Ultrastructure and development of the gametophyte vaginula-sporophyte foot complex in the liverwort Targionia hypophylla L.

The development of the placental complex including the gametophyte vaginula and the bulbous foot of the sporophyte in the liverwort Targionia hypophylla L. (Marchantiales) was studied by transmission electron microscopy. The vaginula and foot are separated by an intervening space and each consist of parenchymatous cells without intercellular spaces. Transfer cells begin to differentiate at the gametophyte-sporophyte interface just prior the onset of meiosis. While a single epidermal transfer-cell layer has developed in the foot by the end of meiosis, a multilayered pattern of transfer cells is formed in the vaginula. Gametophyte transfer cells have wall labyrinths which decrease in complexity with distance from the foot, lack plasmodesmata, and show signs of degeneration in the proximity of the foot. During meiosis, amyloplasts of both vaginula and foot lack starch and develop some thylakoid grana. In the subsequent stage of spore maturation, obliteration of the wall labyrinth occurs in both gametophyte and sporophyte transfer cells. The developmental pattern of the placental complex in Targionia is discussed in relation to that of mosses.     

Hyperspectral imaging microscopy for identification and quantitative analysis of fluorescently‐labeled cells in highly autofluorescent tissue

Standard fluorescence microscopy approaches rely on measurements at single excitation and emission bands to identify specific fluorophores and the setting of thresholds to quantify fluorophore intensity. This is often insufficient to reliably resolve and quantify fluorescent labels in tissues due to high autofluorescence. Here we describe the use of hyperspectral analysis techniques to resolve and quantify fluorescently labeled cells in highly autofluorescent lung tissue. This approach allowed accurate detection of green fluorescent protein (GFP) emission spectra, even when GFP intensity was as little as 15% of the autofluorescence intensity. GFP‐expressing cells were readily quantified with zero false positives detected. In contrast, when the same images were analyzed using standard (single‐band) thresholding approaches, either few GFP cells (high thresholds) or substantial false positives (intermediate and low thresholds) were detected. These results demonstrate that hyperspectral analysis approaches uniquely offer accurate and precise detection and quantification of fluorescence signals in highly autofluorescent tissues. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Synthesis and SAR of piperazinyl-N-phenylbenzamides as inhibitors of hepatitis C virus RNA replication in cell culture

The RNA replication machinery of HCV is a multi-subunit membrane–associated complex. NS5A has emerged as an active component of HCV replicase, possibly involved in regulation of viral replication and resistance to the antiviral effect of interferon. We report here substituted piperazinyl-N-(aryl)benzamides as potent inhibitors of HCV replication exerted via modulation of the dimerization of NS5A.     

A spatial mechanism with higher pairs for modelling the human knee joint

By generalizing a previous model proposed in the literature, a new spatial kinematic model of the knee joint passive motion is presented. The model is based on an equivalent spatial parallel mechanism which relies upon the assumption that fibers within the anterior cruciate ligament (ACL), the medial collateral ligament (MCL) and the posterior cruciate ligament (PCL) can be considered as isometric during the knee flexion in passive motion (virtually unloaded motion). The articular surfaces of femoral and tibial condyles are modelled as 3-D surfaces of general shapes. In particular, the paper presents the closure equations of the new mechanism both for surfaces represented by means of scalar equations that have the Cartesian coordinates of the points of the surface as variables and for surfaces represented in parametric form. An example of simulation is presented in the case both femoral condyles are modelled as ellipsoidal surfaces and tibial condyles as spherical surfaces. The results of the simulation are compared to those of the previous models and to measurements. The comparison confirms the expectation that a better approximation of the tibiofemoral condyle surfaces leads to a more accurate model of the knee passive motion.     

Long-Term Population Dynamics of Phototrophic Sulfur Bacteria in the Chemocline of Lake Cadagno, Switzerland

Population analyses in water samples obtained from the chemocline of crenogenic, meromictic Lake Cadagno, Switzerland, in October for the years 1994 to 2003 were studied using in situ hybridization with specific probes. During this 10-year period, large shifts in abundance between purple and green sulfur bacteria and among different populations were obtained. Purple sulfur bacteria were the numerically most prominent phototrophic sulfur bacteria in samples obtained from 1994 to 2001, when they represented between 70 and 95% of the phototrophic sulfur bacteria. All populations of purple sulfur bacteria showed large fluctuations in time with populations belonging to the genus Lamprocystis being numerically much more important than those of the genera Chromatium and Thiocystis. Green sulfur bacteria were initially represented by Chlorobium phaeobacteroides but were replaced by Chlorobium clathratiforme by the end of the study. C. clathratiforme was the only green sulfur bacterium detected during the last 2 years of the analysis, when a shift in dominance from purple sulfur bacteria to green sulfur bacteria was observed in the chemocline. At this time, numbers of purple sulfur bacteria had decreased and those of green sulfur bacteria increased by about 1 order of magnitude and C. clathratiforme represented about 95% of the phototrophic sulfur bacteria. This major change in community structure in the chemocline was accompanied by changes in profiles of turbidity and photosynthetically available radiation, as well as for sulfide concentrations and light intensity. Overall, these findings suggest that a disruption of the chemocline in 2000 may have altered environmental niches and populations in subsequent years.     

Genetic divergence among invasive and native populations of Plagioscion squamosissimus (Perciformes, Sciaenidae) in Neotropical regions

The genetic divergence among invasive and native populations of Plagioscion squamosissimus from four Neotropical hydrographic basins was assessed using the hypervariable domain of the mitochondrial DNA (mtDNA) control region. Plagioscion squamosissimus is native to the neighbouring hydrographic basins of the Parnaíba and Amazon Rivers, and the latter includes the Araguaia-Tocantins drainage, but it is invasive in other basins due to introductions. The mtDNA nucleotide polymorphism supported the hypothesis that the Amazon and Parnaíba populations constitute the same species and are separated into two independent evolutionary lineages. Absence of nucleotide polymorphism was observed within and among P. squamosissimus populations invasive to the uppper and middle Paraná River basins. Nucleotide divergence was null or low comparing the Paraná invasive populations with the populations native to the Parnaíba River basin, whereas it was significantly high compared to Tocantins populations. These results ascertain that P. squamosissimus populations invasive to the upper Paraná River basin and to the middle Paraná River basin downstream of the Itaipu dam are derived from the Parnaíba River basin. The genetic data presented are potentially useful to assist further studies on P. squamosissimus taxonomic and geographic distribution, development of ecological guidelines for managing populations invasive to the upper Paraná River basin and for preservation of native fish diversity.     

IgG1 and IgG4 Antibody Responses to the Anopheles gambiae Salivary Protein gSG6 in the Sympatric Ethnic Groups Mossi and Fulani in a Malaria Hyperhendemic Area of Burkina Faso

Human antibody response to the Anopheles gambiae salivary protein gSG6 has recently emerged as a potentially useful tool for malaria epidemiological studies and for the evaluation of vector control interventions. However, the current understanding of the host immune response to mosquito salivary proteins and of the possible crosstalk with early response to Plasmodium parasites is still very limited. We report here the analysis of IgG1 and IgG4 subclasses among anti-gSG6 IgG responders belonging to Mossi and Fulani from Burkina Faso, two ethnic groups which are known for their differential humoral response to parasite antigens and for their different susceptibility to malaria. The IgG1 antibody response against the gSG6 protein was comparable in the two groups. On the contrary, IgG4 titers were significantly higher in the Fulani where, in addition, anti-gSG6 IgG4 antibodies appeared in younger children and the ratio IgG4/IgG1 stayed relatively stable throughout adulthood. Both gSG6-specific IgG1 and IgG4 antibodies showed a tendency to decrease with age whereas, as expected, the IgG response to the Plasmodium circumsporozoite protein (CSP) exhibited an opposite trend in the same individuals. These observations are in line with the idea that the An. gambiae gSG6 salivary protein induces immune tolerance, especially after intense and prolonged exposure as is the case for the area under study, suggesting that gSG6 may trigger in exposed individuals a Th2-oriented immune response.     

Genome sequences of three Acinetobacter baumannii strains assigned to the multilocus sequence typing genotypes ST2, ST25, and ST78

Acinetobacter baumannii is an emerging opportunistic gram-negative pathogen responsible for hospital-acquired infections. A. baumannii epidemics described in Europe and worldwide were caused by a limited number of genotypic clusters of multidrug-resistant strains. Here, we report the availability of draft genome sequences for three multidrug-resistant A. baumannii strains assigned to multilocus sequence typing genotypes ST2, ST25, and ST78 that were more frequently isolated during outbreaks occurred in Greece, Italy, Lebanon, and Turkey.