No abstract

The genus Ciona is an interesting ‘taxonomic case’ because its evolutionary history and taxonomy have not yet been resolved completely. In this study, we present new findings, describing specimens of an unidentified Ciona species collected along the north-eastern coasts of Sardinia (Tyrrhenian Sea, Mediterranean Sea). Applying an integrative taxonomic approach, based on the joint examination of morphological and molecular traits, we identify these specimens as a new species, Ciona intermedia sp. nov. Morphological comparisons and peculiarities of the habitat first revealed that these Ciona specimens have intermediate characters compared with other Ciona species. Molecular characterization (based on three mitochondrial regions: two already used for discriminating Ciona cryptic species and a newly developed one) confirmed that our specimens could not be assigned to any previously molecularly-characterized species. Both molecular phylogenetic reconstructions and morphological data clearly indicate C. intermedia as sister clade of Ciona edwardsi. Our findings add further complexity to the taxonomy of Ciona, underlying the importance of an integrative taxonomic approach for the study of the evolutionary history of this enigmatic genus.

In order to accelerate the isolation and characterisation of structurally new or novel secondary metabolites, it is crucial to develop efficient strategies that prioritise samples with greatest promise early in the workflow so that resources can be utilised in a more efficient and costeffective manner. We have developed a metrics-based prioritisation approach using exact LC-HRMS which uses data for 24,618 marine natural products held in the PharmaSea database. Each sample was evaluated and allocated a metric score by a software algorithm based on the ratio of new masses over the total (sample novelty), ratio of known masses over the total (chemical novelty), number of peaks above a defined peak area threshold (sample complexity), and peak area (sample diversity). Samples were then ranked and prioritized based on these metric scores. To validate the approach, 8 marine sponges and 6 tunicate samples collected from the Fiji Islands were analysed, metric scores calculated and samples targeted for isolation and characterisation of new compounds. Structures of new compounds were elucidated by spectroscopic techniques, including 1D and 2D NMR, MS and MS/MS. Structures were confirmed by Computer Assisted Structure Elucidation methods (CASE) using the ACD/Structure Elucidator Suite.

Aquaporins (AQPs) are a family of membrane channels facilitating diffusion of water and small solutes into and out of cells. Despite their biological relevance in osmoregulation and ubiquitous distribution throughout metazoans, the presence of AQPs in annelids has been poorly investigated. Here, we searched and annotated Aqp sequences in public genomes and transcriptomes of annelids, inferred their evolutionary relationships through phylogenetic analyses and discussed their putative physiological relevance. We identified a total of 401 Aqp sequences in 27 annelid species, including 367 sequences previously unrecognized as Aqps. Similar to vertebrates, phylogenetic tree reconstructions clustered these annelid Aqps in four clades: AQP1-like, AQP3-like, AQP8-like and AQP11-like. We found no clear indication of the existence of paralogs exclusive to annelids; however, several gene duplications seem to have occurred in the ancestors of some Sedentaria annelid families, mainly in the AQP1-like clade. Three of the six Aqps annotated in Alitta succinea, an estuarine annelid showing high salinity tolerance, were validated by RT-PCR sequencing, and their similarity to human AQPs was investigated at the level of “key” conserved residues and predicted three-dimensional structure. Our results suggest a diversification of the structures and functions of AQPs in Annelida comparable to that observed in other taxa.