Project description:Sperm proteins presumably play critical roles in reproduction, but in many non-model animals their identities are unknown. Here we report 147 sperm proteins from the aquatic echiuran worm Urechis unicinctus, the first sperm proteome in the phylum Annelida.
Project description:Echiura is one of the most intriguing major subgroups of phylum Annelida because, unlike most other annelids, echiuran adults lack metameric body segmentation. Urechis unicinctus lives in U-shape burrows of soft sediments. Little is known about the molecular mechanisms underlying the development of U. unicinctus. Herein, we overviewed the developmental process from zygote to juvenile U. unicinctus using immunohistochemistry and F-actin staining for the nervous and muscular systems, respectively. Through F-actin staining, we found that muscle fibers began to form in the trochophore phase and that muscles for feeding were produced first. Subsequently, in the segmentation larval stage, the transversal muscle was formed in the shape of a ring in an anterior-to-posterior direction with segment formation, as well as a ventromedian muscle for the formation of a ventral nerve cord. After that, many muscle fibers were produced along the entire body and formed the worm-shaped larva. Finally, we investigated the spatiotemporal expression of Uun_st-mhc, Uun_troponin I, Uun_calponin, and Uun_twist genes found in U. unicinctus. During embryonic development, the striated and smooth muscle genes were co-expressed in the same region. However, the adult body wall muscles showed differential gene expression of each muscle layer. The results of this study will provide the basis for the understanding of muscle differentiation in Echiura.
| S-EPMC7178014 | biostudies-literature
Project description:Intestinal microbes of Urechis unicinctus
Project description:BackgroundSulfide is a common toxin to animals and is abundant in coastal and aquatic sediments. Sulfur dioxygenase (SDO) is thought to be the key enzyme involved in sulfide oxidation in some organisms. The echiuran worm, Urechis unicinctus, inhabits coastal sediment and tolerates high concentrations of sulfide. The SDO is presumably important for sulfide tolerance in U. unicinctus.ResultsThe full-length cDNA of SDO from the echiuran worm U. unicinctus, proven to be located in the mitochondria, was cloned and the analysis of its sequence suggests that it belongs to the metallo-β-lactamase superfamily. The enzyme was produced using an E. coli expression system and the measured activity is approximately 0.80 U mg protein(-1). Furthermore, the expression of four sub-segments of the U. unicinctus SDO was accomplished leading to preliminary identification of functional domains of the enzyme. The identification of the conserved metal I (H113, H115, H169 and D188), metal II (D117, H118, H169 and H229) as well as the potential glutathione (GSH) (R197, Y231, M279 and I283) binding sites was determined by enzyme activity and GSH affinity measurements. The key residues responsible for SDO activity were identified by analysis of simultaneous mutations of residues D117 and H118 located close to the metal II binding site.ConclusionThe recombinant SDO from U. unicinctus was produced, purified and characterized. The metal binding sites in the SDO were identified and Y231 recognized as the mostly important amino acid residue for GSH binding. Our results show that SDO is located in the mitochondria where it plays an important role in sulfide detoxification of U. unicinctus.