Histological, elemental, and ultrastructural analysis of melanin in mantle of Pacific oyster (Crassostrea gigas)
Histological, elemental, and ultrastructural analysis of melanin in mantle of Pacific oyster (Crassostrea gigas)
复制标题
DOI：
10.1002/jemt.24269
复制
发表时间：
2022-11
影响因子：
2.5
通讯作者：
Zhuanzhuan Li;Qi Li;Chengxun Xu;Hong Yu
中科院分区：
文献类型：
--
作者：
Zhuanzhuan Li;Qi Li;Chengxun Xu;Hong Yu
双壳类贝壳的多彩主要是由于生物色素的存在，其中黑色素在贝壳颜色形成中起着重要作用。近年来，对黑色素合成相关基因功能的研究越来越多，但从微观角度对双壳贝类黑色素的生化特性和超微结构的研究相对较少。本文研究了长牡蛎（Crassostrea gigas）壳色为橙子的外套膜的组织结构。组织化学染色证实外套膜中黑色素的分布。此外，免疫荧光技术显示CgTYR强阳性信号特异于外套膜边缘，与H&E染色中棕色颗粒的位置一致。进一步的元素组成分析结果显示，利用扫描透射电镜和能谱分析方法检测到金属元素Ca、Fe和Zn。接下来，基于TEM观察，推测导致黑色素形成和释放的一系列细胞事件。初级黑素细胞线粒体、粗面内质网丰富，高尔基复合体广泛，囊泡与黑素小体混杂。随后，黑素体扩大，颜色逐渐加深，胞质中仍可见高尔基复合体和线粒体。最后，黑素体进入细胞间隙后，部分细胞膜解体，细胞严重空泡化。这些结果丰富了对双壳贝类外套膜超微结构特征和黑色素形成的认识，为进一步在细胞水平上研究贝壳着色奠定了基础。
Colorful shell of bivalve is mainly because of the biological pigments, of which melanin plays an important role in shell color formation. More and more studies focus on the genes function involved in melanin synthesis, but relatively few studies address the biochemical character and ultrastructure of melanin in bivalve from microscopic perspective. Here, we investigated the histological structure of mantle of Crassostrea gigas with orange shell color. Distribution of melanin in mantle was verified with histochemical staining. In addition, immunofluorescence technique showed that strongly positive signal of CgTYR was specific to the mantle margin, which is consistence with the location of brown granules in H&E staining. The further result of elementary composition of melanin displayed that metal Ca, Fe, and Zn were detected using scanning transmission electron microscope and energy dispersive spectroscopy mapping methods. Next, based on TEM observations, it was speculated that the series of cellular events leading to the formation and release of melanin. Melanocyte in the primary stage showed many mitochondria and rough endoplasmic reticulum as well as an extensive Golgi complex with numerous vesicles intermingled with melanosome. Subsequently, melanosome was expended and their hue gradually intensified, and Golgi complex and mitochondria were still observed in the cytoplasm. Finally, after melanosome was discharged into intercellular spaces, the disintegration of membranes in some cells, and severe cellular vacuolization. These data enrich the understanding of ultrastructural characteristic and formation of melanin in mantle of bivalve and pave the way for further investigating shell coloration at the cellular level.