352 research outputs found

    Mitochondrial Genome of Savalia savaglia (Cnidaria, Hexacorallia) and Early Metazoan Phylogeny

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    Mitochondrial genomes have recently become widely used in animal phylogeny, mainly to infer the relationships between vertebrates and other bilaterians. However, only 11 of 723 complete mitochondrial genomes available in the public databases are of early metazoans, including cnidarians (Anthozoa, mainly Scleractinia) and sponges. Although some cnidarians (Medusozoa) are known to possess atypical linear mitochondrial DNA, the anthozoan mitochondrial genome is circular and its organization is similar to that of other metazoans. Because the phylogenetic relationships among Anthozoa as well as their relation to other early metazoans still need to be clarified, we tested whether sequencing the complete mitochondrial genome of Savalia savaglia, an anthozoan belonging to the order Zoantharia (=Zoanthidea), could be useful to infer such relationships. Compared to other anthozoans, S. savaglia's genome is unusually long (20,766 bp) due to the presence of several noncoding intergenic regions (3691 bp). The genome contains all 13 protein coding genes commonly found in metazoans, but like other Anthozoa it lacks most of the tRNAs. Phylogenetic analyses of S. savaglia mitochondrial sequences show Zoantharia branching closely to other Hexacorallia, either as a sister group to Actiniaria or as a sister group to Actiniaria and Scleractinia. The close relationships suggested between Zoantharia and Actiniaria are reinforced by strong similarities in their gene order and the presence of similar introns in the COI and ND5 genes. Our study suggests that mitochondrial genomes can be a source of potentially valuable information on the phylogeny of Hexacorallia and may provide new insights into the evolution of early metazoan

    Diversity of Zoanthids (Anthozoa: Hexacorallia) on Hawaiian Seamounts: Description of the Hawaiian Gold Coral and Additional Zoanthids

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    The Hawaiian gold coral has a history of exploitation from the deep slopes and seamounts of the Hawaiian Islands as one of the precious corals commercialised in the jewellery industry. Due to its peculiar characteristic of building a scleroproteic skeleton, this zoanthid has been referred as Gerardia sp. (a junior synonym of Savalia Nardo, 1844) but never formally described or examined by taxonomists despite its commercial interest. While collection of Hawaiian gold coral is now regulated, globally seamounts habitats are increasingly threatened by a variety of anthropogenic impacts. However, impact assessment studies and conservation measures cannot be taken without consistent knowledge of the biodiversity of such environments. Recently, multiple samples of octocoral-associated zoanthids were collected from the deep slopes of the islands and seamounts of the Hawaiian Archipelago. The molecular and morphological examination of these zoanthids revealed the presence of at least five different species including the gold coral. Among these only the gold coral appeared to create its own skeleton, two other species are simply using the octocoral as substrate, and the situation is not clear for the final two species. Phylogenetically, all these species appear related to zoanthids of the genus Savalia as well as to the octocoral-associated zoanthid Corallizoanthus tsukaharai, suggesting a common ancestor to all octocoral-associated zoanthids. The diversity of zoanthids described or observed during this study is comparable to levels of diversity found in shallow water tropical coral reefs. Such unexpected species diversity is symptomatic of the lack of biological exploration and taxonomic studies of the diversity of seamount hexacorals

    Phylogeny of the order Zoantharia (Anthozoa, Hexacorallia) based on the mitochondrial ribosomal genes

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    Zoantharia (or Zoanthidea) is the third largest order of Hexacorallia, characterised by two rows of tentacles, one siphonoglyph and a colonial way of life. Current systematics of Zoantharia is based exclusively on morphology and follows the traditional division of the group into the two suborders Brachycnemina and Macrocnemina, each comprising several poorly defined genera and species. To resolve the phylogenetic relationships among Zoantharia, we have analysed the sequences of mitochondrial 16S and 12S rRNA genes obtained from 24 specimens, representing two suborders and eight genera. In view of our data, Brachycnemina appears as a monophyletic group diverging within the paraphyletic Macrocnemina. The macrocnemic genus Epizoanthus branches as the sister group to all other Zoantharia that are sampled. All examined genera are monophyletic, except Parazoanthus, which comprises several independently branching clades and individual sequences. Among Parazoanthus, some groups of species can be defined by particular insertion/deletion patterns in the DNA sequences. All these clades show specificity to a particular type of substrate such as sponges or hydrozoans. Substrate specificity is also observed in zoantharians living on gorgonians or anthipatharians, as in the genus Savalia (Gerardia). If confirmed by further studies, the substrate specificity could be used as reliable character for taxonomic identification of some Macrocnemin

    National and regional variations in timely adherence to recommended measles vaccination scheme in 2-years old in Switzerland, 2005–2019

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    BACKGROUND Although monitoring of vaccination program performance is usually evaluated by measurement of vaccine coverage, timely uptake is rarely part of this assessment. This study aims to examine the timeliness of the administration of a measles-containing-vaccine (MCV) for 2-year-old children between 2005 and 2019. METHODS We used data from the Swiss National Vaccination Coverage Survey 2005-2019 for the study. We defined timely vaccinated as a vaccination administered within the recommended age specified in the Swiss National Vaccination Schedule, with an added tolerance period of 30.4 days for both MCV 1 and 2 doses. The median delay time was estimated by Kaplan-Meier survival curve and examined using log-rank test. A Cox hazard ratio was used to identify factors associated with delay. RESULTS 81% (95% CI:79-82%) of toddlers were timely vaccinated for MCV1 and 82% (95% CI:81-83%) for MCV2 in survey period 2017-2019. Between 2005 and 2019, the median age of vaccinated children ranged between 12.2 and 12.5 and 18.3-22.0 months for MCV1 and MCV2 with median delay of 44 and 38 days, respectively, at the national level. Children in the French-, Italian- and German-speaking regions were vaccinated earlier between 2005 and 2019 for MCV1 (vaccination coverage range before 10 months of age: 1.7-45.9%, 1.2-35.3% and 1.4-15.0%, respectively). Nationality, linguistic regions, and survey periods were the strongest predictive factors related to prolonged delay time. CONCLUSION Overall adherence to recommendations has improved over time, as MCV coverage has significantly increased over the years with differences across linguistic regions. Vaccinations were administered earlier and with shorter delay time

    The Coordination Chemistry of the Oxide-Electrolyte Interface; The Dependence of Surface Reactivity (Dissolution, Redox Reactions) on Surface Structure

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    Many heterogeneous processes (formation and dissolution of solid phases, redox and photochemical processes at the solid- -water interface are \u27kinetically controlled by a reaction step at the surface (and not by a transport step). Obviously the surface reactivity depends on the surface species and their structural identity, which — in turn — depend on the coordination chemical interactions that occur at the solid water interface. We discuss these processes for oxide-water interfaces in terms of a unifying rate law: R = kxa P} S, where R is the reaction rate [imolm\u272 s\u271], xa denotes the mole fraction of the reaction-active surface sites [—], Pj represents the probability to find a specific site in a suitable coordinative arrangement [—], and S is the surface concentration of sites [molm\u272]. Thus, for example, the dependency of the dissolution rate of an oxide mineral on pH can be explained in terms of surface protonation (or surface deprotonation). Similarly the effect of ligands such as oxalate on the dissolution can be accounted for by the concentration of ligand surface complexes. We extend this concept to the reductive dissolution of iron(III) hydroxides, to the oxidation of transition metal ions and other redox- and photorerox-reactions occurring at hydrous oxide surfaces and illustrate the dependence of reaction rates on specifically adsorbed oxidants and feductants. The cycling of iron as it occurs in natural systems (water, sediments, soils and atmosphere), dis used to illustrate the various redox processes, including photocatalyzed reactions, that are mediated by surfaces. Furthermore, we try to illustrate that the concepts of surface reactivity should be applicable to the interpretation of corrosion reactions, specyiifically the passivity of iron oxide films

    Worldwide Analysis of Sedimentary DNA Reveals Major Gaps in Taxonomic Knowledge of Deep-Sea Benthos

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    International audienceDeep-sea sediments represent the largest but least known ecosystem on earth. With increasing anthropogenic pressure, it is now a matter of urgency to improve our understanding of deep-sea biodiversity. Traditional morpho-taxonomic studies suggest that the ocean floor hosts extraordinarily diverse benthic communities. However, due to both its remoteness and a lack of expert taxonomists, assessing deep-sea diversity is a very challenging task. Environmental DNA (eDNA) metabarcoding offers a powerful tool to complement morpho-taxonomic studies. Here we use eDNA to assess benthic metazoan diversity in 39 deep-sea sediment samples from bathyal and abyssal depths worldwide. The eDNA dataset was dominated by meiobenthic taxa and we identified all animal phyla commonly found in the deep-sea benthos; yet, the diversity within these phyla remains largely unknown. The large numbers of taxonomically unassigned molecular operational taxonomic units (OTUs) were not equally distributed among phyla, with nematodes and platyhelminthes being the most poorly characterized from a taxonomic perspective. While the data obtained here reveal pronounced heterogeneity and vast amounts of unknown biodiversity in the deep sea, they also expose the difficulties in exploiting metabarcoding datasets resulting from the lack of taxonomic knowledge and appropriate reference databases. Overall, our study demonstrates the promising potential of eDNA metabarcoding to accelerate the assessment of deep-sea biodiversity for pure and applied deep-sea environmental research but also emphasizes the necessity to integrate such new approaches with traditional morphology-based examination of deep-sea organisms
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