Physiological and Anatomical Basis of Differential Tolerance to Soil Flooding of Lotus corniculatus L. and Lotus glaber Mill

Lotus corniculatus L. and Lotus glaber Mill. are warm-season legume species adapted to many kinds of environmental stress, including flooding conditions, whereas other popular forage legumes, like alfalfa or white clover, cannot thrive. This study evaluates the relationship between root aerenchyma, water relations and leaf gas exchange and the differential tolerance to soil flooding of L. corniculatus and L. glaber. Adult plants of these species, established independently in grasslands mesocosms, were subjected to 40 days of early spring flooding at a water depth of 6 cm. Both species presented constitutive aerenchyma tissue in the roots. Under flooding conditions, this parameter was 26.2% in L. glaber and 15.3% in L. corniculatus. In addition, flooded plants of L. glaber presented a leaf biomass 47.5% higher above water while L. corniculatus showed a leaf biomass 59.6% lower in the same layer, in comparison to control plants. Flooded plants of L. glaber maintained the stomatal conductance (g _s) and transpiration rate (E) for 25 days, although these parameters reduce slightly to 40–60% in comparison to controls after 40 days of flooding. In this species, a reduction in photosynthesis (A) in flooding conditions was detected only on the last day of measurement. In L. corniculatus, the same parameters (g _s, E and A) were affected by flooding since day 18 of treatment, and values reached 25–40% in comparison to control plants after 40 days of flooding. Flooding did not affect above-ground biomass in L. glaber; while in L. corniculatus, above-ground biomass was 35% lower than in control plants. Our results confirmed that L. glaber is more able to cope with flooding stress than L. corniculatus, even in the presence of natural competitors. On the whole, this experiment provides information that can aid in the identification of anatomical and physiological parameters associated with flood-tolerance in this forage legume species, with economic potential for the agricultural areas subject to periodic flooding.     

An improved method to identify BAC clones using pooled overgos

Hybridization using overgo probes is an established approach for screening arrayed bacterial artificial chromosome (BAC) libraries. We have improved the use of overgos by increasing the yield of positive clones using reduced levels of radioisotopes and enzyme. The strategy involves labeling with all four radiolabeled nucleotides in a hot pulse followed by a cold nucleotide chase and then extending the exposure time to compensate for reduced specific activity of the probes. The resulting cost savings and reduced human exposure to radiation make the use of highly pooled overgo probes a more attractive approach for screening of BAC libraries from organisms with large genomes.     

Pilot Field Trial of the EG95 Vaccine Against Ovine Cystic Echinococcosis in Rio Negro,Argentina: Second Study of Impact

Background

Cystic echinococcosis (CE) is an important zoonotic disease caused by the cestode parasite Echinococcus granulosus. It occurs in many parts of the world where pastoral activities predominate, including the Rio Negro province of Argentina. Although CE control activities have been undertaken in the western regions of Rio Negro for more than two decades, the disease continues to remain prevalent in both the human and livestock animal populations. Vaccination of animal intermediate hosts of CE with the EG95 vaccine may provide a new opportunity to improve the effectiveness of CE control measures, although data are lacking about field application of the vaccine.

Aims

Evaluate the impact of EG95 vaccination in sheep on the transmission of Echinococcus granulosus in a field environment.

Methodology

Two trial sites were established in western Rio Negro province within indigenous communities. Vaccination of lambs born into one trial site was introduced and continued for 6 years. Prior to initiation of the trial, and at the end of the trial, the prevalence of CE in sheep was determined by necropsy. Weaned lambs received two injections of EG95 vaccine, approximately one month apart, and a single booster injection one year later. Vaccination was not implemented at the second trial site. A total of 2725 animals were vaccinated in the first year. Animals from this cohort as well as age-matched sheep from the control area were evaluated by necropsy.

Key results

Introduction of the vaccine led to a statistically significant in the number and size of hydatid cysts in comparison to the situation prior to the introduction of the vaccine, or compared to CE prevalence in the control area where the vaccine was not applied. The prevalence of infection in the vaccinated area was also significantly reduced by 62% compared to the re-intervention level, being lower than the prevalence seen in the control area, although the difference from the control area after the intervention was not significant possibly due to limitations in the numbers of animals available for necropsy.

Conclusions

Vaccination of sheep with the EG95 vaccine provides a valuable new tool which improves the effectiveness of CE control activities. Vaccination was effective even in a difficult, remote environment where only approximately half the lambs born into the communities were fully vaccinated.     

Hybridization increases canopy arthropod diversity in the <Emphasis Type="Italic">Quercus affinis</Emphasis> × <Emphasis Type="Italic">Quercus laurina</Emphasis> complex

Understanding the factors that influence the diversity and composition of arthropod communities is a major topic in ecology. Canopy arthropod communities are a major constituent of biodiversity and show great variation in time and space according to different factors. Recently, genetic variation within tree species has attracted attention as a significant factor determining the diversity and composition of canopy arthropod communities. A major source of genetic and phenotypic novelty in plant species is interspecific hybridization, and therefore it is of interest to evaluate how this process affects the communities of associated organisms. In this study, we used microsatellite markers and geometric morphometry of leaf shape to analyze genetic and morphological variation in 45 individuals in a local hybrid zone between the oaks Quercus affinis and Q. laurina in Mexico. Individual trees were assigned to one of the parental species or to the hybrid category. The percentage of leaf area removed by herbivores was quantified in each individual and the canopies of five individuals of each categeory (two parental species and hybrids) was fogged with insecticide to assess the diversity and composition of arthropod communities. Results indicated that hybrid trees experience higher levels of herbivory than parental species and also sustain a higher abundance and richness of canopy arthropods. In general, our study supports the “hybrid susceptibility hypothesis” that predicts a higher incidence of associated arthropods on hybrid plants than in their parental species as result of the disruption of co-adapted gene complexes associated to resistance traits.     

Volatile Composition and Biological Activities of the Leaf Essential Oil from Zanthoxylum limoncello Grown in Oaxaca,México

Zanthoxylum limoncello is a native plant from southern Mexico which is used as a timber source, condiment and as a traditional medicine. Herein, we report on the volatile content of the leaf essential oil and its biological activities. The annual essential oils (2015–2018) contained volatile organic compounds which exhibited a moderate growth inhibitory activity against H. pylori ATCC 53504 (MIC 121.4–139.7 μg mL^?1), 26695 (MIC 85.5–94.9 μg mL^?1) and J99 (MIC 94.7–110.4 μg mL^?1). These hydrodistillates contained 2‐undecanone (31.6–36.8 %; MIC 185.3–199.2 μg mL^?1) and 2‐undecenal (25.1–35.7 %; MIC 144.8–111.3 μg mL^?1) as the most abundant compounds which were partially involved in the anti‐H. pylori activity. The human ornithine decarboxylase enzyme (ODC1), which shows increased activity in several cancer types, was non‐competitively inhibited (V_max 2.7>0.8 K_cat s^?1) by the essential oil of Z. limoncello as well as by 2‐undecanone and 2‐undecenal in accordance to in vitro kinetic studies. In silico calculations strongly suggest that the carbonyl group of these oxygenated hydrocarbons interacts with both Asn319 and Ala39 at the subunit A of ODC1. Considering that Ala39 is located close to Asn44, a crucial amino acid of the ODC's allosteric site, the non‐competitive inhibition of the enzyme by 2‐undecanone and 2‐undecenal is endorsed. Finally, the essential oil of Z. limoncello and its main volatiles showed a significant (p<0.01) and prolonged repellent effect against Aedes aegypti.     

Effect of gelation temperature and gel-dissolving solution on cell viability and recovery of two Pseudomonas putida strains co-immobilized within calcium alginate or κ-carrageenan gel beads

Summary Since a lethal effect of an increased temperature (42°C) on Pseudomonas putida strains PaW8 and PaW130 was demonstrated, strictly ionotropic gels such as calcium alginate or -carrageenan type X 0909 were used for cell co-immobilization, rather than a thermoionotropic -carrageenan gel. Among the variety of gel-dissolving solutions tested, only a 0.05M Na₂CO₃/0.02M citric acid solution was able to preserve around 100 % of the cell viability. A complete cell recovery was obtained from calcium alginate gel beads, while only 6 % of viable cells was recovered from the ionotropic -carrageenan gel.     

13C NMR spectral analysis of lignans from Araucaria angustifolia

Pinoresinol dimethyl ether, secoisolariciresinol, lariciresinol, isolariciresinol and isolariciresinol-4′-methyl ether were isolated from the knots of dead trees of Araucaria angustifolia. The ¹³C NMR spectra of these compounds, their methyl and acetyl derivatives, and the corresponding one of matairesinol, have been recorded and the signals assigned. On the basis of these assignments, the structure of the new monomethyl ether of isolariciresinol has been established.     

Reduced capacity of Ca<Superscript>2+</Superscript> retention in liver as compared to kidney mitochondria. ADP requirement

Ca²⁺ loading in mitochondria promotes the opening of a non-selective transmembrane pathway. Permeability transition is also associated with the interaction of cyclophilin D at the internal surface of the non-specific transmembrane pore. This interaction is circumvented by cyclosporin A and ADP. Our results show that, in the absence of ADP, liver mitochondria were unable to retain Ca²⁺, they underwent a fast and large amplitude swelling, as well as a rapid collapse of the transmembrane potential. In contrast, in the absence of ADP, kidney mitochondria retained Ca²⁺, swelling did not occur, and the collapse of the membrane potential was delayed. Ca²⁺ efflux was reversed by the addition of ADP and cyclosporin A. Our findings indicate that the differences between liver and kidney mitochondria are due to the low association of cyclophilin D to the ADP/ATP carrier found in kidney mitochondria as compared to liver mitochondria.     

Triphenyltin as inductor of mitochondrial membrane permeability transition

The effect of triphenyltin on mitochondrial Ca²⁺ content was studied. It was found that this trialkyltin compound induces an increase in membrane permeability that leads to Ca²⁺ release, drop of the transmembrane potential, and efflux of matrix proteins. Interestingly, cyclosporin A was unable to inhibit triphenyltin-induced Ca²⁺ release. Based on these results it is proposed that the hyperpermeable state is produced by modification of 2.25 nmol of membrane thiol groups.