Ross G.R.,National University of Tucuman |
Ross G.R.,CONICET |
Gusils C.,Estacion Experimental Agroindustrial Obispo Colombres. |
Oliszewski R.,CONICET |
And 3 more authors.
Journal of Bioscience and Bioengineering | Year: 2010
In the present work we evaluated the effects of probiotic strains administration in pigs. On the 35th day of age, 30 pigs were distributed into 2 groups: the non-treated control group (initial average BW: 8.3 ± 0.6 kg) and a probiotic supplemented fed group (initial average BW: 8.7 ± 0.4 kg). Each experimental group was fed ad libitum on a commercial diet with free access to tap water for 35 days. A mixed probiotic culture (108 CFU/ml) was orally delivered, every day, to the animals of the probiotic supplemented fed group. Body weight (BW), feed intake (FI), efficiency (BW: Feed), and faecal microflora, were studied before and throughout the experimental trial. At the end of the fifth week, 5 animals of each dietary treatment were slaughtered and intestinal samples were taken for histology. The results obtained showed that the group receiving probiotic bacteria exhibited lower FI values and better efficiency than control group (P ≤ 0.05), but mean final BW values were not significantly different. Only significant changes (P ≤ 0.05) were found in enterobacteria population between control and probiotic supplemented fed group during the experimental period. By histological techniques it was observed that the treatment group has intestinal morphological structures more preserved than control group. These results suggest that probiotic bacteria administrated in this study could be used widespread as a way to improve growth performance parameters of animals avoiding the use of antibiotics as growth-promoting factors. © 2009 The Society for Biotechnology, Japan.
Malamud F.,CONICET |
Conforte V.P.,CONICET |
Rigano L.A.,CONICET |
Castagnaro A.P.,Estacion Experimental Agroindustrial Obispo Colombres |
And 2 more authors.
Molecular Plant Pathology | Year: 2012
Xanthomonas citri ssp. citri (Xcc) is the causal agent of citrus canker. This bacterium develops a characteristic biofilm on both biotic and abiotic surfaces. A biofilm-deficient mutant was identified in a screening of a transposon mutagenesis library of the Xcc 306 strain constructed using the commercial Tn5 transposon EZ-Tn5
Will A.,National University of Tucuman |
Bustos J.,National University of Tucuman |
Bocco M.,National University of Cordoba |
Gotay J.,National University of Tucuman |
Lamelas C.,Estacion Experimental Agroindustrial Obispo Colombres
Renewable Energy | Year: 2013
Prediction of climatic variables, in particular those related to wind and solar radiation, has developed a huge interest in recent years, mainly due to its applications to renewable energy. In many cases there is a large number of factors that influence the climatic variable of interest, and the researcher chooses the most relevant ones (based on previous knowledge of the region, availability, etc.) and runs a series of experiments combining the available data in order to find the combination that provides the best prediction.In this work we present two applications of Niching Genetic Algorithms to solve the problem of selection of variables for the estimation of Solar Radiation. On one hand, this methodology is able to estimate a given climatic variable using databases with missing data, since the algorithm can compensate it by the use of others. On the other hand, we present a methodology that allows us to select the relevant input variables for a given climatic variable estimation or prediction problem, in a systematic way, using the same Genetic Algorithm with different parameters.Both methods were tested in the estimation of daily Global Solar Radiation in El Colmenar (Tucumán, Argentina), using linear regression on data from 14 weather stations spread along the north of Argentina. The results obtained show that the methodology is appropriate, providing an RMSE = 2.36 [MJ/m 2] and R = 0.926 using an average of 64 out of 329 initial variables, on a 70 individuals/85 generations combination. For a 200 individuals/150 generations combination it obtained an RMSE = 2.34 [MJ/m 2] and R = 0.928 using an average of 54 variables. © 2012 Elsevier Ltd.
PubMed | University of Santiago de Chile, Estacion Experimental Agroindustrial Obispo Colombres, Cairo University and University of California at Davis
Type: Journal Article | Journal: Pest management science | Year: 2015
Echinochloa colona is an annual weed affecting field crops and orchards in California. An E. colona population carrying a mutation in the EPSPS gene endowing resistance to glyphosate, the most widely used non-selective herbicide, was recently identified in the Northern Sacramento Valley of California. Plants from this population, from a suspected glyphosate-resistant (GR) population, and from one susceptible (S) population collected in the Northern Sacramento Valley of California, were used to generate three GR and one S selfed lines to study possible mechanisms involved in glyphosate resistance.Based on the amount of glyphosate required to kill 50% of the plants (LD50 ), GR lines were 4-9-fold more resistant than S plants and accumulated less shikimate after glyphosate treatment. GR and S lines did not differ in glyphosate absorption, translocation or metabolism. A different target-site mutation was found in each of two of the GR lines corresponding to Pro106Thr and Pro106Ser substitutions; the mutations were found in different homoeologous EPSPS genes. No mutation was found in the third GR line, which exhibited 1.4-fold higher basal EPSPS activity and a fivefold greater LD50 than S plants. Quantitative RT-PCR revealed that GR lines had similar or lower EPSPS expression than S plants.It is demonstrated that individuals with different glyphosate resistance mechanisms can coexist in the same population, individuals from different populations may carry different resistance mechanisms and different mechanisms can act in concert within single E. colona plants. However, other plant factors or resistance mechanisms appear to modulate plant expression of EPSPS sensitivity to glyphosate.
PubMed | CONICET and Estacion Experimental Agroindustrial Obispo Colombres
Type: Journal Article | Journal: Bulletin of entomological research | Year: 2015
Studies on insect natural enemies and their effects on host populations are of immense practical value in pest management. Predation and parasitism on a citrus pest, the leafminer Phyllocnistis citrella Stainton, were evaluated by sampling over 3 years in four locations within a world leading lemon producing area in Northwest Argentina. Both mortality factors showed seasonal trends consistent across locations, with predation exerting earlier and more sustained pressure than parasitism, which showed wider seasonal variations. The dominant parasitoids, native Cirrospilus neotropicus and introduced Ageniaspis citricola, showed different seasonal trends: C. neotropicus was dominant in spring whereas A. citricola superseded it in autumn and winter. Although parasitism rates were relatively low, the native C. neotropicus revealed favourable features as potential control agent, by showing density-dependence, parasitism rates comparable with those of the specific A. citricola during part of the cycle, and earlier synchronization with the host. The study provides highly relevant information for a sustainable management of this worldwide pest, for which biological control is considered the best long-term option.
PubMed | CONICET, University College Cork, National University of Rosario and Estacion Experimental Agroindustrial Obispo Colombres
Type: Journal Article | Journal: Environmental microbiology | Year: 2015
Xanthomonas citri subsp. citri (Xcc) is the causal agent of citrus canker. Biofilm formation on citrus leaves plays an important role in epiphytic survival of Xcc. Biofilm formation is affected by transposon insertion in XAC3733, which encodes a transcriptional activator of the NtrC family, not linked to a gene encoding a sensor protein, thus could be considered as an orphan regulator whose function is poorly understood in Xanthomonas spp. Here we show that mutation of XAC3733 (named xbmR) resulted in impaired structural development of the Xcc biofilm, loss of chemotaxis and reduced virulence in grapefruit plants. All defective phenotypes were restored to wild-type levels by the introduction of PA2567 from Pseudomonas aeruginosa, which encodes a phosphodiesterase active in the degradation of cyclic diguanosine monophosphate (c-di-GMP). A knockout of xbmR led to a substantial downregulation of fliA that encodes a (28) transcription factor, as well as fliC and XAC0350 which are potential member of the (28) regulon. XAC0350 encodes an HD-GYP domain c-di-GMP phosphodiesterase. These findings suggest that XbmR is a key regulator of flagellar-dependent motility and chemotaxis exerting its action through a regulatory pathway that involves FliA and c-di-GMP.
Alarcon-Reverte R.,University of California |
Garcia A.,University of California |
Watson S.B.,U.S. Department of Agriculture |
Abdallah I.,Cairo University |
And 4 more authors.
Pest Management Science | Year: 2015
BACKGROUND: Echinochloa colona is an annual weed affecting field crops and orchards in California. An E. colona population carrying a mutation in the EPSPS gene endowing resistance to glyphosate, the most widely used non-selective herbicide, was recently identified in the Northern Sacramento Valley of California. Plants from this population, from a suspected glyphosate-resistant (GR) population, and from one susceptible (S) population collected in the Northern Sacramento Valley of California, were used to generate three GR and one S selfed lines to study possible mechanisms involved in glyphosate resistance. RESULTS: Based on the amount of glyphosate required to kill 50% of the plants (LD50), GR lines were 4-9-fold more resistant than S plants and accumulated less shikimate after glyphosate treatment. GR and S lines did not differ in glyphosate absorption, translocation or metabolism. A different target-site mutation was found in each of two of the GR lines corresponding to Pro106Thr and Pro106Ser substitutions; the mutations were found in different homoeologous EPSPS genes. No mutation was found in the third GR line, which exhibited 1.4-fold higher basal EPSPS activity and a fivefold greater LD50 than S plants. Quantitative RT-PCR revealed that GR lines had similar or lower EPSPS expression than S plants. CONCLUSION: It is demonstrated that individuals with different glyphosate resistance mechanisms can coexist in the same population, individuals from different populations may carry different resistance mechanisms and different mechanisms can act in concert within single E. colona plants. However, other plant factors or resistance mechanisms appear to modulate plant expression of EPSPS sensitivity to glyphosate. © 2015 Society of Chemical Industry.
Nagoshi R.N.,U.S. Department of Agriculture |
Gabriela Murua M.,Estacion Experimental Agroindustrial Obispo Colombres |
Gabriela Murua M.,CONICET |
Hay-Roe M.,U.S. Department of Agriculture |
And 3 more authors.
Journal of Economic Entomology | Year: 2012
Fall armyworm is a major economic pest throughout the Western Hemisphere. Previous studies of populations in the southern United States, Brazil, and the Caribbean demonstrated the existence of two morphologically identical but genetically distinct host strains that can only be distinguished using genetic markers, including polymorphisms in the mitochondrial Cytochrome Oxidase I (COI) gene and in the Z-chromosome linked Triose phosphate isomerase (Tpi) gene. The strains differ in some physiological and behavioral characteristics, most notably their preference for different plant hosts, but are capable of hybridizing in the laboratory and in the field. These traits suggest that the strains are in the process of divergence, which may or may not be hemispheric in scope. The objective of this study was to determine whether the two strains are present in Argentina. It was found that the strain-diagnostic haplotypes of the COI and Tpi genes subdivided the Argentina population into two major groups. Each group displayed biases in their distribution among different host plants that were generally consistent with expected strain behavior. The overall results indicated that Argentina fall armyworm exhibit similar genetics and behavior to populations in the rest of the hemisphere. In addition, the Argentina populations had comparable haplotype frequencies to those from Brazil and Texas, consistent with possible interactions with these fall armyworm groups, but appeared to have had minimal exchanges with those from Puerto Rico or Florida. © 2012 Entomological Society of America.
Sorol N.,Estacion Experimental Agroindustrial Obispo Colombres |
Arancibia E.,National University of Tucuman |
Bortolato S.A.,National University of Rosario |
Olivieri A.C.,National University of Rosario
Chemometrics and Intelligent Laboratory Systems | Year: 2010
Several variable selection algorithms were applied in order to sort informative wavelengths for building a partial least-squares (PLS) model relating visible/near infrared spectra to Brix degrees in samples of sugar cane juice. Two types of selection methods were explored. A first group was based on the PLS regression coefficients, such as the selection of coefficients significantly larger than their uncertainties, the estimation of the variable importance in projection (VIP), and uninformative variable elimination (UVE). The second group involves minimum error searches conducted through interval PLS (i-PLS), variable-size moving-window (VS-MW), genetic algorithms (GA) and particle swarm optimization (PSO). The best results were obtained using the latter two methodologies, both based on applications of natural computation. The results furnished by inspection of the spectrum of regression coefficients may be dangerous, in general, for selecting informative variables. This important fact has been confirmed by analysis of a set of simulated data mimicking the experimental sugar cane juice spectra. © 2010 Elsevier B.V.
Jaureguy L.M.,University of Arkansas |
Ledesma Rodriguez F.,Estacion Experimental Agroindustrial Obispo Colombres |
Zhang L.,University of Arkansas |
Chen P.,University of Arkansas |
And 4 more authors.
Crop Science | Year: 2013
Information on crop management practices that may help maximize farm profit is valuable. Because planting date determines the environment to which the crop is exposed during the growing season, it can also have a significant impact on seed composition. In this study, the effects of planting date on seed organic and inorganic composition were investigated using eight specialty soybean [Glycine max (L.) Merr.] breeding lines with modified seed composition (high protein, high oil, high oleic acid, low linolenic acid, low saturated fatty acids, high inorganic phosphorus-low stachyose) grown at two Arkansas locations for 2 yr. The effects of delayed harvest on seed composition were also studied in one of the planting dates. Early planting increased seed protein, oleic acid, and inorganic components and decreased linolenic acid concentrations, whereas late planting increased sucrose but did not affect stachyose concentrations. Production of soybeans with high-protein, high-quality oil should be performed in earlyplanting production systems, whereas planting high-sugar, food-grade cultivars late in the season should fit well in a double-crop system. Delayed harvest had effects on both organic and inorganic seed components. Seed constituents exhibited lower concentration in soybeans that experienced delayed harvest. These research findings may help enhance recommendations to farmers to adjust planting and harvest practices and consequently meet market requirements for specialty soybeans. © © Crop Science Society of America All rights reserved.