A Multi Size-Level Assessment of Benthic Marine Communities in a Coastal Environment: Are They Different Sides of the Same Coin?

Organism body size has been demonstrated to be a discriminating element in shaping the response of living beings to environmental factors, thus playing a fundamental role in community structuring. Despite the importance of studies elucidating relations among communities of different size levels in ecosystems, the attempts that have been made in this sense are still very scarce and a reliable approach for these research still has to be defined. We characterized the benthic communities of bacteria, microbial eukaryotes, meiofauna and macrofauna in a coastal environment, encompassing a 10000-fold gradient in body size, testing and discussing a mixed approach of molecular fingerprinting for microbes and morphological observations for meio- and macrofauna. We found no correlation among structures of the different size-level communities: this suggests that community composition at one size-level could have no (or very low) influence on the community composition at other size-levels. Moreover, each community responds in a different way to the environmental parameters and with a degree of sensitivity which seems to increase with organism size. Therefore, our data indicate that the characterization of all the different size levels is clearly a necessity in order to study the dynamics really acting in a system

Wild Avian Gut Microbiome at a Small Spatial Scale: A Study from a Mediterranean Island Population of Alectoris rufa

This research is one of the few comparative descriptions at an intraspecific level of wild non-passerine microbiomes. We investigated for the first time the gut microbiome of red-legged partridges (Alectoris rufa) using fecal pellets in order to provide a more informed management. We focused on a small Italian population consisting of two demes (WEST, EAST) separated by about 20 km on the opposite sides of Elba Island. Given the small spatial scale, we set up a sampling protocol to minimize contamination from environmental bacteria, as well as differences due to variations in—among others—habitat, season, and age of feces, that could possibly affect the investigation of the three Elban sites. We found a significant divergence between the WEST and EAST Elban subpopulations in terms of microbial composition and alpha diversity. Although most represented bacterial phyla were the same in all the sites (Firmicutes, Actinobacteria, Proteobacteria, and Bacteroidetes), microbiomes displayed a much higher diversity in western than in eastern partridges. This result might be related to locally diverging individual physiological needs and/or to different intensities in past releases of captive-bred birds between the two sides of Elba. We suggest that the two subpopulations should be treated as distinct management units

Summer holidays as break-point in shaping a tannery sludge microbial community around a stable core microbiota

Recently, several investigations focused on the discovery of a bacterial consortium shared among different wastewater treatment plants (WWTPs). Nevertheless, the definition of a core microbiota over time represents the necessary counterpart in order to unravel the dynamics of bacterial communities in these environments. Here we performed a monthly survey on the bacterial community of a consortial industrial plant. Objectives of this study were: (1) to identify a core microbiota constant over time; (2) to evaluate the temporal dynamics of the community during one year. A conspicuous and diversified core microbiota is constituted by operational taxonomic units which are present throughout the year in the plant. Community composition data confirm that the presence and abundance of bacteria in WWTPs is highly consistent at high taxonomic level. Our results indicate however a difference in microbial community structure between two groups of samples, identifying the summer holiday period as the break-point. Changes in the structure of the microbial community occur otherwise gradually, one month after another. Further studies will clarify how the size and diversity of the core microbiota could affect the observed dynamics

Biocomposites based on PHBs and natural fibers for commodity applications in different environments: processing, performance in soil, compost and sea water

Composites based on poly(3-hydroxybutyrate) (PHB) and natural fibres such as fibres of Posidonia oceanica (PO), wood saw dust (WSD) and bran were produced by extrusion in presence of appropriate amounts of plasticizer (Acetyl Tri-n- Butyl Citrate, ATBC) and filler (calcium carbonate). Thermal, rheological, mechanical and morphological characterizations of the developed composites were conducted in order to optimize formulations in terms of processability and mechanical performance. The biodegradability of the optimized composites was investigated under controlled composting conditions in accordance with standard methods (ASTM D5338-98, ISO 20200-2004) and in soil for the PHB/WSD composites, because their expected fate is to be treated in composting plants or used for applications in agriculture; in simulated and natural marine sediments in mesocosms and dune habitat for the PHB/PO composites, because their potential applications are in marine environment, such as natural engineering interventions (restoration of seagrass habitats). The optimized PHB/WSD compounds were used for the production of pots for terrestrial plants, PHB/PO compounds for pots and other items usable in the sea and sand dunes, such as transplanting tools and structures for restoration or protection of coastal habitats, and the PHB/bran fibres for the production of food contact containers. The results showed that the industrial processing by extrusion of the composites did not show any difficulty up to 20 wt. % fibres and the presence of the fibres (PO or WSD) facilitated the disintegration of the PHB matrix and, consequently, accelerated its biodegradation both in compost, soil, sea water and dune. The PHB/WSD composites resulted no-phytotoxic by using cress (Lepidium sativum L.) germination test, compostable in accordance with EN 13427:2000, biodegradable in soil at controlled degradation rate. The PHB/PO composites showed a good controlled biodegradation rate in marine sediments and were suitable to manufacture items usable, for example, in natural engineering interventions and represent an interesting valorisation of the PO fibrous wastes accumulated in large amounts on coastal beaches

Effects of Wood Distillate on Seedling Emergence and First-Stage Growth in Five Threatened Arable Plants

Wood distillate (WD) is an environmentally safe bio-based product stimulating plant growth and yield and allowed in Italy in organic farming. To the best of our knowledge, there are no studies on the effects of WD on spontaneous plants growing among crops, including their functional traits such as biomass. To test such effects, we carried out a lab experiment on artificially reconstructed arable plant communities composed of five species of conservation interest, which are specialist winter cereal crops: Bromus secalinus L., Centaurea cyanus L., Lathyrus aphaca L., Legousia speculum-veneris (L.) Chaix, and Scandix pecten-veneris L. After sowing 45 pots under controlled conditions, we applied WD at three concentrations (0%, 0.2%, and 0.5%) six times over 7 weeks. The number of emerged plants in each pot was counted every two weeks. Finally, we harvested all plants and measured the fresh and dry above-ground weight of each species in each pot. The resulting data were analyzed by Permutational Analysis of Variance. The application of 0.2% and 0.5% WD modified the community composition after two weeks, but such differences later disappeared. Both 0.2% and 0.5% WD had a positive effect on the dry weight of S. pecten-veneris and a negative effect on that of L. speculum-veneris. Moreover, 0.2% and 0.5% WD increased seedling emergence in L. aphaca, and 0.5% WD increased seedling emergence in S. pecten-veneris. Both 0.2% and 0.5% WD enhanced seedling emergence in the entire community. We suggest that the use of WD at low concentrations in winter cereals may be a sustainable agricultural practice that benefits crops without harming the associated plant diversity

Biogeography and Character Evolution of the Ciliate Genus Euplotes (Spirotrichea, Euplotia), with Description of Euplotes curdsi sp. nov.

Ciliates comprise a diverse and ecologically important phylum of unicellular protists. One of the most specious and best-defined genera is Euplotes, which constitutes more than 70 morphospecies, many of which have never been molecularly tested. The increasing number of described Euplotes taxa emphasizes the importance for detailed characterizations of new ones, requiring standardized morphological observations, sequencing of molecular markers and careful comparison with previous literature. Here we describe Euplotes curdsi sp. nov., distinguishable by the combination of the following features: 45±65 μm length, oval or elongated shape with both ends rounded, narrow peristome with 25±34 adoral membranelles, conspicuous paroral membrane, double-eurystomus dorsal argyrome type, 6±7 dorsolateral kineties and 10 frontoventral cirri. Three populations of the novel species have been found in brackish and marine samples in the Mediterranean and the White Sea. We provide the SSU rRNA gene sequences of these populations, and an updated phylogeny of the genus Euplotes. Using the molecular phylogenetic tree, we inferred aspects of the biogeographical history of the genus and the evolution of its most important taxonomic characters in order to provide a frame for future descriptions. Ultimately, these data reveal recurrent trends of freshwater invasion and highlight the dynamic, yet convergent, morphological evolution of Euplotes

Centrin 2: a novel marker of mature and neoplastic human astrocytes

As microtubule organizing centers, centrosomes play a pivotal role in cell division as well as in neurodevelopment and neuronal maturation. Among centrosomal proteins, centrin-2 (CETN2) contributes also to DNA repair mechanisms which are fundamental to prevent genomic instability during neural stem cell pool expansion. Nevertheless, the expression profile of CETN2 in human neural stem cells and their progeny is currently unknown. To address this question, we interrogated a platform of human neuroepithelial stem (NES) cells derived from post-mortem developing brain or established from pluripotent cells, and demonstrated that while CETN2 retains its centrosomal location in proliferating NES cells, its expression pattern changes upon differentiation. In particular, we found that CETN2 is selectively expressed in mature astrocytes with a broad cytoplasmic distribution. We then extended our findings on human autoptic nervous tissue samples. We investigated CETN2 distribution in diverse anatomical areas along the rostro-caudal neuraxis and pointed out a peculiar topography of CETN2-labelled astrocytes in humans which was not appreciable in murine tissues, where CETN2 was mostly confined to ependymal cells. As prototypical condition with glial overproliferation, we also explored CETN2 expression in glioblastoma multiforme, reporting a focal concentration of CETN2 in neoplastic astrocytes. This study expands CETN2 localization beyond centrosomes and reveals a unique expression pattern which makes it eligible as a novel astrocytic molecular marker, thus opening new roads to glial biology and human neural conditions

Polynucleobacter necessarius, a model for genome reduction in both free-living and symbiotic bacteria

We present the complete genomic sequence of the essential symbiont Polynucleobacter necessarius (Betaproteobacteria), which is a valuable case study for several reasons. First, it is hosted by a ciliated protist, Euplotes; bacterial symbionts of ciliates are still poorly known because of a lack of extensive molecular data. Second, the single species P. necessarius contains both symbiotic and free-living strains, allowing for a comparison between closely related organisms with different ecologies. Third, free-living P. necessarius strains are exceptional by themselves because of their small genome size, reduced metabolic flexibility, and high worldwide abundance in freshwater systems. We provide a comparative analysis of P. necessarius metabolism and explore the peculiar features of a genome reduction that occurred on an already streamlined genome. We compare this unusual system with current hypotheses for genome erosion in symbionts and free-living bacteria, propose modifications to the presently accepted model, and discuss the potential consequences of translesion DNA polymerase loss

Candidatus Megaira polyxenophila' gen. nov., sp. nov.: Considerations on Evolutionary History, Host Range and Shift of Early Divergent Rickettsiae

“Neglected Rickettsiaceae” (i.e. those harboured by non-hematophagous eukaryotic hosts) display greater phylogenetic variability and more widespread dispersal than pathogenic ones; yet, the knowledge about their actual host range and host shift mechanism is scarce. The present work reports the characterization following the full-cycle rRNA approach (SSU rRNA sequence, specific in situ hybridization, and ultrastructure) of a novel rickettsial bacterium, herewith proposed as 'Candidatus Megaira polyxenophila' gen. nov., sp. nov. We found it in association with four different free-living ciliates (Diophrys oligothrix, Euplotes octocarinatus, Paramecium caudatum, and Spirostomum sp., all belonging to Alveolata, Ciliophora); furthermore it was recently observed as intracellular occurring in Carteria cerasiformis and Pleodorina japonica (Chlorophyceae, Chlorophyta). Phylogenetic analyses demonstrated the belonging of the candidate new genus to the family Rickettsiaceae (Alphaproteobacteria, Rickettsiales) as a sister group of the genus Rickettsia. In situ observations revealed the ability of the candidate new species to colonize either nuclear or cytoplasmic compartments, depending on the host organism. The presence of the same bacterial species within different, evolutionary distant, hosts indicates that 'Candidatus Megaira polyxenophila' recently underwent several distinct host shifts, thus suggesting the existence of horizontal transmission pathways. We consider these findings as indicative of an unexpected spread of rickettsial infections in aquatic communities, possibly by means of trophic interactions, and hence propose a new interpretation of the origin and phylogenetic diversification of rickettsial bacteria