Disseminated neoplasia in blue mussels, Mytilus galloprovincialis, from the Black Sea, Romania

Disseminated neoplasia, also called leukemia or hemic neoplasia, has been detected in 15 species of marine bivalve mollusks worldwide. The disease is characterized by the presence of single anaplastic cells with enlarged nuclei and sometimes frequent mitosis, in hemolymph vessels and sinuses. The neoplastic cells gradually replace normal hemocytes leading to the increased mortality of animals. The neoplasia reaches epizootic prevalences in blue mussels, Mytilus trossulus, in some areas, whereas prevalences in Mytilus edulis are generally very low. Mytilus galloprovincialis was suggested to be resistant to the disease although very low prevalences were documented from Spain in the Atlantic Ocean and Italy in the Mediterranean Sea. A case of disseminated neoplasia was discovered in M. galloprovincialis from among 200 specimens studied from the coast of the Romanian Black Sea. Histological preparation revealed the presence of large anaplastic cells with lobed nuclei. This observation extends the geographic range of marine bivalve mollusks with disseminated neoplasia to include the Black Sea

Transfert, accumulation et regulation des elements mineraux chez les organismes des sources hydrothermales

Specimens of Riftia pachyptila and Alvinella pompejana were collected during the Biocyarise expedition to hydrothermal vents on the East Pacific Rise at 13 degree N. Quantitative data describing the concentrations of metals in Riftia pachyptila showed that numerous metals are highly concentrated. Analyses of tissues reveal that the plume and the trophosome are the main sites of metal accumulation. Bioconcentration links with the mineral composition of the vent environment are discussed. Mechanisms for metal detoxication were investigated in both species: the presence of metal-rich granules and metallothionein-like proteins were observed. The role of chemolithotrophic bacteria in these mechanisms is discussed

Trace elements and arsenic speciation in tissues of tube dwelling polychaetes from hydrothermal vent ecosystems (East Pacific Rise): An ecological role as antipredatory strategy?

Hydrothermal vent systems are inhabited by dense benthic communities adapted to extreme conditions such as high temperature, hydrogen sulphide (H 2 S) and elevated fluxes of metals. In the present work, a wide range of trace elements (Ag, Al, As, Ba, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Sb, Se, V and Zn) were measured in tissues of three tube dwelling annelids, Alvinella pompejana, Alvinella caudata and Riftia pachyptila, which colonize distinct habitats of the East Pacific Rise (EPR) at 2500 m depth. Metals concentrations in alvinellids were often 2–4 orders of magnitude higher than those commonly found in marine organisms, while much lower values were observed in the vestimentiferan polychaete. Mobility of trace elements was further characterized in tissues of A. pompejana where metals appeared mostly in insoluble forms, i.e. associated with hydrated oxides and sulphides. Arsenic was mainly present in a weakly insoluble form and with concentrations in the branchial tentacles of alvinellids, approximately 5–15 fold higher than those measured in the thorax. Chemical speciation of this element in tissues of the three polychaete species revealed a major contribution of methylated arsenic com- pounds, like dimethylarsinate (DMA) and, to a lower extent, monomethylarsonate (MMA) and trimethylarsine oxide (TMAO). Although the biotransformation of inorganic arsenic might represent a detoxification mechanism in polychaetes from hydrothermal vents, the elevated levels of methylated forms of arsenic in branchial tissues also suggest an ecological role of this element as an antipredatory strategy for more vulnerable tissues toward generalist consumers

Chapter 2 - Metazoan adaptation to deep-sea hydrothermal vents

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