383 research outputs found
Menkia rolani Gittenberger, 1991
CatĂĄlogo do Museo de Historia Natural USC. n. inventario 10032
Zur Systematischen Stellung von Helix lanuginosa Boissy, Mit Neubeschreibung eines Subgenus
Abstract not availabl
Shipwrecks, ascidians and modiolarca subpicta (Bivalvia, Mytildae, Musculinae)
The ovulid gastropod Xandarovula patula (Pennant, 1777) was found 14.vi.2011 on the soft coral Alcyonium digitatum Linnaeus, 1758 (Dead manâs fingers) during a dive in the central North Sea on the wreck âJeanette Kristinaâ on the Dutch Dogger Bank. Later on additional specimens were found, sometimes with egg-capsules, on A. digitatum again, at two locations on the Dutch Cleaver Bank. The species has previously been recorded from the Atlantic coast of southern Spain to the western end of The English Channel, with scattered records from the west coasts of Ireland and Britain, as far north as the Orkneyâs. More recently it has been reported from most Irish coasts, several parts of the Scottish coast and also from some places in the North Sea. We here present the first record of X. patula for the Dutch part of the continental shelf. The specimens and their egg-capsules from both the Dogger Bank and Cleaver Bank, indicate that this species is autochthonous in the central North Sea
The Japanese oyster drill <i>Ocinebrellus inornatus</i> (RĂ©cluz, 1851) (Mollusca, Gastropoda, Muricidae), introduced to the Limfjord, Denmark
The predatory neogastropod Ocinebrellus inornatus was first reported from Europe in W France in 1995 and has since been detected at other sites in NW and N France and The Netherlands. It is native to the North Pacific where it preys on the Pacific oyster Crassostrea gigas. Here we report on the occurrence of the species in beds of European oysters (Ostrea edulis) in the Limfjord, NW Jutland, Denmark. The morphology-based identification has been confirmed by genetic analysis. The species was probably introduced with oysters imported from France in the 1970s and 1980s. The invasion is still relatively localized but as the species has established a reproductive population, it may eventually spread to other parts of the fjord and in time pose a problem to the oyster fishery. The speciesâ invasion history is reviewed
On the identity of broad-shelled mussels (Mollusca, Bivalvia, Mytilus) from the Dutch delta region
Late Quaternary (Eemian) deposits of the Netherlands contain
shells that resemble those of living Mytilus galloprovincialis.
Similar broad-shelled mytilids also occur in estuaries of the
southwestern Netherlands together with slender individuals
typical of M. edulis. We sampled living mussels along a depth
gradient in the Oosterschelde to a) investigate whether a relation
exists between shell shape and depth, b) test if the broadshelled
specimens might represent M. galloprovincialis (or a
hybrid with M. edulis) and c) assess by inference if the Quaternary
specimens might be attributed to M. galloprovincialis as
well. In order to do so, we compared genetic (length polymorphism
of Me 15/16, COIII sequences and AFLPs) and shellmorphological
characteristics (juvenile L/W ratios and socalled
Verduin parameters) of the same specimens. The obtained
dataset indicates that all studied mussels from the Oosterschelde
should be attributed to M. edulis, including those with
broad shell outlines. No correlation of shell-morphology and
depth-distribution was found. The worn and generally damaged
state of the Eemian specimens precluded measurement of the
Verduin parameters, while juvenile L/W ratios turned out not to
be diagnostic. Therefore the shell characters examined in this
study are insufficient to demonstrate the possible presence of
M. galloprovincialis shells in Quaternary deposits of the Netherlands.
The Development of the Vascular System in Quail Embryos: A Combination of Microvascular Corrosion Casts and Immunohistochemical Identification
Although vascular casts, obtained by injection with methacrylates, are frequently used to investigate the adult vascular system, little data are available for embryonic stages. In this paper we use MercoxR in quail embryos in the period of 2 to 7 days after incubation. The microvascular corrosion casts were evaluated in the scanning electron microscope (SEM) with special attention to the development and remodelling of the large arteries and veins. Our results show that the remodelling of the large arteries and veins together with their developing tributary vessels can be visualized from very early embryonic stages onwards. However, complete replication of a developing vascular system depends on diameter and regularity of the lumen. In the stages investigated, the vascular lumen, even of the largest vessels, is still very irregular. Detailed cellular characteristics like nuclear impressions of endothelial cells, as often seen in adult material, were seldom found in the embryos. To examine whether blind-ending sprouts are completely or incompletely replicated in a developing vascular system, additional series of quail embryos were stained immunohistochemically with a monoclonal antibody (MB1) specific for endothelial and hemopoietic cells. It seems that a plexus consisting of endothelial precursors (endothelial cells lacking a lumen) is present in the developing organ before the formation of a lumen and assembly into vessels, which are connected to an adjacent artery or vein. Expansion of the vascular system may in part be due to incorporation of these endothelial precursors in the wall of existing vessels
Left-right asymmetric expression of dpp in the mantle of gastropods correlates with asymmetric shell coiling
This is the final version of the article. Available from BMC via the DOI in this record.BACKGROUND: Various shapes of gastropod shells have evolved ever since the Cambrian. Although theoretical analyses of morphogenesis exist, the molecular basis of shell development remains unclear. We compared expression patterns of the decapentaplegic (dpp) gene in the shell gland and mantle tissues at various developmental stages between coiled-shell and non-coiled-shell gastropods. RESULTS: We analyzed the expression patterns of dpp for the two limpets Patella vulgata and Nipponacmea fuscoviridis, and for the dextral wild-type and sinistral mutant lineage of the pond snail Lymnaea stagnalis. The limpets had symmetric expression patterns of dpp throughout ontogeny, whereas in the pond snail, the results indicated asymmetric and mirror image patterns between the dextral and sinistral lineages. CONCLUSION: We hypothesize that Dpp induces mantle expansion, and the presence of a left/right asymmetric gradient of the Dpp protein causes the formation of a coiled shell. Our results provide a molecular explanation for shell, coiling including new insights into expression patterns in post-embryonic development, which should aid in understanding how various shell shapes are formed and have evolved in the gastropods.This study was supported by the JSPS Grants-in-Aid for Scientific Research 15104009
The grand canonical ABC model: a reflection asymmetric mean field Potts model
We investigate the phase diagram of a three-component system of particles on
a one-dimensional filled lattice, or equivalently of a one-dimensional
three-state Potts model, with reflection asymmetric mean field interactions.
The three types of particles are designated as , , and . The system is
described by a grand canonical ensemble with temperature and chemical
potentials , , and . We find that for
the system undergoes a phase transition from a
uniform density to a continuum of phases at a critical temperature . For other values of the chemical potentials the system
has a unique equilibrium state. As is the case for the canonical ensemble for
this model, the grand canonical ensemble is the stationary measure
satisfying detailed balance for a natural dynamics. We note that , where is the critical temperature for a similar transition in
the canonical ensemble at fixed equal densities .Comment: 24 pages, 3 figure
The complete mitogenome of Cylindrus obtusus (Helicidae, Ariantinae) using Illumina next generation sequencing
Animal science
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