Search

Using the yeast two-hybrid system, a screen was performed for possible interactions between the proteins encoded by the 5′ region of potyviral genomes [P1, helper component-proteinase (HC-Pro), and P3]. A positive self-interaction involving HC-Pro was detected with lettuce mosaic virus (LMV) and potato virus Y (PVY). The possibility of heterologous interaction between the HC-Pro of LMV and of PVY was also demonstrated. No interaction involving either the P1 or the P3 proteins was detected. A series of ordered deletions from either the N- or C-terminal end of the LMV HC-Pro was used to map the domain involved in interaction to the 72 N-terminal amino acids of the protein, a region known to be dispensable for virus viability but necessary for aphid transmission. A similar but less detailed analysis mapped the interacting domain to the N-terminal half of the PVY HC-Pro.

The effects of coca chewing on prolonged submaximal exercise responses were investigated in chronic coca chewers and compared with a group of nonchewers. At rest, coca chewing during a 1-h period was followed by a significant increase in blood glucose, free fatty acid, and norepinephrine concentrations and a significant reduction in insulin plasma level. During prolonged (1-h) submaximal (65-70% peak O2 uptake) exercise, chewers displayed a significantly greater adrenergic activation (as evidenced by a higher level of plasma epinephrine) and an increased use of fat (as evidenced by a lower respiratory exchange ratio). The gradual increase in oxygen uptake (O2 drift) commonly observed during prolonged exercise was blunted in coca chewers. This blunting in O2 drift is not related to coca-induced changes in ventilatory or lactate responses to exercise but could possible be related to an enhanced glucose utilization by chewers during the late phase of exercise. The present results provide experimental evidence of the physiological effects of coca chewing that could explain the better ability of coca users to sustain strenuous work for an extended period of time.

We argue that kava (Piper methysticum Forst. f.) is a Pacific domesticate that originated in Melanesia. We provide botanical, chemical, genetic and cultural evidence to suggest that farmers in the northern part of Vanuatu were the first to select the species as an asexually reproduced root crop. From Vanuatu, cultivars were carried eastward into Polynesia and westward into areas of New Guinea and Micronesia. Using herbarium data, isozyme and AFLP markers, we correlate the information gained from field surveys to HPLC analyses and attempt to demonstrate that chemotypes result from a selection process that is still active. The selection of particular mutants by farmers must have been. and still is, a rational process to preserve new characters when they appeared. Growers have selected cultivars to improve the chemical composition responsible for the physiological effects. Field experiments demonstrate that the chemotype is genetically controlled although the kavalactones content is determined by both genetics and environmental factors. The control and improvement of quality is therefore a cultural approach that aims at the identification of locations suitable for the cultivation of particular kava varieties. The appreciation of quality, appears to reflect the different cultures within Melanesia and between Micronesian, Polynesian and Melanesian consumers. Different ways of benefiting from the psychoactive properties of the plant explain the use of particular chemotypes and therefore the selection operated to preserve them. Clearly, the word kava refers to different beverages that produce different physiological effects according to what consumers desire.

This paper discusses the reasons for and effects of the dramatic expansion of chat production as a cash crop in the Hararghe Highlands of Ethiopia. Despite the Ministry of Agriculture's deliberate attempt to discourage chat production, farmers continue to shift their scarce resources into chat production. Using data generated by a rural livelihood survey front 197 randomly selected households, economic and non-economic factors contributing to the expansion of chat production are identified and its food and nutritional security impact analysed. The case study confirms once more the power of market incentives in encouraging agricultural activity of peasant farmers even in the absence of functional research and extension systems. The case study shows that households producing chat have good food security status and thus the situation presents a policy dilemma: Should the government promote or discourage chat production?

International audience; Résumé — La plante. Le guaraná (Paullinia Cupana var. sorbilis (Mart.) Ducke) est uneplante d’Amazonie qui appartient à la famille des sapindacées. Son fruit rouge est très richeen caféine (environ 4 g ´ 100 g–1 dans la graine). Auparavant exploité dans l’état d’Amazonas,le guaraná est aussi cultivé aujourd’hui dans d’autres états du Brésil. Valorisation. Traditionnellementconsommés par les Indiens Maués d’Amazonie, les fruits sont transformés à l’échellesemi-industrielle et industrielle. La graine est largement utilisée par l’agro-industrie et l’industriepharmaceutique. Divers produits de qualités différentes sont ainsi obtenus essentiellementsous forme de bâton, de poudre ou d’extrait alcoolique pour l’élaboration de boissonsgazeuses. Marché. La production de guaraná ne parvient pas à faire face à la demande mondialecroissante. En effet, les producteurs sont mal organisés, les rendements de productionsont peu élevés et les prix de vente restent faibles. Conclusion. L’obtention par clonage denouveaux plants de Paullinia Cupana plus performants et plus résistants devrait permettre auguaraná de s’affirmer sur le marché international.

The purpose of the present study was to determine the amount of cocaine and benzoylecgonine in the plasma of Aymara Indians from the Bolivian Andes after traditional chewing of coca leaves during exercise performance. The determination was carried out by high performance liquid chromatography after solid-liquid extraction. The results showed that such use of coca leaves is well correlated with pharmacologically active concentration of cocaine in plasma.

We examined the effects of 1 h of coca chewing on metabolic and hormonal responses during incremental exercise to exhaustion in traditional coca chewers (C; n = 8), and the results were compared with a group of nonchewers (n = 13). For 1 h, C chewed approximately 12 g of coca leaves that resulted in the apparition of cocaine in blood that reached 72 +/- 9 ng/ml. In resting conditions, even though sympathoadrenergic activity (as assessed by norepinephrine and epinephrine plasma levels) was similar in both groups, C displayed a higher level of plasma free fatty acids. Oxygen uptake measured at exhaustion and delta work efficiency during exercise were similar in both groups. During the incremental exercise, C displayed a significantly lower arterial oxygen saturation that cannot be explained by a reduced ventilatory response after coca chewing. In fact, even at maximal exercise, both ventilatory output and ventilatory equivalent were higher in C compared with nonchewers. It is concluded that the beneficial effects of coca chewing on exercise tolerance reported frequently by traditional coca users is not related to either an improved maximal exercise capacity or an increased work efficiency. However, during incremental exercise, coca chewing appeared to result in an increased free fatty acid availability that could be beneficial for prolonged submaximal exercise.

Summarizes the literature and research on kava's botany, chemistry, ethnobotany, pharmacology, social usage, distribution and economic potential. The information should provide insights for researchers in many different disciplines, including prehistory, anthropology and pharmacology.

Le CIRAD, Centre de coopération internationale en recherche agronomique pour le développement, est un organisme scientifique spécialisé en agriculture des régions tropicales et subtropicales. Sous la forme d'un établissement public, il est né, en 1984, de la fusion d'instituts de recherche en sciences agronomiques, vétérinaires, forestières et agro-alimentaires des régions chaudes. Sa mission : contribuer au développement de ces régions par des recherches, des réalisations expérimentales, la formation, l'information scientifique et technique. Il emploie 1 900 personnes, dont 900 cadres, qui interviennent dans une cinquantaine de pays. Son budget s'élève à près de 1 milliard de francs, dont plus de la moitié provient de fonds publics. Le CIRAD travaille dans ses propres centres de recherche, au sein de structures nationales de recherche agronomique des pays partenaires, ou en appui à des opérations de développement. Le rapport d'activité 1988 rassemble les contributions de chacun des départements et en souligne les résultats marquants

Cette mission, réalisée du 1er février au 6 mai 1971, avait les buts suivants : 6 2TUDIER LES CONDITIONS DE MANUTENTION, S2CHAGE, STOCKAGE ET CONSERVATI

The 5′ noncoding region (NCR) of grapevine chrome mosaic nepovirus (GCMV) was cloned in a viral vector derived from potato virus X (PVX). The recombinant virus obtained was inoculated to Nicotiana benthamiana, N. clevelandii, and N. tabacum plants. Infected plants developed necrotic symptoms in place of the vein clearing and mosaic typically observed after inoculation with PVX. Northern (RNA) blot analysis showed that the replication of PVX was not specifically altered by the presence of the GCMV 5′ NCR. Inoculation of recombinant PVX harboring deleted forms of the GCMV 5′ NCR showed that the three stem-loop structures at the 3′ end of the 5′ NCR (nucleotides 153 to 206) are dispensable for the induction of necrosis. Further deletion analysis indicated that neither the 5′-most 70 nucleotides of the 5′ NCR nor the downstream region (nucleotides 71 to 217) alone is able to induce the necrotic symptoms. In the presence of both the sequence encoding the GCMV coat protein and the GCMV 3′ NCR, the GCMV 5′ NCR failed to induce necrosis in the PVX background. The mechanisms by which the expression of the 5′ NCR might modify PVX symptoms are discussed.