D., USU, and Kevin Brick, Ph.D., NIDDK, NIH.Genetic recombination occurs at hotspots in cells that form sperm and eggs. At these sites, rearrangements ensure that the combination of genes passed on to every sperm and egg cell is unique. By studying precursors of mouse sperm cells during the early stages of genetic recombination, the scientists have created a precise, first-of-its-kind map of recombination hotspots in a multi-celled organism.
With this map, researchers also hope to pinpoint where, how and why abnormalities in the number of chromosomes can occur. Such abnormalities for instance, the extra copy of chromosome 21 that gives rise to Down syndrome are the leading known cause of miscarriages, congenital birth defects, and mental retardation in the United States.
"We wanted to figure out how recombination varied across the genome," said R. Daniel Camerini-Otero, M.D., Ph.D., one of the senior authors on the pa
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NIH/National Institute of Diabetes and Digestive and Kidney Diseases