Light Sheet Tomography (LST) for <i>in situ</i> imaging of plant roots

The production of crops capable of efficient nutrient use is essential for addressing the problem of global food security. The ability of a plant's root system to interact with the soil micro-environment determines how effectively it can extract water and nutrients. In order to assess this ability and develop the fast and cost effective phenotyping techniques which are needed to establish efficient root systems, in situ imaging in soil is required. To date this has not been possible due to the high density of scatterers and absorbers in soil or because other growth substrates do not sufficiently model the heterogeneity of a soil's microenvironment. We present here a new form of light sheet imaging with novel transparent soil containing refractive index matched particles. This imaging method does not rely on fluorescence, but relies solely on scattering from root material. We term this form of imaging Light Sheet Tomography (LST). We have tested LST on a range of materials and plant roots in transparent soil and gel. Due to the low density of root structures, i.e. relatively large spaces between adjacent roots, long-term monitoring of lettuce root development in situ with subsequent quantitative analysis was achieved

Geochemistry and tectonic setting of pre-collision Cretaceous and Paleogene volcanic rocks of Ecuador

Etude et caractérisation géochimique des roches volcaniques de la zone cotière et de la Cordillère occidentale de la Bolivie. Proposition d'un modèle d'évolution géodynamique de cette partie de la chaîne des Andes au cours du Crétacé supérieur

Development of a System for 3D High-resolution Seismic Reflection Profiling on Lakes

A high-resolution three-dimensional (3D) seismic reflection system for small-scale targets in lacustrine settings has been developed. Its main characteristics include navigation and shot-triggering software that fires the seismic source at regular distance intervals (max. error of 0.25m) with real-time control on navigation using differential GPS (Global Positioning System). Receiver positions are accurately calculated (error<0.20m) with the aid of GPS antennas attached to the end of each of three 24-channel streamers. Two telescopic booms hold the streamers at a distance of 7.5m from each other. With a receiver spacing of 2.5m, the bin dimension is 1.25m in inline and 3.75m in crossline direction. To test the system, we conducted a 3D survey of about 1km2 in Lake Geneva, Switzerland, over a complex fault zone. A 5-m shot spacing resulted in a nominal fold of 6. A double-chamber bubble-cancelling 15/15in3 air gun (40-650Hz) operated at 80 bars and 1m depth gave a signal penetration of 300m below water bottom and a best vertical resolution of 1.1m. Processing followed a conventional scheme, but had to be adapted to the high sampling rates, and our unconventional navigation data needed conversion to industry standards. The high-quality data enabled us to construct maps of seismic horizons and fault surfaces in three dimensions. The system proves to be well adapted to investigate complex structures by providing non-aliased images of reflectors with dips up to 30

Transparent soil for imaging the rhizosphere

Understanding of soil processes is essential for addressing the global issues of food security, disease transmission and climate change. However, techniques for observing soil biology are lacking. We present a heterogeneous, porous, transparent substrate for in situ 3D imaging of living plants and root-associated microorganisms using particles of the transparent polymer, Nafion, and a solution with matching optical properties. Minerals and fluorescent dyes were adsorbed onto the Nafion particles for nutrient supply and imaging of pore size and geometry. Plant growth in transparent soil was similar to that in soil. We imaged colonization of lettuce roots by the human bacterial pathogen Escherichia coli O157:H7 showing micro-colony development. Micro-colonies may contribute to bacterial survival in soil. Transparent soil has applications in root biology, crop genetics and soil microbiology

Responses to Pheromones in a Complex Odor World: Sensory Processing and Behavior

Insects communicating with pheromones, be it sex- or aggregation pheromones, are confronted with an olfactory environment rich in a diversity of volatile organic compounds of which plants are the main releaser. Certain of these volatiles can represent behaviorally relevant information, such as indications about host- or non-host plants; others will provide essentially a rich odor background out of which the behaviorally relevant information needs to be extracted. In an attempt to disentangle mechanisms of pheromone communication in a rich olfactory environment, which might underlie interactions between intraspecific signals and a background, we will summarize recent literature on pheromone/plant volatile interactions. Starting from molecular mechanisms, describing the peripheral detection and central nervous integration of pheromone-plant volatile mixtures, we will end with behavioral output in response to such mixtures and its plasticity

Nutrition for master athletes: From challenges to optimisation strategies

Master athletes are genuine examples of successful ageing thanks to their capacity of maintaining a high level of sports performance during their entire life. Within the last decade many studies have focused on the evolution of performance in many sports with ageing, as well as on the training modalities to reach such performance. On the contrary, there is a paucity of data on the nutritional habits of master athletes and the question of whether they need to adapt their nutrition to the ageing process remains unsolved. This is within this context of the optimisation of nutrition for master athletes that this review stands. The aim is to identify the potential nutritional challenges encountered by master athletes and how to handle them through adapted nutritional strategies. Given the lack of data specific to master athletes, studies including master athletes are considered as a priority, though we also make inferences based on nutrition for young adults and perturbations induced by ageing in non-athletic populations. The first part of this opinion paper tackles the first challenge faced by master athletes which is the gradual reduction in energy intake with ageing. The second challenge is the anabolic resistance and the need for increased protein intake. The third nutritional challenge we present is the episodes of metabolic crisis master athletes may face throughout life. Finally, we gather the main nutritional recommendations for master athletes and suggest the next stage of research. © 2019 ACAPS

Nutrition for master athletes: is there a need for specific recommendations?

Master athletes are often considered exemplars of successful aging, thanks to their capacity to maintain a high sports performance during their entire life. A high training capacity, regular participation in sporting competitions, and delayed alterations in body composition and physiological capacities have been listed among the main factors contributing to impressive master athletes’ performances. However, there is a paucity of data on the metabolism and dietary habits of master athletes, and the question of whether they need to adapt their nutrition to the aging process remains open. Herein, the authors presented a contemporary overview of themetabolic challenges associated with aging, including the risk of low energy availability, anabolic resistance, and periods of metabolic crisis due to forced immobilization. After assembling scientific evidence to show that master athletes must adapt their dietary intake, the authors proposed a summary of nutritional recommendations for master athletes and suggested the next stage of research