From folding to function through compartmentalisation : influence of aminoacid changes and pyridoxal-5'-phosphate on the cell biology of alanine:glyoxylate aminotransferase.

From folding to function through compartmentalisation - influence of aminoacid changes and roles of pyridoxal-5'-phosphate on alanine:glyoxylate aminotransferase. Primary hyperoxaluria type 1 (PH1), is a rare inherited disease caused by a deficiency in the liver-specific, pyridoxal-5’-phosphate (PLP)-dependent enzyme alanine:glyoxylate aminotransferase (AGT). AGT is normally localized to the peroxisomes where it catalyses the conversion of the intermediary metabolite glyoxylate to glycine. In a subset of patients with PH1, linked with the Gly170Arg mutation, AGT is mistargeted to mitochondria and patients may respond to pharmacological doses of pyridoxine, a precursor of PLP. Using a model system of stably transformed CHO cells expressing different AGT variants, we have studied four mutations – Gly170Arg, Phe152Ile, Ile244Thr, Gly41Arg - on the background of a common polymorphism, Pro11Leu, characteristic of a minor AGXT allele. All four mutations unexpectedly result in the peroxisome-to-mitochondrion mistargeting of AGT. However, significant differences were found on AGT quaternary status and catalytic activity. These results emphasize the synergistic effect of the Pro11Leu polymorphism and disease-causing mutations and its potential to act as a mitochondrial targeting signal. Varying the concentration of pyridoxine in cells had a biphasic effect on AGT expression, activity and compartmentalization that differed between constructs. Where some mutants had improved function with additional pyridoxine, normal AGT was inhibited at higher levels. The results provide an explanation for the therapeutic effect of pyridoxine in some patients. Overall, PLP was shown to have both chaperone and prosthetic group effects on mutant AGTs. Using a specially developed cell-based assay of indirect glycolate toxicity, we have shown the lower ability of mutant AGTs to detoxify glyoxylate. This is the basis for a functional assay of AGT in mammalian cells which could be used to screen drugs targeted at AGT

Science et vin : entre mondialisation et terroir. Journée de terrain du 03/04/ 2014 : Sancerre - Pouilly-sur-Loire

Géologie des terroirs vinicoles des appellation contrôlées Sancerre et Pouilly Fumé. Sont présentés les caractéristiques géologiques et géomorphologiques de ces terroirs composites sur d'une part une variété de calcaires et par ailleurs des terrains extrêmement siliceux

Primary Hyperoxaluria

Primary hyperoxalurias (PH) are inborn errors in the metabolism of glyoxylate and oxalate. PH type 1, the most common form, is an autosomal recessive disorder caused by a deficiency of the liver-specific enzyme alanine, glyoxylate aminotransferase (AGT) resulting in overproduction and excessive urinary excretion of oxalate. Recurrent urolithiasis and nephrocalcinosis are the hallmarks of the disease. As glomerular filtration rate decreases due to progressive renal damage, oxalate accumulates leading to systemic oxalosis. Diagnosis is often delayed and is based on clinical and sonographic findings, urinary oxalate assessment, DNA analysis, and, if necessary, direct AGT activity measurement in liver biopsy tissue. Early initiation of conservative treatment, including high fluid intake, inhibitors of calcium oxalate crystallization, and pyridoxine in responsive cases, can help to maintain renal function in compliant subjects. In end-stage renal disease patients, the best outcomes have been achieved with combined liver-kidney transplantation which corrects the enzyme defect

Science et vin : entre mondialisation et terroir. Journée de terrain du 02/04/ 2015 : Cheverny et Cour-Cheverny (Loir et Cher).

Le vignoble des appellations d'origine contrôlée « Cour-Cheverny » et « Cheverny » sont situés dans la région viticole de la vallée de la Loire. Située en rive gauche de la Loire. Ils s’étendent entre les bords du fleuve au nord, et les communes de Cheverny et Cour-Cheverny au sud. Ailleurs ils sont limités par les grandes forêts : la forêt domaniale de Russy au nord-ouest et par les forêts de Sologne l'est et au sud (en particulier les boisements continus du parc de Chambord et de la forêt de Cheverny). La forêt est très importante au sein de la zone géographique, et lorsqu'il n'est pas à proximité de la Loire, le vignoble est au coeur de clairières, entre les nombreux massifs boisés de plus ou moins grande taille

The Socio-Cultural Benefits of Urban Agriculture: A Review of the Literature

© 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).Despite extensive literature on the socio-cultural services of urban open spaces, the role of food-producing spaces has not received sufficient attention. This hampers advocacy for preserving and growing urban agricultural activities, often dismissed on justifications that their contributions to overall food supply are negligible. To understand how the social benefits of urban agriculture have been measured, we conducted a systematic review of 272 peer-reviewed publications, which drew on insights from urban agriculture sites in 57 different countries. Through content analysis, we investigated socio-cultural benefits in four spheres: engaged and cohesive communities, health and well-being, economic opportunities, and education. The analysis revealed growth in research on the social impacts of gardens and farms, with most studies measuring the effects on community cohesion and engagement, followed by increased availability and consumption of fruits and vegetables associated with reduced food insecurity and better health. Fewer studies assessed the impact of urban farming on educational and economic outcomes. Quantifying the multiple ways in which urban agriculture provides benefits to people will empower planners and the private sector to justify future investments. These findings are also informative for research theorizing cities as socio-ecological systems and broader efforts to measure the benefits of urban agriculture, in its many forms.Peer reviewedFinal Published versio

Comparing the carbon footprints of urban and conventional agriculture

Urban agriculture (UA) is a widely proposed strategy to make cities and urban food systems more sustainable. Until now, we have lacked a comprehensive assessment of the environmental performance of UA relative to conventional agriculture, and results from earlier studies have been mixed. This is the first large-scale study to resolve this uncertainty across cities and types of UA, employing citizen science at 73 UA sites in Europe and the United States to compare UA products to food from conventional farms. Results reveal that the carbon footprint of food from UA is six times greater than conventional agriculture (420 gCO2e versus 70 gCO2e per serving). However, some UA crops (for example, tomatoes) and sites (for example, 25% of individually managed gardens) outperform conventional agriculture. These exceptions suggest that UA practitioners can reduce their climate impacts by cultivating crops that are typically greenhouse-grown or air-freighted, maintaining UA sites for many years, and leveraging circularity (waste as inputs)

Food production and resource use of urban farms and gardens: a five-country study

There is a lack of data on resources used and food produced at urban farms. This hampers attempts to quantify the environmental impacts of urban agriculture or craft policies for sustainable food production in cities. To address this gap, we used a citizen science approach to collect data from 72 urban agriculture sites, representing three types of spaces (urban farms, collective gardens, individual gardens), in five countries (France, Germany, Poland, United Kingdom, and United States). We answered three key questions about urban agriculture with this unprecedented dataset: (1) What are its land, water, nutrient, and energy demands? (2) How productive is it relative to conventional agriculture and across types of farms? and (3) What are its contributions to local biodiversity? We found that participant farms used dozens of inputs, most of which were organic (e.g., manure for fertilizers). Farms required on average 71.6 L of irrigation water, 5.5 L of compost, and 0.53 m2 of land per kilogram of harvested food. Irrigation was lower in individual gardens and higher in sites using drip irrigation. While extremely variable, yields at well-managed urban farms can exceed those of conventional counterparts. Although farm type did not predict yield, our cluster analysis demonstrated that individually managed leisure gardens had lower yields than other farms and gardens. Farms in our sample contributed significantly to local biodiversity, with an average of 20 different crops per farm not including ornamental plants. Aside from clarifying important trends in resource use at urban farms using a robust and open dataset, this study also raises numerous questions about how crop selection and growing practices influence the environmental impacts of growing food in cities. We conclude with a research agenda to tackle these and other pressing questions on resource use at urban farms