Phylogenetically and spatially close marine sponges harbour divergent bacterial communities

Recent studies have unravelled the diversity of sponge-associated bacteria that may play essential roles in sponge health and metabolism. Nevertheless, our understanding of this microbiota remains limited to a few host species found in restricted geographical localities, and the extent to which the sponge host determines the composition of its own microbiome remains a matter of debate. We address bacterial abundance and diversity of two temperate marine sponges belonging to the Irciniidae family - Sarcotragus spinosulus and Ircinia variabilis – in the Northeast Atlantic. Epifluorescence microscopy revealed that S. spinosulus hosted significantly more prokaryotic cells than I. variabilis and that prokaryotic abundance in both species was about 4 orders of magnitude higher than in seawater. Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) profiles of S. spinosulus and I. variabilis differed markedly from each other – with higher number of ribotypes observed in S. spinosulus – and from those of seawater. Four PCR-DGGE bands, two specific to S. spinosulus, one specific to I. variabilis, and one present in both sponge species, affiliated with an uncultured sponge-specific phylogenetic cluster in the order Acidimicrobiales (Actinobacteria). Two PCR-DGGE bands present exclusively in S. spinosulus fingerprints affiliated with one sponge-specific phylogenetic cluster in the phylum Chloroflexi and with sponge-derived sequences in the order Chromatiales (Gammaproteobacteria), respectively. One Alphaproteobacteria band specific to S. spinosulus was placed in an uncultured sponge-specific phylogenetic cluster with a close relationship to the genus Rhodovulum. Our results confirm the hypothesized host-specific composition of bacterial communities between phylogenetically and spatially close sponge species in the Irciniidae family, with S. spinosulus displaying higher bacterial community diversity and distinctiveness than I. variabilis. These findings suggest a pivotal host-driven effect on the shape of the marine sponge microbiome, bearing implications to our current understanding of the distribution of microbial genetic resources in the marine realm.This work was financed by the Portuguese Foundation for Science and Technology (FCT - http://www.fct.pt) through the research project PTDC/MAR/101431/2008. CCPH has a PhD fellowship granted by FCT (Grant No. SFRH/BD/60873/2009). JRX’s research is funded by a FCT postdoctoral fellowship (grant no. SFRH/BPD/62946/2009). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Secondary crystalline phases identification in Cu2ZnSnSe4 thin films: contributions from Raman scattering and photoluminescence

In this work, we present the Raman peak positions of the quaternary pure selenide compound Cu2ZnSnSe4 (CZTSe) and related secondary phases that were grown and studied under the same conditions. A vast discussion about the position of the X-ray diffraction (XRD) reflections of these compounds is presented. It is known that by using XRD only, CZTSe can be identified but nothing can be said about the presence of some secondary phases. Thin films of CZTSe, Cu2SnSe3, ZnSe, SnSe, SnSe2, MoSe2 and a-Se were grown, which allowed their investigation by Raman spectroscopy (RS). Here we present all the Raman spectra of these phases and discuss the similarities with the spectra of CZTSe. The effective analysis depth for the common back-scattering geometry commonly used in RS measurements, as well as the laser penetration depth for photoluminescence (PL) were estimated for different wavelength values. The observed asymmetric PL band on a CZTSe film is compatible with the presence of CZTSe single-phase and is discussed in the scope of the fluctuating potentials’ model. The estimated bandgap energy is close to the values obtained from absorption measurements. In general, the phase identification of CZTSe benefits from the contributions of RS and PL along with the XRD discussion.info:eu-repo/semantics/publishedVersio

Passagierdampfer als Hilfskreuzer: kurze Geschichte der Entwicklung einer Schiffsgattung

To date there is no cohesive historical account of the international development of the auxiliary cruiser, and the scattered investigations of various single aspects of this ship category do not add up to a comprehensive survey. These were the circumstances discovered by the author as, upon request of the editor of this publication, he undertook to provide an introduction to the report by Captain Meyer of the only voyage of the "Kaiser Wilhelm der Grosse" as an auxiliary cruiser (see the following article). The first task was thus to gain an overall impression of this history. "Auxiliary cruisers", as defined here, were passenger steamships kept ready for battle by large shipping companies in countries with significant naval power. These ships were technically equipped for the installation of weapons, and their conversion could be carried out within a few days. The auxiliary cruiser was first to put into service by the Russians, who felt threatened by the British Royal Navy after the Russian-Turkish Balkan War. At that time a newly established shipping company, later called the "Russian Voluntary Fleet", bought three steamships from the Hamburg-America Line and had them converted for combat purposes. By the turn of the century, this originally Russian idea had been adopted by all of the world's Iarge navies . This brief study also touches on the various attempt worldwide to incorporate the legal status of the ship type "auxiliary cruiser" into international public and military law. Because of geopolitically based conflicts of interest between the naval powers, these endeavours were only partially successful. ln conclusion the author examines the auxiliary cruiser concept of the Imperial German Navy, whose goal it was to interfere with and impair the enemy's overseas commerce. The express Iiners originally designated for this purpose, however, were for various reasons inconceivably ill-suited to it. As early as 1915 the German Navy proceeded to commission cargo vessels as auxiliary cruisers, as they were inconspicuous and easier to supply. This was then the mode of operation employed by the navy during World War II