|
Cats, like all living organisms, occasionally have mutations that affect their body type. Sometimes, these cat body-type mutations are striking enough that humans select for and perpetuate them. This is not always in the best interests of the cat, as many of these mutations are harmful; some are even lethal in their homozygous form. This page gives a selection of cat body type mutant alleles and the associated mutations with a brief description. == Tail types == Jb = Japanese bobtail gene (recessive). Cats heterozygous for this gene have abnormal tails, but unlike the Manx tailless gene, there are no associated skeletal disorders and the gene is not associated with lethality. M = Manx tailless gene (dominant with high penetrance). Cats with the homozygous genotype (MM) die before birth, and stillborn kittens show gross abnormalities of the central nervous system. Cats with the heterozygous genotype (Mm) show severely shortened tail length, ranging from taillessness to a partial, stumpy tail. Some Manx cats die before 12 months old and exhibit skeletal and organ defects. Because it was discovered in naturally occurring populations of cats, the Manx gene could confer some kind of selective advantage to the cats, or it may simply be an example of the founder effect. The trait also occurred and died out in Cornwall (peninsular England), but became fixed in the Isle of Man population where outbreeding was not frequent due to isolation. Shortened tails, most of which are indistinguishable from the Japanese Bobtail or the variably expressed Manx mutation, may occur sporadically in any cat breed or mixed-breed population. However, some may be novel mutations that have not been investigated. There are multiple types of curly-tailed cats whose tails loop over the back or form tight corkscrews. One such mutation has been developed into the American Ringtail, but others have been regarded as curiosities and not perpetuated. The gene(s) responsible have not been fully investigated. However a research study is under way at UC Davis under the guidance of Leslie A. Lyons. DNA samples are being assembled via http://www.vetmed.ucdavis.edu/Catgenetics/Feline_Research_Projects.html. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Cat body-type mutation」の詳細全文を読む スポンサード リンク
|