Pathogen Populations Evolve to Greater Race Complexity in Agricultural Systems – Evidence from Analysis of Rhynchosporium secalis Virulence Data

Fitness cost associated with pathogens carrying unnecessary virulence alleles is the fundamental assumption for preventing the emergence of complex races in plant pathogen populations but this hypothesis has rarely been tested empirically on a temporal and spatial scale which is sufficient to distinguish evolutionary signals from experimental error. We analyzed virulence characteristics of ∼1000 isolates of the barley pathogen Rhynchosporium secalis collected from different parts of the United Kingdom between 1984 and 2005. We found a gradual increase in race complexity over time with a significant correlation between sampling date and race complexity of the pathogen (r20 = 0.71, p = 0.0002) and an average loss of 0.1 avirulence alleles (corresponding to an average gain of 0.1 virulence alleles) each year. We also found a positive and significant correlation between barley cultivar diversity and R. secalis virulence variation. The conditions assumed to favour complex races were not present in the United Kingdom and we hypothesize that the increase in race complexity is attributable to the combination of natural selection and genetic drift. Host resistance selects for corresponding virulence alleles to fixation or dominant frequency. Because of the weak fitness penalty of carrying the unnecessary virulence alleles, genetic drift associated with other evolutionary forces such as hitch-hiking maintains the frequency of the dominant virulence alleles even after the corresponding resistance factors cease to be used

Physicochemical properties of bacterial cellulose obtained from different Kombucha fermentation conditions

The production of bacterial cellulose has been limited due to its high cost and low productivity. Alternative low‐cost sources of this biopolymer of high purity and biocompatibility are needed in order to benefit from its enormous potential. Kombucha tea is a trend functional beverage whose production is growing exponentially worldwide, and the bacteria present in this fermented beverage belonging to the genus Komagataeibacter are capable of producing a crystalline biofilm with interesting properties. Obtaining bacterial cellulose from Kombucha tea has already been studied, however several fermentation conditions are being optimized in order to scale‐up its production. In this study, we characterized the bacterial cellulose produced from three different Kombucha fermentation conditions. The scanning electron microscopy images revealed the crystalline structure of the biofilms. The energy‐dispersive x‐ray analysis exhibited the chemical composition of the crystals. The thermogravimetric analysis showed a rate of degradation between 490 and 560°C and the differential scanning calorimetry confirmed the presence of crystalline and amorphous regions in the bacterial cellulose samples. The results suggested that crystalline cellulose could be obtained by varying the fermentation conditions of Kombucha tea

Association of the PHACTR1/EDN1 genetic locus with spontaneous coronary artery dissection

Background: Spontaneous coronary artery dissection (SCAD) is an increasingly recognized cause of acute coronary syndromes (ACS) afflicting predominantly younger to middle-aged women. Observational studies have reported a high prevalence of extracoronary vascular anomalies, especially fibromuscular dysplasia (FMD) and a low prevalence of coincidental cases of atherosclerosis. PHACTR1/EDN1 is a genetic risk locus for several vascular diseases, including FMD and coronary artery disease, with the putative causal noncoding variant at the rs9349379 locus acting as a potential enhancer for the endothelin-1 (EDN1) gene. Objectives: This study sought to test the association between the rs9349379 genotype and SCAD. Methods: Results from case control studies from France, United Kingdom, United States, and Australia were analyzed to test the association with SCAD risk, including age at first event, pregnancy-associated SCAD (P-SCAD), and recurrent SCAD. Results: The previously reported risk allele for FMD (rs9349379-A) was associated with a higher risk of SCAD in all studies. In a meta-analysis of 1,055 SCAD patients and 7,190 controls, the odds ratio (OR) was 1.67 (95% confidence interval [CI]: 1.50 to 1.86) per copy of rs9349379-A. In a subset of 491 SCAD patients, the OR estimate was found to be higher for the association with SCAD in patients without FMD (OR: 1.89; 95% CI: 1.53 to 2.33) than in SCAD cases with FMD (OR: 1.60; 95% CI: 1.28 to 1.99). There was no effect of genotype on age at first event, P-SCAD, or recurrence. Conclusions: The first genetic risk factor for SCAD was identified in the largest study conducted to date for this condition. This genetic link may contribute to the clinical overlap between SCAD and FMD

Lignin plasticization to improve binderless fiberboard mechanical properties

International audienceMechanical properties of binderless fiberboard are correlated to the hydrothermal history of the fibers during the board process. Water and temperature thickness gradients allow to calculate a gradient of T-Tg difference (Tg, local glass transition temperature, function of local water content; T, local temperature). This gradient explains the variation of mechanical properties within the thickness and in time. The in situ plasticization of lignin, which is supposed to increase the T-Tg difference, improves the macroscopic mechanical properties of fiberboards. POLYM. ENG. SCI., 45:809-816, 2005

Reducing quartz gangue entrainment in sulphide ore flotation by high molecular weight polyethylene oxide

Polyethylene oxide (PEO) was tested to flocculate and depress fine quartz particles in the batch flotation of artificial mixtures of chalcopyrite-quartz as well as a commercial Au-Cu sulphide ore sample. The aggregation/dispersion behaviors of quartz, chalcopyrite and their mixtures in the presence of PEO with and without potassium amyl xanthate (KAX) were studied by photometric dispersion analysis (PDA), scanning electron microscopy (SEM) and zeta potential measurements. Batch flotation results indicated that the addition of low dosages of PEO improved value mineral recovery and concentrate grade during the flotation of both the artificial mixtures of chalcopyrite-quartz and the Au-Cu sulphide ore sample. Aggregation/dispersion test results revealed that the PEO caused non-selective flocculation of quartz and chalcopyrite, forming large hetero-aggregates. However, the addition of KAX caused the chalcopyrite particles to break away from the hetero-aggregates, leading to separate homo-aggregates of quartz and chalcopyrite. The flotation of the fine chalcopyrite and the depression of the fine quartz were thus both improved

Very small injected samples to study chloroquine and quinine in human serum using capillary-LC and native fluorescence

A comparison between HPLC with conventional fluorescence detection and capillary-LC (mu HPLC) with native laser-induced fluorescence (LIF) detection was done to determine chloroquine (CQ) and quinine (Q) in human serum. HPLC experiments were run with parameters of the conventional fluorimeter set at the highest level of sensitivity. Results were compared with those obtained on mu HPLC coupled to a ZETALIF (He-Cd 325 nm) detector which provided a 50-fold increase in sensitivity. In mu HPLC-LIF injection volumes were 200 nL instead of 10 mu L in conventional HPLC. The separation was completed within 3 min (6 min on HPLC). The limit of detection on mu HPLC-LIF was 1.9 and 1.3 fmol for CQ and Q, respectively. Both experiments were validated on serum samples. The mean recovery was more than 95% for CQ and Q. The intra-and inter-day precision and accuracy were found to be within the acceptable limits (< 10%)