Convocation

The origins of phenotypic variation within mimetic Heliconius butterflies have long fascinated biologists and naturalists. However, the evolutionary processes that have generated this extraordinary diversity remain puzzling. Here we examine intraspecific variation across Heliconius cydno diversification and compare this variation to that within the closely related H. melpomene and H. timareta radiations. Our data, which consist of both mtDNA and genome scan from nearly 2250 AFLP loci, reveal a complex history of differentiation and admixture at different geographic scales. Both mtDNA and AFLP phylogenies suggest that H. timareta and H. cydno are probably geographic extremes of the same radiation that likely diverged from H. melpomene during the Pliocene-Pleistocene boundary. MtDNA suggest that this radiation originated in Central America or the Northwestern region of South America, with a subsequent colonization of the eastern and western slopes of the Andes. Our genome-scan data indicate significant admixture among sympatric H. cydno/H.timareta and H. melpomene populations across the extensive geographic ranges of the two radiations. Within H. cydno, both mtDNA and AFLP data indicate significant population structure at local scales, with strong genetic differences even among adjacent H. cydno color pattern races. These genetic patterns highlight the importance of past geoclimatic events, intraspecific gene flow, and local population differentiation in the origin and establishment of new adaptive forms

Influence of Calcium on the Early Steps of Rotavirus Infection

AbstractThe structure of rotaviruses and many steps of their replication cycle depend on the concentration of calcium in the microenvironment. In this work, to learn about the role of calcium during the early steps of the infection, we characterized the effect of increasing the calcium concentration in the medium on the infectivity of rotaviruses. We found that a fivefold increase in the calcium concentration of the cell culture medium results in an increased viral titer in all rotavirus strains tested. The effect of this divalent ion seems to be mainly on the viral particle and not on the surface of the cell. Analysis of the intrinsic fluorescence spectra of purified triple-layered particles revealed that changes in the environment of tryptophan residues occurred as calcium concentration increased, suggesting that conformational changes in the viral particle might be responsible for the effect of this ion on the viral infectivity

Case Report: Rhinosporidiosis Literature Review

Rhinosporidiosis is caused by Rhinosporidium seeberi, a pathogen currently considered a fungus-like parasite of the eukaryotic group Mesomycetozoea. It is usually a benign condition, with slow growth of polypoid lesions, with involvement of the nose, nasopharynx, or eyes. The clinical characteristics of a painless, friable, polypoid mass, usually unilateral, can guide the diagnosis, but the gold standard for diagnosis is histopathological findings. This article reviews the epidemiology, pathobiology, clinical manifestations, diagnostic strategies, and treatment approach for rhinosporidiosis

Structural and optical characterisation of planar waveguides obtained via sol-gel

8 páginas, 6 figuras, 1 tabla.-- Trabajo presentado a la "International Conference on Applications of Optics and Photonics" celebrada en Braga (Portugal) en Mayo del 2011.Planar waveguides of SiO2:TiO2 (multilayer structure) and SiO2:CeO2 (thick layer) were prepared onto commercial glass substrates using a sol-gel technique combined with dip-coating. These glassy coatings were structural characterised by Transmission Electron Microscopy (TEM) Energy Dispersive X-ray analysis and by Confocal Microscopy. Thicknesses of 1230 nm and 4,15 μm and refractive indices of 1.59 and 1.48 for SiO2:TiO2 (70:30) and SiO2:CeO2 (95:5) waveguides were obtained, respectively, by Spectroscopic Ellypsometry. Losses of 0.8 dB/cm were measured by double prism method in the SiO2:CeO2 system.The authors acknowledge funding from MICINN (TEC2006-10469, CEN 2007-2014, SURFALUX SOL-00030930 and MAT2010-18519), from DGA (Group of Excellence in Laser Material Processing and Characterisation) and XUNTA DE GALICIA (INCITE08PXIB206013PR).Peer reviewe

Layer-by-layer assembly of chitosan and recombinant biopolymers into biomimetic coatings with multiple stimuli-responsive properties

In this work, biomimetic smart thin coatings using chitosan and a recombinant elastin-like recombinamer (ELR) containing the cell attachment sequence arginine–glycine–(aspartic acid) (RGD) are fabricated through a layer-by-layer approach. The synthetic polymer is characterized for its molecular mass and composition using mass spectroscopy and peptide sequencing. The adsorption of each polymeric layer is followed in situ at room temperature and pH 5.5 using a quartz-crystal microbalance with dissipation monitoring, showing that both polymers can be successfully combined to conceive nanostructured, multilayered coatings. The smart properties of the coatings are tested for their wettability by contact angle (CA) measurements as a function of external stimuli, namely temperature, pH, and ionic strength. Wettability transitions are observed from a moderate hydrophobic surface (CAs approximately from 62° to 71°) to an extremely wettable one (CA considered as 0°) as the temperature, pH, and ionic strength are raised above 50 °C, 11, and 1.25 m, respectively. Atomic force microscopy is performed at pH 7.4 and pH 11 to assess the coating topography. In the latter, the results reveal the formation of large and compact structures upon the aggregation of ELRs at the surface, which increase water affinity. Cell adhesion tests are conducted using a SaOs-2 cell line. Enhanced cell adhesion is observed in the coatings, as compared to a coating with a chitosan-ending film and a scrambled arginine–(aspartic acid)–glycine (RDG) biopolymer. The results suggest that such films could be used in the future as smart biomimetic coatings of biomaterials for different biomedical applications, including those in tissue engineering or in controlled delivery systems.EUJCyL - VA034A09, VA030A08Fundação para a Ciência e Tecnologia (FCT) - SFRH/BD/61126/2009, SFRH/BD/61390/2009MICINN - MAT 2007-66275-C02-01, MAT 2007-61604, MAT 2009-14195-C03-03, PSE-300100-2006-1European regional development fund (ERDF)Junta de Castilla y LeonNetwork Center of Regenerative Medicine and Cellular Therapy of Castilla and LeónCIBER-BBN (project CB06-01-0003

Characterization of viroplasm formation during the early stages of rotavirus infection

Abstract Background During rotavirus replication cycle, electron-dense cytoplasmic inclusions named viroplasms are formed, and two non-structural proteins, NSP2 and NSP5, have been shown to localize in these membrane-free structures. In these inclusions, replication of dsRNA and packaging of pre-virion particles occur. Despite the importance of viroplasms in the replication cycle of rotavirus, the information regarding their formation, and the possible sites of their nucleation during the early stages of infection is scarce. Here, we analyzed the formation of viroplasms after infection of MA104 cells with the rotavirus strain RRV, using different multiplicities of infection (MOI), and different times post-infection. The possibility that viroplasms formation is nucleated by the entering viral particles was investigated using fluorescently labeled purified rotavirus particles. Results The immunofluorescent detection of viroplasms, using antibodies specific to NSP2 showed that both the number and size of viroplasms increased during infection, and depend on the MOI used. Small-size viroplasms predominated independently of the MOI or time post-infection, although at MOI's of 2.5 and 10 the proportion of larger viroplasms increased. Purified RRV particles were successfully labeled with the Cy5 mono reactive dye, without decrease in virus infectivity, and the labeled viruses were clearly observed by confocal microscope. PAGE gel analysis showed that most viral proteins were labeled; including the intermediate capsid protein VP6. Only 2 out of 117 Cy5-labeled virus particles colocalized with newly formed viroplasms at 4 hours post-infection. Conclusions The results presented in this work suggest that during rotavirus infection the number and size of viroplasm increases in an MOI-dependent manner. The Cy5 in vitro labeled virus particles were not found to colocalize with newly formed viroplasms, suggesting that they are not involved in viroplasm nucleation.</p

Nanostructured multilayer compartments : towards multifunctionality and ‘‘cell-like’’ hierarchical complexity

In living organisms, there are phenomena that require the presence of specific biomolecules with distinct function and in variable concentrations at a given time, such as the healing and regeneration of tissue and organ lesions. In this work, we propose the use of a compartmented drug delivery device for the multiple release of bioactive agents. It consists of nanostructured microcapsules confined within a millimetric container that can be easily handled, mimicking the concept of cells which possess organelles with specialized functions. Each hierarchical structure was conceived using the layer-by-layer (LbL) method to form micro and macrocapsules that could individually carry either molecules and release them with distinct kinetics or magnetic nanoparticles (MNPs) to be used in targeted therapies. Furthermore, the internal microcontainers were constructed with a temperature-responsive elastin-like recombinamer (ELR) to further add smart properties to the proposed system. Sacrificial CaCO3 microparticles empty or entrapping either rhodamine or Fe3O4 MNPs were incubated in chitosan and ELR solutions using LbL for the conception of the microcapsules. Then, the microcapsules were suspended in alginate which was ionically crosslinked in CaCl2 drop-wise. Rhodamine could be encapsulated at this point in the alginate. The bead was coated with chitosan and alginate to build the external macrocapsule compartment. All structures were coated with 3 bilayers. The CaCO3 cores were chelated and the alginate beads liquefied using EDTA. Fluorescence microscopy using FITC and rhodamine markers showed a uniform distribution of the microcapsules within the macroreservoir. The release of rhodamine from either in the micro or macrocapsule was assessed at 25 and 37 °C in PBS. While the release from the macrocapsule follows a profile similar to that of traditional drug delivery systems, it is more sustained and delayed when released from the internal compartments. Such retention is more pronounced at 37 ºC (65% of release in comparison to 90%). This is due to the temperature responsive behavior of ELRs, which undergo a phase transition and make the LbL shell less permeable. For the magnetic response, the incorporation of the MNPs was observed by transmitted light microscopy. The attraction of the devices was observed by applying an external magnetic field along a defined trajectory. The results let foresee the use of such multilayer devices as compartmented structures to encapsulate growth factors, MNPs and stem cells for their controlled differentiation and maintenance or for guided regeneration of tissues and organs.Fundo Social Europeu (FSE)Fundação para a Ciência e a Tecnologia (FCT)Programa Diferencial de Potencial Humano (POPH

Characterization of a Monoclonal Antibody Directed to the Surface of MA104 Cells That Blocks the Infectivity of Rotaviruses

AbstractRhesus rotavirus (RRV) binds to sialic acid residues on the surface of target cells, and treatment of these cells with neuraminidase greatly reduces virus binding with the consequent reduction of infectivity. Variants that can efficiently infect neuraminidase-treated cells have been isolated, indicating that attachment to sialic acid is not an essential step for animal rotaviruses to infect cells. To identify and characterize the neuraminidase-resistant receptor for rotaviruses, we have isolated a hybridoma that secrets a monoclonal antibody (MAb) (2D9) that specifically blocks the infectivity of wild-type (wt) RRV and of its sialic acid-independent variant nar3, in untreated as well as in neuraminidase-treated cells. The infectivity of a human rotavirus was also inhibited, although to a lesser extent. MAb 2D9 blocks the binding of the variant to MA104 cells, while not affecting the binding of wt RRV; in addition, this MAb blocked the attachment of a recombinant glutathione S-transferase (GST)–VP5 fusion protein, but did not affect the binding of GST–VP8. Altogether these results suggest that MAb 2D9 is directed to the neuraminidase-resistant receptor. This receptor seems to mediate the direct attachment of the variant to the cell, through VP5, while the receptor is used by wt RRV for a secondary interaction, after its initial binding to sialic acid, through VP8. MAb 2D9 interacts specifically with the cell surface by indirect immunofluorescence, immunoelectron microscopy, and FACS. By a solid-phase immunoisolation technique, MAb 2D9 was found to react with three proteins of ca. 47, 55, and 220 kDa, which might form a complex

Scientific evidence for the control of antimicrobial resistance

[Extract]. Antimicrobial resistance (AMR) is one of the greatest global threats to human health. It is estimated that by 2050, AMR will lead to approximately 10 million annual deaths worldwide. Considering the impact of AMR on reproductive capacity and food production, in addition to its direct effect on infected people, the world's population could drop by between 11 and 444 million inhabitants by 2050 if AMR control is not achieved. As migrations and shared economies lead to the transmission of resistant bacteria across borders, the impacts of AMR become regionally significant. In the United States, methicillin-resistant Staphylococcus aureus caused 10 600 deaths in 2017. In Latin American and Caribbean countries, information is available from studies conducted in hospitals and other health facilities on the prevalence of antimicrobial-resistant pathogens. In many hospitals in Mexico, Peru, and Colombia, for example, resistance to third-generation cephalosporins and fluoroquinolones in Escherichia coli isolates is reaching almost 60%. Moreover, the dynamics of colonization and infection of multidrug-resistant organisms (such as carbapenemaseproducing Klebsiella pneumoniae) are unique in endemic areas of Latin America, favoring spread and dissemination. [...

Defining the multiplicity and type of infection for the production of Zaire Ebola virus-like particles in the insect cell baculovirus expression system

Ebola virus hemorrhagic fever affects thousands of people worldwide with high mortality rates. The Ebola virus has a short incubation time between 2-21 days and death usually occurs within 4-10 days1. Ebola virus disease is characterized by a sudden onset of fever, weakness, headache, diarrhea and vomiting, internal and external bleeding2. In the Filovirus family, Zaire Ebola virus (ZEBOV) is the most aggressive and virulent species, its fatality rates have been reported to be up to 90%3. Even when important advances in vaccine development have occurred, the need of safe and effective vaccines persists4. An alternative is the production of virus-like particles, which are formed by the recombinant virus structural proteins that self-assemble into highly immunogenic structures5. The ZEBOV contains three main structural proteins: the glycoprotein (GP), the viral matrix protein 40 (VP40) and the nucleoprotein (NP). GP induces humoral and cellular responses by itself but when VP40 is co-expressed, the immune response increases in a mouse model6. NP determines the structure of the resulting VLP. To our knowledge, there is no information about the production conditions that result in coexpression and assembly of ZEBOV recombinant proteins. In this work, a multifactorial experimental design was used to evaluate 32 different conditions for the production of the ZEBOV structural proteins utilizing the insect cell-baculovirus expression system technology (BEST). Multiplicity (MOI = 0.1 or 5 ufp/cell) and consecutive times of infection (0 or 6 hours after the first infection) were the principal factors, and the production of each recombinant protein and assembly of VLP were the evaluated responses. We observed that multiplicity of infection had an impact over expression of the recombinant proteins, higher multiplicities increased yield and VLP assembly. In contrast, later times of infection reduced the production of each protein. The initial presence of VP40 resulted in a higher concentration of NP. The conditions where the simultaneous expression of the three structural proteins and where VLP were detected were identified. The highest MOIs for bacVP40 and bacGP were needed. bacNP should be added during the initial infection with an MOI of 0.1, or at 6 hpi at MOI of 5. The obtained ZEBOV-VLPs were similar to native virus. The obtained VLP are a candidate vaccine under evaluation. Research performed thanks to the financial support of PAPIIT-UNAM IT200418 and CONACyT 247101. References: 1. Shuaib F, Gunala R, Musa EO, Mahoney FJ, et al., 2014. Ebola virus disease outbreak-Nigeria, July–September 2014. Morb. Mortal. Wkly. Rep. 63 (39),867–872. 2. Qiu X, Audet J, Wong G. Fernando L, et al., 2013. Sustained protection virus infection following treatment of infected nonhuman primates with ZMAb. Sci. Rep. 3, 3. Richardson JS, Wong G, Pillet S, Schindle S, et al., 2011. Evaluation of different strategies for post-exposure treatment of Ebola virus infection in rodents. J.Bioterror. Biodef. S1, 007 4. Ige, Ohimain E, 2016. Recent advances in the development of vaccines for Ebola virus disease. Virus Research 211: 174-185. 5. Palomares LA, Ramírez OT, 2009. Challenges for the production of virus-like particles in insect cells: The case of rotavirus-like particles. Biochem. Eng. J. 45: 158-167. 6. Wahl-Jensen, V. et al (2005). Role of Ebola virus secreted glycoproteins and virus-like particles in activation of human macrophages. Journal of Virology, 79(4), 2413-241