Duke University Marine Laboratory, Nicholas School of the Environment, Duke University, Beaufort, NC, 28516, USA.
Department of Molecular and Cellular Biology, Brown University, Providence, RI, 02912, USA.
Sci Rep. 2024 Nov 18;14(1):28518. doi: 10.1038/s41598-024-79312-3.
Animals of the phylum Echinodermata are characterized by a pentaradially symmetric endoskeleton in adults. Echinoids also have endoskeletal spines ranging in length from several millimeters (sand dollars e.g. Mellita quinquiesperforata of the order Clypeasteroida) to 30 cm (the black sea urchin, Diadema antillarum of the order Euechinoidea). Here we integrate an analysis of genetic, structural and molecular properties of spines from the variegated sea urchin, Lytechinus variegatus. Through genetic crosses we learned that white is dominant over red and green colors, and that pigmentation follows classic Mendelian genetics. The abundance of mRNAs encoding flavin mono-oxygenase variancts and polyketide synthase was predictive of the color of the adult and antibodies identified their histological location in the spine cells. By RNA in situ hybridization, candidate genes important for spine biomineralization and pigmentation were mapped onto the spine epithelia, and MicroCT scans of spines from different color morphs concluded that color morphs are entirely due to pigmentation and not to structural variations of the endoskeleton. By confocal microscopy we localized gene expression along and within the spines and learned that genes involved in pigment biosynthesis showed selective distribution along the spine. Spine epidermis is mitotically active and red spherule immunocytes are highly migratory within the spine. Overall the results provide a key foundation for examining the mechanisms of molecular diversity and patterning in the name sake of the phylum Echinodermata.
棘皮动物门的动物在成体中具有五辐射对称的内骨骼。海胆类动物也有内骨骼棘刺，长度从几毫米（如砂钱 Mellita quinquiesperforata，属于瓣鳃纲）到 30 厘米（黑海参 Diadema antillarum，属于楯手目）不等。在这里，我们整合了对多斑海胆 Lytechinus variegatus 棘刺的遗传、结构和分子特性的分析。通过遗传杂交，我们了解到白色对红色和绿色是显性的，并且色素沉着遵循经典的孟德尔遗传学。编码黄素单加氧酶变异体和聚酮合酶的 mRNA 的丰度可以预测成体的颜色，并且抗体可以鉴定其在棘刺细胞中的组织学位置。通过 RNA 原位杂交，将对棘刺生物矿化和色素沉着很重要的候选基因映射到棘刺上皮上，并且来自不同颜色形态的棘刺的 MicroCT 扫描得出结论，颜色形态完全是由于色素沉着，而不是内骨骼的结构变化。通过共聚焦显微镜，我们沿着和在棘刺内定位了基因表达，并了解到参与色素生物合成的基因在棘刺中表现出选择性分布。棘刺表皮具有有丝分裂活性，红色球体免疫细胞在棘刺内具有高度迁移性。总的来说，这些结果为研究棘皮动物门名义上的分子多样性和模式形成机制提供了重要基础。
