Many toxic plants are unpalatable, so animals avoid them where possible. However, this is not always the case; locoweeds, for example, are addictive and once a horse has eaten them, it will continue to eat them whenever possible, and can never be exposed to them again.
Micrograph of melanosis coli, with the characteristic mucosal lipofuscin-laden macrophages (brown). Melanosis coli, also pseudomelanosis coli, is a disorder of pigmentation of the wall of the colon, often identified at the time of colonoscopy.It is benign, and may have no significant correlation with disease. The brown pigment is lipofuscin in macrophages, not melanin.urther information: Factitious diarrhea. The most common cause of melanosis coli is the extended use of laxatives, and commonly anthraquinone containing laxatives such as Senna and other plant glycosides.
Variation in genes and skin color. One gene responsible for the production of melanin pigment is SLC24A5. It is found that there are two variations of SLC24A5: 1) One variation is with the amino acid called threonine, which is responsible for the light color of the skin.he pigment that gives color to your skin is melanin. It is also responsible for the color of your eyes. Melanin protects our skin from harmful ultraviolet radiation of the sun by absorbing the rays. More melanin pigment is produced by people with dark skin as compared to light skinned persons.