Programa de Pós-Graduação em Genética e Biologia Molecular, Departamento de Genética, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil.
Genet Mol Biol. 2012 Jan;35(1):81-7. doi: 10.1590/s1415-47572012005000015. Epub 2012 Feb 3.
In reptiles, dorsal body darkness often varies with substrate color or temperature environment, and is generally presumed to be an adaptation for crypsis or thermoregulation. However, the genetic basis of pigmentation is poorly known in this group. In this study we analyzed the coding region of the melanocortin-1-receptor (MC1R) gene, and therefore its role underlying the dorsal color variation in two sympatric species of sand lizards (Liolaemus) that inhabit the southeastern coast of South America: L. occipitalis and L. arambarensis. The first is light-colored and occupies aeolic pale sand dunes, while the second is brownish and lives in a darker sandy habitat. We sequenced 630 base pairs of MC1R in both species. In total, 12 nucleotide polymorphisms were observed, and four amino acid replacement sites, but none of them could be associated with a color pattern. Comparative analysis indicated that these taxa are monomorphic for amino acid sites that were previously identified as functionally important in other reptiles. Thus, our results indicate that MC1R is not involved in the pigmentation pattern observed in Liolaemus lizards. Therefore, structural differences in other genes, such as ASIP, or variation in regulatory regions of MC1R may be responsible for this variation. Alternatively, the phenotypic differences observed might be a consequence of non-genetic factors, such as thermoregulatory mechanisms.
在爬行动物中，背部身体颜色通常随基质颜色或温度环境而变化，通常被认为是一种用于伪装或体温调节的适应。然而，该群体的色素沉着遗传基础知之甚少。在这项研究中，我们分析了黑色素皮质素 1 受体 (MC1R) 基因的编码区，因此分析了栖息在南美洲东南海岸的两种共生沙蜥蜴（Liolaemus）背部颜色变化的遗传基础：L. occipitalis 和 L. arambarensis。第一个物种颜色浅，栖息在微风扬起的浅色沙丘上，而第二个物种呈棕色，生活在较暗的沙质栖息地。我们对这两个物种的 MC1R 基因进行了 630 个碱基的测序。总共观察到 12 个核苷酸多态性，4 个氨基酸取代位点，但没有一个与颜色模式相关。比较分析表明，这些分类单元在以前被确定为其他爬行动物中具有功能重要性的氨基酸位点上是单态的。因此，我们的结果表明，MC1R 不参与在 Liolaemus 蜥蜴中观察到的色素沉着模式。因此，ASIP 等其他基因的结构差异，或 MC1R 调控区的变异可能是导致这种变异的原因。或者，观察到的表型差异可能是遗传因素以外的因素的结果，例如体温调节机制。
