IUCN / SSC Cat Specialist Group - Digital Cat Library |
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| Santos, D.C. | |
| Padräes de variabilidade do gene _ASIP (Agouti Signaling Protein)_ em mam¡feros | |
| 2007 Full Book | |
Abstract of Chapter 4: Artigo "Patterns of nucleotide variability in the _Agouti Signaling Protein (ASIP)_ gene in mammals. The regulation of coat color in mammals is controlled mainly by the action of two genes, _MC1R (Melanocortin-1 receptor)_, responsible for inducing the production of dark pigment (eumelanin), and _ASIP (Agouti Signaling Protein)_, which codes for an antagonistic peptide whose action promotes the formation of light pigment (feomelanin). The understanding of the structural characteristics of these loci and of the evolutionary processes influencing their patterns of conservation is still in its infancy, with few species analyzed so far, and no broad comparison available. In this paper we analyzed different regions of the _ASIP_ gene in several mammalian species, with emphasis on the family Felidae (Mammalia, Carnivora). Our goals were to characterize patterns of variability and conservation in the surveyed regions of _ASIP_, and also to investigate the possibility of molecular variants at this locus being associated with melanistic phenotypes in the Geoffroy's cat (_Leopardus geoffroyi_). Complete sequences of exons 2 and 3, intron 2, and part of intron 3, were obtained for a total of five different felid species, in some cases represented by multiple individuals each. These sequences were compared to each other and to two canid species (Carnivora, Canidae) and one representative each of the mammalian orders Cetartiodactyla and Perissodactyla. Our results allow the identification and characterization of several conserved sequence blocks in intronic regions, which present similar or higher levels of sequence conservation when compared to coding regions. The boundaries of these conserved blocks were characterized through comparisons at increasing levels of evolutionary depth, allowing the identification of core areas maintained over ca. 90 million years of evolution, and possibly involved in regulatory activities. No exonic polymorphism was observed in _L. geoffroyi_, including melanistic individuals, indicating that exons 2 and 3 are not involved in this phenotype in this species. |
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