Visacane, an innovative quarantine tool for the exchange of pest and disease-free sugarcane germplasm

Sugarcane varietal improvement can not exclusively rely upon exchange and introduction of genetic resources via true seeds (fuzz). It also requires the introduction of vegetative propagation material (cuttings, tissue-cultured plantlets). The continued increase in international and intercontinental trade in plants has led to the enforcement of quarantine measures before introduction into a country because many plant pathogens can be carried and transmitted by vegetatively propagated material. Visacane is the new name of Cirad's sugarcane quarantine (http://visacane.cirad.fr/en/). It covers three main quarantine procedures: detection of pests and pathogens, elimination of pests and pathogens, and transfer of plant material free of pests and pathogens. It has been devoted to sugarcane quarantining for several decades. Besides phytosanitary constraints, Visacane takes also into account legal constraints and ensures, through appropriate contracts, that plant breeders' intellectual property rights over the transferred material are respected. Unlike most sugarcane quarantines that are essentially used to import sugarcane germplasm into a country, Visacane can import and export varieties from and to most sugarcane growing countries in the world, ensuring that the material is free from any important pest and disease causing pathogen. Until recently, the sugarcane quarantine process was aimed at detecting known pathogens harbored by the plant material and eliminating these pathogens whenever possible. It is an a priori process, because it only takes into account the pathogens that have been previously described and for which efficient detection tools exist. During the last three decades, several new viruses infecting sugarcane have been discovered, including Sugarcane bacilliform virus, Sugarcane yellow leaf virus, Sugarcane streak mosaic virus and the virus associated with Ramu stunt. In addition, the etiology of chlorotic streak, a disease known since 1929, has not been elucidated so far, although there is evidence for its infectious nature. Therefore, it can be assumed that unknown pathogens are still to be discovered in sugarcane, especially if these pathogens do not cause symptoms that can be easily observed. For these reasons, the research team associated with Visacane is setting up a new strategy of diagnostics, the so-called sequence-independent approach which aims at deciphering the virome (= the genomes of all the viruses that inhabit a particular organism). We believe that our forthcoming combined process, that will include our traditional approaches in addition to the metagenomics approach, will drastically improve our routine quarantine diagnostics. (Texte intégral

L'enseignement de concept de "parenté" au regard de la démarche expérimentale

International audienceL'analyse de l'enseignement de l'évolution en classe de terminale scientifique dans les lycées français met en lumière certaines limites de la méthodologie actuelle de l'enseignement des sciences. La " démarche expérimentale " préconisée comme fondement de cet enseignement peut apparaître comme un obstacle quand il s'agit d'enseigner une théorie qui ne s'inscrit pas seulement dans le cadre d'une science expérimentale et ne relève pas de la seule interprétation des faits d'observations. Cette difficulté méthodologique n'est pas questionnée et c'est pourtant là un problème majeur de l'enseignement des sciences. Une première analyse des réponses à un questionnaire sur l'évolution et des fiches d'activités proposées aux élèves sur la phylogénie permet à la fois de repérer des confusions épistémologiques importantes chez les apprenants et de questionner l'implication de la démarche d'enseignement choisie pour cette activité

Visacane, the Cirad quarantine tool for the exchange of pest and disease-free sugarcane germplasm

Sugarcane varietal improvement requires the introduction of vegetative propagation material. The continued increase of international and intercontinental trade of plants has led to the enforcement of quarantine measures in many countries before the introduction of vegetatively propagated material because many plant pathogens can be carried and transmitted by them. Visacane is the CIRAD's sugarcane quarantine (http://visacane.cirad.fr/en/). Visacane has been devoted to sugarcane quarantining for several decades. It covers detection of pests and pathogens, elimination of pests and pathogens, and transfer of plant material free of pests and pathogens. Besides phytosanitary constraints, this quarantine structure also takes into account legal constraints and ensures that plant breeders' intellectual property rights over the transferred material are respected. Visacane can import and export varieties from and to most sugarcane growing countries in the world, ensuring that the material is free from any well-known important pest and disease causing agent. Because it is integrated into a pathology research unit studying various aspects of plant-pathogen interactions, and thanks to its collaborations within a network of sugarcane technologists, Visacane can regularly update its expertise and propose plant material exhibiting the best possible phytosanitary quality. (Résumé d'auteur

Valorisation des actions du Cirad sur la canne à sucre : acquis, forces et faiblesses dans un contexte économique difficile

La filière canne à sucre rassemble une quantité importante d'acteurs : grands groupes industriels, associations privées de recherche, ONG (sucre éthique), usines sucrières, groupements de planteurs, centres de formation, etc. La recherche " canne " Cirad a été jusqu'à maintenant très " tirée " par la demande des industriels et des planteurs. Cette filière ne dispose pas de centres internationaux de recherche (CGIARs) comme d'autres plantes (maïs, sorgho, riz...), ce qui donne un caractère particulier aux recherches sur la canne, essentiellement effectuées dans des centres de recherche adossés aux industries sucrières des pays producteurs. En France, il y a un dispositif unique intégrant la quarantaine " Visacane ", les variétés (Cirad et eRcane) et l'expertise agronomique acquise par le Cirad depuis les années 60. Cette expertise est sollicitée dans tous les domaines scientifiques par nos partenaires habituels francophones et depuis quelques années anglophones. Depuis 2007, les demandes d'appui aux pays ACP de l'Union Européenne se sont multipliées suite à la réforme du prix du sucre. Des restructurations du secteur sucrier dans ces pays ont généré des expertises relayées par les cabinets de consultants sur l'économie et les procédés industriels et la recherche agronomique. Cependant le paysage de la recherche en France a beaucoup évolué et le Cirad est passé d'un stade d'institut technique pour le développement à celui d'un véritable centre de recherche où la science a pris progressivement le pas sur l'expertise. Dans un contexte de crise mondiale et européenne, il est montré dans cet article comment un organisme comme le Cirad s'adapte aux défis de recherche sur les filières comme la canne à sucre, les atouts dont il dispose et la stratégie qu'il peut mettre en oeuvre face aux nécessaires changements et évolution de la recherche internationale. (Résumé d'auteur

Scheduling aircraft landings - the static case

This is the publisher version of the article, obtained from the link below.In this paper, we consider the problem of scheduling aircraft (plane) landings at an airport. This problem is one of deciding a landing time for each plane such that each plane lands within a predetermined time window and that separation criteria between the landing of a plane and the landing of all successive planes are respected. We present a mixed-integer zero–one formulation of the problem for the single runway case and extend it to the multiple runway case. We strengthen the linear programming relaxations of these formulations by introducing additional constraints. Throughout, we discuss how our formulations can be used to model a number of issues (choice of objective function, precedence restrictions, restricting the number of landings in a given time period, runway workload balancing) commonly encountered in practice. The problem is solved optimally using linear programming-based tree search. We also present an effective heuristic algorithm for the problem. Computational results for both the heuristic and the optimal algorithm are presented for a number of test problems involving up to 50 planes and four runways.J.E.Beasley. would like to acknowledge the financial support of the Commonwealth Scientific and Industrial Research Organization, Australia

Body composition changes, metabolic fuel use and energy expenditure during extended fasting in subantarctic fur seal (Arctocephalus tropicalis) pups at Amsterdam Island

The fasting metabolism of 71- to 235-d-old subantarctic fur seal (Arctocephalus tropicalis) pups from Amsterdam Island, southern Indian Ocean, was investigated during the long foraging trips of their mothers. Body lipid reserves were proportionally greater in female than male pups and higher in postmoult (37%) than premoult (10%) animals. The mass-specific rate of mass loss did not differ between the sexes but was lower than observed in other species. Daily mass loss was estimated to 56% fat, 10% protein, and 34% water. The rate of protein catabolism (15 g d&minus;1) was negatively related to the size of initial lipid stores and accounted for 9% (&plusmn;1%) of total energy expenditure. However, body composition changes during the fast were not equal between the sexes, with females relying more on protein catabolism than males (11% and 5% of total energy expenditure, respectively). Energy expenditure (270 kJ kg&minus;1 d&minus;1) and metabolic water production (11.5 mL kg&minus;1 d&minus;1) rates are the lowest reported for an otariid species. These results suggest that subantarctic fur seal pups greatly reduce activity levels to lower energy expenditure in addition to adopting protein-sparing metabolic pathways in order to survive the extreme fasts they must endure on Amsterdam Island.<br /

La conférence électronique Ager sur l'agronomie au Cirad : principaux apports et propositions : Synthèse des débats (4 octobre-19 novembre 1999)

Cette synthèse s'articule autour de cinq grands thèmes : les grands enjeux, l'adaptation au contexte et les priorités ; la structuration du champ scientifique Ager et les contenus des différents domaines ; la pluriactivité de l'agronome au Cirad ; l'activité de formation ; l'animation scientifiqu

Ontogeny of body size and shape of Antarctic and subantarctic fur seals

Pre- and post-weaning functional demands on body size and shape of mammals are often in conflict, especially in species where weaning involves a change of habitat. Compared with long lactations, brief lactations are expected to be associated with fast rates of development and attainment of adult traits. We describe allometry and growth for several morphological traits in two closely related fur seal species with large differences in lactation duration at a sympatric site. Longitudinal data were collected from Antarctic (Arctocephalus gazella (Peters, 1875); 120 d lactation) and subantarctic (Arctocephalus tropicalis (Gray, 1872); 300 d lactation) fur seals. Body mass was similar in neonates of both species, but A. gazella neonates were longer, less voluminous, and had larger foreflippers. The species were similar in rate of preweaning growth in body mass, but growth rates of linear variables were faster for A. gazella pups. Consequently, neonatal differences in body shape increased over lactation, and A. gazella pups approached adult body shape faster than did A. tropicalis pups. Our results indicate that preweaning growth is associated with significant changes in body shape, involving the acquisition of a longer, more slender body with larger foreflippers in A. gazella. These differences suggest that A. gazella pups are physically more mature at approximately 100 d of age (close to weaning age) than A. tropicalis pups of the same age<br /