Project description:LC-MS/MS proteomics was used to identify immune proteins in the plasma of the nurse shark (Ginglymostoma cirratum), using a de novo multi-tissue transcriptome generated for this species. LC-MS/MS was then used to assess the host response to immunization with human serum albumin (HSA) and Complete Freund’s Adjuvant (CFA).
Project description:We determined the complete mitochondrial genome sequence of nurse shark Ginglymostoma cirratum. The circular DNA of 16692 bp comprises 13 protein-coding genes, 22 transfer RNAs, 2 ribosomal RNAs, a non-coding control region and a non-coding origin of light strand replication with typical gene order of vertebrates. The nurse shark formed a well-supported clade that included whale shark Rhincodon typus and zebra shark Stegostoma fasciatum within the Orectolobiformes in a phylogenetic tree constructed with other published mitochondrial genomes of sharks.
Project description:The variable domain of IgNAR shows great potential in biological medicine and therapy. IgNAR has been discovered in sharks and rays, with the nurse shark (Ginglymostoma cirratum) IgNARs being the most extensively studied among sharks. Despite being identified in nurse sharks over 30 years ago, the characteristics and genomic localization of IgNAR remain poorly defined, with significant gaps even in the latest released genome data. In our research, we localized the IgNAR loci in the nurse shark genome and resolved the previously missing regions. We identified three IgNAR loci, designated GcIgNAR1, GcIgNAR2, and GcIgNAR3, with only GcIgNAR1 and GcIgNAR2 being expressed. GcIgNAR1 and GcIgNAR2 belong to type I and type II IgNARs, respectively, and each exhibits several different isoforms. Most nurse shark IgNARs possess five constant domains. However, we found transcripts of GcIgNAR1 and GcIgNAR2 lacking two constant domains, C4 and C5, which differ from the IgNAR of the whitespotted bamboo shark. The protein structures of GcIgNAR1 and GcIgNAR2, generated by AlphaFold3, confirmed the accuracy of the IgNAR loci we identified. Our findings advance scientific understanding of IgNAR in nurse sharks and facilitate future research and medical applications.
Project description:Many animals of scientific importance lack species-specific reagents (e.g., monoclonal antibodies) for in-depth studies of immune proteins. Mass spectrometry (MS)-based proteomics has emerged as a useful method for monitoring changes in protein abundance and modifications in non-model species. It can be used to quantify hundreds of candidate immune molecules simultaneously without the generation of new reagents. Here, we used MS-based proteomics to identify and quantify candidate immune proteins in the plasma of the nurse shark (Ginglymostoma cirratum), a cartilaginous fish and representative of the most basal extant vertebrate lineage with an immunoglobulin-based immune system. Mass spectrometry-based LC-MS/MS was performed on the blood plasma of nurse sharks immunized with human serum albumin (n=4) or sham immunized (n=1), and sampled at days 0 (baseline control), 1, 2, 3, 5, 7, 14, 21, 28, 25, 42 and 49. An antigen-specific antibody response was experimentally confirmed post-immunization. To provide a high-quality reference to identify proteins, we assembled and annotated a multi-tissue de novo transcriptome integrating long- and short-read sequence data. This comprised 62,682 contigs containing open reading frames (ORFs) with a length >80 amino acids. Using this transcriptome, we reliably identified 626 plasma proteins which were broadly categorized into coagulation, immune, and metabolic functional groups. To assess the feasibility of performing LC-MS/MS proteomics in nurse shark in the absence of species-specific protein annotations, we compared the results to an alternative strategy, mapping peptides to proteins predicted in the genome assembly of a related species, the whale shark (Rhincodon typus). This approach reliably identified 297 proteins, indicating that useful data on the plasma proteome may be obtained in many instances despite the absence of a species-specific reference protein database. Among the plasma proteins defined against the nurse shark transcriptome, fifteen showed consistent changes in abundance across the immunized shark individuals, indicating a role in the immune response. These included alpha-2-macroglobulin (A2M) and a novel protein yet to be characterized in diverse vertebrate lineages. Overall, this study enhances genetic and protein-level resources for nurse shark research and vastly improves our understanding of the elasmobranch plasma proteome, including its remodelling following immune stimulation.
Project description:The study presents the first national assessment of a nurse shark (Ginglymostoma cirratum) population, conducted using a combination of transect surveys and baited remote underwater videos (BRUVs). Density of nurse sharks in Belize was found to be higher in reefs than in lagoons, and in the atolls furthest away from the mainland and human settlements. Only large and old protected areas were found to have a positive impact on nurse shark abundance. Absolute abundance of nurse sharks was estimated using distance sampling analysis, giving a total nurse shark population in the range of 3,858 to 14,375 sharks. Thanks to a vast area of suitable habitat for nurse sharks in the country and legislation already in place for the safeguard of the species, Belize could represent an important hotspot for nurse sharks in the Western Atlantic. The data presented here hence offers a baseline for the long-term monitoring of the Belizean nurse shark population and improves our understanding of nurse shark abundance and distribution in the wider Caribbean basin.
Project description:Target cell lysis by complement is achieved by the assembly and insertion of the membrane attack complex (MAC) composed of glycoproteins C5b through C9. The lytic activity of shark complement involves functional analogues of mammalian C8 and C9. Mammalian C8 is composed of alpha, beta, and gamma subunits. The subunit structure of shark C8 is not known. This report describes a 2341 nucleotide sequence that translates into a polypeptide of 589 amino acid residues, orthologue to mammalian C8alpha and has the same modular architecture with conserved cysteines forming the peptide bond backbone. The C8gamma-binding cysteine is conserved in the perforin-like domain. Hydrophobicity profile indicates the presence of hydrophobic residues essential for membrane insertion. It shares 41.1% and 47.4% identity with human and Xenopus C8alpha respectively. Southern blot analysis showed GcC8alpha exists as a single copy gene expressed in most tissues except the spleen with the liver being the main site of synthesis. Phylogenetic analysis places it in a clade with C8alpha orthologs and as a sister taxa to the Xenopus.