Toward a better understanding of the effects of endocrine disrupting compounds on health : Human-relevant case studies from sheep models

The 3 case studies reviewed in this article were supported by funders including: SRF Academic Scholarship Award 2013, the Wellcome Trust (080388), the European Community’s Seventh Framework Programme under grant agreement no 212885 and French Region Midi-Pyrénées [31000642] the French National Research Program for Environmental and Occupational Health of Anses [grant number 2015/1/112, 2015] and the French National Research Agency [ANR-13-CESA0007-1].Peer reviewedPostprin

Life-Long Reduction in MyomiR Expression Does Not Adversely Affect Skeletal Muscle Morphology

We generated an inducible, skeletal muscle-specific Dicer knockout mouse to deplete microRNAs in adult skeletal muscle. Following tamoxifen treatment, Dicer mRNA expression was significantly decreased by 87%. Wild-type (WT) and Dicer knockout (KO) mice were subjected to either synergist ablation or hind limb suspension for two weeks. There was no difference in muscle weight with hypertrophy or atrophy between WT and KO groups; however, even with the significant loss of Dicer expression, myomiR (miR-1, -133a and -206) expression was only reduced by 38% on average. We next aged WT and KO mice for ~22 months following Dicer inactivation to determine if myomiR expression would be further reduced over a prolonged timeframe and assess the effects of myomiR depletion on skeletal muscle phenotype. Skeletal muscle Dicer mRNA expression remained significantly decreased by 80% in old KO mice and sequencing of cloned Dicer mRNA revealed the complete absence of the floxed exons in KO skeletal muscle. Despite a further reduction of myomiR expression to ~50% of WT, no change was observed in muscle morphology between WT and KO groups. These results indicate the life-long reduction in myomiR levels did not adversely affect skeletal muscle phenotype and suggest the possibility that microRNA expression is uniquely regulated in skeletal muscle

Coeficientes de difusión durante la deshidratación osmótica de anco (<i>Cucurbita moschata</i>) : Efecto del tamaño

La deshidratación osmótica del anco surge como un tratamiento mínimo que permite prolongar su vida útil. Esta hortaliza se consume en el Noroeste argentino por su sabor suave, bajo costo y disponibilidad; es rica en fibra, vitaminas y potasio. El objetivo del presente trabajo fue evaluar el ajuste al modelo de Azuara de la cinética de la deshidratación osmótica de cubos de anco de 0,5; 1 y 1,5 cm de espesor y analizar el efecto de la dimensión característica en las difusividades que determinan las transferencias de masa. Se determinaron gravimétricamente la pérdida de peso y la ganancia de sólidos; la pérdida de agua se obtuvo a partir de las variables anteriores. Las mayores pérdidas de agua y ganancias de sólidos se obtuvieron para cubos de menor espesor. Se calcularon los parámetros cinéticos mediante el modelo matemático, lográndose muy buenos ajustes y se determinaron las difusividades para la pérdida de agua y la ganancia de sólidos, obteniéndose coeficientes menores para la ganancia de sólidos. Los valores de difusividad másica calculados aumentaron linealmente con el cuadrado de la dimensión característica de los cubos.Centro de Investigación y Desarrollo en Criotecnología de Alimento

Modelling concentration heterogeneities in streets using the street-network model MUNICH

Populations in urban areas are exposed to high local concentrations of pollutants, such as nitrogen dioxide and particulate matter, because of unfavourable dispersion conditions and the proximity to traffic. To simulate these concentrations over cities, models like the street-network model MUNICH (Model of Urban Network of Intersecting Canyons and Highways) rely on parameterizations to represent the air flow and the concentrations of pollutants in streets. In the current version, MUNICH v2.0, concentrations are assumed to be homogeneous in each street segment. A new version of MUNICH, where the street volume is discretized, is developed to represent the street gradients and to better estimate peoples' exposure. Three vertical levels are defined in each street segment. A horizontal discretization is also introduced under specific conditions by considering two zones with a parameterization taken from the Operational Street Pollution Model (OSPM). Simulations are performed over two districts of Copenhagen, Denmark, and one district of greater Paris, France. Results show an improvement in the comparison to observations, with higher concentrations at the bottom of the street, closer to traffic, of pollutants emitted by traffic (NOx, black carbon, organic matter). These increases reach up to 60 % for NO2 and 30 % for PM10 in comparison to MUNICH v2.0. The aspect ratio (ratio between building height and street width) influences the extent of the increase of the first-level concentrations compared to the average of the street. The increase is higher for wide streets (low aspect ratio and often higher traffic) by up to 53 % for NOx and 18 % for PM10. Finally, a sensitivity analysis with regard to the influence of the street network highlights the importance of using the model MUNICH with a network rather than with a single street.</p

Simultaneous consumption of pentose and hexose sugars: an optimal microbial phenotype for efficient fermentation of lignocellulosic biomass

Lignocellulosic biomass is an attractive carbon source for bio-based fuel and chemical production; however, its compositional heterogeneity hinders its commercial use. Since most microbes possess carbon catabolite repression (CCR), mixed sugars derived from the lignocellulose are consumed sequentially, reducing the efficacy of the overall process. To overcome this barrier, microbes that exhibit the simultaneous consumption of mixed sugars have been isolated and/or developed and evaluated for the lignocellulosic biomass utilization. Specific strains of Escherichia coli, Saccharomyces cerevisiae, and Zymomonas mobilis have been engineered for simultaneous glucose and xylose utilization via mutagenesis or introduction of a xylose metabolic pathway. Other microbes, such as Lactobacillus brevis, Lactobacillus buchneri, and Candida shehatae possess a relaxed CCR mechanism, showing simultaneous consumption of glucose and xylose. By exploiting CCR-negative phenotypes, various integrated processes have been developed that incorporate both enzyme hydrolysis of lignocellulosic material and mixed sugar fermentation, thereby enabling greater productivity and fermentation efficacy

Conversion of rice straw to bio-based chemicals: an integrated process using Lactobacillus brevis

Commercialization of lignocellulosic biomass as a feedstock for bio-based chemical production is problematic due to the high processing costs of pretreatment and saccharifying enzymes combined with low product yields. Such low product yield can be attributed, in large part, to the incomplete utilization of the various carbohydrate sugars found in the lignocellulosic biomass. In this study, we demonstrate that Lactobacillus brevis is able to simultaneously metabolize all fermentable carbohydrates in acid pre-processed rice straw hydrolysate, thereby allowing complete utilization of all released sugars. Inhibitors present in rice straw hydrolysate did not affect lactic acid production. Moreover, the activity of exogenously added cellulases was not reduced in the presence of growing cultures of L. brevis. These factors enabled the use of L. brevis in a process termed simultaneous saccharification and mixed sugar fermentation (SSMSF). In SSMSF with L. brevis, sugars present in rice straw hydrolysate were completely utilized while the cellulase maintained its maximum activity due to the lack of feedback inhibition from glucose and/or cellobiose. By comparison to a sequential hydrolysis and fermentation process, SSMSF reduced operation time and the amount of cellulase enzyme necessary to produce the same amount of lactic acid

Commentary on Viewpoint: Human skeletal muscle wasting in hypoxia: a matter of hypoxic dose?: Skeletal muscle wasting in hypoxia; a matter of altitude.

SKELETAL MUSCLE WASTING IN HYPOXIA; A MATTER OF ALTITUDE TO THE EDITOR: D’Hulst and Deldicque (1) argue that the severity of muscle atrophy incurred at high altitude is dependent on the combined effect of duration and degree of hypoxia exposure, or “hypoxic dose” (1). We do see a limitation of this concept, as it implies that someone residing in Leuven (altitude: 28 m) for 10 years would be subjected to a hypoxic dose of 2,454 km·h and incur 5% atrophy. Although the authors wrote that “it is unknown which parameter, altitude, or time spent at altitude is most decisive in the overall metric of hypoxic dose,” our illustration suggests that altitude is the prime determinant. This is further supported by the cut-off point at 4,000 m in a plot of the degree of atrophy vs. altitude (using the data in Table 1), whereas there was no clear relationship with duration of altitude residence. This cut-off point is likely related to the shape of the hemoglobin dissociation curve, where the oxygen tension at 4,000 m is such that physiologically significant arterial hemoglobin desaturation occurs (2). We acknowledge that one cannot entirely dismiss the importance of duration of hypoxic exposure, simply because skeletal muscle atrophy can only be noticed some time after net protein breakdown is initiated. However, muscle atrophy will not continue indefinitely, but will reach a new steady state (how otherwise can Tibetans still have muscle?). Finally, other adaptations than atrophy, such as an increase in hematocrit and capillarization, serve to attenuate muscle tissue hypoxia and atrophy (3) during residence at altitude. REFERENCES 1. D=Hulst G, Deldicque L. Viewpoint: Human skeletal muscle wasting in hypoxia: a matter of hypoxic dose? J Appl Physiol. doi:10.1152/ japplphysiol.00264.2016. 2. Wagner PD, Wagner HE, Groves BM, Cymerman A, Houston CS. Hemoglobin P(50) during a simulated ascent of Mt. Everest, Operation Everest II. High Alt Med Biol 8: 32–42, 2007. doi:10.1089/ham.2006. 1049. 3. Wüst RCI, Jaspers RT, van Heijst AF, Hopman MT, Hoofd LJ, van der Laarse WJ, Degens H. Region-specific adaptations in determinants of rat skeletal muscle oxygenation to chronic hypoxia. Am J Physiol Heart Circ Physiol 297: H364–H374, 2009. doi:10.1152/ajpheart.00272.2009

Models Analyses for Allelopathic Effects of Chicory at Equivalent Coupling of Nitrogen Supply and pH Level on F. arundinacea, T. repens and M. sativa

Alllelopathic potential of chicory was investigated by evaluating its effect on seed germination, soluble sugar, malondialdehyde (MDA) and the chlorophyll content of three target plants species (Festuca arundinacea, Trifolium repens and Medicago sativa). The secretion of allelochemicals was regulated by keeping the donor plant (chicory) separate from the three target plant species and using different pH and nitrogen levels. Leachates from donor pots with different pH levels and nitrogen concentrations continuously irrigated the target pots containing the seedlings. The allelopathic effects of the chicory at equivalent coupling of nitrogen supply and pH level on the three target plants species were explored via models analyses. The results suggested a positive effect of nitrogen supply and pH level on allelochemical secretion from chicory plants. The nitrogen supply and pH level were located at a rectangular area defined by 149 to 168 mg/l nitrogen supply combining 4.95 to 7.0 pH value and point located at nitrogen supply 177 mg/l, pH 6.33 when they were in equivalent coupling effects; whereas the inhibitory effects of equivalent coupling nitrogen supply and pH level were located at rectangular area defined by 125 to 131 mg/l nitrogen supply combining 6.71 to 6.88 pH value and two points respectively located at nitrogen supply 180 mg/l with pH 6.38 and nitrogen supply 166 mg/l with pH 7.59. Aqueous extracts of chicory fleshy roots and leaves accompanied by treatment at different sand pH values and nitrogen concentrations influenced germination, seedling growth, soluble sugar, MDA and chlorophyll of F. arundinacea, T. repens and M. sativa. Additionally, we determined the phenolics contents of root and leaf aqueous extracts, which were 0.104% and 0.044% on average, respectively