![]() ![]() The 3X cat genome assembly is not contiguous across the Tabby linkage interval ( 7), but comparison to homologous regions in the dog and human genomes suggests a candidate interval of ~5 Mb in length ( fig. ![]() Instead, the difference between mackerel and blotched is controlled by a single locus, Tabby ( Ta), whose genetic position does not suggest an obvious candidate gene ( 7) but whose effects could be manifested via differential control of melanocortin signaling. However, known components of the Agouti-melanocortin pathway do not affect the shape of tabby patterns ( 1, 2, 5, 6). According to this hypothesis, dark tabby stripes are areas in which Agouti signaling is suppressed or surmounted during hair growth and regeneration. S2).Ī logical explanation for tabby patterning involves the Agouti-melanocortin receptor system, in which Agouti protein, a paracrine signaling molecule released from dermal papillae, acts on overlying hair follicle melanocytes to inhibit the melanocortin 1 receptor (Mc1r), causing a switch from the production of black/brown eumelanin to red/yellow pheomelanin ( 3, 4). The T139N allele is associated ( P = 0.0017, Fisher’s exact test) with an atypical swirled pattern but is incompletely penetrant ( table S1 and fig. Mutant allele frequencies are from a survey of 119 feral and outbred cats ( table S1). ![]() ( B) Taqpep encodes a type II membrane protein with aminopeptidase activity encoded by the ectodomain. Diagrams indicate how the distribution of black or brown eumelanin versus yellow or pale pheomelanin within individual hairs underlies the macroscopic color patterns, although in reality cat hairs frequently exhibit multiple pheomelanic bands. (A) Allelic variation at Tabby controls the arrangement of dark- and light-colored areas. ![]()
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