First records of illegal harvesting and trading of black corals (Antipatharia) in Madagascar

Black corals (Cnidaria: Antipatharia) have been used all around the world for a long time, whether as money or for medicinal purposes and jewellery manufacturing. Except in Hawaii where these fisheries are well known, black coral harvests are usually made without any control or any management. This is the case in many tropical islands and particularly in Madagascar, where the illegal trade is continually expanding. Since 2011, an illegal traffic of black corals has been occurring in the main cities of the southern and coastal regions of Ambovombe and Tolagnaro. In 2014 and 2015, hundreds of kilograms of black coral skeletons and a lot of diving material were seized by the authorities in the Anosy and Androy regions. Despite this and the continual harvesting of these natural resources, there has been no study of the excessive exploitation in this region. This paper is the first to talk about this new threat and to analyse and discuss the benefits of these fisheries. The first seizures and the efforts carried out on the island to stop the trade are explained. This paper highlights the urgency of studying these corals before making an appropriate conservation and management plan

How different serols contribute to cytotoxic action of sea cucumber saponins

Saponins form a diverse class of secondary metabolites found in both plants and some marine invertebrates. Holothuroids, or sea cucumbers, produce these molecules as a chemical defense against predators and parasites, but interestingly, tolerate the cytotoxic nature of these chemicals. This tolerance is poorly understood. The aim of this study was therefore to elucidate the mechanisms behind the tolerance of holothuroid cells to the cytotoxic saponins (e.g. Frondoside A) they produce. This investigation was conducted using a suite of complementary biophysical tools, firstly using in vitro techniques such as Isothermal Titration Calorimetry (ITC) and calcein leakage experiments, for measuring interactions between lipid models of various compositions and the saponin Frondoside A, then using in silico approaches such as docking methods and insertion into implicit lipid bilayers, to provide a molecular point of view on our observations. Interactions between Frondoside A and cholesterol were more favorable than those with the holothuroid Δ7 and Δ9(11) sterols. Liposomes containing cholesterol resulted in exothermic interactions with the holothuroid saponin Frondoside A whereas liposomes containing the Δ7 sterol resulted in endothermic interactions. Lipid phase simulations using settings previously developed for plant saponins revealed that the holothuroid saponin Frondoside A has an agglomerating effect on cholesterol domains, similar to that previously observed for the plant saponin α-Hederin. However, when interacting with the Δ7 sterols, the sterol domains were fragmented into small clusters. A significantly lower leakage was observed with liposomes containing the Δ7 holothuroid sterol than that with liposomes containing cholesterol. Our results suggest that the structural peculiarities of holothuroid sterols provide the organisms with a mechanism to mitigate the sterol-agglomerating effect of saponins on the cell membranes, and therefore to protect sea cucumber cells from the cytotoxicity of the saponins they produce

Widest geographic distribution of a shallow and mesophotic antipatharian coral (Anthozoa: Hexacorallia): Antipathes grandis VERRILL, 1928 – confirmed by morphometric and molecular analyses

We provide the first record of the shallow and mesophotic ( 200 m depth) benthic taxa have such wide geographic distributions

On the phylogenetic position of Myzostomida: can 77 genes get it wrong?

<p>Abstract</p> <p>Background</p> <p>Phylogenomic analyses recently became popular to address questions about deep metazoan phylogeny. Ribosomal proteins (RP) dominate many of these analyses or are, in some cases, the only genes included. Despite initial hopes, phylogenomic analyses including tens to hundreds of genes still fail to robustly place many bilaterian taxa.</p> <p>Results</p> <p>Using the phylogenetic position of myzostomids as an example, we show that phylogenies derived from RP genes and mitochondrial genes produce incongruent results. Whereas the former support a position within a clade of platyzoan taxa, mitochondrial data recovers an annelid affinity, which is strongly supported by the gene order data and is congruent with morphology. Using hypothesis testing, our RP data significantly rejects the annelids affinity, whereas a platyzoan relationship is significantly rejected by the mitochondrial data.</p> <p>Conclusion</p> <p>We conclude (i) that reliance of a set of markers belonging to a single class of macromolecular complexes might bias the analysis, and (ii) that concatenation of all available data might introduce conflicting signal into phylogenetic analyses. We therefore strongly recommend testing for data incongruence in phylogenomic analyses. Furthermore, judging all available data, we consider the annelid affinity hypothesis more plausible than a possible platyzoan affinity for myzostomids, and suspect long branch attraction is influencing the RP data. However, this hypothesis needs further confirmation by future analyses.</p

Morpho-functional Characterisation of Cœlomocytes in the Aquacultivated Sea Cucumber Holothuria Scabra: From Cell Diversity to Transcriptomic Immune Response

Holothuria scabra is one of the most valuable species of sea cucumber owing to its exploitation as a seafood product. This study aims to describe the main molecular and cellular actors in the immunology of the holothuroid H. scabra. First of all, a detailed description of the immune cells – the cœlomocytes – is provided, highlighting five main cell types including phagocytes, small round cells (SRCs), spherulocytes, fusiform cells, and crystal cells, with a further five subtypes identified using transmission electron microscopy. Cœlomocyte aggregates were also described morphologically, yielding two main types, one comprising three successive maturation stages. A comparison of the concentration and proportion of cell populations was carried out between the two main body fluids, namely the hydrovascular fluid of the Polian vesicle (HF) and the perivisceral fluid of the general cavity (PF), and no clear relation could be revealed. Next, the cœlomocyte immune response was studied 24 hours after a lipopolysaccharide (LPS) injection. Firstly, the fluctuation in cell populations was assessed, and despite a high inter-individual variability, it shows a decrease in the phagocyte proportion and an increase in the SRC proportion. Secondly, the differential gene expression of PF cœlomocytes was studied by de novo RNA-sequencing between LPS-injected and control-injected individuals: 945 genes were differentially expressed, including 673 up-regulated and 272 down-regulated in the LPS-injected individuals. Among these genes, 80 had a presumed function in immunity based on their annotation, covering a wide range of immune mechanisms. Overall, this study reveals a complex immune system at both molecular and cellular levels and constitutes a baseline reference on H. scabra immunity, which may be useful for the development of sustainable aquaculture and provides valuable data for comparative immunology

Fixed, Free, and Fixed: The Fickle Phylogeny of Extant Crinoidea (Echinodermata) and Their Permian-Triassic Origin

Although the status of Crinoidea (sea lilies and featherstars) as sister group to all other living echinoderms is well-established, relationships among crinoids, particularly extant forms, are debated. All living species are currently placed in Articulata, which is generally accepted as the only crinoid group to survive the Permian–Triassic extinction event. Recent classifications have recognized five major extant taxa: Isocrinida, Hyocrinida, Bourgueticrinina, Comatulidina and Cyrtocrinida, plus several smaller groups with uncertain taxonomic status, e.g., Guillecrinus, Proisocrinus and Caledonicrinus. Here we infer the phylogeny of extant Crinoidea using three mitochondrial genes and two nuclear genes from 59 crinoid terminals that span the majority of extant crinoid diversity. Although there is poor support for some of the more basal nodes, and some tree topologies varied with the data used and mode of analysis, we obtain several robust results. Cyrtocrinida, Hyocrinida, Isocrinida are all recovered as clades, but two stalked crinoid groups, Bourgueticrinina and Guillecrinina, nest among the featherstars, lending support to an argument that they are paedomorphic forms. Hence, they are reduced to families within Comatulida. Proisocrinus is clearly shown to be part of Isocrinida, and Caledonicrinus may not be a bourgueticrinid. Among comatulids, tree topologies show little congruence with current taxonomy, indicating that much systematic revision is required. Relaxed molecular clock analyses with eight fossil calibration points recover Articulata with a median date to the most recent common ancestor at 231–252 mya in the Middle to Upper Triassic. These analyses tend to support the hypothesis that the group is a radiation from a small clade that passed through the Permian–Triassic extinction event rather than several lineages that survived. Our tree topologies show various scenarios for the evolution of stalks and cirri in Articulata, so it is clear that further data and taxon sampling are needed to recover a more robust phylogeny of the group

Triterpenoids in Echinoderms: Fundamental Differences in Diversity and Biosynthetic Pathways

Echinoderms form a remarkable phylum of marine invertebrates that present specific chemical signatures unique in the animal kingdom. It is particularly the case for essential triterpenoids that evolved separately in each of the five echinoderm classes. Indeed, while most animals have ∆5-sterols, sea cucumbers (Holothuroidea) and sea stars (Asteroidea) also possess ∆7 and ∆9(11)-sterols, a characteristic not shared with brittle stars (Ophiuroidea), sea urchins (Echinoidea), and crinoids (Crinoidea). These particular ∆7 and ∆9(11) sterols emerged as a self-protection against membranolytic saponins that only sea cucumbers and sea stars produce as a defense mechanism. The diversity of saponins is large; several hundred molecules have been described in the two classes of these saponins (i.e., triterpenoid or steroid saponins). This review aims to highlight the diversity of triterpenoids in echinoderms by focusing on sterols and triterpenoid glycosides, but more importantly to provide an updated view of the biosynthesis of these molecules in echinoderms

From commensalism to parasitism in Carapidae (Ophidiiformes): heterochronic modes of development?

Phenotypic variations allow a lineage to move into new regions of the adaptive landscape. The purpose of this study is to analyse the life history of the pearlfishes (Carapinae) in a phylogenetic framework and particularly to highlight the evolution of parasite and commensal ways of life. Furthermore, we investigate the skull anatomy of parasites and commensals and discuss the developmental process that would explain the passage from one form to the other. The genus Carapus forms a paraphyletic grouping in contrast to the genus Encheliophis, which forms a monophyletic cluster. The combination of phylogenetic, morphologic and ontogenetic data clearly indicates that parasitic species derive from commensal species and do not constitute an iterative evolution from free-living forms. Although the head morphology of Carapus species differs completely from Encheliophis, C. homei is the sister group of the parasites. Interestingly, morphological characteristics allowing the establishment of the relation between Carapus homei and Encheliophis spp. concern the sound-producing mechanism, which can explain the diversification of the taxon but not the acquisition of the parasite morphotype. Carapus homei already has the sound-producing mechanism typically found in the parasite form but still has a commensal way of life and the corresponding head structure. Moreover, comparisons between the larval and adult Carapini highlight that the adult morphotype “Encheliophis” is obtained by going beyond the adult stage reached by Carapus. The entrance into the new adaptive landscape could have been realised by at least two processes: paedomorphosis and allometric repatterning

Assessment of trophic relationships between symbiotic tropical ophiuroids using C and N stable isotope analysis

Analyses of the natural abundance of carbon and nitrogen stable isotopes were performed to investigate the feeding habits of two ophiurolds, Ophiomastix venosa and Ophiocoma scolopendrina, and to assess the potential benefit obtained by the symbiotic Ophiomastix venosa juveniles. A tracer experiment was also carried Out to clarify the contribution of algae to the nitrogen uptake amongst the tested ophiurolds. Our results suggest that Ophiocoma scolopendrina adults occupy a higher position in the food web than Ophiomastix venosa and mainly feed on neuston. In contrast, O. venosa adults feed on the alga Sargassum densifolium, and on organic matter associated with sediment. Free juveniles and symbiotic juveniles of O. venosa have intermediate PC values between both adult species. The high proportion of C-13 in the symbiotic juveniles compared to the one in their conspecific adults indicates that their diet slightly differs from the latter and is closer to that of Ophiocoma scolopendrina. This raises the hypothesis that symbiotic juveniles steal neuston front their associated host, O. scolopendrina.Etudes des relations symbiotiques chez les échinodermes en milieux tropicaux coralliens (Tuléar, Madagascar) (Prof I. Eekhaut