Draft sequence of the Mouse genome.
In December 2002 the draft sequence of the mouse genome was published. For free
access is available to the paper in Nature. Click here for a link to the Nature Website and
get free access is available to the paper in Nature along with editorial commentaries.
Sequencing of the mouse genome is another major step forward in understanding human
It allows the functionally important areas of the human and mouse genomes to be
identified because they will be subject “purifying selection” – that is areas of the genome
where nucleotide substitution rate that is lower than the neutral rate, indicating that
selection is operating against any changes. About 5% of the genome of the two
organisms is subject to such selection. This is a represents a higher proportion the
genome than that which encodes proteins and indicates that non-coding regions such
as regulatory regions are subject to sequence-dependent selection.
About 90% of each genome can be assigned to regions of synteny – that is
chromosomal regions where the gene order has been conserved from the most recent
common ancestor (MRCA). At the nucleotide level, about 40% of the two genomes can
be directly aligned with each other, representing the sequences that have been
conserved from the MRCA. Aligning the genomes in this way not only tells us about the
evolution of mice and men, but it allows human genes to be rapidly identified when
fundamental research in mice has identified their importance,
A surprising and controversial conclusion of the human genome project was that there
are only about 30,000 human genes. A similar conclusion was reached independently
from analysis of the mouse genome.
Comparison of the two genomes tells us much about the evolution of mammalian
genomes. Some proteins are apparently under positive selection, these are mostly
involved in reproduction, host defence and immunity. In the evolution of the mouse
genome there has been an expansion of gene families concerned with olefaction,
immunity and reproduction.