Evolution of the main skeleton-forming genes in sponges (phylum Porifera) with special focus on the marine Haplosclerida (class Demospongiae)

摘要: Abstract The skeletons of sponges (Phylum Porifera) are comprised collagen, often embedded with small siliceous structures (spicules) arranged in various forms to provide strength and flexibility. main proteins responsible for the formation spicules demosponges silicateins, which related cathepsins L other animals. While silicatein active site, necessary biosilica crystals, is characterized by amino acids SHN, different variants genes have been found, some that retain SHN at site don’t. As part an effort further understand skeleton marine order Haplosclerida, a search all were made Irish species representing clades this large sponge group. For task, transcriptomes sequenced de novo assembled from Haliclona oculata, H. simulans indistincta. Silicatein identified these available genomes Porifera. These analysed along complete silicateins GenBank. Silicateins only found belonging class Demospongiae but excluding Keratosa Verongimorpha there was significant duplication diversity genes. showing polyphyletic. Indeed sequences divided into six major (CHNI, CHNII, CHNIII, SHNI, SHNII C/SQN). In those where haplosclerids well represented phylogeny reflected previous ribosomal mitochondrial topologies. most basal clade (CHNI) contained freshwater while one indistincta more (outgroup) than overall indicating presence old or intermediary form. This data could suggest first groups extant acquire Furthermore, we paucity spicule types group may be due their single copy SHNI variants, lack silintaphin gene.