Influence of pH and calcium on the growth,polysaccharide production and symbiotic association of<Emphasis Type="Italic"> Sinorhizobium meliloti</Emphasis> SEMIA 116 with alfalfa roots

The Sinorhizobium -legume interaction is sensitive to a number of environmental factors, soil acidity being one of the most important. In the typic Hapludoll soil of the central-southern region of Córdoba (Argentine) it was found that the nodulation of alfalfa ( Medicago sativaL.) roots was impaired with a reduction in shoot dry matter under conditions of soil acidity (pH 5.5) Our results showed that the addition of lime as dolomitic limestone at a concentration of 1 t ha ^-1to acid soil caused a significant increase in the nodulation of alfalfa roots inoculated with the strain Sinorhizobium meliloti SEMIA 116 (recommended inoculum for alfalfa) in the greenhouse experiments. The success of the lime treatment may be related not only to an increase in the pH values but also to an increase in the Ca concentration, improving the growth of S. meliloti and its nodulation ability under acidic conditions. In this study, we also demonstrated an increment in the bacterial growth rate as well as in the production of exopolysaccharides and lipopolysaccharides under low pH (5.5) and a high Ca concentration (5 mM) in the culture medium.     

Resistance to yellow rust in Triticum dicoccoides. II. Crosses with resistant Triticum dicoccoides sel. G-25

A comparison was made between the genes in 29 new selections of wild emmer wheat resistant to yellow rust over wide geographic areas and the previously extensively studied selectionTriticum dicoccoides G-25. In 23 selections the resistance may be conferred by 1 dominant gene; these include 11 selections in which the gene is different from the dominant gene in sel. G-25 and two others in which the genes were closely linked or allelic to the gene in G-25, differing from sel. G-25 by race-specificity. Two dominant genes different from the gene in sel. G-25, seem to be present in one selection. In five selections the resistance may be conferred by one or two recessive genes, including three instances in which the recessive gene was associated with a dominat gene. Our findings show that at least 19 out of the 29 selections studied possess genes which are different from the gene inT. dicoccoides sel. G-25.Samenvatting In dit onderzoek werden 29 nieuwe resistente wilde-emmer selecties (Triticum dicoccoides) gekruist met de reeds uitvoerig bestudeerde resistente selectie G-25, om na te gaan of de resistentie van de nieuwe selecties wordt veroorzaakt door genen op dezelfde locus als het dominante gen in sel. G-25 of dat er andere loci bij zijn betrokken. De ouders, de F₁-en F₂-populaties van een bepaalade selectie werden in het kiemplantstadium getoetst met één Israëlisch gele-roest isolaat van fysio 2E0 of van fysio 2E18. In de uitsplitsende F₂-populaties werden de niet-sporulerende planten als resistent beschouwd en de sporulerende als vatbaar.In de F₂-populaties van 12 herkomsten werden geen vatbare planten gevonden, hetgeen er op duidt dat de resistentie wordt veroorzaakt door een gen op dezelfde locus als het gen in G-25 of door een gen dat neuw gekoppeld is aan het gen in G-25. Voor twee van deze herkomsten kan op basis van een fysio-specifieke interactie worden vastgesteld dat de resistentie berust op allelen die verschillen van het allel in sel. G-25. In 11 herkomsten werd een uitsplitsing voor twee dominante gene gevonden (RS=151), waarbij het tweede dominante gen uit de getoetste nieuwe selectie afkomstig is. De aanwezigheid van twee dominante genen verschillend van het gen in sel. G-25 werd gevonden in één herkomst (631). In de overige vijf selecties bleek de resistentie te worden veroorzaakt door één of twee recessieve genen waarnaast in drie gevallen ook nog een dominant gen werd gevonden.De resultaten tonen aan dat tenminste 19 van de 29 bestudeerde selecties resistentiegenen bezitten die verschillen van het gen inT. dicoccoides sel. G-25. Slechts in twee van deze selecties kan het gen allel zijn met het gen in sel. G-25.     

Nitrate Reductase,Micronutrients and Upland Rice Development as Influenced by Soil pH and Nitrogen Sources

The average yield of upland rice under no-tillage system (NTS), a sustainable soil management, is lower than in conventional tillage (one plowing and two disking). One of the reasons given for this drop in crop grain yield would be the low-nitrate assimilation capacity of rice seedlings, due to the low activity of the nitrate reductase (NR) enzyme in the early development phase. A greenhouse experiment was conducted to evaluate the effects of the soil acidic and nitrogen source in the micronutrient concentrations, NR activity and grain yield of upland rice growing under NTS. The soil used in the experiment was an Oxisol. The experimental design was completely randomized in a factorial 3 × 4. Treatments consisted of three levels of soil acidity (high, medium, and low) combined with four nitrogen sources (nitrate, ammonium, ammonium + nitrification inhibitor, and control – without N fertilization). The reduction of soil acidity reduced the concentration of zinc and manganese in rice plants. Generally, the activity of the NR enzyme was higher in plants grown in soils with low acidity and fertilized with calcium nitrate. There was a greater response in growth and yield in rice plants grown in soils with high acidity. Under medium acidity, rice plants grown with ammonium sulfate were more productive (no differences were detected with the addition of the nitrification inhibitor).     

Inhibition of inducible nitric oxide synthase expression by an acetonic extract from Feijoa sellowiana Berg. fruits

Feijoa sellowiana Berg. fruits and especially the acetonic extract have been shown to possess biological activities, although the responsible compounds have never been identified. The present study was designed to evaluate the anti-inflammatory activity of an acetonic extract from F. sellowiana Berg. fruits on the nitric oxide (NO) pathway, which plays an important role in inflammation. To this aim the J774 cell line, which expresses inducible nitric oxide synthase (iNOS) following stimulation with lipopolysaccharide (LPS), has been utilized, and the effects of this extract and its fractions on NO production, iNOS protein expression, and signal pathways involved in its regulation have been evaluated. This study demonstrates that at least some part of the anti-inflammatory activity of the acetonic extract is due to the suppression of NO production by flavone and stearic acid. The mechanism of this inhibition seems to be related to an action on the expression of the enzyme iNOS through the attenuation of nuclear factor kappaB (NF-kappaB) and/or mitogen-activated protein kinase (MAPK) activation.     

Evaluating Binary Sorption of Phenol/Aniline fromAqueous Solutions onto Granular Activated Carbon and Hypercrosslinked Polymeric Resin (MN200)

Sorption equilibrium of phenol and aniline onto the granular activated carbon and hyperreticulated un-functionalized polymeric resin (MN200) was investigated in single and binary component aqueous systems. Higher loading was obtained for aniline than phenol onto both sorbents, which is probably due to hydrophobic difference between both solutes and the greater electronic density of the aromatic ring of the aniline. Granular activated carbon reported larger uptake than resin MN200 for both solutes, which may be attributed to the better physical properties of the granular activated carbon, for instance, larger surface area. The experimental sorption could be properly described by the Langmuir and Freundlich isotherms. Five models for predicting the binary equilibrium sorption isotherm were compared in order to determine the best fit model to correlate binary experimental data: the extended Langmuir isotherm with and without a constant interaction factor, a simplified model based on the single equilibrium factors, the empirical extended Freundlich isotherm and the modified extended Langmuir equation, which considers the synergistic interactions between sorbate–sorbate and not only the competition between them defined by the extended Langmuir model. The modified extended Langmuir model provides the best agreement between predicted and experimental data indicating that the synergistic interactions between solutes play an important role in the binary phenol/aniline sorption system.     

Rhizobia phylogenetically related to common bean symbionts Rhizobium giardinii and Rhizobium tropici isolated from peanut nodules in Central Argentina

Our previous studies of the native rhizobial population associated with peanut nodules in the Córdoba soils of Argentina revealed that this population is highly diverse and includes slow- and fast-growing isolates. The native fast-growing isolates NCHA22 and NET30 were selected on the basis of their plant growth promoting properties and their chromosomal genotypes were determined by 16S rDNA sequencing. NCHA22 and NET30 16S rDNA alleles were found to cluster with those of Rhizobium tropici group IIB and Rhizobium giardinii bv. giardinii strain H152, respectively. We have now characterized these isolates by analyzing the glnA and nifH genes to clarify their taxonomic position. These studies confirmed that fast-growing isolates belonging to species earlier described as bean symbionts were obtained from nodules of a leguminous plant that has been described as efficiently nodulated exclusively by slow-growing rhizobial strains.     

Evaluation of 2-alkylcyclobutanones in irradiated cured pork products during vacuum-packed storage

The 2-Alkylcyclobutanones (2-ACBs) content was determined in three Italian cured pork products (salame Milano, coppa, and pancetta) irradiated at different targeted irradiation doses (2, 5, and 8 kGy) during vacuum-packed storage. Among 2-ACBs, three different compounds were investigated, namely, 2-dodecylcyclobutanone, 2-tetradecylcyclobutanone, and 2-(tetradec-5'-enyl)cyclobutanone. 2-ACBs were absent from the nonirradiated samples, whereas their content increased with irradiation dose. Their presence was recorded occasionally at 2 kGy and constantly at higher irradiation doses (5 and 8 kGy). The plot of 2-ACBs content against targeted irradiation doses showed an exponential relationship. The effect of vacuum-packed storage time on the 2-ACBs content was dependent on the irradiation dose. During vacuum-packed storage for up to 60 days, the 2-ACBs content remained unchanged in the cured pork products irradiated at 2 and 5 kGy, whereas a significant increase was observed in the pork products irradiated at 8 kGy.     

Determination of anthocyanins from camu-camu (Myrciaria dubia) by HPLC-PDA, HPLC-MS, and NMR

Camu-camu [Myrciaria dubia (HBK) McVaugh] is a small fruit native to the Amazonian rain forest. Its anthocyanin profile has now been investigated for the first time. Fruits from two different regions of the S?o Paulo state, Brazil, were analyzed. The major anthocyanins were isolated by high-speed countercurrent chromatography. HPLC-PDA, HPLC-MS/MS, and 1H NMR were used to confirm the identity of the main anthocyanins of camu-camu. Cyanidin-3-glucoside was identified as the major pigment in the fruits from both regions, representing 89.5% in the fruits produced in Iguape and 88.0% in those from Mirandópolis, followed by the delphinidin-3-glucoside, ranging between 4.2 and 5.1%, respectively. Higher total anthocyanin contents were detected in the fruits from Iguape (54.0 +/- 25.9 mg/100 g) compared to those from Mirandópolis (30.3 +/- 6.8 mg/100 g), most likely because of the lower temperatures in the Iguape region.     

Antibacterial activity of coffee extracts and selected coffee chemical compounds against enterobacteria

The in vitro antimicrobial activity of commercial coffee extracts and chemical compounds was investigated on nine strains of enterobacteria. The antimicrobial activity investigated by the disc diffusion method was observed in both the extracts and tested chemical compounds. Even though pH, color, and the contents of trigonelline, caffeine, and chlorogenic acids differed significantly among the coffee extracts, no significant differences were observed in their antimicrobial activity. Caffeic acid and trigonelline showed similar inhibitory effect against the growth of the microorganisms. Caffeine, chlorogenic acid, and protocatechuic acid showed particularly strong effect against Serratia marcescens and Enterobacter cloacae. The IC(50) and IC(90) for the compounds determined by the microtiter plate method indicated that trigonelline, caffeine, and protocatechuic acids are potential natural antimicrobial agents against Salmonella enterica. The concentrations of caffeine found in coffee extracts are enough to warrant 50% of the antimicrobial effect against S. enterica, which is relevant to human safety.     

<Emphasis Type="Italic">Achromobacter insolitus</Emphasis> and <Emphasis Type="Italic">Zoogloea ramigera</Emphasis> associated with wheat plants (<Emphasis Type="Italic">Triticum aestivum</Emphasis>)

This study reports for the first time the presence of diazotrophic bacteria belonging to the genera Achromobacter and Zoogloea associated with wheat plants. These bacterial strains were identified by the analysis of 16S rDNA sequences. The bacterium IAC-AT-8 was identified as Azospirillum brasiliense, whereas isolates IAC-HT-11 and IAC-HT-12 were identified as Achromobacter insolitus and Zoogloea ramigera, respectively. A greenhouse experiment involving a non-sterilized soil was carried out with the aim to study the endophytic feature of these strains. After 40 days from inoculation, all the strains were in the inner of roots, but they were not detected in soil. In order to assess the location inside wheat plants, an experiment was conducted under axenic conditions. Fifteen days after inoculation, preparations of inoculated plants were observed by the scanning electron microscope, using the cryofracture technique, and by the transmission electron microscope. It was observed that all isolates were present on the external part of the roots and in the inner part at the elongation region, in cortex cells, but not in the endodermis or in the vascular bundle region. No colonizing bacterial cells were observed in wheat leaves.