Evolution of biosilicification molecular toolkits in demosponges (Porifera)

作者：Maria Eleonora Rossi, N. Kenny, N. Santodomingo, Sergio Taboada, V. Koutsouveli, Juan A. Hermoso, Rafael Molina, M. Alcorlo, Marta Turon, Irene de Sosa, P. Donoghue, Davide Pisani, A. Riesgo · 发表于：BMC Genomics · 年份：2026 · DOI：10.1186/s12864-026-13212-w

Three out of the four classes of Porifera build siliceous skeletons, but they do this through divergent enzymatic pathways that are still poorly characterised. In demosponges, where the process is best known, the biosilicification occurs by polycondensation of silica using silicatein and other proteins (silica depolymerisers and scaffolding proteins) on an axis made of actin. For silicic acid intake, sponges use several types of membrane transporters with phylogenetic affinities to those in bacteria and plants. Most demosponges can produce more than one spicule type, sometimes beautifully ornamented, but this diversity is not clearly linked to the expression of polycondensing, scaffolding or transporter proteins. Here, we explore the evolution of the molecular toolkit for biosilicification in demosponges and across Porifera, using a time-calibrated phylogeny with an unparalleled dataset of 64 sponge genomes and transcriptomes. Our results indicate a significantly more complex toolkit of genes involved in the biosilicification process than previously described, with a wide array of clade-specific proteins, especially silicateins, which allows us to hypothesise a link between silicatein type and diversity of spicules. We also describe specific putative expansions of the molecular complements for water and silicic acid transporters (aquaporins), some being acquired through horizontal gene transfer, potentially linked to adaptations to freshwater conditions. Our ove...