Department of Chemistry, Ben-Gurion University of the Negev, Beer-Sheba, 8410501, Israel.
Ilse Katz Institute for Nanoscale Science & Technology, Ben-Gurion University of the Negev, Beer-Sheba, 8410501, Israel.
Nat Commun. 2023 Feb 3;14(1):589. doi: 10.1038/s41467-023-35894-6.
Animals precisely control the morphology and assembly of guanine crystals to produce diverse optical phenomena in coloration and vision. However, little is known about how organisms regulate crystallization to produce optically useful morphologies which express highly reflective crystal faces. Guanine crystals form inside iridosome vesicles within chromatophore cells called iridophores. By following iridosome formation in developing scallop eyes, we show that pre-assembled, fibrillar sheets provide an interface for nucleation and direct the orientation of the guanine crystals. The macromolecular sheets cap the (100) faces of immature guanine crystals, inhibiting growth along the π-stacking growth direction. Crystal growth then occurs preferentially along the sheets to generate highly reflective plates. Despite their different physical properties, the morphogenesis of iridosomes bears a striking resemblance to melanosome morphogenesis in vertebrates, where amyloid sheets template melanin deposition. The common control mechanisms for melanin and guanine formation inspire new approaches for manipulating the morphologies and properties of molecular materials.
动物精确地控制着鸟嘌呤晶体的形态和组装，从而在颜色和视觉中产生多样化的光学现象。然而，对于生物体如何调节晶体的形成以产生具有高度反射性晶面的光学有用形态，人们知之甚少。鸟嘌呤晶体在被称为虹彩细胞的色质细胞内的虹彩体小泡中形成。通过观察扇贝眼睛的虹彩体形成过程，我们发现预先组装的纤维片为成核提供了界面，并指导了鸟嘌呤晶体的取向。大分子片层覆盖在不成熟的鸟嘌呤晶体的（100）面上，抑制了沿π-堆积生长方向的生长。然后，晶体生长优先沿着片层进行，从而生成高度反射的薄片。尽管它们具有不同的物理性质，但虹彩体的形态发生与脊椎动物中黑色素体的形态发生惊人地相似，在那里淀粉样片层模板化黑色素的沉积。黑色素和鸟嘌呤形成的共同控制机制为操纵分子材料的形态和性质提供了新的方法。
