Volatile compounds associated to the loss of astringency in persimmon fruit revealed by untargeted GC–MS analysis

High resolution volatile profiling (67 compounds identified) of fruits from 12 persimmon cultivars was established and used to characterize the different astringency types of persimmon fruit before and after deastringency treatment. Analysis of the volatile profile of fruit enables us to differentiate between cultivars that at the moment of harvest produced non-astringent fruit (Pollination Constant Non Astringent—PCNA-type) from astringent ones (non-PCNA-type). Fruit failing to accumulate astringent compounds naturally (PCNA fruit) showed high levels of 3(2H)-benzofuranone, while this compound was not detected in any astringent type fruit (non-PCNA). In addition to this, PCNA cultivars also showed at harvest higher accumulation of benzeneacetaldehyde and lipid-derived aldehydes (hexanal, heptanal, octanal and decanal) than non-PCNA fruit. The application of postharvest deastringency treatment to all non-PCNA cultivars resulted on an important insolubilization of tannins. In general the CO₂-treatment enhanced the levels of acetaldehyde, however those cultivars showing high levels of dihydrobenzofuran at harvest did not present an increment of acetaldehyde. In contrast, all non-PCNA cultivars exhibited an important accumulation of lipid-derived aldehydes due to CO₂-treatment. Therefore, we propose that lipid-derived aldehydes (mainly decanal, octanal and heptanal) may be playing a role in the astringency loss. Our results suggest that 3(2H)-benzofuranone, benzeneacetaldehyde and lipid-derived aldehydes could be used as markers for both natural and artificial loss of astringency.     

Efficient,Cyanine Dye Based Bilayer Solar Cells

Simple bilayer solar cells, using commercially available cationic cyanine dyes as donors and evaporated C₆₀ layer as an acceptor are prepared. Cyanine dyes with absorption maxima of 578, 615 and 697 nm having either perchlorate or hexafluorophosphate counter‐ions are evaluated. The perchlorate dye leads to cells with S‐shape current‐voltage curves; only the dyes with the hexafluorophosphate counter‐ions lead to efficient solar cells. When the wide bandgap dyes are employed, S‐shape current‐voltage curves are obtained when the conductive polymer PEDOT:PSS is used as hole transport layer. Substitution of PEDOT:PSS with MoO₃ leads to cells with more rectangular current–voltage curves and high fill factors. Additionally, the cells using the MoO₃ layer for hole extraction lead to high open circuit voltages of 0.9 V. In the case that a low bandgap hexafluorophosphate dye is used with the HOMO above that of the PEDOT:PSS the cell performance is independent on the type of hole transport layer employed. Using this approach, bilayer solar cells are obtained with power efficiencies ranging from 1.8 to 2.9% depending on the particular dye employed. These are impressive numbers for bilayer solar cell that are partially solution processed in ambient conditions.     

Length-weight relationships of seven fish species from the laguna del cisne basin (Canelones,Uruguay)

This work provides new length-weight information for seven species of freshwater fishes. The analyzed specimens were collected monthly during a year (April 2018–March 2019) in a coastal lagoon system and its associated streams in southern Uruguay. During each sampling campaign, fishes were captured using gillnets in the lagoon and electrofishing in the streams. This study reports a new maximum size for four species and the first length-weight relationship report for Gymnogeophagus terrapurpura. Length-weight estimates and their confidence intervals are provided for all species.     

Molecular docking simulation analysis of alcohol acyltransferases from two related fruit species explains their different substrate selectivities

Tropical papaya (Carica papaya) and mountain papaya (Vasconcellea pubescens) fruits are characterised for their strong and particular aroma. The aroma of both fruits is different and dominated by esters, which are synthesised by alcohol acyltransferases (AATs). The ability to produce esters is contrasting, V. pubescens (VpAAT1) being a very active enzyme towards the production of benzyl acetate, whereas C. papaya (CpAAT1) is more active towards the production of ethyl butanoate and methyl butanoate, but not benzyl acetate. In order to understand the mechanism of action at the molecular level, the structural model of CpAAT1 protein was built by comparative modelling. Conformational interaction between the protein and several ligands was carried out by molecular docking. CpAAT1 structure showed two domains connected by a large crossover loop, with a solvent channel in the centre of the structure. CpAAT1 and VpAAT1 proteins showed similar 3D structures, including their catalytic sites, but their solvent channels showed differences in size and shape. CpAAT1 solvent channel is larger, in agreement with its higher selectivity for large acyl-CoA substrates. In addition, the most favourably predicted substrate orientation in CpAAT1 was observed for methanol and butanoyl-CoA, showing a perfect coincidence with the high production rate of methyl butanoate of C. papaya fruit.     

Alterations in cerebrospinal fluid glycerophospholipids and phospholipase A2 activity in Alzheimer's disease

Our aim is to study selected cerebrospinal fluid (CSF) glycerophospholipids (GP) that are important in brain pathophysiology. We recruited cognitively healthy (CH), minimally cognitively impaired (MCI), and late onset Alzheimer''s disease (LOAD) study participants and collected their CSF. After fractionation into nanometer particles (NP) and supernatant fluids (SF), we studied the lipid composition of these compartments. LC-MS/MS studies reveal that both CSF fractions from CH subjects have N-acyl phosphatidylethanolamine, 1-radyl-2-acyl-sn-glycerophosphoethanolamine (PE), 1-radyl-2-acyl-sn-glycerophosphocholine (PC), 1,2-diacyl-sn-glycerophosphoserine (PS), platelet-activating factor-like lipids, and lysophosphatidylcholine (LPC). In the NP fraction, GPs are enriched with a mixture of saturated, monounsaturated, and polyunsaturated fatty acid species, while PE and PS in the SF fractions are enriched with PUFA-containing molecular species. PC, PE, and PS levels in CSF fractions decrease progressively in participants from CH to MCI, and then to LOAD. Whereas most PC species decrease equally in LOAD, plasmalogen species account for most of the decrease in PE. A significant increase in the LPC-to-PC ratio and PLA₂ activity accompanies the GP decrease in LOAD. These studies reveal that CSF supernatant fluid and nanometer particles have different GP composition, and that PLA₂ activity accounts for altered GPs in these fractions as neurodegeneration progresses.     

Comparison of 26 Sphingomonad Genomes Reveals Diverse Environmental Adaptations and Biodegradative Capabilities

Sphingomonads comprise a physiologically versatile group within the Alphaproteobacteria that includes strains of interest for biotechnology, human health, and environmental nutrient cycling. In this study, we compared 26 sphingomonad genome sequences to gain insight into their ecology, metabolic versatility, and environmental adaptations. Our multilocus phylogenetic and average amino acid identity (AAI) analyses confirm that Sphingomonas, Sphingobium, Sphingopyxis, and Novosphingobium are well-resolved monophyletic groups with the exception of Sphingomonas sp. strain SKA58, which we propose belongs to the genus Sphingobium. Our pan-genomic analysis of sphingomonads reveals numerous species-specific open reading frames (ORFs) but few signatures of genus-specific cores. The organization and coding potential of the sphingomonad genomes appear to be highly variable, and plasmid-mediated gene transfer and chromosome-plasmid recombination, together with prophage- and transposon-mediated rearrangements, appear to play prominent roles in the genome evolution of this group. We find that many of the sphingomonad genomes encode numerous oxygenases and glycoside hydrolases, which are likely responsible for their ability to degrade various recalcitrant aromatic compounds and polysaccharides, respectively. Many of these enzymes are encoded on megaplasmids, suggesting that they may be readily transferred between species. We also identified enzymes putatively used for the catabolism of sulfonate and nitroaromatic compounds in many of the genomes, suggesting that plant-based compounds or chemical contaminants may be sources of nitrogen and sulfur. Many of these sphingomonads appear to be adapted to oligotrophic environments, but several contain genomic features indicative of host associations. Our work provides a basis for understanding the ecological strategies employed by sphingomonads and their role in environmental nutrient cycling.     

Occurrence of Poecilochirus austroasiaticus (Acari: Parasitidae) in forensic autopsies and its application on postmortem interval estimation

Despite the fact that mites were used at the dawn of forensic entomology to elucidate the postmortem interval, their use in current cases remains quite low for procedural reasons such as inadequate taxonomic knowledge. A special interest is focused on the phoretic stages of some mite species, because the phoront-host specificity allows us to deduce in many occasions the presence of the carrier (usually Diptera or Coleoptera) although it has not been seen in the sampling performed in situ or in the autopsy room. In this article, we describe two cases where Poecilochirus austroasiaticus Vitzthum (Acari: Parasitidae) was sampled in the autopsy room. In the first case, we could sample the host, Thanatophilus ruficornis (Küster) (Coleoptera: Silphidae), which was still carrying phoretic stages of the mite on the body. That attachment allowed, by observing starvation/feeding periods as a function of the digestive tract filling, the establishment of chronological cycles of phoretic behavior, showing maximum peaks of phoronts during arrival and departure from the corpse and the lowest values in the phase of host feeding. From the sarcosaprophagous fauna, we were able to determine in this case a minimum postmortem interval of 10 days. In the second case, we found no Silphidae at the place where the corpse was found or at the autopsy, but a postmortem interval of 13 days could be established by the high specificity of this interspecific relationship and the departure from the corpse of this family of Coleoptera.