Letter to the Editor by M.C. DeRuiter and A.C. Gittenberger-de Groot relating to: Technical Improvements in Corrosion Casting of Small Specimens: A Study on Mesonephric Tubules and Vessels of Chicken Embryos. [by A. Carretero, H. Ditrich, M. Navarro, H. Splechtna, J. Ruberte, Scanning Microscopy Vol. 7(4), p. 1333-1338 (1993)].

Dear Editor, The topic of scanning electron microscopy (SEM) investigation of casting of vessels in the embryo still holds our interest. We are particularly focused on the possibilities of early injection as a method to support angiogenesis and vasculogenesis research in the embryo. It is questionable whether our technique leads to unreliable results because of severe trauma to the embryo as suggested by the above mentioned authors. The lower success yield might very well be the result of the higher friability of the embryo in general in this young stage

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 man’s fingers) during a dive in the central North Sea on the wreck ‘Jeanette Kristina’ 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 Orkney’s. 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> (Récluz, 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 species’ invasion history is reviewed

Oesterherpesvirus OsHV-1 µvar in de Waddenzee

Oesterherpesvirus OsHV-1 μvar werd voor het eerst in Nederland in 2010 in de Zeeuwse Delta ontdekt, en blijkt nu ook in de Waddenzee aanwezig te zijn. Het oesterherpesvirus OsHV-1 μvar is verantwoordelijk geweest voor een sterk verhoogde mortaliteit onder Japanse oesters langs de Franse, Engelse en Ierse kusten sinds 2008. Sindsdien worden de lidstaten vanuit EU verband geadviseerd maatregelen te nemen om de verdere verspreiding van dit virus tegen te gaan. Het virus kan zich onder meer verspreiden door verplaatsingen van schelpdieren, mee te liften met schepen waar oesters op groeien en via besmette oesterlarven die zich met de zeestromingen mee verspreiden

First record of a settled stomatopod Platysquilla eusebia in the North Sea (Malacostraca: Stomatopoda)

This paper describes the discovery of a settled juvenile specimen of the stomatopod Platysquilla eusebia on the Dutch part of the Dogger Bank in the central North Sea.This is the northernmost record in Europe. The species is native to the Mediterranean and to the Atlantic coast from Portugal up to France. Further investigations have to show if the species already forms populations this far north. As the planktonic stages of P. eusebia have already been recorded in prior years, the establishment of the species should not be a problem, providing the circumstances are favourable

Automated detection of ncRNAs in the draft genome sequence of a colonial tunicate: the carpet sea squirt Didemnum vexillum

Statistics D. vexillum draft genome. (PDF 485 kb

The jewel anemone corynactis viridis, a new order for the Netherlands Cnidaria: Corallimorpharia)

During an expedition with scuba-divers to the Dutch part of the Brown Ridge in the central North Sea in June 2013, two colonies of the jewel anemone Corynactis viridis were found on the wreck Anna Graebe. With the jewel anemone both a new species and a new animal order, the Corallimorpharia, are added to the autochthonous fauna of the Netherlands. This species typically occurs in the Mediterranean and along the Atlantic coast from Portugal and the west British Isles up to Shetland. As other records of settled colonies of C. viridis in the North Sea were recently reported from Belgian, German and English waters, it is concluded that the jewel anemone, which used to be known as an occasional visitor, should now be considered autochthonous in the North Sea.

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

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 $A$, $B$, and $C$. The system is described by a grand canonical ensemble with temperature $T$ and chemical potentials $T\lambda_A$, $T\lambda_B$, and $T\lambda_C$. We find that for $\lambda_A=\lambda_B=\lambda_C$ the system undergoes a phase transition from a uniform density to a continuum of phases at a critical temperature $\hat T_c=(2\pi/\sqrt3)^{-1}$. For other values of the chemical potentials the system has a unique equilibrium state. As is the case for the canonical ensemble for this $ABC$ model, the grand canonical ensemble is the stationary measure satisfying detailed balance for a natural dynamics. We note that $\hat T_c=3T_c$, where $T_c$ is the critical temperature for a similar transition in the canonical ensemble at fixed equal densities $r_A=r_B=r_C=1/3$.Comment: 24 pages, 3 figure