Scimeca Manuel, Bonfiglio Rita, Colosimo Giuliano, Candi Eleonora, Gerber Glenn P, Lewbart Gregory A, Mauriello Alessandro, Melino Gerry, Sevilla Christian, Shi Yufang, Wang Ying, Gentile Gabriele
Department of Experimental Medicine, University of Rome Tor Vergata, Rome, 00133, Italy.
Department of Biology, University of Rome Tor Vergata, Rome, 00133, Italy.
Biol Direct. 2025 Feb 4;20(1):16. doi: 10.1186/s13062-025-00602-5.
Iguanas exhibit diverse colors and behaviors reflecting evolutionarily adaptation to various habitats; in particular, the Galápagos iguanas represent unique color morphologies with distinct ecological niches. While external coloration in iguanas has ecological implications, comprehensive studies on the histological and ultrastructural aspects of their skin can provide insight into their adaptation to extreme environments, such as high UV exposure. Starting from these considerations the present study investigates the histological, ultrastructural and immunohistochemical features to comprehensively characterize the skin in adults of three species of Galápagos iguanas (A. cristatus, C. subcristatus and C. marthae). Morphological analysis revealed significant differences among the species, with the black-colored skin of A. cristatus showing a melanin-rich but vessel-poor dermis, while C. subcristatus and C. marthae displayed varying distributions of melanosomes and melanocytes. Notably, the absence of iridophores was consistent across all samples due to the absence of birefringent material under the optical microscope. Morphometric evaluations highlighted interspecific differences in the stratum corneum thickness, particularly between black- and non-black-colored (irrespectively if yellowish or pink) skin. The ultrastructural investigation confirmed the absence of iridophores in all analyzed samples. The cytokeratin expression assessed by immunohistochemistry showed stratified epithelium in the epidermis of C. marthae non-black-colored (pink) skin. The presence of a thickened stratum corneum and the stratification of the epidermis in non-pigmented skin could help the pink iguana to cope with the extreme conditions of the Wolf volcano, especially in relation to UV exposure. These skin characteristics may reduce the penetration power of UV rays into the superficial loose dermis, thereby attenuating potential UV-related damage such as DNA breaks and ROS generation. These findings offer insights into the adaptive strategies of these iguanas.
鬣蜥呈现出多样的颜色和行为，这反映了它们在进化过程中对各种栖息地的适应；特别是加拉帕戈斯鬣蜥呈现出独特的颜色形态和不同的生态位。虽然鬣蜥的外部颜色具有生态意义，但对其皮肤的组织学和超微结构方面进行全面研究，可以深入了解它们对极端环境的适应，例如高紫外线照射环境。基于这些考虑，本研究调查了三种加拉帕戈斯鬣蜥（艾氏岛鬣蜥、圣克鲁斯岛鬣蜥和费尔南迪纳岛陆鬣蜥）成体皮肤的组织学、超微结构和免疫组化特征，以全面表征其皮肤特性。形态学分析揭示了不同物种之间的显著差异，艾氏岛鬣蜥的黑色皮肤显示真皮富含黑色素但血管较少，而圣克鲁斯岛鬣蜥和费尔南迪纳岛陆鬣蜥则表现出黑素体和黑素细胞的不同分布。值得注意的是，由于在光学显微镜下未观察到双折射物质，所有样本中均未发现虹彩细胞。形态测量评估突出了角质层厚度的种间差异，特别是黑色皮肤与非黑色皮肤（无论呈淡黄色或粉红色）之间的差异。超微结构研究证实所有分析样本中均不存在虹彩细胞。通过免疫组化评估的细胞角蛋白表达显示，费尔南迪纳岛陆鬣蜥非黑色（粉红色）皮肤的表皮为分层上皮。角质层增厚和非色素沉着皮肤中表皮分层的存在可能有助于粉红色鬣蜥应对沃尔夫火山的极端条件，特别是与紫外线暴露有关的条件。这些皮肤特征可能会降低紫外线穿透到浅表疏松真皮的能力，从而减轻潜在的紫外线相关损伤，如DNA断裂和活性氧生成。这些发现为这些鬣蜥的适应性策略提供了见解。
