Organisms evolve mechanisms that regulate the properties of biogenic crystals to support a wide range of functions, from vision and camouflage to communication and thermal regulation. Yet, the mechanism underlying the formation of diverse intracellular crystals remains enigmatic. Here we unravel the biochemical control over crystal morphogenesis in zebrafish iridophores. We show that the chemical composition of the crystals determines their shape, particularly through the ratio between the nucleobases guanine and hypoxanthine. We reveal that these variations in composition are genetically controlled through tissue-specific expression of specialized paralogs, which exhibit remarkable substrate selectivity. This orchestrated combination grants the organism with the capacity to generate a broad spectrum of crystal morphologies. Overall, our findings suggest a mechanism for the morphological and functional diversity of biogenic crystals and may, thus, inspire the development of genetically designed biomaterials and medical therapeutics.

生物体进化出调节生物晶体特性的机制，以支持从视觉和伪装到通信和热调节的广泛功能。然而，形成不同细胞内晶体的机制仍然是个谜。在这里，我们揭示了斑马鱼虹膜细胞中晶体形态发生的生化控制。我们表明晶体的化学成分决定了它们的形状，特别是通过核碱基鸟嘌呤和次黄嘌呤之间的比例。我们揭示了这些组成的变化是通过特化旁系同源物的组织特异性表达进行遗传控制的，这些旁系同源物表现出显着的底物选择性。这种精心编排的组合使生物体能够产生广泛的晶体形态。总体而言，我们的研究结果表明了生物晶体形态和功能多样性的机制，因此可能激发基因设计的生物材料和医学治疗学的发展。