No abstract

Most of the volatile compounds responsible for the "green" notes to the aroma of fruits and vegetables are produced by the degradation of polyunsaturated fatty acids through the lipoxygenase pathway. The most determinant steps of this pathway are the peroxidation of free linoleic or linolenic acid by the action of lipoxygenase and then the lysis of the resulting hydroperoxides through a reaction catalyzed by the hydroperoxide lyase. This work analyzes the impact of the depletion of these enzymes on the volatile composition of leaves from potato plants. A characterization of the volatile profiles of the different potato mutants, a study of the metabolism of radiolabeled linoleic acid, and a determination of lipoxygenase activity have been carried out. The depletion of hydroperoxide lyase induced an increase in the lipoxygenase activity and the content of C5 volatiles, whereas the lipoxygenase silencing caused a severe decrease in the amount of volatiles produced by the leaves and always in the intensity of their aroma. The changes in the sensory evaluation of leaf aroma, as correlated to depletion of the two enzymes, have been investigated. The perspectives of producing vegetable products with a modified aroma by genetic engineering are discussed in light of the statistical results.

No abstract

Throughout evolution, cytomegaloviruses (CMVs) have been capturing genes from their hosts, employing the derived proteins to evade host immune defenses. We have recently reported the presence of a number of CD48 homologs (vCD48s) encoded by different pathogenic viruses, including several CMVs. However, their properties and biological relevance remain as yet unexplored. CD48, a cosignaling molecule expressed on the surface of most hematopoietic cells, modulates the function of natural killer (NK) and other cytotoxic cells by binding to its natural ligand 2B4 (CD244). Here, we have characterized A43, the vCD48 exhibiting the highest amino acid sequence identity with host CD48. A43, which is encoded by owl monkey CMV, is a soluble molecule released from the cell after being proteolytically processed through its membrane proximal region. A43 is expressed with immediate-early kinetics, yielding a protein that is rapidly detected in the supernatant of infected cells. Remarkably, surface plasmon resonance assays revealed that this viral protein binds to host 2B4 with high affinity and slow dissociation rates. We demonstrate that soluble A43 is capable to abrogate host CD48:2B4 interactions. Moreover, A43 strongly binds to human 2B4 and prevents 2B4-mediated NK-cell adhesion to target cells, therefore reducing the formation of conjugates and the establishment of immunological synapses between human NK cells and CD48-expressing target cells. Furthermore, in the presence of this viral protein, 2B4-mediated cytotoxicity and IFN-γ production by NK cells are severely impaired. In summary, we propose that A43 may serve as a functional soluble CD48 decoy receptor by binding and masking 2B4, thereby impeding effective NK cell immune control during viral infections. Thus, our findings provide a novel example of the immune evasion strategies developed by viruses.

No abstract

Maqui berry (Aristotelia chilensis) is a native Chilean species that produces berries that are exceptionally rich in anthocyanins and natural antioxidants. These natural compounds provide an array of health benefits for humans, making them very desirable in a fruit. At the same time, these substances also interfere with nucleic acid preparations, making RNA extraction from Maqui berry a major challenge. Our group established a method for RNA extraction of Maqui berry with a high quality RNA (good purity, good integrity and higher yield). This procedure is based on the adapted CTAB method using high concentrations of PVP (4 %) and β-mercaptoethanol (4 %) and spermidine in the extraction buffer. These reagents help to remove contaminants such as polysaccharides, proteins, phenols and also prevent the oxidation of phenolic compounds. The high quality of RNA isolated through this method allowed its uses with success in molecular applications for this endemic Chilean fruit, such as differential expression analysis of RNA-Seq data using next generation sequencing (NGS). Furthermore, we consider that our method could potentially be used for other plant species with extremely high levels of antioxidants and anthocyanins.

Edited by Charles E. Samuel This work was supported by Spanish Ministry of Economy and Competitiveness Grants SAF2012-38957 and SAF2015-67485-R and the European Union (European Regional Development Fund). S. M. Pontejo, C. Sanchez, and A. Alcami are inventors of a patent application on the potential use of the variant form of etanercept, but there is no company involved or development of this reagent as a drug so far. This article was selected as one of our Editors' Picks. This article contains Fig. S1 and Table S1.

Here, we report the first draft genome sequence of Lactobacillus kunkeei strain MP2, isolated from a Chilean honeybee gut. The sequenced genome has a total size of 1.58 Mb distributed into 44 contigs and 1,356 protein-coding sequences.