First record of Marphysa chirigota (Annelida: Eunicidae) in the Mediterranean Sea (Gulf of Tunis)

To date, the genus Marphysa is represented by only three species, Marphysa sanguinea, Marphysa aegypti and Marphysa birgeri in the Mediterranean Sea. Combining morphological, molecular data (16S rRNA and cytochrome c oxidase subunit I mitochondrial loci) and environmental information, we are here presenting the first Mediterranean report of Marphysa chirigota, based on the specimens collected at Radès Station (Gulf of Tunis, western Mediterranean). The current information on the distribution of of the Marphysa species strongly supports that M. sanguinea inhabits hard bottoms and has a restricted distribution close to its type location (south English coast and nearby NE European Atlantic). The specimens from Radès Station, as well as all those reported as M. sanguinea along the Tunisian coast, were found in the shallow water soft bottoms. Therefore, we suggest that the presence of M. sanguinea in Tunisia seems is doubtful, and all Marphysa species reports from Tunisia might correspond to M. chirigota

Cigarette Smoking Effect on Microhardness and Flexural Properties of Denture Base Resins

Objective: To identify the tobacco effect on flexural properties and the microhardness of three acrylic resins. Material and Methods: Three resins were tested: two thermo-polymerizable acrylic resins (RMB 20 and BMS 014) and one autopolymerized acrylic resin. The 3-point bending and microhardness tests were carried out with a universal tensile-compression machine and a micro-Vickers hardness tester. The acrylic resin specimens have been exposed for 21 days to cigarette smoke in a smoking room. Their mechanical strength was compared to unexposed samples. Statistical analysis was performed using the data processing software SPSS Statistics 21.0. Results: The flexural properties of the resins were affected by cigarette smoke only in the case of Major Base 20® (drop in strength with p= 0.02; 0.6; 0.7 and in elastic modulus with p= 0.86; 0.74 and 0.85 for Major Base 20®, BMS 014® and Major Repair®). The cigarette smoke affected significantly microhardness for all groups (p<0.001). Conclusion: Cigarette smoking does not affect the flexural properties of the acrylic resin (BMS 014® and Major Repair® unlike Major Base 20®), but it does reduce the microhardness

Folding and binding pathways of BH3-only proteins are encoded within their intrinsically disordered sequence, not templated by partner proteins.

Intrinsically disordered regions are present in one-third of eukaryotic proteins and are overrepresented in cellular processes such as signaling, suggesting that intrinsically disordered proteins (IDPs) may have a functional advantage over folded proteins. Upon interacting with a partner macromolecule, a subset of IDPs can fold and bind to form a well-defined three-dimensional conformation. For example, disordered BH3-only proteins bind promiscuously to a large number of homologous BCL-2 family proteins, where they fold to a helical structure in a groove on the BCL-2-like protein surface. As two protein chains are involved in the folding reaction, and the structure is only formed in the presence of the partner macromolecule, this raises the question of where the folding information is encoded. Here, we examine these coupled folding and binding reactions to determine which component determines the folding and binding pathway. Using Φ value analysis to compare transition state interactions between the disordered BH3-only proteins PUMA and BID and the folded BCL-2-like proteins A1 and MCL-1, we found that, even though the BH3-only protein is disordered in isolation and requires a stabilizing partner to fold, its folding and binding pathway is encoded in the IDP itself; the reaction is not templated by the folded partner. We suggest that, by encoding both its transition state and level of residual structure, an IDP can evolve a specific kinetic profile, which could be a crucial functional advantage of disorder

Evaluación de la acumulación de elementos traza en las costas tunecinas mediante el uso de biomarcadores bioquímicos en Perinereis cultrifera

Our study aimed to evaluate the effect of trace element pollution in the polychaete Perinereis cultrifera (Grube, 1840) from two Tunisian coasts (the port of Rades, S1; and the Punic port of Carthage, S2). To this end, we used an approach based on proximate composition, biomarker responses and trace element bioaccumulation. Our results showed a decreasing order of metals concentrations (Zn>Cu>Cd>Pb) in P. cultrifera from S1 and S2. The accumulation of Cd, Cu and Zn was significantly higher in S1 than in S2, especially in summer. Lipid, protein and glycogen content also changed significantly between S1 and S2 in relation to trace metal accumulation and environmental conditions. The results revealed a higher level of thiobarbituric acid in P. cultrifera from S1 than from S2. In addition, the enzymatic and non-enzymatic antioxidant defence system (catalase, glutathione-S-transferase, superoxide dismutase, glutathione and metallothionein) was enhanced and acetylcholinesterase activities decreased in P. cultrifera in S1 in comparison with S2. A principal component analysis showed that P. cultrifera from S1 exhibited a clear disruption of oxidative stress responses and trace element bioaccumulation among seasons. Overall, these findings revealed the sensitivity of those organisms to environmental conditions.Nuestro estudio tenía como objetivo evaluar el efecto de la contaminación por elementos traza en el poliqueto Perinereis cultrifera (Grube, 1840) de dos costas tunecinas (S1: el puerto de Rades; S2: el puerto púnico de Cartago). Para ello, hemos utilizado un enfoque basado en la composición proximal, las respuestas de los biomarcadores y la bioacumulación de elementos traza. Nuestros resultados mostraron un orden decreciente de las concentraciones de metales (Zn>Cu>Cd>Pb) en P. cultrifera de S1 y S2. Nuestros datos mostraron una acumulación significativa de Cd, Cu y Zn en P. cultrifera recolectada en el puerto de Rades (S1), especialmente durante la temporada de verano, en comparación con las del puerto púnico de Cartago (S2). Asimismo, los contenidos de lípidos, proteínas y glicógenos cambiaron significativamente entre S1 y S2 en relación con la acumulación de metales y las condiciones ambientales. Los resultados obtenidos revelaron un aumento del nivel de ácido barbitúrico (TBARS) en P. cultrifera de S1 en comparación con S2. Además, se observó un aumento significativo del sistema de defensa antioxidante enzimático y no enzimático (catalasa CAT, glutación-S-transferasa: GST, superóxido dismutasa: SOD, glutatión: GSH y metaloproteína: MT) y una disminución de las actividades de la acetilcolinesterasa (AChE) se observaron en P. cultrifera del puerto de Rades (S1) en comparación con las del puerto púnico de Cartago (S2). El análisis de componentes principales (PCA) mostró que la P. cultrifera de S1 presentaba una clara alteración de las respuestas al estrés oxidativo y la bioacumulación de elementos traza entre las estaciones. En general, estos resultados revelaron la sensibilidad de estos organismos frente a las condiciones ambientale

3D-SIM Super Resolution Microscopy Reveals a Bead-Like Arrangement for FtsZ and the Division Machinery: Implications for Triggering Cytokinesis

FtsZ is a tubulin-like GTPase that is the major cytoskeletal protein in bacterial cell division. It polymerizes into a ring, called the Z ring, at the division site and acts as a scaffold to recruit other division proteins to this site as well as providing a contractile force for cytokinesis. To understand how FtsZ performs these functions, the in vivo architecture of the Z ring needs to be established, as well as how this structure constricts to enable cytokinesis. Conventional wide-field fluorescence microscopy depicts the Z ring as a continuous structure of uniform density. Here we use a form of super resolution microscopy, known as 3D-structured illumination microscopy (3D-SIM), to examine the architecture of the Z ring in cells of two Gram-positive organisms that have different cell shapes: the rod-shaped Bacillus subtilis and the coccoid Staphylococcus aureus. We show that in both organisms the Z ring is composed of a heterogeneous distribution of FtsZ. In addition, gaps of fluorescence were evident, which suggest that it is a discontinuous structure. Time-lapse studies using an advanced form of fast live 3D-SIM (Blaze) support a model of FtsZ localization within the Z ring that is dynamic and remains distributed in a heterogeneous manner. However, FtsZ dynamics alone do not trigger the constriction of the Z ring to allow cytokinesis. Lastly, we visualize other components of the divisome and show that they also adopt a bead-like localization pattern at the future division site. Our data lead us to propose that FtsZ guides the divisome to adopt a similar localization pattern to ensure Z ring constriction only proceeds following the assembly of a mature divisome. © 2012 Strauss et al

Super-resolution imaging of the cytokinetic Z ring in live bacteria using fast 3D-structured illumination microscopy (f3D-SIM)

© JoVE 2006-2014. All Rights Reserved. Imaging of biological samples using fluorescence microscopy has advanced substantially with new technologies to overcome the resolution barrier of the diffraction of light allowing super-resolution of live samples. There are currently three main types of super-resolution techniques – stimulated emission depletion (STED), single-molecule localization microscopy (including techniques such as PALM, STORM, and GDSIM), and structured illumination microscopy (SIM). While STED and single-molecule localization techniques show the largest increases in resolution, they have been slower to offer increased speeds of image acquisition. Three-dimensional SIM (3D-SIM) is a wide-field fluorescence microscopy technique that offers a number of advantages over both single-molecule localization and STED. Resolution is improved, with typical lateral and axial resolutions of 110 and 280 nm, respectively and depth of sampling of up to 30 µm from the coverslip, allowing for imaging of whole cells. Recent advancements (fast 3D-SIM) in the technology increasing the capture rate of raw images allows for fast capture of biological processes occurring in seconds, while significantly reducing photo-toxicity and photobleaching Here we describe the use of one such method to image bacterial cells harboring the fluorescently-labelled cytokinetic FtsZ protein to show how cells are analyzed and the type of unique information that this technique can provide