Effect of physicochemical conditions on peptide-peptide interactions in a tryptic hydrolysate of beta-lactoglobulin and identification of aggregating peptides

The objective of this study was to characterize the changes in peptide solubility resulting from changing some physicochemical conditions in a tryptic hydrolysate of beta-lactoglobulin (beta-LG). The turbidity (500 nm) of a 1% solution of tryptic peptides was measured at pH 3-10, at 5, 25, and 50 degrees C, in the presence of different salt concentrations (0, 0.5, and 1 M NaCl), in the presence of denaturing and reducing agents (6 M urea, 5% SDS, or 5% beta-mercaptoethanol), and under an electric field (isoelectric focusing). The results reveal an increase in turbidity of the peptide solution at pH 4, but a slight increase in turbidity was also observed at pH 8, which is attributable to peptides linked by disulfide bridges. The effect of temperature and ionic strength on the turbidity occurring at pH 4 indicates that mainly hydrophobic interactions are involved in the aggregation process. The material in the precipitate at pH 4 was identified as the peptides beta-LG 1-8, 15-20, and 41-60 and non-hydrolyzed alpha-lactalbumin. These results suggest that a limited number of peptides are involved in the aggregation process observed at pH 4, some of which having bioactive (beta-LG 15-20, ACE inhibitor, and opioid) or emulsifying properties (beta-LG 41-60). Aggregation of these peptides at acidic pH indicates that a simple acidification step could represent an easy process for isolating peptidic fractions enriched in bioactive or functional peptides.     

Distribution of a new rosmarinic acid derivative in Eryngium alpinum L. and other Apiaceae

The roots of Eryngium alpinum L. (Apiaceae) demonstrated radical scavenging properties toward the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical in a TLC autographic assay. Isolation of the bioactive compounds allowed the identification of R-(+)-3'-O-beta-D-glucopyranosyl rosmarinic acid, a new rosmarinic acid derivative. The quantitative determination of the antioxidant capacity of the compound by chemoluminescence demonstrated half the activity of R-(+)-rosmarinic acid. To find another source richer in this compound, a chemotaxonomic study was conducted. The higher content was found in the aerial parts of Sanicula europeae L., also belonging to the Saniculoideae subfamily. Although present in most of the Eryngium species, this compound was not detected in Imperatoria ostruthium L., Pimpinella peregrina L., and Levisticum officinalis L. species from the Apioideae subfamily and Hydrocotyle asiatica L. from the Hydrocotyloideae subfamily. The results indicate that the new derivative R-(+)-3'-O-beta-D-glucopyranosyl rosmarinic acid is a potential chemotaxonomic marker of the Saniculoideae subfamily.     

Combining permanent aerobiological networks and molecular analyses for large-scale surveillance of forest fungal pathogens: A proof-of-concept

Forest disease management relies principally on a preventive approach in which epidemiological surveillance plays a crucial role. However, efficient and cost-effective surveillance methods are not currently available for large spatial scales. Nevertheless, aerobiological networks have been set up for several decades in many countries to monitor pollen dispersal and provide real-time assessments of allergenic risk. Here, we suggest that the same approach could be used for the surveillance of forest pathogens. Using molecular methods, we analysed samples from 12 sites of the French aerobiological network, at different dates. Both metabarcoding by high-throughput sequencing (using two markers and two different bioinformatics approaches) and real-time PCR targeting eight important forest pathogens were conducted. To validate the approach, temporal and spatial trends of spore detection were compared with field disease data. The metabarcoding approach demonstrated that many fungal plant pathogens could be found in aerobiological samples. Moreover, five of the eight targeted forest pathogens were detected by real-time PCR, with temporal and spatial trends of spore capture consistent with field data. In particular, Hymenoscyphus fraxineus was detected at high frequency in aerobiological samples in the areas where ash dieback has been present for the longest period of time, and at lower frequency in areas with more recent invasion. Spore detection of seasonal pathogens showed a temporal pattern similar to that of disease reports. Overall, our study provides a proof of concept that permanent aerobiological networks combined with molecular methods may provide a useful tool for large-scale surveillance of forest pathogens.     

Comparison of cytologic and histologic evaluations of the conjunctiva in the normal equine eye

OBJECTIVE: To describe the cells observed in conjunctival brush cytology (CBC) from normal horses and compare these findings with conjunctival structural histology so as to understand which cells are recovered from CBC. METHODS: This study was divided into three parts. (1) Conjunctival brush smears were collected from 20 healthy horses on both eyes and a differential count on 300 cells was carried out on May Grünwald-Giemsa (MGG) smears. (2) A similar protocol was used for whole eyes from five horses obtained rapidly after death from a slaughterhouse. The eyes were then assessed for conjunctival histology. (3) Cytobrush smears were collected from five healthy horses. Smears were examined after MGG or periodic acid Schiff (PAS) staining. RESULTS: The differential cell count showed a majority of deep and intermediate epithelial cells with very few superficial and goblet cells in both eyes. A stratified columnar to cuboidal epithelium was observed on nearly the whole surface of the conjunctiva. A stratified squamous type was observed at the palpebral and bulbar edges. Areas with highest mucus cell indices were found from the nasal to the temporal edge of the equine inferior conjunctiva in the upper palpebral segment near the fornix and in a part of the nasal fornix. In MGG smears no mucus cells were identified; however, they were numerous in PAS smears (22.6% +/- 11) and were mostly cylindrical cells (42.5% +/- 14.4 PAS positive). CONCLUSIONS: Cytobrush smears in the healthy horse are characterized by a majority of polyhedral and cylindrical cells and a few squamous cells. The cylindrical cells may be mucous cells and probably originate from the main stratified columnar to cuboidal epithelium.     

Reliability of coprological diagnosis of Paramphistomum sp. infection in cows

A modified MacMaster method was tested to check its reliability for the diagnosis of bovine paramphistomosis in France. A total number of 148 fecal samples from cows examined post-mortem were analysed. Coprological results were in accordance with necropsic examinations. Bayesian techniques (Markov Chain Monte Carlo) were used to estimate the diagnostic parameters of each of these tests. Two scenarios were envisaged: one assuming a sensitivity of the necropsic examination equal to 1 and one assuming the specificity of the coprology equal to 1. Whatever the scenarios, each test presented good estimated parameters, always superior to 0.9. A significant relationship was clearly established between epg counts and parasites burden: more than 100 epg indicated the presence of more than 100 adult paramphistomes in rumen and/or reticulum.