Structural and Functional Characterization of Ribosomal Protein Gene Introns in Sponges

Ribosomal protein genes (RPGs) are a powerful tool for studying intron evolution. They exist in all three domains of life and are much conserved. Accumulating genomic data suggest that RPG introns in many organisms abound with non-protein-coding-RNAs (ncRNAs). These ancient ncRNAs are small nucleolar RNAs (snoRNAs) essential for ribosome assembly. They are also mobile genetic elements and therefore probably important in diversification and enrichment of transcriptomes through various mechanisms such as intron/exon gain/loss. snoRNAs in basal metazoans are poorly characterized. We examined 449 RPG introns, in total, from four demosponges: Amphimedon queenslandica, Suberites domuncula, Suberites ficus and Suberites pagurorum and showed that RPG introns from A. queenslandica share position conservancy and some structural similarity with “higher” metazoans. Moreover, our study indicates that mobile element insertions play an important role in the evolution of their size. In four sponges 51 snoRNAs were identified. The analysis showed discrepancies between the snoRNA pools of orthologous RPG introns between S. domuncula and A. queenslandica. Furthermore, these two sponges show as much conservancy of RPG intron positions between each other as between themselves and human. Sponges from the Suberites genus show consistency in RPG intron position conservation. However, significant differences in some of the orthologous RPG introns of closely related sponges were observed. This indicates that RPG introns are dynamic even on these shorter evolutionary time scales

Structural Characterization of FAU Gene/Protein from Marine Sponge Suberites domuncula

Finkel-Biskis-Reilly murine sarcoma virus (FBR-MuSV) ubiquitously expressed (FAU) gene is down-regulated in human prostate, breast and ovarian cancers. Moreover, its dysregulation is associated with poor prognosis in breast cancer. Sponges (Porifera) are animals without tissues which branched off first from the common ancestor of all metazoans. A large majority of genes implicated in human cancers have their homologues in the sponge genome. Our study suggests that FAU gene from the sponge Suberites domuncula reflects characteristics of the FAU gene from the metazoan ancestor, which have changed only slightly during the course of animal evolution. We found pro-apoptotic activity of sponge FAU protein. The same as its human homologue, sponge FAU increases apoptosis in human HEK293T cells. This indicates that the biological functions of FAU, usually associated with “higher” metazoans, particularly in cancer etiology, possess a biochemical background established early in metazoan evolution. The ancestor of all animals possibly possessed FAU protein with the structure and function similar to evolutionarily more recent versions of the protein, even before the appearance of true tissues and the origin of tumors and metastasis. It provides an opportunity to use pre-bilaterian animals as a simpler model for studying complex interactions in human cancerogenesis

Adriatic calcarean sponges (Porifera, Calcarea), with the description of six new species and a richness analysis

In this study we analyze the calcarean sponge diversity of the Adriatic Sea, the type locality of some of the first described species of calcarean sponges. Morphological and molecular approaches are combined for the taxonomic identification. Our results reveal six species new to science and provisionally endemic to the Adriatic Sea (Ascandra spalatensis sp. nov., Borojevia croatica sp. nov., Leucandra falakra sp. nov., L. spinifera sp. nov., Paraleucilla dalmatica sp. nov., and Sycon ancora sp. nov.), one species previously known only from the Southwestern Atlantic (Clathrina conifera), and three already known from the Adriatic Sea (Ascaltis reticulum, Borojevia cerebrum, and Clathrina primordialis). We confirm the presence of the alien species Paraleucilla magna in the Adriatic and again record Clathrina blanca, C. clathrus, and C. rubra. We emend the description of the genus Ascaltis, propose a lectotype for Borojevia cerebrum and synonymise B. decipiens with B. cerebrum. A checklist of all calcarean species previously and currently known from the Adriatic Sea (39 species) is given. The Central Adriatic is indicated as the richest calcarean sponge fauna sector; however, the biodiversity of this class is underestimated in the whole Adriatic Sea and new systematic surveys are desirable

Characterization of Bruton’s Tyrosine Kinase Gene and Protein from Marine Sponge Suberites domuncula

Bruton’s tyrosine kinase (Btk) is a member of Tec family of protein tyrosine kinases. It is expressed in B cells and myeloid cells in humans and it is crucial for maturation of B-lineage lymphoid cells. Mutations in the gene encoding human Btk result in hereditary immunodeficiency X-linked agammaglobulinemia. Sponge proteins can probably reflect characteristics of the ancestral metazoan homologues before their diversifications and specializations in complex animals. Gene coding for sponge Btk-like protein was fully characterized and its structure was compared with homologous genes from other organisms. Kinase activity of sponge protein was compared to human Btk activity. We showed that sponge Btk-like gene is probably the most ancient member of Tec family while other members arose from the ancestral gene present in chordate ancestor. The ancestral-type protein was structurally and functionally similar to the highly sophisticated enzyme it is today, whose functions are usually associated with higher Metazoa. (doi: 10.5562/cca1862

A potential 28S rRNA target (A) and secondary structure of a novel snoRNA found in the last intron of the <i>RPS19</i> gene in <i>S. domuncula</i> (B), <i>S. ficus</i> (C) and <i>S. pagurorum</i> (D).

<p>A potential 28S rRNA target (A) and secondary structure of a novel snoRNA found in the last intron of the <i>RPS19</i> gene in <i>S. domuncula</i> (B), <i>S. ficus</i> (C) and <i>S. pagurorum</i> (D).</p

Size distribution of the RPG introns in sponge <i>A. queenslandica</i> (black bars), cnidarian <i>N. vectensis</i> (gray bars), and placozoan <i>T. adhaerens</i> (white bars).

<p>Size distribution of the RPG introns in sponge <i>A. queenslandica</i> (black bars), cnidarian <i>N. vectensis</i> (gray bars), and placozoan <i>T. adhaerens</i> (white bars).</p