On the welding of different materials by diode laser

In technical literature, there are few papers about the use of diode lasers in material processing and particularly in metal welding. In this paper, different materials, according to specific and particular industrial needs and requests, have been tested with a welding process by a diode laser, emitting a 808 nm laser radiation. Beads on plate have been studied. The goal was to evaluate the maximum weldable thickness and define the best process parameters for each material. The experimental evaluation has been carried out considering the following parameters: power level, welding speed (WS), shielding gas, gas nozzle and orientation of the focused elliptical spot as to the welding direction

Laser cutting of different polymeric plastics (PE, PP and PC) by a CO2 laser beam

Thiswork investigates the application of theCO2 laser cutting process to three thermoplastic polymers, polyethylene (PE), polypropylene (PP), polycarbonate (PC) in different thicknesses ranging from 2 to 10 mm. The process parameters examined were: laser power, range of cutting speed, type of focusing lens, pressure and flow of the covering gas, thickness of the samples. Furthermore, the values of kerf widths on top (Lsup) and bottom (Linf ) thicknesses, the melted transverse area, the melted volume per unit time and surface roughness values (Ra) on cut edges were also measured

Experimental bio-artificial liver: Importance of the architectural design on ammonia detoxification performance

AIM To determine the influence of the construction design over the biological component's performance in an experimental bio-artificial liver (BAL) device. METHODS Two BAL models for liver microorgans (LMOs) were constructed. First, we constructed a cylindrical BAL and tested it without the biological component to establish its correct functioning. Samples of blood and biological compartment (BC) fluid were taken after 0, 60, and 120 min of perfusion. Osmolality, hematocrit, ammonia and glucose concentrations, lactate dehydrogenase (LDH) release (as a LMO viability parameter), and oxygen consumption and ammonia metabolizing capacity (as LMO functionality parameters) were determined. CPSI and OTC gene expression and function were measured. The second BAL, a "flat bottom" model, was constructed using a 25 cm2 culture flask while maintaining all other components between the models. The BC of both BALs had the same capacity (approximately 50 cm3) and both were manipulated with the same perfusion system. The performances of the two BALs were compared to show the influence of architecture. RESULTS The cylindrical BAL showed a good exchange of fluids and metabolites between blood and the BC, reflected by the matching of osmolalities, and glucose and ammonia concentration ratios after 120 min of perfusion. No hemoconcentration was detected, the hematocrit levels remained stable during the whole study, and the minimal percentage of hemolysis (0.65% ± 0.10%) observed was due to the action of the peristaltic pump. When LMOs were used as biological component of this BAL they showed similar values to the ones obtained in a Normothermic Reoxygenation System (NRS) for almost all the parameters assayed. After 120 min, the results obtained were: LDH release (%): 14.7 ± 3.1 in the BAL and 15.5 ± 3.2 in the NRS (n = 6); oxygen consumption (μmol/min·g wet tissue): 1.16 ± 0.21 in the BAL and 0.84 ± 0.15 in the NRS (n = 6); relative expression of Cps1 and Otc: 0.63 ± 0.12 and 0.67 ± 0.20, respectively, in the BAL, and 0.86 ± 0.10 and 0.82 ± 0.07, respectively, in the NRS (n = 3); enzymatic activity of CPSI and OTC (U/g wet tissue): 3.03 ± 0.86 and 222.0 ± 23.5, respectively, in the BAL, and 3.12 ± 0.73 and 228.8 ± 32.8, respectively, in the NRS (n = 3). In spite of these similarities, LMOs as a biological component of the cylindrical BAL were not able to detoxify ammonia at a significant level (not detected vs 35.1% ± 7.0% of the initial 1 mM NH4 + dose in NRS, n = 6). Therefore, we built a second BAL with an entirely different design that offers a flat base BC. When LMOs were placed in this "flat bottom" device they were able to detoxify 49.3% ± 8.8% of the initial ammonia overload after 120 min of perfusion (n = 6), with a detoxification capacity of 13.2 ± 2.2 μmol/ g wet tissue. CONCLUSION In this work, we demonstrate the importance of adapting the BAL architecture to the biological component characteristics to obtain an adequate BAL performance.Fil: Pizarro, María Dolores. Universidad Nacional del Litoral; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Mamprin, María Eugenia. Universidad Nacional de Rosario; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Daurelio, Lucas Damian. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Litoral; ArgentinaFil: Rodriguez, Joaquin Valentin. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Rosario; ArgentinaFil: Mediavilla, Maria Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Rosario; Argentin

Genetic characterization of Paspalum notatum accessions by AFLP markers

Paspalum notatum Flügge is a warm-season forage grass with sexual diploid and apomictic tetraploid races. Genetic improvement was achieved in out-breeding diploids. The acquisition of artificial sexual tetraploids has raised the possibility of performing crosses and plant improvement at the tetraploid level. The objective of our study was to obtain a genetic and cytoembryological characterization of a germplasm collection of P. notatum, including 31 accessions from seven countries of America and 11 experimentally obtained genotypes. Morphology of mature gametophytes was observed to assess the mode of reproduction of the accessions. A total of 1342 AFLP fragments were generated across the 42 genotypes and from two reference taxa: P. urvillei and P. procurrens. AFLP data were converted into a binary matrix and similarity relationships were established. The genetic distance among all the accessions showed a maximum value of 0.36. In addition, eleven AFLP fragments were observed exclusively in apomictic plants, which could be linked to genomic regions implicated in the control of aposporyFil: Espinoza, Francisco. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Botánica del Nordeste. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Instituto de Botánica del Nordeste; ArgentinaFil: Daurelio, Lucas Damian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Pessino, Silvina Claudia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Valle, Estela Marta. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Quarin, Camilo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Botánica del Nordeste. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Instituto de Botánica del Nordeste; Argentin

Genome-wide analysis of AGO, DCL and RDR gene families reveals RNA-directed DNA methylation is involved in fruit abscission in Citrus sinensis

Background: Small RNAs regulate a wide variety of processes in plants, from organ development to both biotic and abiotic stress response. Being master regulators in genetic networks, their biogenesis and action is a fundamental aspect to characterize in order to understand plant growth and development. Three main gene families are critical components of RNA silencing: DICER-LIKE (DCL), ARGONAUTE (AGO) and RNA-DEPENDENT RNA POLYMERASE (RDR). Even though they have been characterized in other plant species, there is no information about these gene families in Citrus sinensis, one of the most important fruit species from both economical and nutritional reasons. While small RNAs have been implicated in the regulation of multiple aspects of plant growth and development, their role in the abscission process has not been characterized yet. Results: Using genome-wide analysis and a phylogenetic approach, we identified a total of 13 AGO, 5 DCL and 7 RDR genes. We characterized their expression patterns in root, leaf, flesh, peel and embryo samples using RNA-seq data. Moreover, we studied their role in fruit abscission through gene expression analysis in fruit rind compared to abscission zone from samples obtained by laser capture microdissection. Interestingly, we determined that the expression of several RNA silencing factors are down-regulated in fruit abscission zone, being particularly represented gene components of the RNA-dependent DNA Methylation pathway, indicating that repression of this process is necessary for fruit abscission to take place in Citrus sinensis. Conclusions: The members of these 3 families present characteristic conserved domains and distinct expression patterns. We provide a detailed analysis of the members of these families and improved the annotation of some of these genes based on RNA-seq data. Our data suggests that the RNA-dependent DNA Methylation pathway is involved in the important fruit abscission process in C. sinensis.Fil: Sabbione, Agustín Andrés. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Daurelio, Lucas Damian. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Veggeti, A.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; ArgentinaFil: Talón, Manuel. Institut Valencià Dinvestigacions Agràries; EspañaFil: Tadeo, Francisco. Institut Valencià Dinvestigacions Agràries; EspañaFil: Dotto, Marcela Claudia. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentin

Use of raw and composted poultry litter in lettuce produced under field conditions: microbiological quality and safety assessment

Lettuce (Lactuca sativa L.) constitutes one the most important vegetable crops worldwide. Poultry litter is being applied as an economically suitable alternative to nitrogen fertilizers in lettuce cultivation. However, little is known about the effects of this practice over this fresh product safety that is usually consumed as a salad. The aim of this work was to determine the microbiological quality and the nitrate content in lettuce produced, under field conditions, using either raw or composted poultry litter, coming from the same original batch. Two experiments were conducted in the experimental field of Facultad de Ciencias Agrarias (UNL, Santa Fe, Argentina) to assess the effects of recently extracted poultry litter that consisted of broiler chicken manure plus rice husk, or composted for 12 mo. The application amounts were: 20 T ha−1 (T1); 40 T ha−1 (T2); and no application of manure (T). Increasing the applied quantities had also increased the health risk associated with lettuce consumption, due to higher nitrate levels and microbial contamination. However, these risks were reduced by composting the material. Even when lettuce contamination with faecal bacteria was mainly due to the use of poultry litter, the number and incidence of pathogens were reduced when properly composted manure was applied instead of raw one. Increasing the dose of poultry litter applied also increases the health risk in lettuce. Though, when the material is properly composted, its fertilizing capacity is maintained, giving proper yields with lower nitrate levels and microbial contamination by enterobacteria.Fil: Pizarro, María Dolores. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; ArgentinaFil: Céccoli, Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; ArgentinaFil: Muñoz, Fernando Felipe. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; ArgentinaFil: Frizzo, Laureano Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Ciencias Veterinarias del Litoral. Universidad Nacional del Litoral. Facultad de Ciencias Veterinarias. Instituto de Ciencias Veterinarias del Litoral; ArgentinaFil: Daurelio, Lucas Damian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; ArgentinaFil: Bouzo, Carlos Alberto. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentin

Antagonism of Bacillus safensis strain against phytopathogenic bacteria

Citrus canker caused by Xanthomonas citri subsp. citri (Xcc), is a bacterial disease which affects all the citrics. One alternative to manage it is the use of antagonist bacteria. The aim of this work was to investigate the antagonist activity of Bacillus safensis (S9) against Xcc. The activity was tested by diffusion assays. Xcc and S9 were grown overnight in Luria Bertani (LB) and potato dextrose (PD) medium, respectively, with continuous agitation at 28°C and then, were diluted to a concentration of 108 CFU/mL. Petri dishes were covered with 15 mL of LB-agar containing 100 μL of the Xcc dilution. Once the medium was solidified, 4 μL drops of S9 were inoculated 3 times in each Petri dish, and the experiment was made by triplicate. After 48 hours of incubation at 28°C, the inhibition zone was measured, and the average inhibition area was calculated as IA = average area of the inhibition zone - average area of the colony. A significant inhibition area of 5.18 cm2 was obtained (one-sample t- test, p<0.05). At the same time, diffusion assays with the supernatant were made to prove its inhibitory ability. Petri dishes were prepared as described above. The supernatant was obtained by centrifugation of the S9 culture grown in PD medium, and then by bacteria filtration. Three filter paper discs embedded with the supernatant were placed per Petri dish, by triplicate. The inhibition zone was measured after 48 hours and calculated the IA. A significant inhibition area of 2.29 cm2 was obtained (one-sample t-test, p<0.05). Besides, a study at genomic level comparing S9 with ten Bacillus strains was made. Different clusters of secondary metabolite synthesis pathways were detected, three common with B. velezensis strains (surfactin, basilicin and bacilibactin). These strains were tested as inhibitors of Xcc and they did not show inhibition (Bacillus sp and B. megaterium) or showed less inhibition (B. velezensis). The difference might be on the expression level of the clusters. These results suggest the potential use of S9 as a canker control agent and further studies will be necessary to identify the Xcc- inhibitor metabolite.Fil: Olivella, Laura. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Instituto de Ciencias Agropecuarias del Litoral. - Universidad Nacional del Litoral. Instituto de Ciencias Agropecuarias del Litoral.; ArgentinaFil: Gaido, Jimena Daiana. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Instituto de Ciencias Agropecuarias del Litoral. - Universidad Nacional del Litoral. Instituto de Ciencias Agropecuarias del Litoral.; ArgentinaFil: Torres Manno, Mariano Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Centro de Estudios Fotosintéticos y Bioquímicos. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Centro de Estudios Fotosintéticos y Bioquímicos; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Departamento de Química Orgánica; ArgentinaFil: Petitti, Tomás Denis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Espariz, Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Daurelio, Lucas Damian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaLVII Annual Meeting of the Argentine Society for Biochemistry and Molecular Biology Research; XVI Annual Meeting of the Argentinean Society for General MicrobiologyBuenos AiresArgentinaSociedad Argentina de Bioquímica y Biología MolecularSociedad Argentina de Microbiología Genera

The LOV Protein of Xanthomonas citri subsp. citri Plays a Significant Role in the Counteraction of Plant Immune Responses during Citrus Canker

Pathogens interaction with a host plant starts a set of immune responses that result in complex changes in gene expression and plant physiology. Light is an important modulator of plant defense response and recent studies have evidenced the novel influence of this environmental stimulus in the virulence of several bacterial pathogens. Xanthomonas citri subsp. citri is the bacterium responsible for citrus canker disease, which affects most citrus cultivars. The ability of this bacterium to colonize host plants is influenced by bacterial blue-light sensing through a LOV-domain protein and disease symptoms are considerably altered upon deletion of this protein. In this work we aimed to unravel the role of this photoreceptor during the bacterial counteraction of plant immune responses leading to citrus canker development. We performed a transcriptomic analysis in Citrus sinensis leaves inoculated with the wild type X. citri subsp. citri and with a mutant strain lacking the LOV protein by a cDNA microarray and evaluated the differentially regulated genes corresponding to specific biological processes. A down-regulation of photosynthesis-related genes (together with a corresponding decrease in photosynthesis rates) was observed upon bacterial infection, this effect being more pronounced in plants infected with the lov-mutant bacterial strain. Infection with this strain was also accompanied with the up-regulation of several secondary metabolism- and defense response-related genes. Moreover, we found that relevant plant physiological alterations triggered by pathogen attack such as cell wall fortification and tissue disruption were amplified during the lov-mutant strain infection. These results suggest the participation of the LOV-domain protein from X. citri subsp. citri in the bacterial counteraction of host plant defense response, contributing in this way to disease development.Fil: Kraiselburd, Ivana. Consejo Nacional de Invest.cientif.y Tecnicas. Centro Cientifico Tecnol.conicet - Rosario. Instituto de Biologia Molecular y Celular de Rosario;Fil: Daurelio, Lucas Damian. Consejo Nacional de Invest.cientif.y Tecnicas. Centro Cientifico Tecnol.conicet - Rosario. Instituto de Biologia Molecular y Celular de Rosario;Fil: Tondo, Maria Laura. Consejo Nacional de Invest.cientif.y Tecnicas. Centro Cientifico Tecnol.conicet - Rosario. Instituto de Biologia Molecular y Celular de Rosario;Fil: Merelo, Paz. INSTITUT VALENCIÀ D'INVESTIGACIONS AGRÀRIES (IVIA);Fil: Cortadi, Adriana Amalia. Consejo Nacional de Invest.cientif.y Tecnicas. Centro Cientifico Tecnol.conicet - Rosario. Instituto de Biologia Molecular y Celular de Rosario;Fil: Talón, Manuel. INSTITUT VALENCIÀ D'INVESTIGACIONS AGRÀRIES (IVIA);Fil: Tadeo, Francisco R.. INSTITUT VALENCIÀ D'INVESTIGACIONS AGRÀRIES (IVIA);Fil: Orellano, Elena Graciela. Consejo Nacional de Invest.cientif.y Tecnicas. Centro Cientifico Tecnol.conicet - Rosario. Instituto de Biologia Molecular y Celular de Rosario

A plant natriuretic peptide-like molecule of the pathogen Xanthomonas axonopodis pv. citri causes rapid changes in the proteome of its citrus host

<p>Abstract</p> <p>Background</p> <p>Plant natriuretic peptides (PNPs) belong to a novel class of peptidic signaling molecules that share some structural similarity to the N-terminal domain of expansins and affect physiological processes such as water and ion homeostasis at nano-molar concentrations. The citrus pathogen Xanthomonas axonopodis pv. citri possesses a PNP-like peptide (XacPNP) uniquely present in this bacteria. Previously we observed that the expression of <it>XacPNP </it>is induced upon infection and that lesions produced in leaves infected with a XacPNP deletion mutant were more necrotic and lead to earlier bacterial cell death, suggesting that the plant-like bacterial PNP enables the plant pathogen to modify host responses in order to create conditions favorable to its own survival.</p> <p>Results</p> <p>Here we measured chlorophyll fluorescence parameters and water potential of citrus leaves infiltrated with recombinant purified XacPNP and demonstrate that the peptide improves the physiological conditions of the tissue. Importantly, the proteomic analysis revealed that these responses are mirrored by rapid changes in the host proteome that include the up-regulation of Rubisco activase, ATP synthase CF1 α subunit, maturase K, and α- and β-tubulin.</p> <p>Conclusions</p> <p>We demonstrate that XacPNP induces changes in host photosynthesis at the level of protein expression and in photosynthetic efficiency in particular. Our findings suggest that the biotrophic pathogen can use the plant-like hormone to modulate the host cellular environment and in particular host metabolism and that such modulations weaken host defence.</p