Department of Evolution, The Ohio State University, 318 W 12th Avenue, Columbus, OH 43210, USA.
J Exp Biol. 2013 Apr 15;216(Pt 8):1373-80. doi: 10.1242/jeb.079889. Epub 2012 Dec 21.
A fundamental challenge facing physiological ecologists is to understand how variation in life history at the whole-organism level might be linked to cellular function. Thus, because tropical birds have higher annual survival and lower rates of metabolism, we hypothesized that cells from tropical species would have greater cellular resistance to chemical injury than cells from temperate species. We cultured dermal fibroblasts from 26 tropical and 26 temperate species of birds and examined cellular resistance to cadmium, H(2)O(2), paraquat, thapsigargin, tunicamycium, methane methylsulfonate (MMS) and UV light. Using ANCOVA, we found that the values for the dose that killed 50% of cells (LD(50)) from tropical birds were significantly higher for H(2)O(2) and MMS. When we tested for significance using a generalized least squares approach accounting for phylogenetic relationships among species to model LD(50), we found that cells from tropical birds had greater tolerance for Cd, H(2)O(2), paraquat, tunicamycin and MMS than cells from temperate birds. In contrast, tropical birds showed either lower or no difference in tolerance to thapsigargin and UV light in comparison with temperate birds. These findings are consistent with the idea that natural selection has uniquely fashioned cells of long-lived tropical bird species to be more resistant to forms of oxidative and non-oxidative stress than cells from shorter-lived temperate species.
生理生态学家面临的一个基本挑战是了解整体生物体水平的生活史变化如何与细胞功能相关联。因此，由于热带鸟类的年存活率较高，代谢率较低，我们假设热带物种的细胞对化学损伤的细胞抵抗力要强于温带物种的细胞。我们培养了 26 种热带鸟类和 26 种温带鸟类的真皮成纤维细胞，并检查了细胞对镉、H₂O₂、百草枯、他普西加林、衣霉素、甲烷甲基磺酸酯（MMS）和紫外线的抵抗能力。使用协方差分析（ANCOVA），我们发现，热带鸟类细胞的半数致死剂量（LD₅₀）值对于 H₂O₂和 MMS 显著更高。当我们使用广义最小二乘法（generalized least squares approach）来检验物种之间的系统发育关系对 LD₅₀进行建模时，我们发现，与温带鸟类的细胞相比，热带鸟类的细胞对 Cd、H₂O₂、百草枯、衣霉素和 MMS 的耐受性更强。相比之下，与温带鸟类相比，热带鸟类对他普西加林和紫外线的耐受性要么较低，要么没有差异。这些发现与这样一种观点一致，即自然选择独特地塑造了长寿热带鸟类物种的细胞，使其对氧化和非氧化应激的形式具有更强的抵抗力，而不是对寿命较短的温带物种的细胞。
