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41.
Julie Sardos Sara Muller Marie-France Duval Jean-Louis Noyer Vincent Lebot 《Agriculture and Human Values》2016,33(3):721-736
In Vanuatu (Oceania), small-scale farmers’ subsistence still largely relies on the sustainable use and maintenance of a wide-ranging biodiversity out of which root and tuber crops provide the bulk of daily subsistence. In neighboring countries, foreign influence since the first European contacts, further associated changes and the introduction of new crop species have induced a loss of cultivated diversity. This paper presents a baseline study of the diversity of root and tuber crops in ten communities throughout Vanuatu. In a context where the smallholders’ agrosystems are increasingly considered as key components for the global conservation of crop genetic resources, this study provides clues to better understand the effective roles of biodiversity in traditional agrosystems. It also provides insights on the rationale behind the constitution of agricultural portfolios and discusses how the cultivated diversity allows communities to cope with changes and pressures. The paper also shows that recently introduced crops neither seem to have compromised agricultural diversity nor drastically changed the agrosystems in Vanuatu. On the contrary, such crops are used by farmers to strengthen the resilience of their agrosystems. A discussion then presents the idea of continuity through change and novelty as a critical factor for resilience. The paper concludes by discussing the role of indigenous agriculture and culture in ensuring food security and in development strategies in a larger context. 相似文献
42.
Gianluca Tondi Jinbo Hu Filippo Rizzo Janez Buh Sergej Medved Alexander Petutschnigg Marie-France Thevenon 《Annals of Forest Science》2017,74(1):19
Key message
This article presents the leaching, fire and weathering resistance improvements of samples treated with tannin-based wood preservatives added of caprolactam. PEG-added formulations show limited applicability. The FT-IR and 13 C-NMR analyses of the caprolactam-added formulations show some evidences of copolymerization.Context
Tannin-boron wood preservatives are known for their high resistance against leaching, biological attacks, fire as well as for the good mechanical properties that they impart to wood. These properties promoted these formulations for being a candidate for the protection of green buildings. However, the low elasticity of these polymers and their dark colour implied limited weathering resistances.Aims
The aim of the study is to find suitable additives for tannin-based formulations to overcome their limited weathering resistances, without compromising the other properties.Methods
Treatment, leaching and fire tests, dimensional stability as well as artificial and natural weathering of the timber treated with caprolactam-added and PEG-added formulations were performed. FT-IR and 13C-NMR of the formulations were presented.Results
The presence of caprolactam improved the properties of the formulation with particularly significant results in terms of resistance against leaching and dimensional stability. These enhancements were imparted also to the weathering resistance of the tannin-caprolactam formulations. Indeed, the colour changes during the artificial and natural exposures were stable for longer periods. FT-IR and 13C-NMR investigations of the advanced formulations were led, and covalent copolymerization of the caprolactam with the tannin-hexamine polymer was observed.Conclusion
The tannin formulations with caprolactam improved the durability of the wood specimens, while the PEG-tannin presented strong application drawbacks.43.
Jinbo Hu Marie-France Thevenon Sabrina Palanti Gianluca Tondi 《Annals of Forest Science》2017,74(1):18
Key Message
This article presents the enhancement in boron fixation as well as the improved biological resistance against fungi and termites for wood samples treated with tannin-caprolactam and tannin-PEG formulations.Context
Although the recently developed tannin-boron wood preservatives have shown high biological protection, they presented also average resistance against weathering. The tannin-caprolactam formulations have shown improved weathering resistances and dimensional stability.Aims
For this reason, more detailed biological tests were performed to evaluate the influence of the caprolactam and PEG on the biological resistance.Methods
In this paper, the boron leaching of the tannin-caprolactam and tannin-PEG impregnated Scots pine specimens was observed and the biocidal effect against fungi (Antrodia spp. and Coniophora puteana) and insects (Reticulitermes flavipes and Hylotrupes bajulus) were determined according to the guidelines of EN 113, EN 117, and EN 47.Results
The advanced formulations containing PEG have shown interesting resistance against fungal decay, but very low penetration and weak resistance against larvae while the tannin-caprolactam preservatives have shown overall improved biological performances and higher boron fixations.Conclusion
The biocidal activity of the caprolactam-added formulations was overall enhanced and therefore these formulations are confirmed to be an interesting alternative for the wood preservation in outdoor environment.44.
Yasmina Ouadou Djamel Aliouche Marie-France Thevenon Mohamed Djillali 《Journal of Wood Science》2017,63(3):288-294
Aging is the irreversible change of mechanical, physical, and chemical properties of materials; the main objective of this work was to study the photochemical degradation and structural changes of three major Algerian wood species. For this, we evaluated the photodegradation mechanism for Maritime Pine (Pinus pinaster), zeen oak (Quercus canariensis), and afares oak (Quercus afares) by accelerated aging in a Xenon test chamber. Degradation of the samples was established by an initial color change (after 30 h exposure), followed by roughening and cracking (120 h exposure) as translated by scanning electron microscopy and Fourier transform infrared spectroscopy. The discoloration of irradiated wood samples was primarily related to the decomposition of lignin which is the key structure in wood photodegradation. As expected, a decrease in mechanical properties was observed; for all samples, the modulus of elasticity decreased after aging, indicating that the wood specimens loss some of their stiffness. 相似文献
45.
Mélanie Bergeron Simon Lacombe Robert L. Bradley Joann Whalen A. Cogliastro Marie-France Jutras Paul Arp 《Agroforestry Systems》2011,83(3):321-330
Tree-based intercropping (TBI) systems, combining agricultural alley crops with rows of hardwood trees, are largely absent
in Canada. We tested the hypothesis that the roots of 5–8 years old hybrid poplars, growing in two TBI systems in southern
Québec, would play a “safety-net” role of capturing nutrients leaching below the rooting zone of alley crops. TBI research
plots at each site were trenched to a depth of 1 m on each side of an alley. Control plots were left with tree roots intact.
In each treatment at each site, leachate at 70 cm soil depth was repeatedly sampled over two growing seasons using porous
cup tension lysimeters, and analyzed for nutrient concentrations. Daily water percolation rates were estimated with the forest
hydrology model ForHyM. Average nutrient concentrations for all days between consecutive sampling dates were multiplied by
water percolation rates, yielding daily nutrient leaching loss estimates for each sampling step. We estimated that tree roots
in the TBI system established on clay loam soil decreased subsoil NO3
− leaching by 227 kg N ha−1 and 30 kg N ha−1 over two consecutive years, and decreased dissolved organic N (DON) leaching by 156 kg N ha−1 year−1 in the second year of the study. NH4
+ leaching losses at the same site were higher when roots were present, but were 1–2 orders of magnitude lower than NO3
− or DON leaching. At the sandy textured site, the safety net role of poplar roots with respect to N leaching was not as effective,
perhaps because N leaching rates exceeded root N uptake by a wider margin than at the clay loam site. At the sandy textured
site, significant and substantial reductions of sodium leaching were observed where tree roots were present. At both sites,
tree roots reduced DON concentrations and the ratio of DON to inorganic N, perhaps by promoting microbial acquisition of DON
through rhizodeposition. This study demonstrated a potential safety-net role by poplar roots in 5–8 year-old TBI systems in
cold temperate regions. 相似文献
46.
47.
Poly(ADP-ribose) polymerase-1 (PARP-1) (ADP, adenosine diphosphate) has a modular domain architecture that couples DNA damage detection to poly(ADP-ribosyl)ation activity through a poorly understood mechanism. Here, we report the crystal structure of a DNA double-strand break in complex with human PARP-1 domains essential for activation (Zn1, Zn3, WGR-CAT). PARP-1 engages DNA as a monomer, and the interaction with DNA damage organizes PARP-1 domains into a collapsed conformation that can explain the strong preference for automodification. The Zn1, Zn3, and WGR domains collectively bind to DNA, forming a network of interdomain contacts that links the DNA damage interface to the catalytic domain (CAT). The DNA damage-induced conformation of PARP-1 results in structural distortions that destabilize the CAT. Our results suggest that an increase in CAT protein dynamics underlies the DNA-dependent activation mechanism of PARP-1. 相似文献
48.
Humblet MF Guyot H Boudry B Mbayahi F Hanzen C Rollin F Godeau JM 《Veterinary clinical pathology / American Society for Veterinary Clinical Pathology》2006,35(2):188-193
BACKGROUND: Haptoglobin and serum amyloid A are major acute phase proteins in cattle. Dairy cattle often develop pathologic conditions in the peripartum period; acute phase proteins may be useful in their diagnosis. OBJECTIVES: The purpose of this study was to compare the accuracy of serum haptoglobin (Hp) and serum amyloid A (SAA) concentrations with clinical health status for diagnosing disease during the peripartum period in dairy cattle. METHODS: Dairy cows from 4 herds were evaluated every 15 days over a 6-month period. Health status was determined by thorough clinical examination. Haptoglobin and SAA concentrations were measured in serum using validated methods and the results were classified as positive or negative based on defined cutoff points. Disease prevalence, sensitivity, and specificity were compared using clinical examination as the gold standard. RESULTS: A total of 1896 samples from 158 cows were analyzed. Significant increases in mean Hp and SAA concentrations were observed in the week following parturition in both primiparous and multiparous cows, although high interindividual variability was observed. Both Hp and SAA had low sensitivity but higher specificity in determining disease status compared with clinical examination. Increased concentrations of Hp and SAA were found in <10% of samples from clinically healthy cows, except in the week after parturition. CONCLUSIONS: Haptoglobin and serum amyloid A should be used with caution as markers of inflammation in the week after calving. Poor sensitivity in other postpartum periods could be related to the higher incidence of chronic (vs acute) inflammation. Haptoglobin may be appropriate for routine screening, but further work needs to be done to assess its value as an indicator of herd health. 相似文献
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50.
Valérie Jaulneau Claude Lafitte Marie-France Corio-Costet Marciel J. Stadnik Sylvie Salamagne Xavier Briand Marie-Thérèse Esquerré-Tugayé Bernard Dumas 《European journal of plant pathology / European Foundation for Plant Pathology》2011,131(3):393-401
The protective activity of a crude extract prepared from the green macroalga, Ulva armoricana, previously shown to induce plant defence responses, was evaluated on three plant species, common bean, grapevine and cucumber,
cultivated in the greenhouse and inoculated with three powdery mildew pathogens Erysiphe polygoni, E. necator and Sphareotheca fuliginea respectively. Chemical analyses showed that the extract was enriched in ulvans, which are green algae polysaccharides essentially
composed of uronic acid and sulphated rhamnose. Weekly applications were performed by spraying of the green algal extract
at various dilutions on bean, grapevine and cucumber leaves. A significant effect (50% protection) was observed using a dilution
corresponding to about 3 g l−1 dry matter and up to 90% reduction of symptom severity was obtained for the highest concentration (1/9 dilution, 6 g l−1 dry matter) for the three plant species. To study the natural variability of the protective activity, five extracts prepared
from algae batches harvested at different year periods were evaluated. Although polysaccharide composition varied among batches,
all extracts elicit a reporter gene regulated by a defence-gene promoter in a transgenic tobacco line, and protect cucumber
plants against powdery mildew infection. Together, these data demonstrate that U. armoricana is a reproducible source of active compounds which can be used to efficiently protect crop plants against powdery mildew
diseases. 相似文献