The Escherichia coli BtuE Protein Functions as a Resistance Determinant against Reactive Oxygen Species

This work shows that the recently described Escherichia coli BtuE peroxidase protects the bacterium against oxidative stress that is generated by tellurite and by other reactive oxygen species elicitors (ROS). Cells lacking btuE (ΔbtuE) displayed higher sensitivity to K2TeO3 and other oxidative stress-generating agents than did the isogenic, parental, wild-type strain. They also exhibited increased levels of cytoplasmic reactive oxygen species, oxidized proteins, thiobarbituric acid reactive substances, and lipoperoxides. E. coli ΔbtuE that was exposed to tellurite or H2O2 did not show growth changes relative to wild type cells either in aerobic or anaerobic conditions. Nevertheless, the elimination of btuE from cells deficient in catalases/peroxidases (Hpx−) resulted in impaired growth and resistance to these toxicants only in aerobic conditions, suggesting that BtuE is involved in the defense against oxidative damage. Genetic complementation of E. coli ΔbtuE restored toxicant resistance to levels exhibited by the wild type strain. As expected, btuE overexpression resulted in decreased amounts of oxidative damage products as well as in lower transcriptional levels of the oxidative stress-induced genes ibpA, soxS and katG

Enhancing the Antibiotic Antibacterial Effect by Sub Lethal Tellurite Concentrations: Tellurite and Cefotaxime Act Synergistically in Escherichia coli

The emergence of antibiotic-resistant pathogenic bacteria during the last decades has become a public health concern worldwide. Aiming to explore new alternatives to treat antibiotic-resistant bacteria and given that the tellurium oxyanion tellurite is highly toxic for most microorganisms, we evaluated the ability of sub lethal tellurite concentrations to strengthen the effect of several antibiotics. Tellurite, at nM or µM concentrations, increased importantly the toxicity of defined antibacterials. This was observed with both Gram negative and Gram positive bacteria, irrespective of the antibiotic or tellurite tolerance of the particular microorganism. The tellurite-mediated antibiotic-potentiating effect occurs in laboratory and clinical, uropathogenic Escherichia coli, especially with antibiotics disturbing the cell wall (ampicillin, cefotaxime) or protein synthesis (tetracycline, chloramphenicol, gentamicin). In particular, the effect of tellurite on the activity of the clinically-relevant, third-generation cephalosporin (cefotaxime), was evaluated. Cell viability assays showed that tellurite and cefotaxime act synergistically against E. coli. In conclusion, using tellurite like an adjuvant could be of great help to cope with several multi-resistant pathogens

ESTUDIO LECTINHISTOQUÍMICO DEL ÚTERO DE ALPACAS (Vicugna pacos) BAJO TRATAMIENTO SUPEROVULATORIO.

The aim of this study was to determine the glycosylation pattern in the uterine endometrium of alpacas with and without superovulation treatment. Uterine tissues were obtained from five non-treated alpacas with ovarian follicles less than 4 mm and five superovulated alpacas where FSH, GnRH and hCG was used. Samples from theuterus and uterine horns were analyzed by histochemistry (PAS and alcian blue) and lectinhistochemistry techniques. Fourteen lectins were used and PNA, RCA-1, ConA, DBA, WGA, Swga, GS, LCA, SJA and PHA-L showed different glycosilation patterns in the endometrium between both groups, indicating that the hormonal treatment could affect the expression of glycoconjugates that have affinity for these lectins. Lectins PNA, SJA, SBA, ConA, LCA and PSA showed different glycosilation patterns between the two uterine horns, indicating that the glycoconjugates that have affinity for these lectins can be implicated in the uterine environment during the implantation, which in most cases in the alpaca take place on the left horn. In conclusion, the glycosylation pattern in the alpaca can change due to superovulation hormone therapy.El objetivo del presente estudio fue determinar el patrón de glicosilación del endometrio uterino en alpacas con y sin tratamiento de superovulación. Se utilizaron cinco alpacas no superovuladas con folículos ováricos menores de 4 mm y cinco alpacas que fueron sometidas a un tratamiento de superovulación en base a FSH, GnRH y hCG. Se tomaron muestras del cuerpo del útero y de ambos cuernos uterinos y se trabajaron con las técnicas histoquímicas PAS y Azul Alcián y con la técnica de lectinhistoquímica. Para esta última se utilizaron 14 lectinas, de las cuales PNA, RCA-I, ConA, DBA, WGA,sWGA, GS, LCA, SJA y PHA-L presentaron un patrón de glicosilación diferente entre ambos grupos, sugiriendo que el tratamiento hormonal influenció en la expresión de los glicoconjugados que se unen a estas lectinas. Asimismo, las lectinas PNA, SJA, SBA,ConA, LCA y PSA presentaron diferencias entre el cuerno derecho y el cuerno izquierdo, lo que sugiere que los glicoconjugados de unión a estas lectinas podrían participar en generar un ambiente propicio para la implantación, que por lo general se da en el cuerno izquierdo en la alpaca. Se concluye que la alpaca tiene un patrón de glicosilación que puede variar con tratamientos hormonales de superovulación

Lectinhistochemistry study of the uterus ofalpacas (Vicugna pacos) under superovulation treatment

El objetivo del presente estudio fue determinar el patrón de glicosilación del endometrio uterino en alpacas con y sin tratamiento de superovulación. Se utilizaron cinco alpacas no superovuladas con folículos ováricos menores de 4 mm y cinco alpacas que fueron sometidas a un tratamiento de superovulación en base a FSH, GnRH y hCG. Se tomaron muestras del cuerpo del útero y de ambos cuernos uterinos y se trabajaron con las técnicas histoquímicas PAS y Azul Alcián y con la técnica de lectinhistoquímica. Para esta última se utilizaron 14 lectinas, de las cuales PNA, RCA-I, ConA, DBA, WGA, sWGA, GS, LCA, SJA y PHA-L presentaron un patrón de glicosilación diferente entre ambos grupos, sugiriendo que el tratamiento hormonal influenció en la expresión de los glicoconjugados que se unen a estas lectinas. Asimismo, las lectinas PNA, SJA, SBA, ConA, LCA y PSA presentaron diferencias entre el cuerno derecho y el cuerno izquierdo, lo que sugiere que los glicoconjugados de unión a estas lectinas podrían participar en generar un ambiente propicio para la implantación, que por lo general se da en el cuerno izquierdo en la alpaca. Se concluye que la alpaca tiene un patrón de glicosilación que puede variar con tratamientos hormonales de superovulación.The aim of this study was to determine the glycosylation pattern in the uterine endometrium of alpacas with and without superovulation treatment. Uterine tissues were obtained from five non-treated alpacas with ovarian follicles less than 4 mm and five superovulated alpacas where FSH, GnRH and hCG was used. Samples from the uterus and uterine horns were analyzed by histochemistry (PAS and alcian blue) and lectinhistochemistry techniques. Fourteen lectins were used and PNA, RCA-1, ConA, DBA, WGA, Swga, GS, LCA, SJA and PHA-L showed different glycosilation patterns in the endometrium between both groups, indicating that the hormonal treatment could affect the expression of glycoconjugates that have affinity for these lectins. Lectins PNA, SJA, SBA, ConA, LCA and PSA showed different glycosilation patterns between the two uterine horns, indicating that the glycoconjugates that have affinity for these lectins can be implicated in the uterine environment during the implantation, which in most cases in the alpaca take place on the left horn. In conclusion, the glycosylation pattern in the alpaca can change due to superovulation hormone therapy.Facultad de Ciencias Veterinaria

Lectinhistochemistry study of the uterus ofalpacas (Vicugna pacos) under superovulation treatment

El objetivo del presente estudio fue determinar el patrón de glicosilación del endometrio uterino en alpacas con y sin tratamiento de superovulación. Se utilizaron cinco alpacas no superovuladas con folículos ováricos menores de 4 mm y cinco alpacas que fueron sometidas a un tratamiento de superovulación en base a FSH, GnRH y hCG. Se tomaron muestras del cuerpo del útero y de ambos cuernos uterinos y se trabajaron con las técnicas histoquímicas PAS y Azul Alcián y con la técnica de lectinhistoquímica. Para esta última se utilizaron 14 lectinas, de las cuales PNA, RCA-I, ConA, DBA, WGA, sWGA, GS, LCA, SJA y PHA-L presentaron un patrón de glicosilación diferente entre ambos grupos, sugiriendo que el tratamiento hormonal influenció en la expresión de los glicoconjugados que se unen a estas lectinas. Asimismo, las lectinas PNA, SJA, SBA, ConA, LCA y PSA presentaron diferencias entre el cuerno derecho y el cuerno izquierdo, lo que sugiere que los glicoconjugados de unión a estas lectinas podrían participar en generar un ambiente propicio para la implantación, que por lo general se da en el cuerno izquierdo en la alpaca. Se concluye que la alpaca tiene un patrón de glicosilación que puede variar con tratamientos hormonales de superovulación.The aim of this study was to determine the glycosylation pattern in the uterine endometrium of alpacas with and without superovulation treatment. Uterine tissues were obtained from five non-treated alpacas with ovarian follicles less than 4 mm and five superovulated alpacas where FSH, GnRH and hCG was used. Samples from the uterus and uterine horns were analyzed by histochemistry (PAS and alcian blue) and lectinhistochemistry techniques. Fourteen lectins were used and PNA, RCA-1, ConA, DBA, WGA, Swga, GS, LCA, SJA and PHA-L showed different glycosilation patterns in the endometrium between both groups, indicating that the hormonal treatment could affect the expression of glycoconjugates that have affinity for these lectins. Lectins PNA, SJA, SBA, ConA, LCA and PSA showed different glycosilation patterns between the two uterine horns, indicating that the glycoconjugates that have affinity for these lectins can be implicated in the uterine environment during the implantation, which in most cases in the alpaca take place on the left horn. In conclusion, the glycosylation pattern in the alpaca can change due to superovulation hormone therapy.Facultad de Ciencias Veterinaria

Lectinhistochemistry study of the uterus ofalpacas (Vicugna pacos) under superovulation treatment

El objetivo del presente estudio fue determinar el patrón de glicosilación del endometrio uterino en alpacas con y sin tratamiento de superovulación. Se utilizaron cinco alpacas no superovuladas con folículos ováricos menores de 4 mm y cinco alpacas que fueron sometidas a un tratamiento de superovulación en base a FSH, GnRH y hCG. Se tomaron muestras del cuerpo del útero y de ambos cuernos uterinos y se trabajaron con las técnicas histoquímicas PAS y Azul Alcián y con la técnica de lectinhistoquímica. Para esta última se utilizaron 14 lectinas, de las cuales PNA, RCA-I, ConA, DBA, WGA, sWGA, GS, LCA, SJA y PHA-L presentaron un patrón de glicosilación diferente entre ambos grupos, sugiriendo que el tratamiento hormonal influenció en la expresión de los glicoconjugados que se unen a estas lectinas. Asimismo, las lectinas PNA, SJA, SBA, ConA, LCA y PSA presentaron diferencias entre el cuerno derecho y el cuerno izquierdo, lo que sugiere que los glicoconjugados de unión a estas lectinas podrían participar en generar un ambiente propicio para la implantación, que por lo general se da en el cuerno izquierdo en la alpaca. Se concluye que la alpaca tiene un patrón de glicosilación que puede variar con tratamientos hormonales de superovulación.The aim of this study was to determine the glycosylation pattern in the uterine endometrium of alpacas with and without superovulation treatment. Uterine tissues were obtained from five non-treated alpacas with ovarian follicles less than 4 mm and five superovulated alpacas where FSH, GnRH and hCG was used. Samples from the uterus and uterine horns were analyzed by histochemistry (PAS and alcian blue) and lectinhistochemistry techniques. Fourteen lectins were used and PNA, RCA-1, ConA, DBA, WGA, Swga, GS, LCA, SJA and PHA-L showed different glycosilation patterns in the endometrium between both groups, indicating that the hormonal treatment could affect the expression of glycoconjugates that have affinity for these lectins. Lectins PNA, SJA, SBA, ConA, LCA and PSA showed different glycosilation patterns between the two uterine horns, indicating that the glycoconjugates that have affinity for these lectins can be implicated in the uterine environment during the implantation, which in most cases in the alpaca take place on the left horn. In conclusion, the glycosylation pattern in the alpaca can change due to superovulation hormone therapy.Facultad de Ciencias Veterinaria

The Subantarctic Rayadito (Aphrastura subantarctica), a new bird species on the southernmost islands of the Americas

We describe a new taxon of terrestrial bird of the genus Aphrastura (rayaditos) inhabiting the Diego Ramírez Archipelago, the southernmost point of the American continent. This archipelago is geographically isolated and lacks terrestrial mammalian predators as well as woody plants, providing a contrasted habitat to the forests inhabited by the other two Aphrastura spp. Individuals of Diego Ramírez differ morphologically from Aphrastura spinicauda, the taxonomic group they were originally attributed to, by their larger beaks, longer tarsi, shorter tails, and larger body mass. These birds move at shorter distances from ground level, and instead of nesting in cavities in trees, they breed in cavities in the ground, reflecting different life-histories. Both taxa are genetically differentiated based on mitochondrial and autosomal markers, with no evidence of current gene flow. Although further research is required to define how far divergence has proceeded along the speciation continuum, we propose A. subantarctica as a new taxonomic unit, given its unique morphological, genetic, and behavioral attributes in a non-forested habitat. The discovery of this endemic passerine highlights the need to monitor and conserve this still-pristine archipelago devoid of exotic species, which is now protected by the recently created Diego Ramírez Islands-Drake Passage Marine Park.Fil: Rozzi, Ricardo. Universidad de Magallanes; Chile. University of North Texas; Estados UnidosFil: Quilodrán, Claudio S.. Universidad de Magallanes; Chile. Universite de Fribourg;Fil: Botero Delgadillo, Esteban. Max Plank Institute for Ornithology; Alemania. Universidad de Chile; ChileFil: Napolitano, Constanza. Universidad de Magallanes; Chile. Universidad de Los Lagos; Chile. Instituto de Ecología y Biodiversidad; ChileFil: Torres Mura, Juan C.. Universidad de Magallanes; Chile. Union de Ornitologos de Chile; ChileFil: Barroso, Omar. Universidad de Magallanes; ChileFil: Crego, Ramiro D.. Conservation Ecology Center; Estados UnidosFil: Bravo, Camila. Universidad de Chile; ChileFil: Ippi, Silvina Graciela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Quirici, Verónica. Universidad Andrés Bello; ChileFil: Mackenzie, Roy. Universidad de Magallanes; ChileFil: Suazo, Cristián G.. Universidad de Magallanes; Chile. Justus Liebig Universitat Giessen; AlemaniaFil: Rivero de Aguilar, Juan. Universidad de Magallanes; ChileFil: Goffinet, Bernard. Universidad de Magallanes; Chile. University of Connecticut; Estados UnidosFil: Kempenaers, Bart. Max Plank Institute for Ornithology; SuizaFil: Poulin, Elie. Universidad de Magallanes; Chile. Universidad de Chile; ChileFil: Vásquez, Rodrigo A.. Universidad de Magallanes; Chile. Universidad de Chile; Chil

Bacterial Toxicity of Potassium Tellurite: Unveiling an Ancient Enigma

Biochemical, genetic, enzymatic and molecular approaches were used to demonstrate, for the first time, that tellurite (TeO(3) (2−)) toxicity in E. coli involves superoxide formation. This radical is derived, at least in part, from enzymatic TeO(3) (2−) reduction. This conclusion is supported by the following observations made in K(2)TeO(3)-treated E. coli BW25113: i) induction of the ibpA gene encoding for the small heat shock protein IbpA, which has been associated with resistance to superoxide, ii) increase of cytoplasmic reactive oxygen species (ROS) as determined with ROS-specific probe 2′7′-dichlorodihydrofluorescein diacetate (H(2)DCFDA), iii) increase of carbonyl content in cellular proteins, iv) increase in the generation of thiobarbituric acid-reactive substances (TBARs), v) inactivation of oxidative stress-sensitive [Fe-S] enzymes such as aconitase, vi) increase of superoxide dismutase (SOD) activity, vii) increase of sodA, sodB and soxS mRNA transcription, and viii) generation of superoxide radical during in vitro enzymatic reduction of potassium tellurite

Catalases Are NAD(P)H-Dependent Tellurite Reductases

Reactive oxygen species damage intracellular targets and are implicated in cancer, genetic disease, mutagenesis, and aging. Catalases are among the key enzymatic defenses against one of the most physiologically abundant reactive oxygen species, hydrogen peroxide. The well-studied, heme-dependent catalases accelerate the rate of the dismutation of peroxide to molecular oxygen and water with near kinetic perfection. Many catalases also bind the cofactors NADPH and NADH tenaciously, but, surprisingly, NAD(P)H is not required for their dismutase activity. Although NAD(P)H protects bovine catalase against oxidative damage by its peroxide substrate, the catalytic role of the nicotinamide cofactor in the function of this enzyme has remained a biochemical mystery to date. Anions formed by heavy metal oxides are among the most highly reactive, natural oxidizing agents. Here, we show that a natural isolate of Staphylococcus epidermidis resistant to tellurite detoxifies this anion thanks to a novel activity of its catalase, and that a subset of both bacterial and mammalian catalases carry out the NAD(P)H-dependent reduction of soluble tellurite ion (TeO(3) (2−)) to the less toxic, insoluble metal, tellurium (Te°), in vitro. An Escherichia coli mutant defective in the KatG catalase/peroxidase is sensitive to tellurite, and expression of the S. epidermidis catalase gene in a heterologous E. coli host confers increased resistance to tellurite as well as to hydrogen peroxide in vivo, arguing that S. epidermidis catalase provides a physiological line of defense against both of these strong oxidizing agents. Kinetic studies reveal that bovine catalase reduces tellurite with a low Michaelis-Menten constant, a result suggesting that tellurite is among the natural substrates of this enzyme. The reduction of tellurite by bovine catalase occurs at the expense of producing the highly reactive superoxide radical

Biomimetic, Mild Chemical Synthesis of CdTe-GSH Quantum Dots with Improved Biocompatibility

Multiple applications of nanotechnology, especially those involving highly fluorescent nanoparticles (NPs) or quantum dots (QDs) have stimulated the research to develop simple, rapid and environmentally friendly protocols for synthesizing NPs exhibiting novel properties and increased biocompatibility