Marine isolates of Aspergillus flavus: denizens of the deep or lost at sea?

Most fungal species from marine environments also live on land. It is not clear whether these fungi reach the sea from terrestrial sources as spores or other propagules, or if there are separate ecotypes that live and reproduce in the sea. The emergence of marine diseases has created an urgency to understand the distribution of these fungi. Aspergillus flavus is ubiquitous in both terrestrial and marine environments. This species is an opportunistic pathogen in many hosts, making it a good model to study the relationship between genetic diversity and specificity of marine fungi. In this study, an intraspecific phylogeny of A. flavus isolates based on Amplified Fragment Length Polymorphisms (AFLPs) was used to determine if terrestrial and marine isolates form discrete populations, and to determine if phylogeny predicts substratum specificity. Results suggest lack of population structure in A. flavus. All isolates may compose a single population, with no clade particular to marine environments.     

Hydrostatic pressure and cellular respiration: are the values observed post-decompression representative of the reality under pressure?

The goal of this article was to assess whether a pressure change can constitute a bias of interpretation of pressure effects on pressure-acclimatized fishes. This work consisted first in a study of the recompression effects of mitochondrial extracts from eels pressure-acclimatized; and then in a study of red muscle fibre compression/decompression. The first experimental series shows a decrease of mitochondrial performances after recompression when compared with the decompressed group. It is concluded that recompression does not allow to get rid of decompression effects. This is confirmed by the second experimental series which show that a decompression induces a stronger reduction of MO2 than the previous compression.     

Heat-shock proteins maintain the viability of ATP-deprived cells: what is the mechanism?

ATP depletion causes necrosis in mammalian cells. However, a previous heat shock can protect cells from the effects of energy deprivation, probably as a result of the synthesis and accumulation of heat-shock proteins (hsps). We propose that hsps protect ATP-depleted cells from rapid necrotic death by inhibiting the aggregation of cytoskeletal proteins that occurs when ATP synthesis is blocked.     

The structures at the termini of chromosomes: what is there hidden under the cap ?

The telomeres are the nucleoproteic structures present at the ends of eukaryotic chromosomes. One can compare them to the protective ends of a shoelace; when the ends get eroded, the shoelace disintegrates and we dispose of it. The same thus applies to the chromosomes; when telomeres reach a critical threshold for function, the genome becomes unstable and the cell senesces. Therefore, telomeres, and particularly their terminal DNA structures, are critical for the integrity of the genome.     

Does phosphatidylinositol 3-kinase play a role in insulin-induced outgrowth of pseudopodial cables in cultured cells derived from micromeres of sea urchin embryos?

Cultured cells derived from micromeres isolated from sea urchin embryos at the 16-cell stage, which have insulin receptors, undergo pseudopodial cable growth and spicule rod formation in culture with horse serum and only cable growth in culture with insulin. Genistein, an inhibitor of protein tyrosine kinase, and wortmannin, an inhibitor of phosphatidylinositol 3-kinase (PI3kinase), inhibited pseudopodial cable growth in micromere-derived cells cultured with insulin and also growth accompanied by spicule rod formation in horse serum-treated cells. The PI3kinase activity in the immunoprecipitates obtained by anti-phosphotyrosine antibody from the cells cultured with insulin was higher than that in cells cultured without insulin or with insulin and genistein. Following immunoblotting with antibody of SH-2, Src homology 2 domains in PI3kinase regulatory subunit, a band appeared at 85 kDa in SDS-PAGE of the immunoprecipitate, obtained from the micromere-derived cells by anti-phosphotyrosine antibody. This SDS-PAGE also showed protein bands at molecular weights similar to IRS-1 and the insulin receptor β subunit. These indicate that the insulin signal transduction pathway in micromere-derived cells is somewhat similar to the pathway, in which PI3kinase is involved, in mammalian cells.     

Antigen presentation by endothelial cells: what role in the pathophysiology of malaria?

Disruption of the endothelial cell (EC) barrier leads to pathology via edema and inflammation. During infections, pathogens are known to invade the EC barrier and modulate vascular permeability. However, ECs are semi-professional antigen-presenting cells, triggering T-cell costimulation and specific immune-cell activation. This in turn leads to the release of inflammatory mediators and the destruction of infected cells by effectors such as CD8(+) T-cells. During malaria, transfer of parasite antigens to the EC surface is now established. At the same time, CD8 activation seems to play a major role in cerebral malaria. We summarize here some of the pathways leading to antigen presentation by ECs and address the involvement of these mechanisms in the pathophysiology of cerebral malaria.     

A new species of the deep‐sea copepod genus Scutogerulus (Calanoida: Arietellidae) from the hyperbenthic waters of Okinawa,Japan

A new species of the rare arietellid genus Scutogerulus is described from deep hyperbenthic waters off Okinawa, southwestern Japan. This is the second species of the genus. Phylogenetically significant characteristics known only on the basis of the type species are confirmed by the discovery of the new congener, in particular: (1) the genital system of the female exhibits the most plesiomorphic condition of any arietellid genus; (2) the well developed setae on the endopodal segments of the maxillae and maxillipeds are modified into ‘shield‐like setae’ similar to the ‘button setae’ in another arietelloidean family, the Augaptilidae; (3) the outer distal spine on the first exopodal segment of leg 1 is absent.     

Stability diagram and unfolding of a modified cytochrome c: what happens in the transformation regime?

We determined the stability diagram of a modified cytochrome c protein in a glycerol water mixture by measuring the first and the second moment of the fluorescence from the chromophore as a function of temperature and pressure. Temperature and pressure were varied between 273 and 363 K and 0.0001 and 1 GPa, respectively. The shift of the fluorescence maximum showed a characteristic sigmoid-like pattern from which information on the microscopic processes during unfolding is obtained: as the transformation regime is entered, the fluorescence shows a significant blue shift. The conclusion is that water molecules get into contact with the chromophore. They lead to strong electrostatic contributions in the solvent shift, which counteract the red shifting dispersion interactions. Assuming that there are just two relevant states that determine the stability diagram, the complete set of thermodynamic parameters can be determined from the data. However, under certain pressure-temperature conditions the fluorescence pattern is more complicated, pointing toward reentrant transitions and, possibly, to consecutive steps in the unfolding process.     

Proteomics of blood and derived products: what’s next?

Proteomics has changed the way proteins are analyzed in living systems. This approach has been applied to blood products and protein profiling has evolved in parallel with the development of techniques. The identification of proteins belonging to red blood cell, platelets or plasma was achieved at the end of the last century. Then, the questions on the applications emerged. Hence, several studies have focused on problems related to blood banking and products, such as the aging of blood products, identification of biomarkers, related diseases and the protein–protein interactions. More recently, a mass spectrometry-based proteomics approach to quality control has been applied in order to offer solutions and improve the quality of blood products. The current challenge we face is developing a closer relationship between transfusion medicine and proteomics. In this article, these issues will be approached by focusing first on the proteome identification of blood products and then on the applications and future developments within the field of proteomics and blood products.     

The immune status of Schwann cells: what is the role of the P2X7 receptor?

The peripheral nervous system (PNS) displays structural barriers and a lack of lymphatic drainage which strongly limit the access of molecules and cells from the immune system. In addition, the PNS has the ability to set up some specific mechanisms of immune protection to limit the pathogenicity of inflammation processes following insults by pathogens or inflammatory autoimmune diseases like the Guillain-Barré syndrome. Schwann cells are among the most prominent cells which can display immune capabilities in the PNS. Numerous in vitro studies have shown that Schwann cells were indeed able to display a large repertoire of properties, ranging from the participation to antigen presentation, to secretion of pro- and anti-inflammatory cytokines, chemokines and neurotrophic factors. In vivo studies have confirmed the immune capabilities of Schwann cells. The aim of this review is to present how Schwann cells can participate to the initiation, the regulation and the termination of the immune response in the light of the recent discovery of the Schwann cell expression of purinergic P2X7 receptors.     

Restoration of a Danube floodplain forest: what happens to species richness of terrestrial beetles?

Along the upper Danube, between river kilometer 2,472 and 2,464 (Bavaria, Germany), a managed hardwood forest was reconnected to the river via a newly carved floodplain channel. We report the stepwise alteration of the diversity of terrestrial beetles for six successive years from 2007 to 2012. In a 2‐year preliminary period (2007–2008), we recorded the baseline stage before the technical measures were implemented (2009–2010) and the onset of restoration occurred (2011–2012) with a continuous water flow in the new channel and seven flooding events. Each sample plot was equipped with a pitfall trap, an emergence photo‐eclector, an arboreal photo‐eclector, and a flight interception trap in breast height and in the canopy, respectively. The beetle communities act as an indicator to detect possible disturbance events when a riparian hardwood forest is stepwise transformed to become a new floodplain ecosystem. Within the 6‐year study period, we trapped 62,107 individual beetles, representing 85 families, 544 genera, and 1,191 species. Compared to the baseline stage, the abundance and the number of species decreased, including rare and red list species. On functional level, the species decline was particularly pronounced for zoophagous and mycetophagous species. Finally, we suppose that the 2‐year period since the launch of the new channel is too short for the establishment of a beetle community adjusted to the terrestrial part of the developing new floodplain forest.     

Deep-sea endemic fungi? The discovery of Alisea longicolla from artificially immersed wood in deep sea off the Nansei Islands,Japan

We report the discovery of the deep-sea fungus, Alisea longicolla on a wood log artificially immersed at 495 m depths in deep sea, off the Nansei Islands, Japan. Three different species of wood logs, whale bones and coconuts were deployed at approximate depths of 250, 500, 1000, 2000, 3000 and 5000 m. Densely colonised A. longicolla was found on the Ubame oak (Quercus phillyraeoides) wood log from the 500 m deployment site, which was collected 1302 d (about 3 y and 7 mo) after the deployment. Alisea longicolla was originally described as a new genus of deep-sea ascomycete within the family Halosphaeriaceae, associated with sunken wood collected in 630–791 m water depths off the Vanuatu Islands. Our results provide further evidence to support that A. longicolla may be an endemic deep-sea fungus, and it grows slowly but is active and reproductive in deep-sea environments. The occurrence of obligate deep-sea fungi appears to be very rare in the environments and few data is available. Further investigation on A. longicolla will extend our understanding of the ecology, physiology and evolution of deep-sea fungi.     

How many demersal fish species in the deep sea? A test of a method to extrapolate from local to global diversity

Grassle and Maciolek (1992) estimated that there were of the order of 107 species of benthic macro-invertebrates in the world's deep sea soft sediments. Their estimate was extrapolated from the 798 species they sampled and the pattern of species diversity observed along a 176km transect on the continental slope of the northeast Atlantic Ocean. Relative to the deep sea invertebrate fauna, the deep sea fish fauna has been better sampled, at least in the upper 1500m. To test the validity of the Grassle and Maciolek method of extrapolation, we applied it to data from a survey of fishes along the continental slope off western Australia, a diverse and previously unsurveyed region. The resulting global estimate for the deep sea demersal fishes – 60000 species – was then compared with the number described to date, about 2650 species, and an estimate of total extant species. Our estimate, which considers the proportion of new species found in little-explored regions of the world ocean, such as off western Australia, and the number of new species expected in future taxonomic revisions, is a total of 3000–4000 species. The Grassle and Maciolek method appears invalid as a means to extrapolate global biodiversity from local surveys.     

PEDF derived from glial Müller cells: a possible regulator of retinal angiogenesis

A precise balance between stimulators and inhibitors of angiogenesis, such as vascular endothelial growth factor (VEGF) and pigment epithelium-derived factor (PEDF), respectively, is essential for angiogenic homeostasis in ocular tissues. Retinal hypoxia is accompanied by some pathological conditions that may promote intraocular neovascularization. Here we demonstrate that retinal glial (Müller) cells express and release pigment epithelium-derived factor (PEDF). Decreasing oxygen concentrations cause strong attenuation of PEDF release resulting in enhanced VEGF/PEDF ratios. Exposure of Müller cells to VEGF suppressed PEDF release in a dose-dependent manner. This may represent a novel mechanism of ocular angiogenic homeostasis sufficient in the control of PEDF levels during normoxia or mild hypoxia but supplemented by other (hitherto unknown) mechanisms in cases of strong hypoxia. In spite of the enhanced VEGF/PEDF ratios resulting from hypoxia, conditioned media of Müller cells failed to stimulate additional proliferation of retinal endothelial cells. These findings suggest that in the ischemic retina, Müller cells generate a permissive condition for angiogenesis by secreting more VEGF and less PEDF, but the onset of retinal endothelial cell proliferation requires another triggering signal that remains to be identified.     

Hepatic stem cells: from inside and outside the liver?

The liver is normally proliferatively quiescent, but hepatocyte loss through partial hepatectomy, uncomplicated by virus infection or inflammation, invokes a rapid regenerative response from all cell types in the liver to perfectly restore liver mass. Moreover, hepatocyte transplants in animals have shown that a certain proportion of hepatocytes in foetal and adult liver can clonally expand, suggesting that hepatoblasts/hepatocytes are themselves the functional stem cells of the liver. More severe liver injury can activate a potential stem cell compartment located within the intrahepatic biliary tree, giving rise to cords of bipotential transit amplifying cells (oval cells), that can ultimately differentiate into hepatocytes and biliary epithelial cells. A third population of stem cells with hepatic potential resides in the bone marrow; these haematopoietic stem cells may contribute to the albeit low renewal rate of hepatocytes, but can make a more significant contribution to regeneration under a very strong positive selection pressure. In such instances, cell fusion rather than transdifferentiation appears to be the underlying mechanism by which the haematopoietic genome becomes reprogrammed.