Cambios en la composición de los ácidos grasos y evaluación de la oxidación de lípidos y proteínas en almejas comerciales (Ruditapes decussatus) cocinadas

This study aimed to provide information about the changes in fatty acid composition and quality in Ruditapes decussatus tissue after four culinary treatments (steamed, baked, grilled and fried). All treated samples showed a significant decrease in moisture and protein. In contrast, a significant increase in fat content resulted from the grilled and fried treatments. Saturated fatty acid was significantly higher in fresh clams than all cooking processes, except in fried ones. Monounsaturated fatty acid and polyunsaturated fatty acid varied significantly between fresh and cooked clams with high values recorded for fried clams. The n-3/n-6 ratio, peroxide index, EPA+DHA and atherogenicity index decreased significantly after the cooking processes particularly in fried clams. The mineral levels (Mg, Ca and Mn) of cooked clams decreased considerably with grilled and fried treatments. The impacts of cooking on the fatty acid composition and protein content in clam tissue was evaluated by lipid peroxidation (TBARS, PV, FFA, TOR) and protein oxidation (AOPP and PCO), which varied statistically in fried, steamed, grilled and baked samples; indicating alterations in cooked clam tissues structure. Based on our results, steaming is recommended for the preparation of clams because it preserves the most nutritional tissue quality.El presente estudio tuvo como objetivo proporcionar información innovadora sobre los cambios en la composición y calidad de los ácidos grasos presentes en el tejido de Ruditapes decussatus tras cuatro tratamientos culinarios distintos (vapor, horno, parrilla y fritura). Todas las muestras tratadas mostraron una disminución significativa en el contenido de humedad y proteínas. Por el contrario, los tratamientos a la parrilla y frito resultaron en un aumento significativo de la cantidad de grasa. El contenido en ácidos grasos saturados fue significativamente mayor en las almejas frescas comparado con todas las almejas cocinadas, a excepción de las fritas. Los ácidos grasos mono- y poliinsaturados variaron significativamente entre las almejas frescas y cocinadas, mostrando el valor más alto en las almejas fritas. La relación n-3/n-6, el índice de peróxidos, el contenido de EPA + DHA y el índice de aterogenicidad disminuyeron significativamente después de todos los procesos de cocción, especialmente en las almejas fritas. Los niveles de minerales (Mg, Ca y Mn) de las almejas cocinadas disminuyeron considerablemente tras los tratamientos a la parrilla y frito. El impacto del cocinado sobre la calidad de los ácidos grasos y las proteínas se evaluó mediante la medida de la peroxidación de lípidos (TBARS, PV, FFA, TOR) y la oxidación de proteínas (AOPP y PCO), valores que variaron significativamente en las muestras fritas, al vapor, a la parrilla y al horno, indicando una alteración de la estructura de los tejidos de la almeja cocinada. De acuerdo a los resultados obtenidos, se recomienda la cocción al vapor para la preparación de las almejas, ya que es el tratamiento que mejor preserva calidad nutricional de los tejidos

Deciphering resistance to Zymoseptoria tritici in the Tunisian durum wheat landrace accession ‘Agili39’

Septoria tritici blotch (STB), caused by Zymoseptoria tritici (Z. tritici), is an important biotic threat to durum wheat in the entire Mediterranean Basin. Although most durum wheat cultivars are susceptible to Z. tritici, research in STB resistance in durum wheat has been limited. Results: In our study, we have identified resistance to a wide array of Z. tritici isolates in the Tunisian durum wheat landrace accession ‘Agili39’. Subsequently, a recombinant inbred population was developed and tested under greenhouse conditions at the seedling stage with eight Z. tritici isolates and for five years under field conditions with three Z. tritici isolates. Mapping of quantitative trait loci (QTL) resulted in the identification of two major QTL on chromosome 2B designated as Qstb2B_1 and Qstb2B_2. The Qstb2B_1 QTL was mapped at the seedling and the adult plant stage (highest LOD 33.9, explained variance 61.6%), conferring an effective resistance against five Z. tritici isolates. The Qstb2B_2 conferred adult plant resistance (highest LOD 32.9, explained variance 42%) and has been effective at the field trials against two Z. tritici isolates. The physical positions of the flanking markers linked to Qstb2B_1 and Qstb2B_2 indicate that these two QTL are 5 Mb apart. In addition, we identified two minor QTL on chromosomes 1A (Qstb1A) and chromosome 7A (Qstb7A) (highest LODs 4.6 and 4.0, and explained variances of 16% and 9%, respectively) that were specific to three and one Z. tritici isolates, respectively. All identified QTL were derived from the landrace accession Agili39 that represents a valuable source for STB resistance in durum wheat. Conclusion: This study demonstrates that Z. tritici resistance in the ‘Agili39’ landrace accession is controlled by two minor and two major QTL acting in an additive mode. We also provide evidence that the broad efficacy of the resistance to STB in ‘Agili 39’ is due to a natural pyramiding of these QTL. A sustainable use of this Z. tritici resistance source and a positive selection of the linked markers to the identified QTL will greatly support effective breeding for Z. tritici resistance in durum wheat

Stress and sexual reproduction affect the dynamics of the wheat pathogen effector AvrStb6 and strobilurin resistance

Host resistance and fungicide treatments are cornerstones of plant-disease control. Here, we show that these treatments allow sex and modulate parenthood in the fungal wheat pathogen Zymoseptoria tritici. We demonstrate that the Z. tritici–wheat interaction complies with the gene-for-gene model by identifying the effector AvrStb6, which is recognized by the wheat resistance protein Stb6. Recognition triggers host resistance, thus implying removal of avirulent strains from pathogen populations. However, Z. tritici crosses on wheat show that sex occurs even with an avirulent parent, and avirulence alleles are thereby retained in subsequent populations. Crossing fungicide-sensitive and fungicide-resistant isolates under fungicide pressure results in a rapid increase in resistance-allele frequency. Isolates under selection always act as male donors, and thus disease control modulates parenthood. Modeling these observations for agricultural and natural environments reveals extended durability of host resistance and rapid emergence of fungicide resistance. Therefore, fungal sex has major implications for disease control

ZnMn₂O₄ Nanopyramids Fabrication by Hydrothermal Route: Effect of Reaction Time on the Structural, Morphological, and Electrochemical Properties

ZnMn2O4 spinels are prepared by a simple hydrothermal route with control of the reaction time, ranging from 6 h to 18 h. The evolution of the structural and morphological parameters under the effect of time was analyzed by XRD, ATR-FTIR, XPS, and SEM-EDS. The XRD results show that for longer reaction times (18 h), the ZnMn2O4 spinel samples present a tetragonal structure with high crystallinity and an average crystallite size of 32.3 ± 1.7 nm, larger than those obtained for 6 h and 12 h. The ATR-FTIR spectra confirm the structural results, with well-defined peaks related to stretching vibrations of M-O (M = Zn, Mn) functional groups. XPS reveals the co-existence of several metal oxides and hydroxides at the outermost surface. SEM analysis shows that the samples present a pyramid morphology, better defined at 18 h, with an average particle size of 6.2 ± 1.5 µm. EDS analysis of ZnMn2O4 (18 h) reveals atomic ratios of 0.45, 0.22, and 0.50 for Zn/Mn, Zn/O, and Mn/O, respectively, in good agreement with the expected values. Based on the CVs, the synthesized ZnMn2O4 samples formed at 18 h showed the most promising electrochemical properties, with a specific capacity of 102 F g−1, offering great potential in supercapacitor applications

Antibiotic resistance and virulence of faecal enterococci isolated from food-producing animals in Tunisia

Antimicrobial agents exert a selection pressure not only on pathogenic, but also on commensal bacteria of the intestinal tract of humans and animals. The aim of this work was to determine the occurrence of different enterococcal species and to analyse the prevalence of antimicrobial resistance and the mechanisms implicated, as well as the genetic diversity in enterococci recovered from faecal samples of food-producing animals (poultry, beef and sheep) in Tunisia. Antimicrobial resistance and the mechanisms implicated were studied in 87 enterococci recovered from 96 faecal samples from animals of Tunisian farms. Enterococcus faecium was the most prevalent species detected (46 %), followed by E. hirae (33.5 %). High percentages of resistance to erythromycin and tetracycline were found among our isolates, and lower percentages to aminoglycosides and ciprofloxacin were identified. Most of the tetracycline-resistant isolates carried the tet(M) and/or tet(L) genes. The erm(B) gene was detected in all erythromycin-resistant isolates. The ant(6)-Ia, aph(3\u2032)-Ia and aac(6\u2032)-aph(2\u2033) genes were detected in nine aminoglycoside-resistant isolates. Of our isolates, 11.5 % carried the gelE gene and exhibited gelatinase acitivity. The esp gene was detected in 10 % of our isolates and the hyl gene was not present in any isolate. The predominant species (E. faecium and E. hirae) showed a high genetic diversity by repetitive extragenic palindromic (REP)-PCR. Food animals might play a role in the spread through the food chain of enterococci with virulence and resistance traits to humans