C57BL/6

C57BL/6, often referred to as 'C57 black 6', 'C57' or 'black 6', is a common inbred strain of laboratory mouse. C57BL/6, often referred to as 'C57 black 6', 'C57' or 'black 6', is a common inbred strain of laboratory mouse. It is the most widely used 'genetic background' for genetically modified mice for use as models of human disease. They are the most widely used and best-selling mouse strain, due to the availability of congenic strains, easy breeding, and robustness. C57BL/6 mice have a dark brown, nearly black coat. They are more sensitive to noise and odours and are more likely to bite than the more docile laboratory strains such as BALB/c. They are good breeders. Group-housed B6 female mice display barbering behavior, in which the dominant mouse in a cage selectively removes hair from its subordinate cage mates. Mice that have been barbered have large bald patches on their bodies, commonly around the head, snout, and shoulders, although barbering may appear anywhere on the body. Both hair and whiskers may be removed. C57BL/6 has many unusual characteristics that make it useful for some work and inappropriate for other: It is unusually sensitive to pain and to cold, and analgesic medications are less effective in it. Unlike most mouse strains, it drinks alcoholic beverages voluntarily. It is more susceptible than average to morphine addiction, atherosclerosis, and age-related hearing loss. The C57BL/6 mouse was the second-ever mammalian species to have its entire genome published. The dark coat make the mouse strain convenient for creating transgenic mice: it is crossed with a light-furred 129 mouse, and the desirable crosses can be easily identified by their mixed coat colors. There now exist colonies of mice derived from the original C57BL/6 colony that have been bred in isolation from one another for many hundreds of generations. Owing to genetic drift these colonies differ widely from one another (and, it goes without saying, from the original mice isolated at the Bussey Institute). Responsible scientists, including those at accredited repositories, are careful to point out this fact and take pains to distinguish sublines such as C57BL/6J (the established subline at The Jackson Laboratory) from C57BL/6N, etc. But even within these sublines, the potential for drift exists in colonies maintained by individual laboratories who do not have a systematic practice of reestablishing breeders from a centralized, vetted stock. By far the most popular laboratory rodent, the C57BL/6 mouse accounts for half to five-sixths of all rodents shipped to research laboratories from American suppliers. Its overwhelming popularity is due largely to inertia: it has been widely used and widely studied, and therefore it is used even more.