Polymerase chain reaction amplification of repetitive intergenic consensus and repetitive extragenic palindromic sequences for molecular typing of Pseudomonas anguilliseptica and Aeromonas salmonicida

The aim of this study was to evaluate the use of two molecular techniques, repetitive extragenic palindromic polymerase chain reaction (REP-PCR) and repetitive intergenic consensus PCR (ERIC-PCR), as epidemiological tools with which to discriminate among genetically distinct strains within two bacterial fish pathogens, Pseudomonas anguilliseptica and Aeromonas salmonicida. A total of 30 A. salmonicida and 52 P. anguilliseptica were analyzed. For P. anguilliseptica, three different major fingerprints were obtained with both techniques, which defined three genomic groups: one was composed of strains isolated from eels Anguilla spp., the second of strains from turbot Scophthalmus maximus and blackspot seabream (also known as red seabream) Pagellus bogaraveo, and the third of strains from other fish species, such as gilthead seabream (also known as gilthead bream) Sparus auratus, sea bass Dicentrarchus labrax (also known as European bass Morone labrax), and salmonids. In the case ofA. salmonicida, promising results were obtained with both techniques for subspecies differentiation. Thus, two genomic profiles were obtained by ERIC-PCR. The first profile consisted of A. salmonicida subsp. salmonicida strains isolated from the different hosts. The second profile was composed of two A. salmonicida subsp. masoucida and one A. salmonicida subsp. achromogenes. Using REP-PCR, three genotypes were obtained within this pathogen that were related to the diverse subspecies analyzed. In summary, both methodologies are useful for typing distinct strains associated with different host species and therefore are helpful in epidemiological studies of P. anguilliseptica. In contrast, in the case of A. salmonicida, more studies are needed to determine their utility in discriminating the subspecies salmonicida from the other two subspecies.     

Glutamine and glutamate levels and related metabolizing enzymes in tomato fruits with different shelf-life

Free amino acids composition and glutamate dehydrogenase (GDH) and glutamine synthetase (GS) levels were evaluated in fruits of Lycopersicon esculentum var. esculentum genotypes having standard (cv. Caimanta) and altered (nor and rin mutants) ripening characteristics. Two accessions of the wild L. esculentum var. cerasiforme (LA1385 and LA1673) were also assayed. Shelf-life (SL) of these fruits ranged from 12 (cv. Caimanta) to 36 (nor mutant) days. The relative glutamate content (as percentage of total free amino acid content) of ripe mature fruits differed considerably among lines, having cv. Caimanta and the nor mutant the highest and the lowest values, respectively. A negative correlation between the relative glutamate content and fruit SL was also found. In the standard ripening cv. Caimanta, GS was principally present in green mature fruits while GDH was found in ripe mature fruits. In the other lines, GS and GDH were detected at both maturation stages. Summarizing, standard SL correlates with higher relative glutamate content and reciprocal induction pattern of GS and GDH, while long SL is associated with lower relative glutamate content and simultaneous presence of both enzymes in the pericarp of tomato fruits. These data suggest that the regulation of the level of glutamate, GS and GDH during fruit ripening is related to the final SL of fruits.     

Elucidation of turnip yellows virus (TuYV) spectral reflectance pattern in Nicotiana benthamiana by non-imaging sensor technology

Journal of Plant Diseases and Protection - Turnip yellows virus (TuYV), belonging to the genus Polerovirus of the family Solemoviridae, is an aphid transmissible, pathogenic virus causing...     

Elicitor(s) production is involved in red-light-induced resistance during spore germination of <Emphasis Type="Italic">Bipolaris oryzae</Emphasis> in the presence of host tissues

In the present study, the effect of red light on the infection behavior of Bipolaris oryzae on rice leaves and the effects of chemical inhibitors and spore germination fluid (SGF) of B. oryzae on red-light-induced resistance against brown spot disease were investigated. Red light irradiation and natural light did not differ significantly with respect to their effect on spore germination and appressorium formation of B. oryzae 24 h after inoculation. However, formation of infection hyphae was significantly inhibited under red light compared to that under natural light. Pretreatment with the photosynthetic inhibitor 3-(3,4-dichorophenyl)-1,1-dimethylurea (DCMU) or with the aromatic amino acid inhibitor N-(phosphonomethyl) glycine (glyphosate) for 24 h inhibited the development of resistance in rice leaves. To elucidate the elicitor(s) produced during the B. oryzae–rice plant interaction, the effect of SGF prepared in the absence (A-SGF) or presence (P-SGF) of rice leaves on red-light-induced resistance was investigated. When rice plants were pretreated with A-SGF or P-SGF for 24 h, P-SGF had elicitor activity under red light, but not under natural light or with A-SGF. These results suggest that germinating spore of B. oryzae produced an elicitor(s) under red light conditions in a host-dependent manner. In conclusion, we hypothesize that an unidentified elicitor(s) produced at an early stage of fungal infection during the B. oryzae–rice interaction contributes to the inhibition of cell death in rice leaves under red light and enhances resistance-related tryptophan and phenylpropanoid pathways.     

Urban ants of the city of Buenos Aires,Argentina: species survey and practical control

ABSTRACT

Ants are among the most diverse, abundant and ecologically significant organisms on earth. They have colonized almost all existing habitats, including urban areas, where they may pose serious problems for human activities. Here, we present different aspects of our studies on urban ants in the city of Buenos Aires aimed at collecting information on the species present in the city and at improving bait control strategies via laboratory assays. The use of these baits represents a control strategy that is environment-friendly as it avoids indiscriminate pesticide release. Moreover, we show that our baits exhibit higher efficiency when compared to a commercial bait, as it is optimized in terms of the ants’ feeding behavior even when both have the same active compound and at the same concentration. This work represents the first integrative study on urban ants in the city of Buenos Aires and indicates that the control of invasive species in urban settings may be improved by increasing the scientific knowledge of the biology of the target species.     

Development of Laboratory Techniques to Mimic Industrial‐Scale Nixtamalization

A laboratory nixtamalization process was developed to imitate larger scale cooking/steeping conditions. Corn (45 kg) was cooked in a pilot plant gas‐fired cook/steep tank and temperature was monitored every 30 sec. Cooling and heating rates were mimicked in the laboratory using a digital temperature programmable hot plate that adjusted grain‐water‐lime temperature changes at a specified rate. A Response Surface Central Composite Design was used to model pasting and thermal properties of nixtamal and masa as a function of cooking temperature (86–96°C), cooking time (20–40 min), and steeping time (3–11.77 hr). Nixtamal and masa moisture, dry matter loss, nixtamal and masa RVA peak temperature, shear thinning, nixtamal peak viscosity, masa final viscosity, nixtamal and masa DSC enthalpy peak and end temperatures, and nixtamal onset temperature were explained by the same regression terms for results obtained using both processes conditions. The intercept and slopes of the fitted models for the pilot plant and laboratory responses were not significantly different (P < 0.05). The laboratory method can be used to mimic larger scale processing over a wide range of nixtamalization conditions.     

Soil‐less bioassays for early screening for resistance to imazapyr in sunflower (Helianthus annuus L.)

BACKGROUND: Rapid and efficient diagnostic tests for early screening of herbicide resistance are convenient alternatives to field screening methods. There is a need for a quick, reliable and cost‐effective method for rapid diagnosis of imidazolinone resistance in sunflower (Helianthus annuus L.). RESULTS: Two seed germination bioassays were developed. Seeds from three sunflower inbred lines differing in resistance to imidazolinones were germinated either on solid culture medium or placed in plastic pots filled with commercial perlite. After 8 days incubation under controlled conditions, both assays successfully distinguished susceptible genotype from the resistant and intermediate ones. The susceptible genotype showed arrested root growth at all herbicide treatments (root length < 1 cm). The resistant genotype developed a complete root system even when exposed to the highest dose of herbicide. However, no definite differences were observed for the intermediate and resistant genotypes with respect to root growth under the different herbicide treatments. CONCLUSION: The simple and rapid screening assays described in the present study were useful in discriminating imidazolinone resistance at the seedling stage. Therefore, these bioassays could be potential tools for early screening of imidazolinone resistance genes from large sunflower populations. Copyright © 2009 Society of Chemical Industry     

Interaction of a cationic acrylate polymer with caseins: biphasic effect of Eudragit E100 on the stability of casein micelles

When whole or skim milk was incubated with the cationic acrylate polymer Eudragit E100, a biphasic effect on the stability of casein micelles was observed. A precipitation phase was observed at low polymer/casein ratios. Strikingly, a solubilization phase of the aggregates was observed when the ratios of polymer/casein were increased. Purified alpha(s)-, beta-, and kappa-caseins or dephosphorylated caseins were equally precipitated and resolubilized by the cationic polymer, indicating no special selectivity for a particular protein or phosphate residue for these events. An increase in the size of the aggregates as the optimum precipitating amount of Eudragit E100 was reached suggests a crossbridging of the micelles by the polymer. The inhibition of the precipitation phase by high ionic strength indicates that electrostatic interactions play a critical role in complex formation. Furthermore, a dramatic reduction in size of the protein colloidal particles upon solubilization of the aggregates was observed by dynamic light scattering, indicating a dissociation of the micellar structure. Taken together, the results indicate that at low concentration Eudragit E100 may act as a precipitant of casein micelles, mainly by ionic interaction and at high concentration as an amphipathic agent, solubilizing casein micelles with a disruption of their internal structure.     

Breeding effects on sensitivity of barley grain weight and quality to events of high temperature during grain filling

Monogenic inheritance and linkage were established on the basis of F₁ observations and analysis of 13,498 plants in 42 crosses for leaf colour, 7046 plants in 27 crosses for plant pubescence, 1926 plants in 8 crosses for number of leaflets per leaf, and 3182 plants in 12 crosses for plant height under field conditions. Normal green colour of foliage was found to be dominant over light green, pubescent plant over glabrous, high number of leaflets per leaf over low number of leaflets, and tall plant over dwarf. Linkage was estimated from joint segregation analysis, taking two characters at a time in all possible combinations as significant χ² values were recorded for these genes. Gene symbols Gl, Pub, Ph, and Hl are proposed for these four traits, respectively. The genes are arranged in the order of Ph-Gl-Pub-Hl with the map distances of 21.1, 28.9, and 17.5 cM between them. This short sequence of four linked genes spanning over 37.2 cM has been called Linkage Group 2 of lentil.