•Under solar panels, the ETR of irrigated crops was reduced by 10–40% of full sun.•A theoretical framework allowed identifying drivers of evapotranspiration reduction.•Specific field measurements ...allowed ranking drivers of evapotranspiration reduction.•The main driver of ETR decrease is the reduction of the climatic demand in the shade.•Cover rate is a major driver to play on to increase WUE of watered crops in the shade.
Associating on the same land area an upper layer of solar panels together with a crop layer at the ground level has been shown to allow significant saving of land resource compared to separate energy and food productions (Marrou et al., 2013a). Indeed, crops can achieve high yield under the fluctuating shade of these agrivoltaic systems. Moreover, under dry Mediterranean climate, microclimate measurements at crop level below these panels suggest that these systems could contribute to alleviate climatic stress and to save water. On two experimental prototypes of these agrivoltaic systems, we combined two complementary approaches to assess the impact of the solar panels cover on crop water use. First we calculated the bulk actual evapotranspiration (AET) of irrigated lettuces and cucumbers grown in agrivoltaic systems and in the full sun, from field measurements using the water balance equation for a crop–soil system. Then, we proposed a conceptual framework to analyze AET modifications in the partial shade and assess the contribution of identified drivers to this change. This conceptual framework breaks AET into two components (plant transpiration and soil evaporation) and four drivers: climatic demand at canopy level (ET0), fraction of radiation intercepted by the vegetation, plant stomatal conductance, and soil surface hydraulic conductance. From specific field measurements, we assessed the contribution of each driver to the variations of evapotranspiration below the photovoltaic panels (PVP), in comparison with the full sun. Crop AET calculated with the first approach (water balance) was reduced in agrivoltaic systems by 10–30% when available light was equal to 50–70% of full sun radiation, with variations according to the weather season. The second approach showed that reduction of evapotranspiration was mainly driven by the reduction of the climatic demand below the solar panels and did not result systematically in an increase of the water use efficiency, depending on the genotypic plant sensibility of dry matter accumulation to shade. The conceptual framework suggest that water use efficiency in agrivoltaic systems could be increased by selecting crop species and varieties with a rapid soil covering, which contributes to increased light capture and to decreased soil evaporation, leaving more water for plant transpiration and thereby for biomass production.
► Relative yields were higher than the relative light availability in the shade. ► Measured radiation interception efficiency (RIE) was increased in the shade. ► Increased RIE in the shade resulted ...from increased foliar areas and leaf sizes. ► Morphological traits may help selecting best varieties for agrivoltaic systems.
Combining photovoltaic panels (PVPs) and crops on the same land unit were recently proposed as an alternative to the conversion of cropland into photovoltaic plants. This could alleviate the increasing competition for land between food and energy production. In such agrivoltaic systems, an upper layer of PVPs partially shades crops at ground level. The aim of this work was to (i) assess the effect on crop yield of two PVPs densities, resulting in two shade levels equal to 50% and 70% of the incoming radiation and (ii) identify morphological and physiological determinants of the plant response to shade. Experiments were conducted on four varieties of lettuces (two crisphead lettuces and two cutting lettuces), during two seasons. In all cases, the relative lettuce yield at harvest was equal or higher than the available relative radiation. Lettuce yield was maintained through an improved Radiation Interception Efficiency (RIE) in the shade, while Radiation Conversion Efficiency (RCE) did not change significantly. Enhanced RIE was explained by (i) an increase in the total leaf area per plant, despite a decrease in the number of leaves and (ii) a different distribution of leaf area among the pool of leaves, the maximal size of leaves increasing in the shade. Our result provides a framework for the selection of adapted varieties according to their morphological traits and physiological responses to PVP shade, in order to optimize agrivoltaic systems.
•Daily air temperature and VPD are not modified under the solar panels (PVPs).•PVPs reduce day night amplitude of crop temperature and decrease soil temperature.•PVPs affect the distribution of ...incident solar beams and thus crop thermal pattern.•Growth rate is not reduced below the PVPs except during the juvenile phase of crops.•Adoption of agrivoltaic systems may require little adaptation in cropping practices.
Agrivoltaic systems are mixed systems that associate, on the same land area at the same time, food crops and solar photovoltaic panels (PVPs). The aim of the present study is to assess whether the growth rate of crops is affected in the specific shade of PVPs. Changes in air, ground and crop temperature can be suspected due to the reduction of incident radiation below the photovoltaic shelter. Soil temperature (5cm and 25cm depth), air temperature and humidity, wind speed as well as incident radiations were recorded at hourly time steps in the full sun treatment and in two agrivoltaic systems with different densities of PVPs during three weather seasons (winter, spring and summer). In addition, crop temperatures were monitored on short cycle crops (lettuce and cucumber) and a long cycle crop (durum wheat). The number of leaves was also assessed periodically on the vegetable crops.
Mean daily air temperature and humidity were similar in the full sun treatments and in the shaded situations, whatever the climatic season. On the contrary, mean daily soil temperature significantly decreased below the PVPs compared to the full sun treatment. The hourly pattern of crop temperature during day-time (24h) was affected in the shade. In this experiment, the ratio between crop temperature and incident radiation was higher below the PVPs in the morning. This could be due to a reduction of sensible heat losses by the plants (absence of dew deposit in the early morning or reduced transpiration) in the shade compared to the full sun treatment. However, mean daily crop temperature was found not to change significantly in the shade and the growth rate was similar in all the treatments. Significant differences in the leaf emission rate were measured only during the juvenile phase (three weeks after planting) in lettuces and cucumbers and could result from changes in soil temperature. As a conclusion, this study suggests that little adaptations in cropping practices should be required to switch from an open cropping to an agrivoltaic cropping system and attention should mostly be focused on mitigating light reduction and on selection of plants with a maximal radiation use efficiency in these conditions of fluctuating shade.
The need for new sources of renewable energies and the rising price of fossil fuels have induced the hope that agricultural crops may be a source of renewable energy for the future. We question in ...this paper the best strategies to convert solar radiation into both energy and food. The intrinsic efficiency of the photosynthetic process is quite low (around 3%) while commercially available monocristalline solar photovoltaic (PV) panels have an average yield of 15%. Therefore huge arrays of solar panels are now envisaged. Solar plants using PV panels will therefore compete with agriculture for land. In this paper, we suggest that a combination of solar panels and food crops on the same land unit may maximise the land use. We suggest to call this an agrivoltaic system. We used Land Equivalent Ratios to compare conventional options (separation of agriculture and energy harvesting) and two agrivoltaic systems with different densities of PV panels. We modelled the light transmission at the crop level by an array of solar panels and used a crop model to predict the productivity of the partially shaded crops. These preliminary results indicate that agrivoltaic systems may be very efficient: a 35–73% increase of global land productivity was predicted for the two densities of PV panels. Facilitation mechanisms similar to those evidenced in agroforestry systems may explain the advantage of such mixed systems. New solar plants may therefore combine electricity production with food production, especially in countries where cropping land is scarce. There is a need to validate the hypotheses included in our models and provide a proof of the concept by monitoring prototypes of agrivoltaic systems.
► Agrivoltaic (AV) systems mix solar photovoltaic panels and crops on the same land unit. ► A land equivalent ratio of AV systems is a measure of their efficiency. ►
Ex ante modelling predicts a very high productivity of such AV systems. ► AV may be a win–win option to alleviate the pressure on cropland for energy production.
Inherited retinal degenerations are caused by mutations in >250 genes that affect photoreceptor cells or the retinal pigment epithelium and result in vision loss. For autosomal recessive and X-linked ...retinal degenerations, significant progress has been achieved in the field of gene therapy as evidenced by the growing number of clinical trials and the recent commercialization of the first gene therapy for a form of congenital blindness. However, despite significant efforts to develop a treatment for the most common form of autosomal dominant retinitis pigmentosa (adRP) caused by >150 mutations in the rhodopsin (RHO) gene, translation to the clinic has stalled. Here, we identified a highly efficient shRNA that targets human (and canine) RHO in a mutation-independent manner. In a single adeno-associated viral (AAV) vector we combined this shRNA with a human RHO replacement cDNA made resistant to RNA interference and tested this construct in a naturally occurring canine model of RHO-adRP. Subretinal vector injections led to nearly complete suppression of endogenous canine RHO RNA, while the human RHO replacement cDNA resulted in up to 30% of normal RHO protein levels. Noninvasive retinal imaging showed photoreceptors in treated areas were completely protected from retinal degeneration. Histopathology confirmed retention of normal photoreceptor structure and RHO expression in rod outer segments. Long-term (>8 mo) follow-up by retinal imaging and electroretinography indicated stable structural and functional preservation. The efficacy of this gene therapy in a clinically relevant large-animal model paves the way for treating patients with RHO-adRP.
The inherited childhood blindness caused by mutations in NPHP5, a form of Leber congenital amaurosis, results in abnormal development, dysfunction, and degeneration of photoreceptors. A naturally ...occurring NPHP5 mutation in dogs leads to a phenotype that very nearly duplicates the human retinopathy in terms of the photoreceptors involved, spatial distribution of degeneration, and the natural history of vision loss. We show that adeno-associated virus (AAV)-mediated NPHP5 gene augmentation of mutant canine retinas at the time of active degeneration and peak cell death stably restores photoreceptor structure, function, and vision with either the canine or human NPHP5 transgenes. Mutant cone photoreceptors, which failed to form outer segments during development, reform this structure after treatment. Degenerating rod photoreceptor outer segments are stabilized and develop normal structure. This process begins within 8 weeks after treatment and remains stable throughout the 6-month posttreatment period. In both photoreceptor cell classes mislocalization of rod and cone opsins is minimized or reversed. Retinal function and functional vision are restored. Efficacy of gene therapy in this large animal ciliopathy model of Leber congenital amaurosis provides a path for translation to human treatment.
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Using the canine NPHP5 model of Leber congenital amaurosis, the authors show that gene therapy is highly effective at the stage of disease when there is rapid cell death and active degeneration. After treatment, cone outer segments reform, retinal and visual function is restored, and degeneration is arrested.
The form of hereditary childhood blindness Leber congenital amaurosis (LCA) caused by biallelic RPE65 mutations is considered treatable with a gene therapy product approved in the US and Europe. The ...resulting vision improvement is well accepted, but long-term outcomes on the natural history of retinal degeneration are controversial. We treated four RPE65-mutant dogs in mid-life (age = 5–6 years) and followed them long-term (4–5 years). At the time of the intervention at mid-life, there were intra-ocular and inter-animal differences in local photoreceptor layer health ranging from near normal to complete degeneration. Treated locations having more than 63% of normal photoreceptors showed robust treatment-related retention of photoreceptors in the long term. Treated regions with less retained photoreceptors at the time of the intervention showed progressive degeneration similar to untreated regions with matched initial stage of disease. Unexpectedly, both treated and untreated regions in study eyes tended to show less degeneration compared to matched locations in untreated control eyes. These results support the hypothesis that successful long-term arrest of progression with RPE65 gene therapy may only occur in retinal regions with relatively retained photoreceptors at the time of the intervention, and there may be heretofore unknown mechanisms causing long-distance partial treatment effects beyond the region of subretinal injection.
Using the canine RPE65 model that provided the impetus for clinical trials and commercialization of LCA gene therapy, the authors now show that long-term therapy outcomes depend on the status of the photoreceptor layer at the time of treatment. When it is <63% of normal, there is continuing degeneration.
SignificanceCanine models of inherited retinal diseases have helped advance adeno-associated virus (AAV)-based gene therapies targeting specific cells in the outer retina for treating blinding ...diseases in patients. However, therapeutic targeting of diseases such as congenital stationary night blindness (CSNB) that exhibit defects in ON-bipolar cells (ON-BCs) of the midretina remains underdeveloped. Using a leucine-rich repeat, immunoglobulin-like and transmembrane domain 3 (
) mutant canine model of CSNB exhibiting ON-BC dysfunction, we tested the ability of cell-specific AAV capsids and promotors to specifically target ON-BCs for gene delivery. Subretinal injection of one vector demonstrated safety and efficacy with robust and stable rescue of electroretinography signals and night vision up to 1 y, paving the way for clinical trials in patients.
In every agroforestry system, the tree canopy reduces the incident radiation for the crop. However, cereal varieties were selected, and most crop growth models were designed for unshaded conditions, ...so both may be unsuited to agroforestry conditions and performance. In southern France, durum wheat productivity was monitored over 2 years in an agroforestry system including walnut trees and under artificial shade conditions. Yield components were measured in both full and reduced light conditions. The cereal yield was always decreased by shade; by almost 50% for the heaviest shade conditions (31% of light reduction). The main effect of the shade was the reduction in the number of grains per spike (35% at the most) and in the weight of grains (16% at the most). The mean grain weight was moderately affected, while the protein content was increased in shaded conditions (by up to 38% for artificial shade). Consequently, the protein yield per hectare was less reduced by the shade than the dry matter grain yield. A crop model (STICS) was also used to simulate the crop productivity in full light and shaded conditions, but the crop LAI and the yield components were not correctly simulated in the shade. The simulations emphasized the sensitivity of the wheat grain filling to shade during the critical period, 30 days before flowering, for yield elaboration. Further experimental and modelling studies should take into account the heterogeneity of shade intensity due to the shape of the tree crown, the width of the crop alley and the orientation of the tree rows and the modification of carbon allocation inside the plant.
Purpose
Staphylococcus aureus
is one of the most common pathogens causing bloodstream infection. A rapid characterisation of resistance to methicillin and, occasionally, to aminoglycosides for ...particular indications, is therefore crucial to quickly adapt the treatment and improve the clinical outcomes of septic patients. Among analytical technologies, targeted liquid chromatography-tandem mass spectrometry (LC-MS/MS) has emerged as a promising tool to detect resistance mechanisms in clinical samples.
Methods
A rapid proteomic method was developed to detect and quantify the most clinically relevant antimicrobial resistance effectors in
S. aureus
in the context of sepsis: PBP2a, PBP2c, APH(3’)-III, ANT(4’)-I, and AAC(6’)-APH(2’’), directly from positive blood cultures and in less than 70 min including a 30-min cefoxitin-induction step. The method was tested on spiked blood culture bottles inoculated with 124
S.aureus,
accounting for the known genomic diversity of SCC
mec
types and the genetic background of the strains.
Results
This method provided 99% agreement for PBP2a (
n
= 98/99 strains) detection. Agreement was 100% for PBP2c (
n
= 5/5), APH(3’)-III (
n
= 16/16), and ANT(4’)-I (
n
= 20/20), and 94% for AAC(6')-APH(2'') (
n
= 16/17). Across the entire strain collection, 100% negative agreement was reported for each of the 5 resistance proteins. Additionally, relative quantification of ANT(4’)-I expression allowed to discriminate kanamycin-susceptible and -resistant strains, in all strains harbouring the
ant(4’)-Ia
gene.
Conclusion
The LC-MS/MS method presented herein demonstrates its ability to provide a reliable determination of
S. aureus
resistance mechanisms, directly from positive blood cultures and in a short turnaround time, as required in clinical laboratories.
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