Scientific passion and religious commitment in the Republic of Letters: Nicolas Fatio of Duillier (1664-1753)

International audienceOn August 27th, 1745, Nicolas Fatio of Duillier, 81 years old, wrote those words to his nephew François Calandrin: « While working in the Spiritual to a New World, [the Providence] is turning most of the foundations of the Scientists‘ Astronomical System upside down ; and makes us discover a whole new and more glorious Earth ; and a whole new Sky, of which It gives us a very accurate measurement with yards and feet. »At the end of his life, Fatio was clearly convinced that all the scientific discoveries of his time -and especially mathematics- were directly linked to a providential design. He also thought that he had been chosen by Providence to discover new truths through mathematical demonstrations. Fatio was part of the scientific and intellectual network of the Republic of Letters. He was a fellow of the Royal Society of London and a friend of Isaac Newton. Both shared a passion for alchemy. Fatio also discovered chemical medicine, which he practised on several people and sometimes on himself. He then became the defender, secretary and witness of a group of French fanatics Protestants who had fled to London, trying to escape the Protestants hunt organised in their country. Fatio travelled through Europe until Constantinople with them, writing down their warnings about the End of the world and the coming of God’s judgment. Being back to England after several years, he spent the rest of his life quite isolated, practising at the same time mathematics and calculations, biblical studies and translations from Hebrew to English. His life was shared between various interests and reveals us the porosity that then existed between the world and networks of the new academic European science, and practises as alchemy, medicine and biblical studies, that are today considered as irrational and clearly different from science but were very meaningful and omnipresent at that time

Mineralisation of crop residues on the soil surface or incorporated in the soil under controlled conditions

In the present work, we compare the effect of mature crop residues mixed into a ferralitic soil or placed as a single layer on soil surface on the mineralisation of C and N over 55days. As residues, we used dry stems of rice, soybean, sorghum, brachiaria and wheat. There were no significant effects of residue placement on C mineralisation kinetics. Decomposition of the residues on the soil surface slightly increased net N mineralisation for residues having the smallest C/N rati

Modification of a commercial dna extraction kit to simultaneously recover rna, safely and rapidly, and to assess molecular biomass of the total and the active part of microbial communities, from soils with diverse mineralogy and carbon content : S11.04-P -15

We have modified a commercial DNA extraction kit for soil to simultaneously co-extract RNA. In this new procedure RNA and DNA are separated by two selective purifications in cascade without the need of DNAase or RNAse digestion. Consequently DNA and RNA are respectively purified from the whole co-extraction solution. Nucleic acids extraction is based on the action of SDS coupled with an efficient bead-beating step, but it does not require any solvent. Avoiding the use of solvents, which are damaging for human health and environmental quality, was one of our most important motivations to develop this protocol. In a second time, we have optimized this protocol to improve the DNA and RNA yield, but kipping those yields below the saturation limit of the kit to assess and quantify the variations of molecular biomass of the total (DNA) and the active (RNA) part of microbial communities in natural samples. We have also introduced a first step of homogenization of soil sample in liquid nitrogen to improve the reliability of the fungal 18S gene sequence quantification. Finally, we have shown that this protocol can be applied to a wide diversity of soils whatever their mineralogy and metal content (2 Ferralsols, 1 Vertisol, 2 Andosols from Madagascar), texture or biomass content (1 poor sandy soil from Congo and one carbon rich temperate soil sample submitted or not to a 1 month cold stress). * E Tournier, L. Amenc and AL. Pablo contributed equally to this study. (Texte intégral

Résidus de récolte en système de travail du sol réduit: La température de l'air déterminante dans la cinétique de décomposition

Résidus de récolte en système de travail du sol réduit. La température de l'air déterminante dans la cinétique de décompositio

Root and Shoot Contribution to Carbon and Nitrogen Inputs in the Topsoil Layer in No-Tillage Crop Systems under Subtropical Conditions

Recycling of carbon (C) and nitrogen (N) from plants into soils is decisive for maintaining soil organic matter and soil fertility. Therefore, we quantified plant biomass and C and N in the shoots and roots from the topsoil layer for a wide range of annual crops grown under subtropical conditions. We grew 26 species, 13 main crops, and 13 cover crops, in the field in standard sowing arrangements. Root biomass was recovered from the 0.00-0.20 m soil layer at flowering, and shoot biomass was measured at flowering for all crops and at maturity only for the main crops. Root dry matter (DM) exhibited an average of 14.9 ± 5.7 % of the total shoot biomass at flowering, and the mean shoot DM to root DM ratio was 6.9 (2.8-15.0) for the 26 crops considered. Leguminous species had less root DM (0.5 to 1.0 Mg ha-1) than grass species (1.1 to 2.3 Mg ha-1). The shoot C to root C ratio varied consistently with DM, while the root N to shoot N ratio varied considerably among species. Proportionally more biomass, C, and N was allocated to the root systems of grasses (Poaceae species) than non-grass species (especially Fabaceae species). The findings of this study contribute to designing rotations to include species that promote cycling of N and have high potential for adding C to the soil through roots. In this sense, the use of intercropped grasses and legumes is a promising strategy, especially for cover crops

Decomposition in soil and chemical changes of maize roots with genetic variations affecting cell wall quality

Summary Roots of brown-midrib (F2bm1 and F292bm3) maize mutants and their normal isogenic counterparts (F2 and F292) were used to evaluate the changes in chemical cell wall features with regard to polysaccharides, lignin composition and interconnecting phenolic acids during root degradation in soil. To this end, the chemical variability of roots of brown-midrib mutants and their normal counterparts was compared and its subsequent impact on carbon (C) mineralization determined under controlled conditions. The bm1 mutation mainly caused an increase in lignin content and a decrease in polysaccharide content of maize roots whereas the bm3 mutation caused only a decrease in polysaccharide content. The lignin composition of bm roots differed from that of normal lines and the proportion of cell wall ester-linked hydroxycinnamic acids was also different. C mineralization kinetics differed markedly between the genotypes. Certain relevant factors concerning root decomposition in soil were studied from the relationships between the chemical characteristics of maize roots at different stages of decomposition and C mineralization rates. The Klason lignin-to-glucose ratio (KL/Glu), the Klason lignin-to-arabinoxylans ratio (KL/AX) and the arabinose-to-xylose ratio (A/X) were proposed as promising predictive indicators of C mineralization kinetics. Future estimations of soil residue decomposition could be improved by taking these initial chemical criteria into account on a wider range of residues. Décomposition dans le sol et évolution de la qualité chimique des racines de maïs présentant des modifications génétiques de la qualité des parois cellulaires' Résumé Les racines des maı¨s mutants brown-midrib (F2bm1 et F292bm3) et celles de leurs ligne´es isoge´niques normales (F2 et F292) ont e´te´utilise´es pour e´valuer les modifications des caracte´ristiques chimiques des parois cellulaires, a`travers la composition des polysaccharides, de la lignine et la nature des acides phe´noliques, au cours de la de´gradation des racines dans le sol. Pour cela, nous avons examine´, en conditions controˆle´es, l'impact d'une variabilite´de la qualite´chimique des racines, en comparant les mutants bm et leurs ligne´es isoge´niques normales, sur la mine´ralisation du C. La mutation bm1 engendre principalement une augmentation de la teneur en lignine et une diminution de la teneur en polysaccharides dans les racines de maı¨s alors que la mutation bm3 cause uniquement une diminution de la teneur en polysaccharides. Dans les racines des mutants bm, la composition de la lignine ainsi que les proportions en acides hydroxycinnamiques este´rifie´s des parois cellulaires diffe`rent de celles des ligne´es non mutantes. Les cine´tiques de mine´ralisation du C varient fortement entre les ge´notypes. Les relations entre les caracte´r-istiques chimiques des racines de maı¨s a`diffe´rents stades de de´composition et les taux de mine´ralisation du C ont permis d'e´tudier certains facteurs pertinents concernant la de´composition des racines dans le sol. Les rapports lignine Klason sur glucose (KL/Glu), lignine Klason sur arabinoxylanes (KL/AX) et arabinose sur xylose (A/X) ont e´te´identifie´s comme e´tant de bons indicateurs de pre´diction des cine´tiques de mine´ralisation du C. La prise en compte de ces crite`res de qualite´chimique initiale sur une plus large gamme de re´sidus pourrait ame´liorer l'estimation de la de´composition des re´sidus dans le sol