Browsing by Author "Chuong, Cheng-Ming"
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- Cis-acting mutation affecting GJA5 transcription is underlying the Melanotic within-feather pigmentation pattern in chickensLi, Jingyi; Lee, Mi-Ok; Chen, Junfeng; Davis, Brian W.; Dorshorst, Benjamin J.; Siegel, Paul B.; Inaba, Masafumi; Jiang, Tingxin; Chuong, Cheng-Ming; Andersson, Leif (2021-10-12)Melanotic (Ml) is a mutation in chickens that extends black (eumelanin) pigmentation in normally brown or red (pheomelanin) areas, thus affecting multiple within-feather patterns [J. W. Moore, J. R. Smyth Jr, J. Hered. 62, 215-219 (1971)]. In the present study, linkage mapping using a back-cross between Dark Cornish (Ml/Ml) and Partridge Plymouth Rock (ml(+)/ml(+)) chickens assigned Ml to an 820-kb region on chromosome 1. Identity-by-descent mapping, via whole-genome sequencing and diagnostic tests using a diverse set of chickens, refined the localization to the genomic region harboring GJA5 encoding gap-junction protein 5 (alias connexin 40) previously associated with pigmentation patterns in zebrafish. An insertion/deletion polymorphism located in the vicinity of the GJA5 promoter region was identified as the candidate causal mutation. Four different GJA5 transcripts were found to be expressed in feather follicles and at least two showed differential expression between genotypes. The results showed that Melanotic constitutes a cis-acting regulatory mutation affecting GJA5 expression. A recent study established the melanocortin-1 receptor (MC1R) locus and the interaction between the MC1R receptor and its antagonist agoutisignaling protein as the primary mechanism underlying variation in within-feather pigmentation patterns in chickens. The present study advances understanding the mechanisms underlying variation in plumage color in birds because it demonstrates that the activity of connexin 40/GJA5 can modulate the periodic pigmentation patterns within individual feathers.
- The feather pattern autosomal barring in chicken is strongly associated with segregation at the MC1R locusThalmann, Doreen Schwochow; Bornelov, Susanne; Jiang, Tingxin; Li, Jingyi; Gourichon, David; Bed'Hom, Bertrand; Dorshorst, Benjamin J.; Chuong, Cheng-Ming; Tixier-Boichard, Michele; Andersson, Leif (2021-04-01)Color patterns within individual feathers are common in birds but little is known about the genetic mechanisms causing such patterns. Here, we investigate the genetic basis for autosomal barring in chicken, a horizontal striping pattern on individual feathers. Using an informative backcross, we demonstrate that the MC1R locus is strongly associated with this phenotype. A deletion at SOX10, underlying the dark brown phenotype on its own, affects the manifestation of the barring pattern. The coding variant L133Q in MC1R is the most likely causal mutation for autosomal barring in this pedigree. Furthermore, a genetic screen across six different breeds showing different patterning phenotypes revealed that the most striking shared characteristics among these breeds were that they all carried the MC1R alleles Birchen or brown. Our data suggest that the presence of activating MC1R mutations enhancing pigment synthesis is an important mechanism underlying pigmentation patterns on individual feathers in chicken. We propose that MC1R and its antagonist ASIP play a critical role for determining within-feather pigmentation patterns in birds by acting as activator and inhibitor possibly in a Turing reaction-diffusion model.