Quantification of beta casein in milk and cheese using an optical immunosensor

beta-Casein was quantified in milk and cheese, using an optical immunosensor, based on surface plasmon resonance (SPR) measurement. The assay consists of a two-step sandwich strategy, with two anti-beta-casein antibodies directed against each extremity of the casein. This strategy permits only native beta-casein to be quantified and not its degradation products. The calibration curve was obtained with a reference milk powder of known beta-casein concentration. The analysis time per sample was less than 10 minutes. The antibody-coated surface could be used for more than 250 determinations. The detection limit was established at 85 ng x mL(-)(1) and the intra- and inter-assay variation coefficients were 2.6 and 6.2% respectively. The method was applied to raw milk to quantify intact beta-casein, with no pretreatment of the sample. A second application was realized with cheese, to follow the proteolysis of beta-casein during ripening.     

Isolation of microsatellites from an enriched genomic library of the plant-parasitic nematode <Emphasis Type="Italic">Meloidogyne incognita</Emphasis> and their detection in other root-knot nematode species

The root-knot nematode Meloidogyne incognita is a polyphagous pest distributed from temperate to tropical regions. However, the lack of suitable markers leads to a poor knowledge of its population genetic structure and colonization process. Here we describe the first characterization of 15 microsatellite loci from this nematode, that were developed from an enriched genomic library. Although the variability of these microsatellites was generally low, three of them exhibited a significant level of intrapopulation polymorphism, with three to seven alleles detected. The observed and expected heterozygosities ranged from 0.025 to 0.385 and from 0.024 to 0.779, respectively. Thus, these new microsatellite markers have potential value for the implementation of genotyping experiments in this nematode. Furthermore, successful cross-amplification of the variable microsatellite loci in seven other Meloidogyne species provides the opportunity of using these markers for population genetic studies in these damaging plant-parasitic nematodes.     

SIMBA,a model for designing sustainable banana-based cropping systems

Banana monocultures (Musa spp., AAA, Cavendish sub-group cv. Grande Naine) can have a detrimental impact on the environment. In these agro-systems, pesticide treatments can lead to surface and groundwater pollution, as is the case in the tropical insular conditions of the French West Indies. Using models to design alternative cropping systems is of growing interest but most of the research work has been concentrated on annual crops and most often in temperate climate. A specific model called SIMBA was built to assess environmental risks under a large range of cropping techniques and to help design more sustainable cropping systems. SIMBA simulates banana-cropping systems at field level over several cropping cycles. It includes sub-models that simulate soil structure, water balance, root nematode populations, yield, and economic outputs with a sound balance between representing the major phenomena well and keeping the model simple to reduce the parameterization costs in a large range of conditions. Agro-environmental indicators generated by the model make it possible to assess the major potential environmental impacts. The model has been developed and calibrated in Guadeloupe and Martinique and is used to draw up practical recommendations for farmers and for virtual experiments of agro-technological innovations or field management strategies. The structure of SIMBA is presented and a methodology is proposed for designing sustainable banana-based cropping systems using the model. SIMBA has been evaluated in a broad range of cropping systems in Guadeloupe by comparing model estimates to data collected in field experiments and surveys. Simulations lead to trends in rotation-based cropping systems characterized by systems that can be considered as intensive for profit evaluation, and combinations of frequent replanting, low nematicide application, no ploughing, and low fertilization level, for environmental evaluation. Simulations performed to optimize the replanting decision rule showed that relatively frequent replanting is good for profit while low frequency replantations (over four banana cycles) give a better environmental evaluation.     

Effects of drought on weed emergence and growth vary with the seed burial depth and presence of a cover crop

In conservation agriculture, weed seed germination could decrease with the presence of a cover crop, surface weed seed location and temporal drought in summer just after seed shedding. This study simultaneously examined the effects of a cover crop, burial depth (seed location) and hydric stress on weed emergence and early growth. It was hypothesized that drought would reduce weed emergence and the initial growth of weed seeds and that this effect would be greater when the seeds were on the soil surface and in the presence of a cover crop. Four annual weed species were chosen that are frequently found (Anisantha sterilis, Vulpia myuros, Sonchus asper, Veronica persica) and not frequently found (Alopecurus myosuroides, Poa annua, Cyanus segetum, Capsella bursa‐pastoris) in fields that implement conservation agriculture. The unburied seeds had 26% lower emergence, on average, than the buried seeds (significant for six of the eight species), hydric stress reduced emergence by 20% (for seven of the eight species) and the presence of a cover crop reduced the level of emergence by 17% (for all species). The unburied seeds with hydric stress were emerging under the “most stressful” set of factors, with a 45% decrease in emergence, compared with the seeds emerging under the “least stressful” set of factors (buried seeds without hydric stress). All the weed growth measurements (height, dry matter content and number of leaves) decreased with the presence of a cover crop. The species that are found frequently in the fields that implement conservation agriculture, compared with the species that are not frequently found in conservation agriculture fields, had higher rates of germination and a higher tolerance of hydric stress when their seeds were unburied.     

BANAD: A farm model for ex ante assessment of agro-ecological innovations and its application to banana farms in Guadeloupe

The ex ante assessment of innovative agro-ecological innovations is a key step in the development of more sustainable crop management systems. To this end, models are useful tools because they make it possible to rapidly assess numerous innovations in different contexts. Whereas many farm optimisation models focusing on the farmer’s strategic decision to adopt new crop management systems have been published, little attention has been given to the ex ante modelling of the dynamic operational impacts of innovation adoption at the farm level. BANAD, a mechanistic model for such applications, is proposed. It allows the ex ante assessment of innovative management systems including new agro-ecological techniques, while taking into account different farming contexts and policy and market conditions. It includes three components: (i) a crop management system model, (ii) a crop model (SIMBA) and (iii) a farming system model. Our results applied to the ex ante assessment of six innovative banana management systems for three contrasted farm types in Guadeloupe showed that the impacts of agro-ecological innovations, which include rotations, improved fallow, intercropping, pest-resistant cultivar, and an integrated organic system, can vary considerably according to (i) the farm type in which the innovation is integrated, (ii) the nature of the agro-ecological innovations, and (iii) the criteria considered and the temporal horizon of the assessment. Innovative intercropping systems that were effective at the field level in terms of the yield improvement and decreased pesticide use could be problematic at the farm level because they increased the workload and decreased income. The adoption of rotations or improved fallow seemed to be relevant for smallholders but could induce a critical period of 1.5-2.5 years during which income decreased drastically. Under certain conditions of markets and subsidies, very environmentally friendly innovations that are less productive can however be economically effective.     

The Sa Pa marketplace,Lao Cai Province,Vietnam

Sa Pa market, in its current shape, is a typical mainland Southeast Asia highland market. Here, highland produce cultivated or gathered by montagnards dispersed in isolated hamlets is sold to, or exchanged with, other montagnards and lowlanders for various commodities and consumer goods. Over the last few years, a fast growing tourist influx has contributed to modifying the architecture and size of the marketplace, while the range of goods on display has increased to fit both direct and indirect tourist demand. Using historical data covering one century, this research shows that despite recent transformations, for most of the montagnards, the market in Sa Pa is still used for the same social purposes as in the past. Unequivocally, it is chiefly for the outside traders and local Kinh authorities and residents that the locally booming economy has opened new opportunities. The numbers of Kinh traders in Sa Pa town have soared to the point that they are now taking over the marketplace, both in a physical and a legal sense, leaving little space for the montagnards. Yet the question as to whether the montagnards actually ever want to carve a position for themselves in the marketplace is still open to debate.     

Quantification of Common Wheat Adulteration of Durum Wheat Pasta Using Real‐Time Quantitative Polymerase Chain Reaction (PCR)

Common wheat adulteration of durum wheat pasta was quantified using real‐time duplex polymerase chain reaction (PCR). The total DNA content of pasta was determined by amplifying part of a wheat gene encoding a lipid transfer protein, and common wheat DNA was quantified by amplifying part of the puroindoline‐b gene. Under the conditions defined by this study, for pasta with a theoretical adulteration of 3%, the experimentally determined mean value was 2.6–3.4%, depending on drying temperature. Pure durum wheat pastas were distinguished from adulterated pastas without ambiguity. This study demonstrates the feasibility of using real‐time duplex PCR to quantify common wheat adulteration of pasta dried at high temperature, quantification that was impossible with the French official peroxidase‐marker method.