Cyanotoxins: Bioaccumulation and Effects on Aquatic Animals

Cyanobacteria are photosynthetic prokaryotes with wide geographic distribution that can produce secondary metabolites named cyanotoxins. These toxins can be classified into three main types according to their mechanism of action in vertebrates: hepatotoxins, dermatotoxins and neurotoxins. Many studies on the effects of cyanobacteria and their toxins over a wide range of aquatic organisms, including invertebrates and vertebrates, have reported acute effects (e.g., reduction in survivorship, feeding inhibition, paralysis), chronic effects (e.g., reduction in growth and fecundity), biochemical alterations (e.g., activity of phosphatases, GST, AChE, proteases), and behavioral alterations. Research has also focused on the potential for bioaccumulation and transferring of these toxins through the food chain. Although the herbivorous zooplankton is hypothesized as the main target of cyanotoxins, there is not unquestionable evidence of the deleterious effects of cyanobacteria and their toxins on these organisms. Also, the low toxin burden in secondary consumers points towards biodilution of microcystins in the food web as the predominant process. In this broad review we discuss important issues on bioaccumulation and the effects of cyanotoxins, with emphasis on microcystins, as well as drawbacks and future needs in this field of research

Biodiversidad de Hirudinea en ambientes dulciacuícolas serranos (Provincia de Buenos Aires), Argentina

Leeches are important benthic members in rivers and streams of low altitude mountain environments and show a high grade of endemic species in the Neotropical Region (Ringuelet, 1944; 1947; 1985; Christoffersen, 2009). As members of food chains they act as predators or as preys. They are intermediate host in life cycles ofDigenea, Cestoda and parasitic Protozoa. Their medicinal use is known, as well as their rol as pollution bioindicator (Sawyer, 1986). On the other hand, there are many contributions to the knowledge of this group, particularly: the discovery of new species Siddall; et al. (2001, 2004), Gullo (2006, 2008); Kutchera et al (2013), the redescription of others in the basis of molecular analysis (Mosser, et al. 2012 a y b; 2013); the contruction of phylogeny (Siddall, et al. 2003, 2005) and the contribution to the global Hirudinea diversity (Sket, 2008). Despite their importance as benthic members, it is not common to include them in the analysis of benthic macroinvertebrates, because of their difficult identification. There is a lack of studies of leech biodiversity in Argentina and no antecedents for low altitude mountain environments are recorded. The heart of the investigation lies in the specific conditions of the area in question, where slightly varying environments provide the proper ecological requirements for a variety of species which are essential for biodiversity conservation. The specimens were collected in seasonal samplings during 2009, 2010 and 2011. The selected sampling locations were: Sauce Grande and Sauce Chico rivers; San Bernardo, El Negro, Rivera and El Divisorio streams. Physical and chemical parameters as temperature, pH, dissolved oxygen, oxygensaturation, conductivity and total disolved solids were recorded in each location. Three Surber samples (0.09 m2, 250 μm mesh size) were taken in each stream. The collected specimens were fixed in 5% formaldehyde solution for 24 hours and preserved in alcohol 70%. Associations between species and environmental variables were analyzed using correspondence canonical analysis (CCA) taking into account the seven most plentiful species and four environment variables.Associations among species were analyzed using clustering analysis (UPGMA) and the Jaccard similarity index. Pearson´s correlation coefficient and Student's t-distribution were used as well. Ten leech species were recorded in a freshwater environment at Sierra de la Ventana: Helobdella simplex (Moore, 1911); Helobdella brasiliensis Weber, 1915; Helobdella triserialis triserialis (Blanchard, 1849); Helobdella adiastola Ringuelet, 1972; Helobdella hyalina (Ringuelet, 1942);Helobdella triserialis lineata (Verril, 1874), Helobdella duplicata duplicata (Moore, 1911); Theromyzon propinquum Ringuelet, 1947 and Helobdella cordobensis Ringuelet, 1943. Helobdella cordobensis represents the first recording of its kind in the Buenos Aires province. The three most frequent and abundant species (more than 150) individuals in total) were H. simplex (31,55% n=348), H. triserialis s. st. (30%, n=331) and H. brasiliensis (14,50%; n=160), while H. hyalina (6,98%, n=77), H. adiastola (5,25%, n=58), H. cordobensis (4,98% n=54), H. triserialis lineata (n=33, 2,99%), H. duplicata (2,17 n=24), H. michaelseni (1,17% n=13) and T. propinquum (0,36% n=4) showed lower frequency of occurrence and a lower number of individuals. Associations among species were analyzed using clustering analysis with the Jaccard index. The clustering analysis revealed two species assemblages. A first group is represented by six species: H. brasiliensis, H. triserialis s.st., H. triserialis lineata, H. simplex, H. hyalina and H. adiastola and thesecond group is constituted by only one species, H. cordobensis. Relationships between species and environmental variables were examined with CCA. Axis 1 ofthe ordination diagram shows 99.1 % correlation between species and environmental variables. The occurrence of H. simplex, H. triserialis s. st., H. triserialis lineata, H. brasiliensis and H. hyalina near the centre of the ordination diagram is a  consequence of their wide range of tolerance. H. adiastola (r = 0.44, p < 0.05) and H. brasiliensis (r = 0.30, p < 0.05) are positively correlated to pH, whereas H. cordobensis (r = -0.80, p < 0.01) is negatively correlated to that variable. In addition, H. adiastola (r = -0.90 p < 0.01) and H. brasiliensis (r = -0.77, p < 0.01) are negatively correlated to water temperature and the specific richness shows the same trend (r = -0.79, p < 0.01). Leeches in Sierra de la Ventana do not differ from that found in other lentic and lotic environments of Buenos Aires province (Gullo, 1991; Darrigran et al., 1998; Gullo, 2007; César et al., 2009). The present records in Buenos Aires province indicate that Helobdella cordobensis is only found in freshwater low-altitude mountainous environment at Sierra de la Ventana. Hirudinea are more abundant into submerged vegetation and their amount decreases with depthas a consequence of the lack of vegetation, adequate substrates and nutrients. Several factors limit the leech number and species found in an environment. In order of importance, they are: nutrient availability, type of substrate, water depth, stream, size and type of the water body, water hardness, pH, temperature, dissolved oxygen, cloudiness and salinity (Sawyer, 1986). The UPGMA clustering showed the  association among H. brasiliensis, H. triserialis s.st., H. simplex, H. triserialis lineata, H. hyalina and H. adiastola, being the first three species the more frequent and abundant in the sampling sites. It should be pointed out that H. triserialis s. st., H. simplex and H. hyalina were the more abundant and frequent species recorded by César et al. (2009) in Martín García Island. After analyzing the relationships among species and environment variables it is concluded that H. simplex, H. triserialis s. st., H. triserialis lineata, H. brasiliensis and H. hyalina, which are the more frequent species, have a wide range of tolerance to the fluctuations of environmental parameters, and as a consequence they are located close to the center of the ACC diagram. No statistically significant results were obtained for the correlation of H. simplex with pH and of H. hyalina with conductivity. In this respect, these results differ from those obtained by César et al., 2009. On the other hand, H. adistola and H. cordobensis, which are less frequent, seem to be more sensitive to pH fluctuations. Sawyer (1986) points out that this parameter could affect the organisms that leeches take for feeding. Hirudinea are considered organisms with great physiological plasticity because they can survive under anoxia conditions for some days and under hyperoxia during long periods of time (Davies & Govedich, 2001). No statistically significant results were obtained for the correlation with dissolved oxygen. The measured values of dissolved oxygen did not show fluctuations during the year.Diez especies de hirudíneos Glossiphoniidae fueron recolectadas en ambientes dulceacuícolas de Sierra de la Ventana: Helobdella simplex (Moore, 1911); Helobdella brasiliensis Weber, 1915; Helobdella triserialis (Blanchard, 1849);, Helobdella adiastola Ringuelet, 1972; Helobdella hyalina (Ringuelet, 1942); Helobdella  lineata (Verril, 1874), Helobdella duplicata duplicata (Moore, 1911); Theromyzon propinquum Ringuelet, 1947 y Helobdella cordobensis Ringuelet, 1943. Esta última representa un nuevo registro para la provincia de Buenos Aires. La asociación entre las especies fue analizada empleando análisis de agrupamiento y coeficiente de similitud de Jaccard, revelando la existencia de dos grupos. Las relaciones entre las especies y variables ambientales fueron analizadas con Análisis Canónico de Correspondencia (ACC). El análisis sugiere que el 99,1% de la correlación entre las especies y variables se distribuye sobre el eje 1 del diagrama de ordenamiento. H. simplex, H. triserialis, H.  lineata, H. brasiliensis y H. hyalina se hallan próximas al centro del diagrama debido a su mayor rango de tolerancia. H. adiastola, y H. brasiliensis están correlacionadas positivamente con el pH, mientras que H. cordobensis está negativamente correlacionada con esta variable. Por otra parte, H. adiastola y H. brasiliensis están correlacionadas negativamente con la temperatura del agua y la riqueza específica mostró la misma tendencia. La importancia de la investigación radica en las particularidades locales del área, donde los ambientes constituyen verdaderos refugios de especies con diferentes requerimientos ecológicos que resultan fundamentales para la conservación de la biodiversidad

Communication and culture in international business – Moving the field forward

The centrality of communication in international business (IB) is undeniable; yet our understanding of the phenomenon is partially constrained by a cross-cultural comparative focus as opposed to intercultural, process-oriented research designs that capture the dynamic nature of communicative interactions. Our brief review of studies at the intersection of culture and communication in the context of global work interactions reveals the dominant research trends that guided IB scholarship to date in this domain. We propose eight shifts in perspective to advance the field\u27s theorizing and create avenues for further research

Evaluación histológica del efecto de enzimas con actividad depilatoria sobre piel vacuna

La industria curtidora genera una variedad de desechos potencialmente tóxicos que dependen del proceso de depilado utilizado. Para atenuar esta contaminación, se desarrollaron sistemas alternativos de depilado, entre ellos el enzimático. En la epidermis, a nivel del estrato corneo, se ubican lípidos que ocupan casi por completo el espacio intercelular entre los queratinocitos y desempeñan un importante papel como barrera hidrofóbica. Esta barrera debe transformarse para permitir el paso de las enzimas depilatorias hacia sus sitios de acción: folículo piloso/pelo y membrana basal. Las estructuras mencionadas deben eliminarse sin dañar el colágeno, proteína determinante de la calidad del cuero. Sobre trozos de piel bovina fueron analizados los efectos de diferentes pretratamientos tendientes a favorecer la penetración de enzimas depilatorias. Se utilizaron tensioactivos y sulfito de sodio como pretratamiento y posteriormente tratamientos con proteasas comerciales, una de origen pancréático y otra alcalina. El control fue tratado con buffer de bicarbonato de sodio. Las muestras se colorearon con Hematoxilina Eosina y Tricrómico de Masson. En los cortes sometidos a acción enzimática se encontraron cambios en el colágeno que podrían alterar la calidad del cuero.Se concluye que el estudio histológico de la piel permite evaluar los cambios que pueden ocasionar los tratamientos que se realizan para convertirla en cuero

Enzyme prodrug therapy achieves site-specific, personalized physiological responses to the locally produced nitric oxide

Nitric oxide (NO) is a highly potent but short-lived endogenous radical with a wide spectrum of physiological activities. In this work, we developed an enzymatic approach to the site-specific synthesis of NO mediated by biocatalytic surface coatings. Multilayered polyelectrolyte films were optimized as host compartments for the immobilized β-galactosidase (β-Gal) enzyme through a screen of eight polycations and eight polyanions. The lead composition was used to achieve localized production of NO through the addition of β-Gal–NONOate, a prodrug that releases NO following enzymatic bioconversion. The resulting coatings afforded physiologically relevant flux of NO matching that of the healthy human endothelium. The antiproliferative effect due to the synthesized NO in cell culture was site-specific: within a multiwell dish with freely shared media and nutrients, a 10-fold inhibition of cell growth was achieved on top of the biocatalytic coatings compared to the immediately adjacent enzyme-free microwells. The physiological effect of NO produced via the enzyme prodrug therapy was validated ex vivo in isolated arteries through the measurement of vasodilation. Biocatalytic coatings were deposited on wires produced using alloys used in clinical practice and successfully mediated a NONOate concentration-dependent vasodilation in the small arteries of rats. The results of this study present an exciting opportunity to manufacture implantable biomaterials with physiological responses controlled to the desired level for personalized treatment

Liver fatty acid-binding protein binds monoacylglycerol in vitro and in mouse liver cytosol

Liver fatty acid-binding protein (LFABP; FABP1) is expressed both in liver and intestinal mucosa. Mice null for LFABP were recently shown to have altered metabolism of not only fatty acids but also monoacylglycerol, the two major products of dietary triacylglycerol hydrolysis (Lagakos, W. S., Gajda, A. M., Agellon, L., Binas, B., Choi, V., Mandap, B., Russnak, T., Zhou, Y. X., and Storch, J. (2011) Am. J. Physiol. Gastrointest. Liver Physiol. 300, G803-G814). Nevertheless, the binding and transport of monoacylglycerol (MG) by LFABP are uncertain, with conflicting reports in the literature as to whether this single chain amphiphile is in fact bound by LFABP. In the present studies, gel filtration chromatography of liver cytosol from LFABP-/- mice shows the absence of the low molecular weight peak of radiolabeled monoolein present in the fractions that contain LFABP in cytosol from wild type mice, indicating that LFABP binds sn-2 MG in vivo. Furthermore, solution-state NMRspectroscopy demonstrates two molecules of sn-2 monoolein bound in the LFABP binding pocket in positions similar to those found for oleate binding. Equilibrium binding affinities are ~2-fold lower for MG compared with fatty acid. Finally, kinetic studies examining the transfer of a fluorescent MG analog show that the rate of transfer of MG is 7-fold faster from LFABP to phospholipid membranes than from membranes to membranes and occurs by an aqueous diffusion mechanism. These results provide strong support for monoacylglycerol as a physiological ligand for LFABP and further suggest that LFABP functions in the efficient intracellular transport of MG.Instituto de Investigaciones Bioquímicas de La Plat

Taxon-specific metagenomics of Trichoderma reveals a narrow community of opportunistic species that regulate each other’s development

In this paper, we report on the in situ diversity of the mycotrophic fungus Trichoderma (teleomorph Hypocrea, Ascomycota, Dikarya) revealed by a taxon-specific metagenomic approach. We designed a set of genus-specific internal transcribed spacer (ITS)1 and ITS2 rRNA primers and constructed a clone library containing 411 molecular operational taxonomic units (MOTUs). The overall species composition in the soil of the two distinct ecosystems in the Danube floodplain consisted of 15 known species and two potentially novel taxa. The latter taxa accounted for only 1.5 % of all MOTUs, suggesting that almost no hidden or uncultivable Hypocrea/Trichoderma species are present at least in these temperate forest soils. The species were unevenly distributed in vertical soil profiles although no universal factors controlling the distribution of all of them (chemical soil properties, vegetation type and affinity to rhizosphere) were revealed. In vitro experiments simulating infrageneric interactions between the pairs of species that were detected in the same soil horizon showed a broad spectrum of reactions from very strong competition over neutral coexistence to the pronounced synergism. Our data suggest that only a relatively small portion of Hypocrea/Trichoderma species is adapted to soil as a habitat and that the interaction between these species should be considered in a screening for Hypocrea/Trichoderma as an agent(s) of biological control of pests

Application of cupuassu shell as biosorbent for the removal of textile dyes from aqueous solution

AbstractThe cupuassu shell (Theobroma grandiflorum) which is a food residue was used in its natural form as biosorbent for the removal of C.I. Reactive Red 194 and C.I. Direct Blue 53 dyes from aqueous solutions. This biosorbent was characterized by infrared spectroscopy, scanning electron microscopy, and nitrogen adsorption/desorption curves. The effects of pH, biosorbent dosage and shaking time on biosorption capacities were studied. In acidic pH region (pH 2.0) the biosorption of the dyes were favorable. The contact time required to obtain the equilibrium was 8 and 18 h at 298 K, for Reactive Red 194 and Direct Blue 53, respectively. The Avrami fractionary-order kinetic model provided the best fit to experimental data compared with pseudo-first-order, pseudo-second-order and chemisorption kinetic adsorption models. The equilibrium data were fitted to Langmuir, Freundlich, Sips and Radke–Prausnitz isotherm models. For both dyes the equilibrium data were best fitted to the Sips isotherm model

Hydrogen Production by Formic Acid Decomposition over Ca Promoted Ni/SiO2 Catalysts: Effect of the Calcium Content

Formic acid, a major product of biomass processing, is regarded as a potential liquid carrier for hydrogen storage and delivery. The catalytic dehydrogenation of FA to generate hydrogen using heterogeneous catalysts is of great interest. Ni based catalysts supported on silica were synthesized by incipient wet impregnation. The eect of doping with an alkaline earth metal (calcium) wasstudied, and the solids were tested in the formic acid decomposition reaction to produce hydrogen.The catalysts were characterized by X-ray diraction (XRD), X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction (TPR), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and programmed temperature surface reaction (TPSR).The catalyst doped with 19.3 wt.% of Ca showed 100% conversion of formic acid at 160 C, with a 92% of selectivity to hydrogen. In addition, all the tested materials were promising for their application, since they showed catalytic behaviors (conversion and selectivity to hydrogen) comparable to thoseof noble metals reported in the literature.Fil: Faroldi, Betina María Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; ArgentinaFil: Paviotti, María Aneley. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; ArgentinaFil: Camino-Manjarrés, M.. Universidad de Salamanca; EspañaFil: González-Carrazán, S.. Universidad de Salamanca; EspañaFil: López-Olmos, C.. Consejo Superior de Investigaciones Científicas. Instituto de Catálisis y Petroleoquímica; EspañaFil: Rodríguez-Ramos, I.. Consejo Superior de Investigaciones Científicas. Instituto de Catálisis y Petroleoquímica; Españ

Parasitosis intestinales y factores ambientales en una población rural de Argentina, 2002-2003

We evaluate the prevalence of intestinal parasites in 504 people and the degree of association between environmental variables and parasites found in population, soil and water in a rural area of Argentina during 2002-2003. A structured survey was used to evaluate the environmental variables and fecal-human, soil and water samples were analyzed. The prevalence of parasites was 45.4%. Most prevalent protozoa were Blastocystis hominis (27.2%) and Giardia lamblia (6.9%), while the most prevalent helminth was Ascaris lumbricoides (3.8%). The analyzed environmental variables showing association (p < 0.05) with presence of parasites in population were: cardboard-tin or wooden house, dirt floor, home or communal water pump, faucet outside the house or public faucet and cesspool or latrine. Parasite forms were found in 82.3% of the soil samples and in 84.2% of the water samples. In both samples we found parasites that were also found in people. In this study we have found deficient sanitary conditions associated with presence of parasites in population and we have evidenced that contaminated soil and water were the source of these parasites.Hemos evaluado la prevalencia de parásitos intestinales en 504 personas y el grado de asociación entre las variables ambientales y los parásitos intestinales hallados en la población, el suelo y el agua de una zona rural de Argentina durante 2002-2003. Se utilizó una encuesta estructurada para relevar las variables ambientales y se examinaron muestras fecales humanas, de agua y de suelo. La prevalencia parasitaria fue de 45,4%. Los protozoos prevalentes fueron Blastocystis hominis (27,2%) y Giardia lamblia (6,9%), mientras que el helminto mas prevalente fue Ascaris lumbricoides (3,8%). Las variables ambientales analizadas que mostraron asociación (p < 0,05) con la presencia de parásitos en la población fueron: casa de cartón-chapa o de madera con piso de tierra, bomba de agua domiciliaria o comunitaria, canilla fuera de la casa o pública y pozo ciego o letrina. Elementos parasitarios fueron hallados en el 82,3% de las muestras de suelo y en el 84,2% de las muestras de agua. En ambas muestras fueron hallados parásitos que también se encontraron en las personas. En este trabajo hemos hallado deficientes condiciones sanitarias asociadas con la presencia de parásitos en las personas y hemos evidenciado que el suelo y el agua contaminada fueron la fuente de esos parasitos