Centre for Marine Sciences, School of Biological Sciences, The University of Queensland, Brisbane 4072, Australia.
Centre for Marine Sciences, School of Biological Sciences, The University of Queensland, Brisbane 4072, Australia.
Acta Biomater. 2014 Sep;10(9):3855-65. doi: 10.1016/j.actbio.2014.03.031. Epub 2014 Apr 2.
Tyrosinase is a copper-containing enzyme that mediates the hydroxylation of monophenols and oxidation of o-diphenols to o-quinones. This enzyme is involved in a variety of biological processes, including pigment production, innate immunity, wound healing, and exoskeleton fabrication and hardening (e.g. arthropod skeleton and mollusc shell). Here we show that the tyrosinase gene family has undergone large expansions in pearl oysters (Pinctada spp.) and the Pacific oyster (Crassostrea gigas). Phylogenetic analysis reveals that pearl oysters possess at least four tyrosinase genes that are not present in the Pacific oyster. Likewise, C. gigas has multiple tyrosinase genes that are not orthologous to the Pinctada genes, indicating that this gene family has expanded independently in these bivalve lineages. Many of the tyrosinase genes in these bivalves are expressed at relatively high levels in the mantle, the organ responsible for shell fabrication. Detailed comparisons of tyrosinase gene expression in different regions of the mantle in two closely related pearl oysters, P. maxima and P. margaritifera, reveals that recently evolved orthologous tyrosinase genes can have markedly different expression profiles. The expansion of tyrosinase genes in these oysters and their co-option into the mantle's gene regulatory network is consistent with mollusc shell formation being underpinned by a rapidly evolving transcriptome.
酪氨酸酶是一种含铜酶，介导单酚的羟化和邻二酚的氧化为邻醌。该酶参与多种生物过程，包括色素生成、先天免疫、伤口愈合以及外骨骼的制造和硬化（例如节肢动物骨骼和软体动物壳）。在这里，我们表明珍珠贝（Pinctada spp.）和太平洋牡蛎（Crassostrea gigas）中的酪氨酸酶基因家族发生了大规模扩张。系统发育分析表明，珍珠贝至少拥有四个在太平洋牡蛎中不存在的酪氨酸酶基因。同样，C. gigas 拥有多个与 Pinctada 基因没有同源关系的酪氨酸酶基因，表明该基因家族在这些双壳类动物谱系中独立扩张。这些双壳类动物的许多酪氨酸酶基因在负责制造贝壳的器官——套膜中表达水平相对较高。对两个亲缘关系密切的珍珠贝 P. maxima 和 P. margaritifera 套膜不同区域的酪氨酸酶基因表达进行详细比较表明，最近进化的同源酪氨酸酶基因可能具有明显不同的表达谱。这些牡蛎中酪氨酸酶基因的扩张及其被纳入套膜的基因调控网络与软体动物壳形成由快速进化的转录组支持的观点是一致的。
