Alejandro Vianey, Hernández América, Pérez-Rodríguez Lorenzo, Montoya Bibiana
Maestría en Ciencias Biológicas, Centro Tlaxcala de Biología de la Conducta (CTBC), Universidad Autónoma de Tlaxcala, Tlaxcala, México.
Doctorado en Ciencias Biológicas, Centro Tlaxcala de Biología de la Conducta (CTBC), Universidad Autónoma de Tlaxcala, Tlaxcala, México.
J Exp Zool A Ecol Integr Physiol. 2025 Jan;343(1):59-69. doi: 10.1002/jez.2865. Epub 2024 Sep 18.
Colorful traits play an important role in animal communication. Melanin-based colorations are the most extended color traits in animals and are produced by two types of endogenous melanic pigments: eumelanins and pheomelanins, the last ones being the least studied in the context of communication. The production of pheomelanin requires a semi-essential amino acid, cysteine, which is also used for the synthesis of an important endogenous antioxidant, glutathione. Hence, it has been proposed that the synthesis of pheomelanin and glutathione may compete for the cysteine available in the organism. In that case, pheomelanic colorations are predicted to be less intense when the individual is facing an oxidative challenge, and therefore, they would provide information on the oxidative status of the bearer. Here, we experimentally evaluated this hypothesis using male Japanese quails (Coturnix japonica) as a model of study, a species with pheomelanin-based plumage in the breast and cheeks. During feather growth, individuals were exposed to one of three possible conditions: Control (saline), an endogenous oxidative challenge (Escherichia coli lipopolysaccharide injections), or an exogenous oxidative challenge (paraquat injections). Contrary to predictions, we found that: (1) Birds from the three groups exhibited less intense pheomelanic colorations in feathers after the experimental manipulation, and the magnitude of this change did not differ among groups. (2) There was no effect of the experimental treatments on the proportion reduced/oxidized glutathione, an index of oxidative status. (3) Lipid peroxidation was lower after the experimental manipulation, with birds exposed to the paraquat challenge experiencing a stronger decline than other groups. (4) Cysteine and total glutathione levels decreased after the experimental manipulation, with no differences per group in the magnitude of the decline. Taken together the results do not support the hypothesis that oxidative status plays a key role at determining the variation in the intensity of pheomelanic colorations.
色彩斑斓的特征在动物交流中起着重要作用。基于黑色素的色素沉着是动物中最广泛的颜色特征，由两种内源性黑色素产生：真黑色素和褐黑素，后者在交流背景下的研究最少。褐黑素的产生需要一种半必需氨基酸——半胱氨酸，它也用于合成一种重要的内源性抗氧化剂——谷胱甘肽。因此，有人提出褐黑素和谷胱甘肽的合成可能会竞争生物体中可用的半胱氨酸。在这种情况下，当个体面临氧化应激时，预计褐黑素色素沉着会不那么强烈，因此，它们会提供有关携带者氧化状态的信息。在这里，我们以雄性日本鹌鹑（Coturnix japonica）为研究模型，通过实验评估了这一假设，该物种胸部和脸颊有基于褐黑素的羽毛。在羽毛生长过程中，个体被暴露于三种可能的条件之一：对照（生理盐水）、内源性氧化应激（注射大肠杆菌脂多糖）或外源性氧化应激（注射百草枯）。与预测相反，我们发现：（1）实验处理后，三组鸟类羽毛中的褐黑素色素沉着都变浅，且这种变化的幅度在各组之间没有差异。（2）实验处理对氧化状态指标——还原型/氧化型谷胱甘肽的比例没有影响。（3）实验处理后脂质过氧化水平降低，接受百草枯应激的鸟类下降幅度比其他组更大。（4）实验处理后半胱氨酸和总谷胱甘肽水平下降，各组下降幅度没有差异。综合来看，这些结果不支持氧化状态在决定褐黑素色素沉着强度变化中起关键作用的假设。
