Discrimination of Cognacs and other distilled drinks by mid-infrared spectropscopy

Mid-infrared spectroscopy was applied to the analysis and discrimination of Cognacs and other distilled drinks (Armagnacs, whiskies, brandies, bourbons, rums, and counterfeit products). Strong correlations were found between dry extract spectra, polyphenolic dry extract spectra, and the total polyphenol concentration of samples, notably of Cognacs. Principal component analysis applied to spectral data made it possible to emphasize the importance of dry extract data when a distinction is made between Cognacs and Armagnacs, whiskies, bourbons, and rums, and of polyphenol concentration when Cognacs, brandies, and counterfeit products are separated. Ninety-six percent of samples in the test set were correctly assigned to Cognacs and non-Cognacs by partial least-squares discriminant analysis.     

A comparative histochemical study of plant polyphenols in southern African grasses

Recent anatomical studies have shown that tannin‐like substances (TLS) occur in the epidermal cells of a number of southern African tropical grasses, and the presence of condensed tannins in grasses has been confirmed by chemical analyses. A number of species from four of the five subfamilies of the Poaceae were compared for their responses to a range of histochemical tests which differ in their specificity for phenolic compounds. These included: ferrous sulphate, acidified vanillin, diazotized sulphanilic acid, Fast Blue‐BB, dimethoxybenzaldehyde and nitrous acid, Safranin and Fast Green. In addition, the radial diffusion test for protein precipitation was used. Comparative histochemical tests indicated that most taxa known to contain TLS showed comparable responses to the tests used here, with variations in intensity and hue of the coloured products formed. These qualitative differences suggest the presence of a number of different compounds including oligomeric procyanidins, oligomeric prodelphinidins, monomeric and/or dimeric flavan‐3‐ols and flavan‐3,4‐diols. The presence flavan‐4‐ols has been confirmed in the andropogonoid grasses by previous workers. Histochemical tests are adequate to identify the presence of condensed tannins and their precursors in plant tissue. However, they do not provide a means to identify those compounds which precipitate protein and function as digestibility‐reducing compounds in plant‐herbivore interactions.     

Effects of high salinity and the exogenous application of an osmolyte on growth,photosynthesis, and mineral composition in two ornamental shrubs

A greenhouse experiment was carried out to determine the growth, photosynthetic activity, and mineral composition in two ornamental shrubs [Viburnum lucidum L. (arrow-wood) and Callistemon citrinus (Curtis) Stapf. (red bottlebrush)] that had been treated or not treated with 2.5 mM glycine betaine (GB) or 5.0 mM proline (Pro). Plants were supplied with a non-salinised or salinised nutrient solution containing 200 mM NaCl. Salinity caused reductions in plant growth parameters, shoot biomass production, and net CO₂ assimilation in both species. Neither Pro nor GB were able to mitigate the adverse effects of salinity in bottlebrush, whereas GB reduced the deleterious effects of salt stress on arrow-wood, indicating a differential species-specific response to these osmolytes. The application of GB to salt-stressed arrow-wood increased apical and lateral shoot lengths, the number of leaves per plant, and shoot dry biomass by 222%, 113%, 238%, and 49%, respectively, compared to untreated or Pro-treated plants. The improved performance of salt-stressed arrow-wood plants whose roots were treated with 2.5 mM GB was attributed to partial suppression of Na uptake, higher chlorophyll concentrations, and the better nutritional status (higher K) of shoots.     

Estimating symbiotic N2 fixation in Robinia pseudoacacia

Estimating symbiotic di‐nitrogen (N₂) fixation is challenging, especially when working with woody N₂ fixers in field trials. Fortunately, isotope methods based on ¹⁵N natural abundance or on ¹⁵N artificial enrichment (dilution method) make it possible to estimate the proportion of nitrogen derived from the atmosphere (Ndfa) in N₂‐fixing species. These methods have been extensively used in the field for herbaceous species, much less for tree species such as alder and acacia, and rarely for black locust (Robinia pseudoacacia). The objectives of this study were to characterize the fixation potential of black locust in a plantation by using the two ¹⁵N isotope methods in the field, and to document values of isotope fractionation occurring during N₂ fixation (the B value). B values were estimated both by growing trees on an N‐free medium in controlled conditions (B_lab) and by making Ndfa calculated with the natural abundance method converge with Ndfa calculated with the ¹⁵N dilution method in the field (B_field). The two methods gave consistent estimates of the B value. B values ranging between –1.4 and –3.2‰ were found, varying with the age of the plant material. Up to 76% of the N in the black locust trees came from the atmosphere, representing more than 45 kg N ha^?1 over five years and confirming that black locust may be well adapted to N‐poor soils.     

Interactions between mycorrhizal fungi and mycorrhizosphere bacteria during mineral weathering: Budget analysis and bacterial quantification

The impact of ectomycorrhizal fungi or rhizosphere bacteria on tree seedling growth and nutrient uptake is well known. However, few studies have combined those microorganisms in one experiment to clarify their relative contribution and interactions in nutrient acquisition. Here, we monitored the respective contributions of pine roots, two ubiquitous forest ectomycorrhizal fungi Scleroderma citrinum and Laccaria bicolor, and two S. citrinum-mycorrhizosphere bacterial strains of Burkholderia glathei and Collimonas sp., on mineral weathering, nutrient uptake, and plant growth. Pinus sylvestris plants were grown on quartz–biotite substrate and inoculated or not with combinations of mycorrhizal fungi and/or bacterial strains. Magnesium and potassium fluxes were measured and nutrient budgets were calculated. Both ectomycorrhizal fungi significantly increased Mg plant uptake. No significant effects of the two bacterial strains were detected on the K and Mg budgets, but co-inoculating the mycorrhizal fungus S. citrinum and the efficient mineral-weathering B. glathei bacterial strain significantly improved the Mg budget. Similarly, co-inoculating S. citrinum with the Collimonas sp. bacterial strain significantly improved the pine biomass compared to non-inoculated pine plants. In order to better understand this process, we monitored the survival of the inoculated bacterial strains in the quartz–biotite substrate, the pine rhizosphere, and the mycorrhizal niche. The results showed that the two bacterial strains harboured different colonization behaviours both of which depended on the presence of the ectomycorrhizal partner. The populations of the Burkholderia strain were maintained in all these environments with a significantly higher density in the mycorrhizal niche, especially of S. citrinum. In contrast the population of the Collimonas strain reached the detection level except in the treatment inoculated with S. citrinum. These results highlight the need for taking into account the ecology of the microorganisms, and more specifically the fungal–bacterial interactions, when studying mineral weathering and plant nutrition.     

Genetic diversity within two Tunisian wild jirds: Meriones shawi and Meriones libycus (Rodentia,Gerbillinae)

Three Meriones species inhabit Tunisia, namely M. shawi, M. libycus and M. crassus, but little genetic data exist on these gerbils. We collected Meriones from eight localities in Tunisia, and obtained mitochondrial (cytochrome b) and nuclear (IRBP) gene sequence data for 37 and 13 specimens, respectively, belonging to two species: M. shawi and M. libycus. We also optimised three microsatellite markers previously described in M. unguiculatus to obtain a finer analysis of their genetic diversity and geographic structure, given their wide distribution. Phylogenetic inferences of cyt b and IRBP data for these species, in the context of other gerbillin data, corroborate their taxonomic affinities reported by previous studies. High cyt b haplotype diversity was observed in both species (25 haplotypes in 29 and 27 sequences for M. shawi and M. libycus, respectively) with little geographical structure for M. shawi but three divergent groups in M. libycus. The average microsatellite diversity within each population was high (H_O ≥ 0.6, H_E ≥ 0.8) with M. libycus populations attaining the highest values. Population differentiation was moderate for several population pairs (F_st ≥ 0.1), the highest being between M. shawi populations. However, genetic distance among populations was not significantly correlated with geographic distance in either M. shawi or M. libycus. Our results contribute to a better characterisation of Tunisian Meriones species, suggesting high geographic structure in mtDNA of M. libycus populations within North Africa.     

Inner Alpine conifer response to 20th century drought swings

Tree rings from the Alpine area have been widely used to reconstruct variations in summer temperature. In contrast, estimates of changes in the hydrological cycle are rather scarce. In order to detect altitudinal and species-specific patterns of growth responses to anomalous dry and wet conditions, a large network of 53 tree-ring width site chronologies along the Rhone valley (Valais, Switzerland) covering the 1751–2005 period was compiled and analyzed. A total of 1,605 measurement series from four conifer species—pine, larch, spruce, fir—were detrended to allow inter-annual to multi-decadal scale variability to be preserved. Site chronologies were combined to four altitudinal (colline: <800 m asl, sub-montane: 800–1,000 m asl, montane: 1,000–1,450 m asl, sub-alpine: >1,450 m asl) and species-specific mean time-series. These records were compared with temperature, precipitation, and drought (scPDSI) data. Among the altitudinal records, the colline chronologies showed highest correlation with June precipitation and scPDSI (0.5 and 0.7). Altitudinal effects, via control on climatic conditions, were superimposed upon species-specific characteristics in affecting tree growth and response to moisture variations. In particular, species-specific differences affected the significance level of drought response, with decreasing drought sensitivity towards higher elevations. Growth conditions were found to be optimal at ~1,300 m asl, with precipitation/drought limiting tree growth below and temperature above. Common years of extreme drought and low growth for the colline sites occurred in 1921, 1944, 1976, 1992, and 1998. Our results demonstrate the potential of lower elevation conifers for reconstructing long-term changes in Alpine hydro-climate.     

Outbreak investigation of porcine epidemic diarrhea in swine in Ontario

Porcine epidemic diarrhea virus was first diagnosed in Ontario in January of 2014. An outbreak investigation was conducted and it was hypothesized that feed containing spray-dried porcine plasma contaminated with the virus was a risk factor in the introduction and spread of the disease in Ontario.     

Positive correlation between high levels of ochratoxin A and resveratrol-related compounds in red wines

The natural occurrence of ochratoxin A in red wines has been widely reported by several authors, as well as a that of group of stilbenes including cis- and trans-resveratrols and related glucosylated forms. In the present study 112 samples of retail red wines were collected from northern (17), central (46), and southern (49) Italy and were analyzed for both ochratoxin A and resveratrol-related stilbenes. The mean levels of total resveratrols and total piceids were 3.14 and 5.80 mg/L, respectively, whereas the ochratoxin A mean level was 0.64 microg/L. The Merlot wines showed the highest mean value of total stilbenes, followed by Negroamaro and Negroamaro blend, Aglianico, and Syrah, all with mean levels of >10 mg/L. Ochratoxin A was detected in 70, 59, and 100% of wine samples from northern, central, and southern Italy, with mean levels of 0.12, 0.07, and 1.36 microg/L, respectively. The highest values of ochratoxin A were recorded in Negroamaro- and Primitivo-based wine samples from southern Italy, showing also the highest content of stilbenes. In wine samples from southern Italy, a positive correlation was obtained between levels of ochratoxin A and total stilbenes (r = 0.74) as well as between ochratoxin A and total resveratrols (r = 0.50) and between ochratoxin A and total piceids (r = 0.74). These results suggest that toxic levels of ochratoxin A in red wine may be, at some extent, counterbalanced by the beneficial effects of resveratrol derivatives. Further investigation should be warranted in this regard.