Etude du comportement morphologique sous deficit hydrique de categories de palmier a huile(Elaeis guineensis Jacq.) en phase juvenile

L’une des voies préconisées pour augmenter la production de l’huile de palme est l’élargissement de l’espace culturale du palmier à huile. L’élargissement de ce espace culturale va conduire à exploiter les zones à déficit hydrique. Il devient nécessaire de détecter des catégories de palmiercapables de réaliser leur cycle dans ces zones de culture. Le matériel de l’essai réalisé à la station de la Me se compose de 150 plants de 4 mois, de 5 catégories de palmier. Le schéma expérimental est un bloc de Fisher de deux facteurs à cinq niveaux différents : le matériel végétal (5 catégories) et les traitements hydriques (5 traitements) durant 45 jours sous serre. La valeur témoin de 725 ml est la capacité de rétention en eau de 3500 g de terre d’un sachet. Les déficits hydriques sont obtenus par la réduction graduelle de la valeur témoin : 725ml (100 %), 544 ml (75 %), 363 ml (50 %), 73 ml (10 %). Les paramètres étudiés (longueur racine, poids, hauteur et circonférence au collet des plants) ont été affectés à chaque niveau de déficit hydrique. Aux sévères déficits, la baisse du poids, la hauteur et la circonférence au collet des catégories en comparaison avec le témoin est élevée pour C1001, C2501, faible pour C1001F, C2401, C7001. L’adaptation des racines aux sévères déficits est développée chez C1001F, C2401, C7001. L’analyse de la variation des valeurs des paramètres montre une bonne tolérance au déficit hydrique des catégories C1001F, C7001, C2401.Cette étude permettant de distinguer  morphologiquement des catégories tolérantes au déficit hydrique, sertd’étude préliminaire à la détection de catégories tolérantes au déficit  hydrique.Mots clés : Elaeis guineensis, déficit hydrique, tolérance, poids, racine, hauteur, circonférence au collet. English Title: Morphological behavior under water deficit of five categories of oil palm (Eleais guineensis jacq</i>.) in the juvenile phaseThe climatic factors such as insufficient rainfall limit the cultivation of oil palm. It is therefore important for the stability of elaeis culture to detect at a young age, categories of palms tolerant to drought. The material in our research consists of 150 seedlings of 4 months, come from five categories of palms. The experimental set-up is a Fisher block allowing the study of two factors at five different levels : plant material (five categories) and water treatments (5 treatments) during a period of 45 days under a greenhouse. The witness value of 725 ml is the water retention capacity of 3500 g of soil of a sachet. Water deficits are obtained by the gradual reduction of the control value : 725 ml (100%), 544 ml (75%), 363 ml (50%), 181 ml (25%), 73 ml (10%). The parameters studied (weight, root, height, collar circumference of plants) were assigned to each level of water deficit. At severe water deficit, the weight losses, The reduction of the height and the circumferentiel collar are high in the C1001 and C 2501and weak for the C 1001F, C 2401 and C 7001 category. Root adaptation to severe deficits is developed in C 1001F, C 2401, C 7001. The analysis of the variations of the values of the parameters under the action of the water stress showed us that the categories C1001F, C 7001 and C 2401 had a fairly developed a tolerance to the water deficit. These results are interest because they make it possible at young age to morphologically distinguish categories that are tolerant to drought.Key words: Elaeis guineensis, oil palm, water deficit, categories, parameter, weight, root, growth, collar circumference

Combining ability for grain yield, agronomic traits and striga hermonthica resistance of yellow endosperm maize

Open Access Article; Published online: 17 Aug 2018Maize production is constrained by Striga hermonthica in Mali leading to high yield losses. Breeding resistant hybrid maize is a promising alternative for increasing farmers’ income. The objective of this study was to evaluate the response of test crosses to Striga hermonthica and identify high yielding and adopted hybrid. Forty-five F1 hybrids and three checks were evaluated under Striga-infested and Striga-free conditions in Sanankoroba and Sotuba rainy season. Data collection was carried on grain yield, anthesis silking interval, plant aspect, plant height, days to 50% tasselling and silking, Striga damage ratings and Striga count at 8 and 10 weeks after planting. General combining ability (GCA) of line and Specific combining ability (SCA) of hybrids effects were significant for most traits under both conditions. GCA effects had greater proportion of variance than SCA effects suggesting additive gene effects controlling the inheritance of yield and Striga resistance. Parental lines TZISTR112, TZISTR1214, TZISTR1222, TZISTR1223, tester TZISTR1207 and TZISTR106 were the best combiner for grain yield under both conditions and they could be used in hybrid development

Different Plasmodium falciparum clearance times in two Malian villages following artesunate monotherapy.

BACKGROUND: Artemisinin resistance described as increased parasite clearance time (PCT) is rare in Africa. More sensitive methods such as qPCR might better characterize the clearance phenotype in sub-Saharan Africa. METHODS: PCT is explored in Mali using light microscopy and qPCR after artesunate for uncomplicated malaria. In two villages, patients were followed for 28 days. Blood smears and spots were collected respectively for microscopy and qPCR. Parasitemia slope half-life was calculated after microscopy. Patient residual parasitemia were measured by qPCR. RESULTS: Uncorrected adequate clinical and parasitological responses (ACPR) observed in Faladje and Bougoula-Hameau were 78% and 92%, respectively (p=0.01). This reached 100% for both after molecular correction. Proportions of 24H microscopy positive patients in Faladje and Bougoula-Hameau were 97.2% and 72%, respectively (p<0.0001). Slope half-life was 2.8h in Faladje vs 2H in Bougoula-Hameau (p<0.001) and Proportions of 72H patients with residual parasitemia were 68.5% and 40% in Faladje and Bougoula-Hameau, respectively (p=0.003). The mean residual parasitemia was 2.9 in Faladje vs. 0.008 in Bougoula-Hameau (p=0.002). Although artesunate is efficacious in Mali, the longer parasite clearance time with submicroscopic parasitemia observed may represent early signs of developing P. falciparum resistance to artemisinins

Differential infectivity of gametocytes after artemisinin-based combination therapy of uncomplicated falciparum malaria

Background: Most malaria-endemic countries use artemisinin-based combination therapy (ACT) as their first-line treatment. ACTs are known to be highly effective on asexual stages of the malaria parasite. Malaria transmission and the spread of resistant parasites depend on the infectivity of gametocytes. The effect of the current ACT regimens on gametocyte infectivity is unclear. Objectives: This study aimed to determine the infectivity of gametocytes to Anopheles gambiae following ACT treatment in the field. Methods: During a randomised controlled trial in Bougoula-Hameau, Mali, conducted from July 2005 to July 2007, volunteers with uncomplicated malaria were randomised to receive artemether-lumefantrine, artesunate-amodiaquine, or artesunate-sulfadoxine/pyrimethamine. Volunteers were followed for 28 days, and gametocyte carriage was assessed. Direct skin feeding assays were performed on gametocyte carriers before and after ACT administration. Results: Following artemether-lumefantrine treatment, gametocyte carriage decreased steadily from Day 0 to Day 21 post-treatment initiation. In contrast, for the artesunate-amodiaquine and artesunate-sulfadoxine/pyrimethamine arms, gametocyte carriage increased on Day 3 and remained constant until Day 7 before decreasing afterward. Mosquito feeding assays showed that artemether-lumefantrine and artesunate-amodiaquine significantly increased gametocyte infectivity to Anopheles gambiae sensu lato (s.l.) (p < 10−4), whereas artesunate-sulfadoxine/pyrimethamine decreased gametocyte infectivity in this setting (p = 0.03). Conclusion: Different ACT regimens could lead to gametocyte populations with different capacity to infect the Anopheles vector. Frequent assessment of the effect of antimalarials on gametocytogenesis and gametocyte infectivity may be required for the full assessment of treatment efficacy, the potential for spread of drug resistance and malaria transmission in the field

The effect of latency on bone lengthening force and bone mineralization: an investigation using strain gauge mounted on internal distractor device

BACKGROUND: The purpose of this study was to investigate the effect of latency on the development of bone lengthening force and bone mineralization during mandible distraction osteogenesis. METHODS: Distraction tensions were investigated at different latency period in 36 rabbits using internal unilateral distractor. Strain gauges were prepared and attached to the distractor to directly assess the level of distraction tension during mandible lengthening. The tensile force environment of the mandible of rabbit during distraction was evaluated through in vivo experiments using two gauges. The animals were divided into 3 groups each containing 12 rabbits. Latency periods of 0, 4 and 7 days respectively were observed prior to beginning distraction. The distraction protocol consisted of a lengthening rate of 1 mm once daily for 8 days, followed by a consolidation phase of 2 weeks after which the animals were killed. Biopsies specimens were taken from the distracted area at the end of the distraction period. A non-distracted area of the mandible bone served as control. The specimens were analyzed by scanning electron microscopy to assess the ultrastructural pattern, and the bone mineralization. RESULTS: The resting tension acting on the distraction gap increases through distraction. The 7-day latency groups exhibit higher tension then those of 0-day and 4-days latency groups. Quantitative energy dispersive spectral analysis confirmed that immediate distractions were associated with lower calcium and phosphate atomic weight ratio. CONCLUSION: the latency periods could affect the bone lengthening tension and the bone mineralization process

Evaluation and optimization of membrane feeding compared to direct feeding as an assay for infectivity

<p>Abstract</p> <p>Background</p> <p>Malaria parasite infectivity to mosquitoes has been measured in a variety of ways and setting, includind direct feeds of and/or membrane feeding blood collected from randomly selected or gametocytemic volunteers. <it>Anopheles gambiae s.l </it>is the main vector responsible of <it>Plasmodium falciparum </it>transmission in Bancoumana and represents about 90% of the laboratory findings, whereas <it>Plasmodium malariae </it>and <it>Plasmodium ovale </it>together represent only 10%.</p> <p>Materials and methods</p> <p>Between August 1996 and December 1998, direct and membrane feeding methods were compared for the infectivity of children and adolescent gametocyte carriers to anopheline mosquitoes in the village of Bancoumana in Mali. Gametocyte carriers were recruited twice a month through a screening of members of 30 families using Giemsa-stained thick blood smears. F1 generation mosquitoes issued from individual female wild mosquitoes from Bancoumana were reared in a controlled insectary conditions and fed 5% sugar solution in the laboratory in Bamako, until the feeding day when they are starved 12 hours before the feeding experiment. These F1 generation mosquitoes were divided in two groups, one group fed directly on gametocyte carriers and the other fed using membrane feeding method.</p> <p>Results</p> <p>Results from 372 <it>Plasmodium falciparum </it>gametocyte carriers showed that children aged 4–9 years were more infectious than adolescents (p = 0.039), especially during the rainy season. Data from 35 carriers showed that mosquitoes which were used for direct feeding were about 1.5 times more likely to feed (p < 0.001) and two times more likely to become infected, if they fed (p < 0.001), than were those which were used for membrane feeding. Overall, infectivity was about three-times higher for direct feeding than for membrane feeding (p < 0.001).</p> <p>Conclusion</p> <p>Although intensity of infectivity was lower for membrane feeding, it could be a surrogate to direct feeding for evaluating transmission-blocking activity of candidate malaria vaccines. An optimization of the method for future trials would involve using about three-times more mosquitoes than would be used for direct feeding.</p