Biogenic antimicrobial silver nanoparticles produced by fungi

Aspergillus tubingensis and Bionectria ochroleuca showed excellent extracellular ability to synthesize silver nanoparticles (Ag NP), spherical in shape and 35?±?10 nm in size. Ag NP were characterized by transmission electron microscopy, X-ray diffraction analysis, and photon correlation spectroscopy for particle size and zeta potential. Proteins present in the fungal filtrate and in Ag NP dispersion were analyzed by electrophoresis (sodium dodecyl sulfate polyacrylamide gel electrophoresis). Ag NP showed pronounced antifungal activity against Candida sp, frequently occurring in hospital infections, with minimal inhibitory concentration in the range of 0.11–1.75 μg/mL. Regarding antibacterial activity, nanoparticles produced by A. tubingensis were more effective compared to the other fungus, inhibiting 98.0 % of Pseudomonas. aeruginosa growth at 0.28 μg/mL. A. tubingensis synthesized Ag NP with surprisingly high and positive surface potential, differing greatly from all known fungi. These data open the possibility of obtaining biogenic Ag NP with positive surface potential and new applications.     

Structural Insights on Two Hypothetical Secretion Chaperones from <Emphasis Type="Italic">Xanthomonas axonopodis</Emphasis> pv<Emphasis Type="Italic">. citri</Emphasis>

Several Gram-negative bacterial pathogens have developed type III secretion systems (T3SSs) to deliver virulence proteins directly into eukaryotic cells in a process essential for many diseases. The type III secretion processes require customized chaperones with high specificity for binding partners, thus providing the secretion to occur. Due to the very low sequence similarities among secretion chaperones, annotation and discrimination of a great majority of them is extremely difficult and a task with low scores even if genes are encountered that codify for small (<20 kDa) proteins with low pI and a tendency to dimerise. Concerning about this, herein, we present structural features on two hypothetical T3SSs chaperones belonging to plant pathogen Xanthomonas axonopodis pv. citri and suggest how low resolution models based on Small Angle X-ray Scattering patterns can provide new structural insights that could be very helpful in their analysis and posterior classification.     

Mapping contacts between regulatory domains of skeletal muscle TnC and TnI by analyses of single-chain chimeras

The troponin (Tn) complex is formed by TnC, TnI and TnT and is responsible for the calcium-dependent inhibition of muscle contraction. TnC and TnI interact in an antiparallel fashion in which the N domain of TnC binds in a calcium-dependent manner to the C domain of TnI, releasing the inhibitory effect of the latter on the actomyosin interaction. While the crystal structure of the core cardiac muscle troponin complex has been determined, very little high resolution information is available regarding the skeletal muscle TnI-TnC complex. With the aim of obtaining structural information regarding specific contacts between skeletal muscle TnC and TnI regulatory domains, we have constructed two recombinant chimeric proteins composed of the residues 1-91 of TnC linked to residues 98-182 or 98-147 of TnI. The polypeptides were capable of binding to the thin filament in a calcium-dependent manner and to regulate the ATPase reaction of actomyosin. Small angle X-ray scattering results showed that these chimeras fold into compact structures in which the inhibitory plus the C domain of TnI, with the exception of residues 148-182, were in close contact with the N-terminal domain of TnC. CD and fluorescence analysis were consistent with the view that the last residues of TnI (148-182) are not well folded in the complex. MS analysis of fragments produced by limited trypsinolysis showed that the whole TnC N domain was resistant to proteolysis, both in the presence and in the absence of calcium. On the other hand the TnI inhibitory and C-terminal domains were completely digested by trypsin in the absence of calcium while the addition of calcium results in the protection of only residues 114-137.     

Genetic and phenotypic variation in central and northern European populations of Aedes (Aedimorphus) vexans (Meigen, 1830) (Diptera,Culicidae)

The floodwater mosquito Aedes vexans can be a massive nuisance in the flood plain areas of mainland Europe, and is the vector of Tahyna virus and a potential vector of Dirofilaria immitis. This epidemiologically important species forms three subspecies worldwide, of which Aedes vexans arabiensis has a wide distribution in Europe and Africa. We quantified the genetic and phenotypic variation in Ae. vexans arabiensis in populations from Sweden (northern Europe), Hungary, and Serbia (central Europe). A landscape genetics approach (F_ST, STRUCTURE, BAPS, GENELAND) revealed significant differentiation between northern and southern populations. Similar to genetic data, wing geometric morphometrics revealed two different clusters, one made by Swedish populations, while another included Hungarian and Serbian populations. Moreover, integrated genetic and morphometric data from the spatial analysis suggested groupings of populations into three clusters, one of which was from Swedish and Hungarian populations. Data on spatial analysis regarding an intermediate status of the Hungarian population was supported by observed Isolation‐by‐Distance patterns. Furthermore, a low proportion of interpopulation vs intrapopulation variance revealed by AMOVA and low‐to‐moderate F_ST values on a broader geographical scale indicate a continuous between‐population exchange of individuals, including considerable gene flow on the regional scale, are likely to be responsible for the maintenance of the observed population similarity in Aе. vexans. We discussed data considering population structure in the light of vector control strategies of the mosquito from public health importance.     

The Cenomanian–Turonian boundary in the northwestern part of the Adriatic Carbonate Platform (Ćićarija Mtn., Istria,Croatia): characteristics and implications

The Cenomanian–Turonian boundary (CTB) in the ?i?arija Mountain region (northern Istria, Croatia) is characterized by calcisphere limestone successions with a firmground and glauconite horizon, bioturbated intervals, tempestites, and slumped structures as well as microbially laminated and organic-rich interbeds deposited in the northwestern part of the intra-Tethyan Adriatic Carbonate Platform (AdCP). Compilation of the results from three studied sections (Vodice–Jelovica, Martinjak and Planik) of litho-, bio-, and microfacies analyses, X-ray diffraction, SEM, EDS, and stable isotope analyses allowed reconstruction of marine paleoenvironmental conditions during this time period. Shallow-marine carbonate deposits of the Milna Formation underlie a drowned-platform succession of the Sveti (Sv.) Duh Formation. The contact between these two formations is sharp and commonly marked by slumped deposits. The Sv. Duh Formation consists of about 100 m of calcisphere wackestone enriched in organic matter. The results of preliminary δ¹³C and δ¹⁸O stable isotope analyses indicate the influence of the global Oceanic Anoxic Event (OAE2) on the deposition of this carbonate succession. Anoxic and hypoxic conditions in the water column lead to major changes in the shallow-marine carbonate system of the AdCP. Numerous benthic foraminifera declined during that time, but planktonic foraminifera and calcareous dinoflagellates diversified and expanded greatly. The results of this research provide new insights into the character of the CTB interval in this part of the Tethyan realm. Local and regional synsedimentary tectonics combined with global upper Cretaceous sea-level dynamics allows the correlation of the investigated deeper-marine lithostratigraphic units with OAE2.     

Functional significance of isoform diversification in the protocadherin gamma gene cluster

The mammalian Protocadherin (Pcdh) alpha, beta, and gamma gene clusters encode a large family of cadherin-like transmembrane proteins that are differentially expressed in individual neurons. The 22 isoforms of the Pcdhg gene cluster are diversified into A-, B-, and C-types, and the C-type isoforms differ from all other clustered Pcdhs in sequence and expression. Here, we show that mice lacking the three C-type isoforms are phenotypically indistinguishable from the Pcdhg null mutants, displaying virtually identical cellular and synaptic alterations resulting from neuronal apoptosis. By contrast, mice lacking three A-type isoforms exhibit no detectable phenotypes. Remarkably, however, genetically blocking apoptosis rescues the neonatal lethality of the C-type isoform knockouts, but not that of the Pcdhg null mutants. We conclude that the role of the Pcdhg gene cluster in neuronal survival is primarily, if not specifically, mediated by its C-type isoforms, whereas a separate role essential for postnatal development, likely in neuronal wiring, requires isoform diversity.     

Comparison of short-term and medium-term swimming training on cardiodynamics and coronary flow in high salt-induced hypertensive and normotensive rats

Dbl-family guanine nucleotide exchange factors (GEFs) can activate RhoGTPases by facilitating the exchange of GDP for GTP, the aberrant expression of which has been implicated in tumorigenicity and metastasis of human cancers. ARHGEF39, as a member of Dbl-family GEFs, was reported to be a potential oncogene in human hepatocellular carcinoma previously. However, the role of ARHGEF39 in gastric cancer (GC) remains unclear so far. In the current study, we demonstrated that ARHGEF39 expression was significantly upregulated in GC tissues compared with paired adjacent normal tissues by quantitative real-time PCR analysis. Functional analyses revealed that ARHGEF39 overexpression could promote proliferation, colony formation, and migration of GC cells in vitro, whereas ARHGEF39 knockdown markedly suppressed these phenotypes. Moreover, ARHGEF39 enhanced tumorigenicity and lung metastasis potential of GC cells in nude mice model. Mechanistically, we found that overexpressed ARHGEF39 significantly increased the phosphorylation level of Akt (p-Akt), and its effect on cell proliferation was attenuated by PI3K inhibitor LY294002. Thus, our findings suggest that ARHGEF39 may contribute to cell proliferation and migration in GC via a possible mechanism involving Akt signaling.     

A global double-fluorescent Cre reporter mouse

The Cre/loxP system has been used extensively for conditional mutagenesis in mice. Reporters of Cre activity are important for defining the spatial and temporal extent of Cre-mediated recombination. Here we describe mT/mG, a double-fluorescent Cre reporter mouse that expresses membrane-targeted tandem dimer Tomato (mT) prior to Cre-mediated excision and membrane-targeted green fluorescent protein (mG) after excision. We show that reporter expression is nearly ubiquitous, allowing visualization of fluorescent markers in live and fixed samples of all tissues examined. We further demonstrate that mG labeling is Cre-dependent, complementary to mT at single cell resolution, and distinguishable by fluorescence-activated cell sorting. Both membrane-targeted markers outline cell morphology, highlight membrane structures, and permit visualization of fine cellular processes. In addition to serving as a global Cre reporter, the mT/mG mouse may also be used as a tool for lineage tracing, transplantation studies, and analysis of cell morphology in vivo.     

Structure proof of muricatin B: 11-hydroxy hexadecanoic acid dirhamnoside

Synthesis of (+)-11-hydroxyhexadecanoic acid-O-(4-O-α-L-rhamnopyranosyl)-α-L- rhamnopyranoside showed that muricatin B from Ipomoea muricata does not contain the proposed β- but an α-linked dirhamnoside moiety. This is the first reported synthesis of a naturally occurring O-glycoside of a long chain hydroxy-fatty acid.