The Tangled Tale of Black 6 Unraveled
What the Human Genome Project did for sequencing the genes of human DNA, the Mouse Genome Sequencing Consortium has now accomplished for the furry rodent for which this blog is named.
According to a study recently published in the open-access online journal PLoS Biology, a group of scientists have finished mapping the 20,000-plus sequence of genes existing in mice DNA — an accomplishment that could have a big impact on the study of human disease and treatment.
All together more than 150 scientists, in at least 13 different locations, analyzed the DNA of the “Black 6" mouse — a common strain of mouse used in laboratory trails — to complete the genome “assembly.” They found that despite having 20 chromosome pairs compared to humankind’s 23, mice have more than 1,000 additional protein-coding genes than humans (mice have 20,210 and humans have 19,042).
The mouse genome contained 3,767 genes described as “lineage specific” (i.e. gene sequences that are not found in other species). In total, however, mice and humans share 15,187 genes that have not changed since the two species diverged from their last common ancestor more than 90 million years ago.
The new research improves upon a 2002 study published in Nature where a draft of the mouse genome, which contained more than 176,000 gaps and other errors, was presented. The newly finished genome contains 2,185 genes that were missing or misassembled in the 2002 sequence — 1,259 of which were mouse specific.
Because of their small size and relatively quick reproduction ability, mice are researchers’ animal model of choice in human disease, development and psychology research. The now fully mapped mouse genome assembly will help scientists both interpret the human genome itself (only 5 percent of the human genome contains actual genes) and identify new ways to use mice as model systems in human disease and treatment research.
For example, research groups like the Knock Out Mouse Project will be able to use the completed mouse genome as a map to systematically knock out individual genes with mutations in order to better understand each gene’s specific function in mice and, where possible, in humans.
“The better we understand the mouse genome, the better we can understand the mouse,” says Deanna Church, a genetics researcher at the National Center for Biotechnology Information and one of the lead scientists of the study, “This will allow us to better interpret mouse models, especially when they don’t exactly replicate a human phenotype. Understanding the differences is key to getting the most out of (this) model organism.”
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