Variability of Chemical Profile in Almonds (Prunus dulcis) of Different Cultivars and Origins.

Almonds show a great variability in their chemical composition. This variability is a result of the existence of a diverse range of almond cultivars, the self-incompatibility of most almond cultivars, and the heterogeneous harvesting conditions found around the different locations where almons are grown. In the last years, the discrimination among almond cultivars has been the focal point of some research studies to avoid fraud in protected geographical indications in almond products and also for selecting the best cultivars for a specific food application or the most interesting ones from a nutritional point of view. In this work, a revision of the recent research works related to the chemical characterization and classification of almond cultivars from different geographical origins has been carried out. The content of macronutrients, tocopherols, phytosterols, polyphenols, minerals, amino acids, and volatile compounds together with DNA fingerprint have been reported as possible cultivar and origin markers. The analysis of the results showed that no individual almond compound could be considered a universal biomarker to find differences among different almond cultivars. Hence, an adequate selection of variables or the employment of metabolomics and the application of multivariate statistical techniques is necessary when classification studies are carried out to obtain valuable results. Meanwhile, DNA fingerprinting is the perfect tool for compared cultivars based on their genetic origin.

Chemometric comparison of almond oxidation rates using kinetic parameters obtained by infrared spectroscopy.

BACKGROUND: The study of almond fat stability is essential from a quality control perspective meanly because, in most of the cases, almonds are sold skinned and thermally treated. In this work an alternative method to Rancimat test based on attenuated total reflectance-Fourier-transform infrared (ATR-FTIR) spectrometry was adapted for checking the induced degradation at 75 °C of seven almond oil cultivars, three of the top Californian producing varieties, and, four traditional cultivars harvested in Spain. RESULTS: The thermal oil degradation evolution was followed by measuring the changes in the absorbance of the selected FTIR spectra bands (3470, 3006, 1730, 1630, 988 and 970 cm-1 ). A first-order kinetic behaviour was observed, after an induction time in all bands. CONCLUSIONS: Kinetic coefficients and induction times were easily obtained as the absorbance values (from difference spectra) fitted to pseudo-first-order kinetics after the induction time. Principal component analysis was applied to the kinetic parameters to visualize which variables could be useful to classify the almond cultivars based on their resistance to thermal oxidation processes. It was found that selecting only the induction times corresponding to the bands 3470, 3006, 1630 and 970 cm-1 a separate classification of the Californian cultivars from the Spanish ones was possible. Finally, a linear discriminant analysis was assayed using only the four induction times previously selected. Validated classification and correct in 100% of the cases was obtained for all the samples based on their Spanish or Californian origin. © 2020 Society of Chemical Industry.

Chromatin regulation by Histone H4 acetylation at Lysine 16 during cell death and differentiation in the myeloid compartment.

Histone H4 acetylation at Lysine 16 (H4K16ac) is a key epigenetic mark involved in gene regulation, DNA repair and chromatin remodeling, and though it is known to be essential for embryonic development, its role during adult life is still poorly understood. Here we show that this lysine is massively hyperacetylated in peripheral neutrophils. Genome-wide mapping of H4K16ac in terminally differentiated blood cells, along with functional experiments, supported a role for this histone post-translational modification in the regulation of cell differentiation and apoptosis in the hematopoietic system. Furthermore, in neutrophils, H4K16ac was enriched at specific DNA repeats. These DNA regions presented an accessible chromatin conformation and were associated with the cleavage sites that generate the 50 kb DNA fragments during the first stages of programmed cell death. Our results thus suggest that H4K16ac plays a dual role in myeloid cells as it not only regulates differentiation and apoptosis, but it also exhibits a non-canonical structural role in poising chromatin for cleavage at an early stage of neutrophil cell death.

Kinetic study of olive oil degradation monitored by fourier transform infrared spectrometry. Application to oil characterization.

A new approach for the determination of kinetic parameters of the cis/trans isomerization during the oxidation process of 24 virgin olive oils belonging to 8 different varieties is presented. The accelerated process of degradation at 100 °C was monitored by recording the Fourier transform infrared spectra. The parameters obtained confirm pseudo-first-order kinetics for the degradation of cis and the appearance of trans double bonds. The kinetic approach affords the induction time and the rate coefficient; these parameters are related to the fatty acid profile of the fresh olive oils. The data obtained were used to compare the oil stability of the samples with the help of multivariate statistical techniques. Fatty acid allowed a classification of the samples in five groups, one of them constituted by the cultivars with higher stability. Meanwhile, the kinetic parameters showed greater ability for the characterization of olive oils, allowing the classification in seven groups.

Contribution of hydrophobic interactions to the folding and fibrillation of histone H1 and its carboxy-terminal domain.

Histone H1 is involved in chromatin structure and gene regulation. H1 also performs functions outside cell nuclei, which may depend on its properties as a lipid-binding protein. The H1 CTD behaves as an intrinsically disordered protein (IDP) with coupled binding and folding. Here, we used neutral detergents and anionic SDS to study the contribution of hydrophobic interactions to the folding of the CTD. In the presence of neutral detergents, the CTD folded with proportions of secondary structure motifs similar to those observed in the DNA complexes. These results identify a folding pathway for the CTD based on hydrophobic interactions, and independent of charge compensation. The CTD is phosphorylated to different extents by cyclin-dependent kinases. The general effect of phosphorylation in the presence of detergents was a decrease in the α-helix content and an increase in that of the ß-structure. The greatest effect was observed in the fully phosphorylated CTD (three phosphate groups) in the presence of anionic SDS (7:1, detergent/CTD molar ratio); in these conditions, the CTD became an all-ß protein, with 83% ß-structure and no α-helix. The CTD in all-ß conformation readily formed ribbon-like fibers. The entire H1 also formed fibers when fully phosphorylated in the CTD. Fibers were of the amyloid type, as judged by strong birefringence in the presence of Congo red and thioflavin fluorescence enhancement. Amyloid fiber formation was only observed in SDS, suggesting that it requires the joint effects of partial charge neutralization and hydrophobic interactions, together with the all-ß potential provided by full phosphorylation.