Marques Cristiana I, Rodríguez-Martínez Sol, Araújo Pedro Miguel, Afonso Sandra, Zougagh Mohammed, Ríos Ángel, Carneiro Miguel, Galván Ismael
CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO Laboratório Associado, Campus de Vairão, Universidade do Porto, 4485-661 Vairão, Portugal.
Departamento de Biologia, Faculdade de Ciências, Universidade do Porto, 4099-002 Porto, Portugal.
iScience. 2025 Jun 18;28(7):112937. doi: 10.1016/j.isci.2025.112937. eCollection 2025 Jul 18.
Melanins are fundamental vertebrate pigments. Pheomelanin synthesis utilizes cysteine, a precursor for the antioxidant glutathione. Sustained pheomelanin synthesis may thus reduce cysteine availability for antioxidant defenses, resulting in a trade-off most relevant in stressful environments. Here, we investigated how pheomelanin may influence birds' response to oxidative stress. We began by determining the genetic bases of three independent melanin-based zebra finch varieties. Two previously established melanin genes can explain () and () mutations, while a novel pigmentation gene () was associated with the eumelanin-to-pheomelanin shift in the phenotype. individuals exhibited higher DNA damage and a gene expression profile compatible with cellular redox imbalance. During oxidative stress, these birds minimized DNA damage and changed pheomelanin concentration, consistent with cysteine/glutathione economization. Further analyses revealed downregulation of glutathione S-transferases in pheomelanic morphs across species. We propose that pheomelanic birds might have an adaptive built-in physiological plasticity under environmental oxidative stress.
黑色素是脊椎动物的基本色素。褐黑素的合成利用半胱氨酸，它是抗氧化剂谷胱甘肽的前体。因此，持续的褐黑素合成可能会减少用于抗氧化防御的半胱氨酸的可用性，从而在压力环境中产生一种最为相关的权衡。在此，我们研究了褐黑素如何影响鸟类对氧化应激的反应。我们首先确定了三种独立的基于黑色素的斑胸草雀变种的遗传基础。两个先前确定的黑色素基因可以解释（）和（）突变，而一个新的色素沉着基因（）与表型中真黑素向褐黑素的转变有关。个体表现出更高的DNA损伤以及与细胞氧化还原失衡相符的基因表达谱。在氧化应激期间，这些鸟类将DNA损伤降至最低，并改变了褐黑素浓度，这与半胱氨酸/谷胱甘肽的节约一致。进一步分析发现，跨物种的褐黑素形态中谷胱甘肽S-转移酶下调。我们认为，在环境氧化应激下，褐黑素鸟类可能具有适应性的内在生理可塑性。
