Eukaryotes Genomes - MUS MUSCULUS

Mus musculus (more commonly known as the House Mouse ) originated in Asia but have since spread throughout the world. Along with brown rats, they are considered to be the most widespread terrestrial mammal other than humans. They have a life span of up to two years.

House mice have brown-grey fur, with slightly lighter under-parts, large ears, a pointed snout and a long tail, body length is approximately 6.5-10cm and weight between 12-22g.

Although they are thought to be native to Asia, house mice now have an almost worldwide distribution, they are typically found in areas near to human habitation and open fields. They are omnivores and feed on practically everything, but prefer to eat cereals and insects.

House mice are nocturnal. Wild populations are poor competitors with other rodents, and are often displaced by other species when away from human habituation. They are typically aggressive to each other, and fighting is common, although females have an aggression inhibiting hormone in their urine to prevent attack from other mice. House mice build tunnel systems which may be a short tunnel with just one chamber or a complex network with several exits and chambers. Some of these chambers may contain bedding material. Females produce about 5-10 litters per year, consisting of 4-8 young. The young are independent after 3 weeks.

House mice are ubiquitous and are considered to be a major pest as they spoil a large amount of stored food and are a carrier of several diseases (including salmonellosis,  plague, leptospirosis,  hantaviriruses, and  rickettsial pox) and can transmit these diseases directly by biting, infecting food with their droppings, infecting food with urine, or indirectly by fleas, or dying in a water supply.

House Mice are excellent climbers and can run up most roughened surfaces without breaking stride, they can can swim, and apparently hold their breath. Many have been reported being flushed only to reappear minutes later. Mice do not have bladders, they will relieve themselves at will anywhere. Mice can jump a vertical distance of 12 inches.

Sequencing of the complete genome for Mus musculus was completed in 2000. The mouse genome is essentially a reference manual for understanding the human genome. Virtually every gene in the mouse is also present in humans, and the neighbourhoods in which these genes reside are strikingly similar in humans and mice, although the mouse genome is fourteen percent smaller than the human genome . Researchers report that approximately 99 percent of mouse genes have counterparts in humans. The genes in humans and mice are essentially the same genes, they were inherited from a common mammalian ancestor millions of years ago however evolution changes genomes through the duplication and specialisation of genes. In fact, though many human and mouse genes appear to be similar, they may have taken on slightly different roles, or be active at different times during the life of a person or a mouse. Although both man and mouse share genes, they also share 'non-gene' regions that may regulate genes and these could be critical to understanding why humans develop certain diseases.

Comparing humans and mice has the potential to reveal key features of mammalian biology, and more insights will emerge as more genomes are completed. Researchers state that having a publicly available mouse genome sequence draft means we can move from knowing that a general region of the genome is contributing to a disease state or biological process, to actually looking at that region and seeing directly what genes are there. It will save investigators months, if not years, of gene-hunting efforts.

References:

Nature 5 420(6915):520-62 (2002 )
Hum. Mol. Genet. 12(3):329-339(2003)
http://www.bbc.co.uk/nature/wildfacts/factfiles/270.shtml
http://www.scapest.com/rodents.html
http://www.genomenewsnetwork.org/articles/12_02/mouse.shtml
http://jaxmice.jax.org/library/notes/489j.html
http://www.sanger.ac.uk/Projects/M_musculus/