Rice Marlen C, Little Jordan H, Forrister Dale L, Machado Julane, Clark Nathan L, Gagnon James A
School of Biological Sciences, University of Utah, SLC, UT 84112, USA.
Department of Human Genetics, University of Utah, SLC, UT 84112, USA.
bioRxiv. 2023 Jan 31:2023.01.30.526370. doi: 10.1101/2023.01.30.526370.
Ultraviolet radiation (UVR) and its deleterious effects on living cells selects for UVR-protective mechanisms. Organisms across the tree of life evolved a variety of natural sunscreens to prevent UVR-induced cellular damage and stress. However, in vertebrates, only melanin is known to act as a sunscreen. Here we demonstrate that gadusol, a transparent compound discovered over 40 years ago in fish eggs, is a maternally provided sunscreen required for survival of embryonic and larval zebrafish exposed to UVR. Mutating an enzyme involved in gadusol biosynthesis increases the formation of cyclobutane pyrimidine dimers, a hallmark of UVB-induced DNA damage. Compared to the contributions of melanin and the chorion, gadusol is the primary sunscreening mechanism in embryonic and larval fish. The gadusol biosynthetic pathway is retained in the vast majority of teleost genomes but is repeatedly lost in species whose young are no longer exposed to UVR. Our data demonstrate that gadusol is a maternally provided sunscreen that is critical for early-life survival in the most species-rich branch of the vertebrate phylogeny.
紫外线辐射（UVR）及其对活细胞的有害影响促使了UVR防护机制的形成。生命之树上的各种生物进化出了多种天然防晒剂，以防止UVR诱导的细胞损伤和应激。然而，在脊椎动物中，已知只有黑色素起到防晒剂的作用。在此，我们证明了鲱精醇，一种40多年前在鱼卵中发现的透明化合物，是暴露于UVR的斑马鱼胚胎和幼体生存所需的一种由母体提供的防晒剂。使参与鲱精醇生物合成的一种酶发生突变会增加环丁烷嘧啶二聚体的形成，这是UVB诱导的DNA损伤的一个标志。与黑色素和卵膜的作用相比，鲱精醇是胚胎和幼体鱼类中的主要防晒机制。鲱精醇生物合成途径在绝大多数硬骨鱼基因组中得以保留，但在其幼体不再暴露于UVR的物种中反复丢失。我们的数据表明，鲱精醇是一种由母体提供的防晒剂，对脊椎动物系统发育中物种最丰富的分支的早期生命生存至关重要。
