Absorption,translocation and metabolism of aminocyclopyrachlor in young plants of Ipomoea purpurea and Ipomoea triloba

Members of the Convolvulaceae family are known to be sensitive to aminocyclopyrachlor, although little is known about the absorption, translocation and metabolism of the herbicide in these species of weed. The aim of this study was to evaluate the absorption, translocation and metabolism of ¹⁴C‐aminocyclopyrachlor in young plants of Ipomoea purpurea and Ipomoea triloba. Assessments were performed at 3, 6, 12, 24, 48 and 72 h after treatment (HAT) for the study of absorption and translocation. Metabolism was assessed at three time points (3, 24 and 72 HAT). In terms of absorption, was observed a difference between species at the 3 and 48 HAT time points, where I. purpurea had a higher absorption of ¹⁴C‐aminocyclopyrachlor. No differences were observed between species at any other time points. Of the total absorbed herbicide, 90.9% for I. purpurea and 91.8% for I. triloba were detected on the treated leaf. I. purpurea presented higher translocation to the leaf above the treated leaf, while I. triloba showed higher translocation to the lower leaves and roots. No increase in absorption of ¹⁴C‐aminocyclopyrachlor was observed above 24 HAT for I. purpurea and above 6 HAT for I. triloba, and translocation was low (<1%) for both species in all plant parts. This suggests that post‐emergence application of aminocyclopyrachlor cannot be effective for the control of I. purpurea and I. triloba and alternative approaches are required. Nevertheless, no ¹⁴C‐aminocyclopyrachlor metabolites were observed in the studied plants, which indicated sensitivity in I. purpurea and I. triloba to the herbicide.     

Structure Elucidation and Functional Studies of a Novel β-hairpin Antimicrobial Peptide from the Marine Polychaeta Capitella teleta

Endogenous antimicrobial peptides (AMPs) are evolutionary ancient molecular factors of innate immunity that play a key role in host defense. Among the most active and stable under physiological conditions AMPs are the peptides of animal origin that adopt a β-hairpin conformation stabilized by disulfide bridges. In this study, a novel BRICHOS-domain related AMP from the marine polychaeta Capitella teleta, named capitellacin, was produced as the recombinant analogue and investigated. The mature capitellacin exhibits high homology with the known β-hairpin AMP family—tachyplesins and polyphemusins from the horseshoe crabs. The β-hairpin structure of the recombinant capitellacin was proved by CD and NMR spectroscopy. In aqueous solution the peptide exists as monomeric right-handed twisted β-hairpin and its structure does not reveal significant amphipathicity. Moreover, the peptide retains this conformation in membrane environment and incorporates into lipid bilayer. Capitellacin exhibits a strong antimicrobial activity in vitro against a wide panel of bacteria including extensively drug-resistant strains. In contrast to other known β-hairpin AMPs, this peptide acts apparently via non-lytic mechanism at concentrations inhibiting bacterial growth. The molecular mechanism of the peptide antimicrobial action does not seem to be related to the inhibition of bacterial translation therefore other molecular targets may be assumed. The reduced cytotoxicity against human cells and high antibacterial cell selectivity as compared to tachyplesin-1 make it an attractive candidate compound for an anti-infective drug design.     

Mechanism of Action and Therapeutic Potential of the β-Hairpin Antimicrobial Peptide Capitellacin from the Marine Polychaeta Capitella teleta

Among the most potent and proteolytically resistant antimicrobial peptides (AMPs) of animal origin are molecules forming a β-hairpin structure stabilized by disulfide bonds. In this study, we investigated the mechanism of action and therapeutic potential of the β-hairpin AMP from the marine polychaeta Capitella teleta, named capitellacin. The peptide exhibits a low cytotoxicity toward mammalian cells and a pronounced activity against a wide range of bacterial pathogens including multi-resistant bacteria, but the mechanism of its antibacterial action is still obscure. In view of this, we obtained analogs of capitellacin and tachyplesin-inspired chimeric variants to identify amino acid residues important for biological activities. A low hydrophobicity of the β-turn region in capitellacin determines its modest membranotropic activity and slow membrane permeabilization. Electrochemical measurements in planar lipid bilayers mimicking the E. coli membrane were consistent with the detergent-like mechanism of action rather than with binding to a specific molecular target in the cell. The peptide did not induce bacterial resistance after a 21-day selection experiment, which also pointed at a membranotropic mechanism of action. We also found that capitellacin can both prevent E. coli biofilm formation and destroy preformed mature biofilms. The marked antibacterial and antibiofilm activity of capitellacin along with its moderate adverse effects on mammalian cells make this peptide a promising scaffold for the development of drugs for the treatment of chronic E. coli infections, in particular those caused by the formation of biofilms.     

Determination of microbial phenolic acids in human faeces by UPLC-ESI-TQ MS

The aim of the present work was to develop a reproducible, sensitive, and rapid UPLC-ESI-TQ MS analytical method for determination of microbial phenolic acids and other related compounds in faeces. A total of 47 phenolic compounds including hydroxyphenylpropionic, hydroxyphenylacetic, hydroxycinnamic, hydroxybenzoic, and hydroxymandelic acids and simple phenols were considered. To prepare an optimum pool standard solution, analytes were classified in 5 different groups with different starting concentrations according to their MS response. The developed UPLC method allowed a high resolution of the pool standard solution within an 18 min injection run time. The LOD of phenolic compounds ranged from 0.001 to 0.107 μg/mL and LOQ from 0.003 to 0.233 μg/mL. The method precision met acceptance criteria (<15% RSD) for all analytes, and accuracy was >80%. The method was applied to faecal samples collected before and after the intake of a flavan-3-ol supplement by a healthy volunteer. Both external and internal calibration methods were considered for quantification purposes, using 4-hydroxybenzoic-2,3,4,5-d4 acid as internal standard. For most analytes and samples, the level of microbial phenolic acids did not differ by using one or another calibration method. The results revealed an increase in protocatechuic, syringic, benzoic, p-coumaric, phenylpropionic, 3-hydroxyphenylacetic, and 3-hydroxyphenylpropionic acids, although differences due to the intake were only significant for the latter compound. In conclusion, the UPLC-DAD-ESI-TQ MS method developed is suitable for targeted analysis of microbial-derived phenolic metabolites in faecal samples from human intervention or in vitro fermentation studies, which requires high sensitivity and throughput.     

Occurrence of Lipophilic Marine Toxins in Shellfish from Galicia (NW of Spain) and Synergies among Them

Lipophilic marine toxins pose a serious threat for consumers and an enormous economic problem for shellfish producers. Synergistic interaction among toxins may play an important role in the toxicity of shellfish and consequently in human intoxications. In order to study the toxic profile of molluscs, sampled during toxic episodes occurring in different locations in Galicia in 2014, shellfish were analyzed by liquid chromatography tandem mass spectrometry (LC–MS/MS), the official method for the detection of lipophilic toxins. The performance of this procedure was demonstrated to be fit for purpose and was validated in house following European guidelines. The vast majority of toxins present in shellfish belonged to the okadaic acid (OA) group and some samples from a particular area contained yessotoxin (YTX). Since these toxins occur very often with other lipophilic toxins, we evaluated the potential interactions among them. A human neuroblastoma cell line was used to study the possible synergies of OA with other lipophilic toxins. Results show that combination of OA with dinophysistoxin 2 (DTX2) or YTX enhances the toxicity triggered by OA, decreasing cell viability and cell proliferation, depending on the toxin concentration and incubation time. The effects of other lipophilic toxins as 13-desmethyl Spirolide C were also evaluated in vitro.     

Foliar Iron Fertilization: A Critical Review

Application of foliar iron (Fe) sprays is a common means of correcting Fe deficiency of agricultural crops. However, variable plant responses to iron sprays, ranging from no effect to defoliation, have often been described in the Fe-fertilization literature. Knowledge is still limited concerning the mechanisms of penetration of a leaf-applied, Fe-containing solution and the role of Fe in the leaf. The complex and multi-disciplinary character of the factors determining the effects of Fe sprays hinder the development of suitable foliar fertilization strategies, applicable under variable local conditions and for different plant types. This review describes some key factors involved on the process of penetration of a leaf-applied, Fe-containing solution before briefly analyzing the available foliar Fe-fertilization literature. Iron chemistry, leaf penetration, and plant-nutrition principles will be merged with the aim of clarifying the constraints, opportunities, and future perspectives of foliar Fe sprays to cure plant Fe deficiency.     

Genetic evidence for multi-event imports of avian influenza virus A (H5N1) into Bavaria, Germany.

The almost simultaneous initial detections of avian influenza A H5N1 viruses in central Europe in February 2006, at a time devoid of migratory bird activity, raised the question of the origin of these viruses. This report presents molecular data from Europe providing evidence for multiple and spatially overlapping H5N1 introductions into Bavaria, Germany.