Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo, 113-0033, Japan.
Department of Biology, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan.
Sci Rep. 2024 Nov 3;14(1):26488. doi: 10.1038/s41598-024-74794-7.
Although the mechanisms of molluscan shell growth have been studied using mathematical models, little is known about the molecular basis underpinning shell morphogenesis. Here, we performed Wnt activation experiments to elucidate the potential roles of Wnt signaling in the shell growth of Lymnaea stagnalis. In general, we observed following three types of shell malformations in both dose- and developmental stage-dependent manners: (i) cap-shaped shell, (ii) cap-shaped shell with hydropic soft tissues, and (iii) compressed shell with a smaller number of coiling. We analyzed the morphologies of these malformed shells using the growing tube model, revealing that the compressed malformations show significantly larger values for T (torsion), with no significant changes in the values for the remaining parameters E (expansion) and C (curvature). We also found that cap-shaped malformations have significantly larger values for E, suggesting that the effects of BIO on shell formation may change during growth. Since the changes in T and/or E parameter values can greatly alter the shell morphologies from a planispiral or a cap-shaped one to various three-dimensional helices, changes in shell developmental processes possibly controlled by Wnt signaling may account for at least a part of the evolution of diverse shell forms in molluscs.
尽管已经使用数学模型研究了软体动物贝壳生长的机制，但对于支持贝壳形态发生的分子基础知之甚少。在这里，我们进行了 Wnt 激活实验，以阐明 Wnt 信号在田螺贝壳生长中的潜在作用。总的来说，我们以剂量和发育阶段依赖的方式观察到以下三种类型的贝壳畸形：（i）帽状贝壳，（ii）帽状贝壳伴水肿软组织，和（iii）卷曲数较少的压缩贝壳。我们使用生长管模型分析了这些畸形贝壳的形态，结果表明压缩畸形的 T（扭转）值显著增大，而其余参数 E（膨胀）和 C（曲率）的值没有显著变化。我们还发现帽状畸形的 E 值显著增大，这表明 BIO 对贝壳形成的影响可能在生长过程中发生变化。由于 T 和/或 E 参数值的变化可以极大地改变贝壳的形态，从平面螺旋形到各种三维螺旋形，由 Wnt 信号控制的贝壳发育过程的变化可能至少解释了软体动物中不同贝壳形式进化的一部分。
