Effect of adenovirus-mediated overexpression of decorin on metalloproteinases, tissue inhibitors of metalloproteinases and cytokines secretion by human gingival fibroblasts.

Decorin is a small leucine-rich proteoglycan that plays a role in control of cell proliferation, cell migration, collagen fibrillogenesis and modulation of the activity of TGF-beta. In the present study, we investigated the effects of decorin on the production of metalloproteinases (MMP-1, -2, -3, -9 and -13), tissue inhibitors of metalloproteinases (TIMP-1, -2) and cytokines (TGF-beta, IL-1beta, IL-4 and TNF-alpha). Decorin was overexpressed in cultured human gingival fibroblasts using adenovirus-mediated gene transfer. Decorin infection resulted in decreased protein levels of MMP-1 and MMP-3 whereas MMP-2 and TIMP-2 secretion was increased. MMP-9, MMP-13 and TIMP-1 were not affected by decorin infection. Cytokine measurements by ELISA showed that decorin overexpression reduced TGF-beta and IL-1beta. In contrast, IL-4 and TNF-alpha levels were markedly increased in decorin-infected cells. These results suggest that decorin could modulate the expression of certain metalloproteinases and their inhibitors, as well as the production of cytokines. Altogether, our data suggest that decorin might play a pivotal role in tissue remodeling by acting on the balance between extracellular matrix synthesis and degradation.     

Resource-based habitat definition, niche overlap and conservation of two sympatric glacial relict butterflies

The precise knowledge of ecological resources and conditions required by species threatened by rapidly changing environmental conditions is of prime importance for conservation biology. Transferability of this knowledge between species with similar ecological requirements is often assumed, but rarely tested. This is especially the case for glacial relict populations confined to climate‐habitat traps from where they cannot move to rejoin areas with suitable environmental conditions. Using two glacial relict butterflies as model organisms, we first quantitatively define larval and adult resource‐based habitat use of each species. Secondly, we test the transferability of ecological profiles (both habitat and ecological niche) between these two species that share both the same biotope and the same host plant. Our results show that both species have markedly different ecological requirements relating to differences in life history and behavioural traits (i.e. egg‐laying strategies and mate‐locating behaviour). Although the two species share many ecological features, they use different functional habitats within our study site. The high degree of interspecific niche overlap should indicate a high interspecific competition. However, we argue that their co‐existence can be explained by the non‐limiting abundance of some resources (e.g. host plants), by the partial separation in time of adult flight periods and by the territorial behaviour of one of the species. We discuss the following general messages: (1) functional habitat of a (threatened) species should be defined in a spatial context corresponding to individual station keeping, and (2) quick diagnosis based on similar ecological requirements may be misleading for the design of reliable conservation and restoration strategies. Detailed mechanistic and quantitative ecological understanding of resource‐use and environmental tolerances across an organism's life cycle is essential for effective conservation in changing environments, like for glacial relict species.     

Molecular surveillance for avian influenza A virus in king penguins (<Emphasis Type="Italic">Aptenodytes patagonicus</Emphasis>)

An investigation of the presence of influenza A virus has been conducted in king penguins (Aptenodytes patagonicus) at the Possession Island in the Crozet Archipelago, Antarctica, using a rapid molecular diagnostic method based on real-time polymerase chain reaction. No evidence of outbreak or positive viral infection of influenza A virus was found in this study. We however recommend the implementation of long-term surveillance in seabird populations of polar ecosystems to detect the potential introduction of exotic strains and potential existence of a local epidemiological cycle for avian influenza viruses.     

Assessing the diversity and abundances of larvae and juveniles of coral reef fish: a synthesis of six sampling techniques

Due to an increasing emphasis for fish population survey and regulation, efficient tools for evaluating the abundance and diversity of fish from various life stages are needed, especially for coral reef species that present a high taxonomic diversity. The characteristics of six different techniques used for sampling pelagic larvae (a plankton-net and two light-traps), newly settled juveniles (one type of artificial reef), and older juveniles (an underwater seine net in seagrass and macroalgal beds, and rotenone poisoning in coral patches) are described in this study. Larvae belonging to 70 families and juveniles belonging to 34 families were collected. An analysis of similarity (ANOSIM) showed that the taxonomic composition of assemblages collected with the plankton-net and the two light-traps were overlapping but clearly different, due to the higher occurrence of Gobiidae in the plankton-net and of Pomacentridae in both light-traps. Larvae being 2–4 mm standard length (SL) dominated in the plankton-net, whereas larvae being 9–11 mm SL dominated in both light-traps. Pomacentridae juveniles were more abundant in rotenone samples, whereas Labridae dominated in the underwater seine. Juvenile fish collected with the artificial reefs, the underwater seine, and rotenone poisoning largely overlapped in size, with mean sizes of 22, 38, and 33 mm SL, respectively. Seven families were caught by the six sampling techniques, but with unequal success. This study provides ecologists and managers with a unique review of six techniques for sampling a wide range of developmental stages of young fish in different habitats of a coral reef lagoon.

Scarlet-Rz1, an EMS-generated hexaploid wheat with tolerance to the soilborne necrotrophic pathogens <Emphasis Type="Italic">Rhizoctonia solani</Emphasis> AG-8 and <Emphasis Type="Italic">R. oryzae</Emphasis>

The necrotrophic root pathogens Rhizoctonia solani AG-8 and R. oryzae cause Rhizoctonia root rot and damping-off, yield-limiting diseases that pose barriers to the adoption of conservation tillage in wheat production systems. Existing control practices are only partially effective, and natural genetic resistance to Rhizoctonia has not been identified in wheat or its close relatives. We report the first genetic resistance/tolerance to R. solani AG-8 and R. oryzae in wheat (Triticum aestivum L. em Thell) germplasm ‘Scarlet-Rz1’. Scarlet-Rz1 was derived from the allohexaploid spring wheat cultivar Scarlet using EMS mutagenesis. Tolerant seedlings displayed substantial root and shoot growth after 14 days in the presence of 100–400 propagules per gram soil of R. solani AG-8 and R. oryzae in greenhouse assays. BC₂F₄ individuals of Scarlet-Rz1 showed a high and consistent degree of tolerance. Seedling tolerance was transmissible and appeared to be dominant or co-dominant. Scarlet-Rz1 is a promising genetic resource for developing Rhizoctonia-tolerant wheat cultivars because the tolerance trait immediately can be deployed into wheat breeding germplasm through cross-hybridization, thereby avoiding difficulties with transfer from secondary or tertiary relatives as well as constraints associated with genetically modified plants. Our findings also demonstrate the utility of chemical mutagenesis for generating tolerance to necrotrophic pathogens in allohexaploid wheat. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. P. A. Okubara and C. M. Steber contributed equally to this work.     

Extracellular Iron Biomineralization by Photoautotrophic Iron-Oxidizing Bacteria

Iron oxidation at neutral pH by the phototrophic anaerobic iron-oxidizing bacterium Rhodobacter sp. strain SW2 leads to the formation of iron-rich minerals. These minerals consist mainly of nano-goethite (α-FeOOH), which precipitates exclusively outside cells, mostly on polymer fibers emerging from the cells. Scanning transmission X-ray microscopy analyses performed at the C K-edge suggest that these fibers are composed of a mixture of lipids and polysaccharides or of lipopolysaccharides. The iron and the organic carbon contents of these fibers are linearly correlated at the 25-nm scale, which in addition to their texture suggests that these fibers act as a template for mineral precipitation, followed by limited crystal growth. Moreover, we evidence a gradient of the iron oxidation state along the mineralized fibers at the submicrometer scale. Fe minerals on these fibers contain a higher proportion of Fe(III) at cell contact, and the proportion of Fe(II) increases at a distance from the cells. All together, these results demonstrate the primordial role of organic polymers in iron biomineralization and provide first evidence for the existence of a redox gradient around these nonencrusting, Fe-oxidizing bacteria.Fe(II) can serve as a source of electrons for phylogenetically diverse microorganisms that precipitate iron minerals as products of their metabolism (see, e.g., references 3, 5, 25, and 30). For example, mixotrophic or autotrophic bacteria can couple the oxidation of Fe(II) to the reduction of nitrate in anoxic and neutral-pH environments. With Fe(III) being highly insoluble at neutral pH, this metabolism leads to the formation of poorly to well-crystallized iron minerals (3, 18, 26, 27) that precipitate partly within the cell periplasm for some strains (22). Similar Fe minerals are also synthesized by autotrophic bacteria that perform anoxygenic photosynthesis, using Fe(II) as an electron donor and light as a source of energy for CO₂ fixation (8, 12, 30), according to the equation HCO₃⁻ + 4 Fe²⁺ + 10 H₂O ⇆ <CH₂O> + 4 Fe(OH)₃ + 7 H⁺.However, the biological mechanisms of iron oxidation in these bacteria and in particular the way they cope with the formation of minerals within their ultrastructures are still not fully understood. Indeed, iron minerals are potentially lethal since their precipitation may alter cellular ultrastructures but also catalyze the production of free radicals (2). Recent genetic studies of the phototrophic, iron-oxidizing bacteria Rhodobacter sp. strain SW2 (6) and Rhodopseudomonas palustris strain TIE-1 (16) have identified genes (fox and pio operons, respectively) encoding proteins specific for iron oxidation. Interestingly, Jiao and Newman (16) suggested that one of these proteins could have a periplasmic localization. However, in contrast to what has been observed in some other phototrophic iron oxidizers (25) and in some nitrate-reducing, iron-oxidizing bacteria (22), no iron-mineral precipitation occurs within the periplasm of the purple nonsulfur iron-oxidizing bacterium Rhodobacter sp. strain SW2 (3). Similarly to some other anaerobic neutrophilic (22, 25) and microaerobic iron-oxidizing bacteria (5, 10), this strain seems indeed to have the ability to localize iron biomineralization at a distance from the cells, leaving large areas of the cells free of precipitates (17, 25). While it has been shown that the Gallionella and Leptothrix genera, for example, produce extracellular polymers that facilitate the nucleation of iron minerals outside cells (see, e.g., references 5 and 9), only a little is known about the existence and function of such polymers in anaerobic, neutrophilic iron-oxidizing bacteria and particularly in the phototrophic strain SW2. In the present study, we investigate iron biomineralization by the photoautotrophic iron-oxidizing bacterium Rhodobacter sp. strain SW2. We use scanning transmission X-ray microscopy (STXM) to map and identify organic polymers produced by the cells as well as the redox state of iron at the 25-nanometer scale regularly during a 2 week-period. These results demonstrate the primordial role of organic polymers in iron biomineralization and provide the first evidence for the existence of a redox gradient around SW2 cells.