Department of Marine Biotechnology and Resources, National Sun Yat-sen University, 80424, Kaohsiung, Taiwan.
Institute for Advanced Study, Shenzhen University, Shenzhen, China.
BMC Genomics. 2021 Nov 1;22(1):783. doi: 10.1186/s12864-021-08049-4.
Barnacles are sessile crustaceans that attach to underwater surfaces using barnacle cement proteins. Barnacles have a calcareous or chitinous membranous base, and their substratum varies from biotic (e.g. corals/sponges) to abiotic surfaces. In this study, we tested the hypothesis that the cement protein (CP) composition and chemical properties of different species vary according to the attachment substrate and/or the basal structure. We examined the histological structure of cement glands and explored the variations in cement protein homologs of 12 barnacle species with different attachment habitats and base materials.
Cement gland cells in the rocky shore barnacles Tetraclita japonica formosana and Amphibalanus amphitrite are eosinophilic, while others are basophilic. Transcriptome analyses recovered CP homologs from all species except the scleractinian coral barnacle Galkinia sp. A phylogenomic analysis based on sequences of CP homologs did not reflect a clear phylogenetic pattern in attachment substrates. In some species, certain CPs have a remarkable number of paralogous sequences, suggesting that major duplication events occurred in CP genes. The examined CPs across taxa show consistent bias toward particular sets of amino acid. However, the predicted isoelectric point (pI) and hydropathy are highly divergent. In some species, conserved regions are highly repetitive.
Instead of developing specific cement proteins for different attachment substrata, barnacles attached to different substrata rely on a highly duplicated cementation genetic toolkit to generate paralogous CP sequences with diverse chemical and biochemical properties. This general CP cocktail might be the key genetic feature enabling barnacles to adapt to a wide variety of substrata.
藤壶是固着的甲壳类动物，它们使用藤壶胶蛋白附着在水下表面。藤壶有一个钙质或几丁质的膜状基底，其附着物从生物（如珊瑚/海绵）到无生命的表面不等。在这项研究中，我们检验了这样一个假设，即不同物种的胶蛋白（CP）组成和化学性质根据附着基质和/或基底结构而变化。我们检查了胶腺的组织学结构，并探索了 12 种具有不同附着生境和基底材料的藤壶物种的胶蛋白同源物的变化。
岩岸藤壶 Tetraclita japonica formosana 和 Amphibalanus amphitrite 的胶腺细胞呈嗜酸性，而其他物种则呈嗜碱性。转录组分析从除石珊瑚藤壶 Galkinia sp. 以外的所有物种中回收了 CP 同源物。基于 CP 同源物序列的系统发育基因组分析并没有反映出附着基质的明显系统发育模式。在某些物种中，某些 CP 具有显著数量的旁系同源序列，表明 CP 基因发生了重大复制事件。在所研究的跨类群的 CP 中，始终存在对特定氨基酸集的偏向。然而，预测的等电点（pI）和疏水性高度发散。在某些物种中，保守区域高度重复。
藤壶附着在不同的基质上，而不是为不同的附着基质开发特定的胶蛋白，而是依赖于高度复制的胶结遗传工具包，产生具有不同化学和生化特性的旁系同源 CP 序列。这种通用的 CP 混合物可能是使藤壶能够适应广泛的基质的关键遗传特征。
