Batzel G O, Moreno B K, Lopez L S, Nguyen C K, Livingston B T, Joester D, Lyons D C
Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, UCSD, La Jolla, CA 92037, USA.
Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA.
Integr Org Biol. 2022 Aug 10;4(1):obac023. doi: 10.1093/iob/obac023. eCollection 2022.
The gastropod shell is a composite composed of minerals and shell matrix proteins (SMPs). SMPs have been identified by proteomics in many molluscs, but few have been studied in detail. Open questions include (1) what gene regulatory networks regulate SMP expression, (2) what roles individual SMPs play in biomineralization, and (3) how the complement of SMPs changes over development. These questions are best addressed in a species in which gene perturbation studies are available; one such species is the slipper snail, . Here, SEM and pXRD analysis demonstrated that the adult shell of exhibits crossed lamellar microstructure and is composed of aragonite. Using high-throughput proteomics we identified 185 SMPs occluded within the adult shell. Over half of the proteins in the shell proteome have known biomineralization domains, while at least 10% have no homologs in public databases. Differential gene expression analysis identified 20 SMP genes that are up-regulated in the shell-producing mantle tissue. Over half of these 20 SMPs are expressed during development with two, CfSMP1 and CfSMP2, expressed exclusively in the shell gland. Together, the description of the shell microstructure and a list of SMPs now sets the stage for studying the consequences of SMP gene knockdowns in molluscs.
腹足纲动物的外壳是一种由矿物质和贝壳基质蛋白（SMPs）组成的复合物。蛋白质组学已在许多软体动物中鉴定出SMPs，但对其进行详细研究的却很少。悬而未决的问题包括：（1）哪些基因调控网络调节SMP的表达；（2）单个SMP在生物矿化中起什么作用；（3）SMP的组成如何随发育而变化。这些问题最好在一个可进行基因扰动研究的物种中解决；拖鞋蜗牛就是这样一个物种。在此，扫描电子显微镜（SEM）和粉末X射线衍射（pXRD）分析表明，拖鞋蜗牛的成年外壳呈现交叉层状微结构，由文石组成。我们使用高通量蛋白质组学鉴定出185种包埋在成年外壳中的SMPs。外壳蛋白质组中超过一半的蛋白质具有已知的生物矿化结构域，而至少10%在公共数据库中没有同源物。差异基因表达分析确定了20个在产生外壳的外套膜组织中上调的SMP基因。这20个SMPs中超过一半在发育过程中表达，其中CfSMP1和CfSMP2仅在贝壳腺中表达。总之，外壳微结构的描述和SMPs列表为研究软体动物中SMP基因敲低的后果奠定了基础。
