Heterosis Increases Fertility, Fecundity and Survival of Laboratory-Produced F1 Hybrid Males of the Malaria Mosquito Anopheles coluzzii

The success of vector control strategies aiming to decrease disease transmission via the release of sterile or genetically-modified male mosquitoes critically depends on mating between laboratory-reared males and wild females. Unfortunately, mosquito colonization, laboratory rearing, and genetic manipulations can all negatively affect male competitiveness. Heterosis is commonly used to produce domestic animals with enhanced vigor and homogenous genetic background and could therefore potentially improve the mating performance of mass-reared male mosquitoes. Here, we produced enhanced hybrid males of the malaria mosquito Anopheles coluzzii by crossing two strains colonized 35+ and 8 years ago. We compared the amount of sperm and mating plug proteins they transferred to females, as well as their insemination rate, reproductive success and longevity under various experimental conditions. Across experiments widespread adaptations to laboratory mating were detected in the older strain. In large-group mating experiments, no overall hybrid advantage in insemination rates and the amount of sperm and accessory gland proteins transferred to females was detected. Despite higher sperm activity, hybrid males did not appear more fecund. However, individual-male mating and laboratory-swarm experiments revealed that hybrid males, while inseminating fewer females than older inbred males, were significantly more fertile, producing larger mating plugs and drastically increasing female fecundity. Heterotic males also showed increased longevity. These results validate the use of heterosis for creating hybrid males with improved fitness from long-established inbred laboratory strains. Therefore, this simple approach could facilitate disease control strategies based on male mosquito releases with important ultimate benefits to human health

Target-site resistance mutations (kdr and RDL), but not metabolic resistance, negatively impact male mating competiveness in the malaria vector Anopheles gambiae

The implementation of successful insecticide resistance management strategies for malaria control is currently hampered by poor understanding of the fitness cost of resistance on mosquito populations, including their mating competiveness. To fill this knowledge gap, coupled and uncoupled Anopheles gambiae s.l. males (all M form (Anopheles coluzzii)) were collected from mating swarms in Burkina Faso. This multiple insecticide resistant population exhibited high 1014F kdrR allele frequencies (460%) and RDLR (480%) in contrast to the Ace-1R allele (o6%). Kdr heterozygote males were more likely to mate than homozygote resistant (OR=2.36; Po0.001), suggesting a negative impact of kdr on An. coluzzii mating ability. Interestingly, heterozygote males were also more competitive than homozygote susceptible (OR=3.26; P=0.006), suggesting a heterozygote advantage effect. Similarly, heterozygote RDLR/RDLS were also more likely to mate than homozygote-resistant males (OR=2.58; P=0.007). Furthermore, an additive mating disadvantage was detected in male homozygotes for both kdr/RDL-resistant alleles. In contrast, no fitness difference was observed for the Ace-1 mutation. Comparative microarray-based genome-wide transcription analysis revealed that metabolic resistance did not significantly alter the mating competitiveness of male An. coluzzii mosquitoes. Indeed, no significant difference of expression levels was observed for the main metabolic resistance genes, suggesting that metabolic resistance has a limited impact on male mating competiveness. In addition, specific gene classes/GO terms associated with mating process were detected including sensory perception and peroxidase activity. The detrimental impact of insecticide resistance on mating competiveness observed here suggests that resistance management strategies such as insecticide rotation could help reverse the resistance, if implemented early

Food Insecurity and Psychological Well-Being Among Women Living with HIV/AIDS on Antiretroviral Therapy in the Alabama Black Belt

The objective of this research was to estimate the prevalence of food insecurity and determine if food insecurity is associated with psychological well-being among women living with HIV/AIDS. Survey data were collected from 268 women living with HIV/AIDS attending two clinics that provide medical and social support services to HIV-positive patients who live in 23 counties in Southeast Alabama. The results indicated that, using USDA food security scale, 54% of the women were food insecure. Multiple regression analysis results indicated that income, depressive symptoms, race, and participation in SNAP were significant predictors of food insecurity; employment and education were not statistically significant predictors. The overall model was significant at the 5% level reflecting the validity of the model. Based on these results, programs that address food insecurity should be a critical component of HIV/AIDS treatment in the Alabama Black Belt

Factors Associated with Belief in Conspiracies about HIV/AIDS among HIV-Positive African-American Patients

Abstract The purpose of this study is to examine factors associated with belief in conspiracies about HIV/AIDS among HIV-Positive African American patients. Survey data were collected from 256 African American patients living with HIV/AIDS attending two HIV clinics in Montgomery and Dothan, Alabama. The study used multiple regression analysis to examine how sociodemographic factors contribute to belief in conspiracies about HIV/AIDS. Education and age were significantly related to belief in conspiracies about HIV/AIDS among men and women. Beliefs in conspiracies about HIV/AIDS may be a barrier to HIV prevention among African Americans. Public health officials should work toward obtaining the trust of African Americans by addressing the existing discrimination within the health care system and acknowledging the existence of HIV/AIDS conspiracy beliefs. Conspiracies about HIV/AIDS may be a manifestation to African Americans’ mistrust of the U.S. government and the health system. Keywords: HIV/AIDS, African Americans, Conspiracy Belief

Negative Cross Resistance Mediated by Co-treated bed nets: A Potential Means of Restoring Pyrethroid-susceptibility to Malaria Vectors.

Insecticide-treated nets and indoor residual spray programs for malaria control are entirely dependent on pyrethroid insecticides. The ubiquitous exposure of Anopheles mosquitoes to this chemistry has selected for resistance in a number of populations. This threatens the sustainability of our most effective interventions but no operationally practicable way of resolving the problem currently exists. One innovative solution involves the co-application of a powerful chemosterilant (pyriproxyfen or PPF) to bed nets that are usually treated only with pyrethroids. Resistant mosquitoes that are unaffected by the pyrethroid component of a PPF/pyrethroid co-treatment remain vulnerable to PPF. There is a differential impact of PPF on pyrethroid-resistant and susceptible mosquitoes that is modulated by the mosquito's behavioural response at co-treated surfaces. This imposes a specific fitness cost on pyrethroid-resistant phenotypes and can reverse selection. The concept is demonstrated using a mathematical model

Evaluation de l’introgression du caractère croissance lente de quelques géniteurs Akpadanou (origine Bénin) chez quelques géniteurs améliorés de palmier à huile (E. guineensis Jacq.) de l’origine La Mé (Côte d’Ivoire)

La vitesse de croissance en hauteur de 294 arbres appartenant à 11 descendances de palmier à huile a été évaluée selon la méthode décrite par Jacquemard (1980). Ces descendances ont été obtenues à partir de plusieurs croisements de type (AKN3 x La Mé) x La Mé et (AKN3 x La Mé) x (La Mé x La Mé) qui visaient à introduire le caractère croissance lente de l’origine Akpadanou (Benin) chez des géniteurs améliorés de l’origine La Mé, Côte d’Ivoire. Les descendances ont été comparées à un témoin vulgarisé de type DA10D x LM2T. Les résultats ont montré que l’ensemble des descendances testées ont une vitesse de croissance en hauteur moyenne inférieure au témoin. En effet, les valeurs obtenues ont varié de 19,86 à 35,89 cm/an au sein de ces descendances testées, contre 45,25 cm/an pour le témoin de l’essai. Une réduction de plus de 20% de la vitesse de croissance en hauteur a donc été observée au niveau de ces descendances. Ces résultats laissent entrevoir la perspective de sélection, à terme, de matériel végétal à croissance en hauteur fortement réduite et possédant un bon niveau de production de régimes et d’huile de palme.Mots clés : Sélection, palmier amélioré, croissance en hauteur réduite

Inhibitive effects of 2-mercaptobenzimidazole (MBI) and 2-thiobenzylbenzimidazole (TBBI) on copper corrosion in 1 M nitric acid solution

The inhibitive actions of 2-mercaptobenzimidazole (MBI) and 2-thiobenzylbenzimidazole (TBBI) on copper corrosion in 1M HNO3 medium were studied, using weight loss method, at 25 to 65°C and concentrations of 5.10-5M to 10-3M. The results showed that the two compounds had fairly good inhibiting properties for copper corrosion in the medium, with efficiencies of 90.0% for TBBI and 87.7% for MBI at 25°C and concentration of 10-3M. Modified Langmuir isotherm was found to provide an accurate description of the behavior of the two compounds. The thermodynamic functions of adsorption (ΔG°ads,Qads) and the activation energy (Ea) were calculated. Negative values of changes in free energies were obtained, indicating the spontaneity of the adsorption process. From thermodynamic adsorption and dissolution functions, both physisorption and chemisorption were proposed. Quantum chemical parameters such as highest occupied molecular orbital energy (EHOMO), lowest unoccupied molecular orbital energy (ELUMO), energy gap (ΔE) and dipole moment (μ) were calculated for these compounds, using DFT/B3LYP/6-31G (d,p) method in order to discuss the correlation between theoretical data and experimental results. It was found that theoretical data support the experimental results.Key words: Corrosion Inhibitor, inhibition efficiency, adsorption isotherm, free adsorption energy, adsorption heat, theoretical calculation, dipole moment

Étude de l’influence du facteur antécédent cultural palmiers et cocotiers sur l’évolution de la fusariose vasculaire chez six clones de palmiers à huile de Côte d’Ivoire

Objectif : La fusariose vasculaire du palmier à huile, causée par le champignon Fusarium oxysporum f.sp. elaeidis, est une contrainte pathologique majeure pour la culture du palmier à huile en Afrique, notamment en Côte d’Ivoire. Dans la zone dite « savane de Dabou », en Côte d’Ivoire où la maladie sévit de manière endémique, les travaux de recherche de lutte intégrée à la fusariose, ont été réalisés dans le cadre de cette étude sur des parcelles à antécédent cultural cocotier ou palmier. Aussi, notre étude a-t-elle pour objectif général de confirmer les résultats de recherche obtenus pour l’amélioration du matériel végétal en vue de minimiser l’impact de la fusariose en Côte d’Ivoire. Spécifiquement, il s’est agi d’étudier l’évolution de la fusariose d’une part, et d’analyser cette évolution selon l’antécédent cultural d’autre part.Méthodologie et résultats : L’étude a porté sur l’observation des symptômes de fusariose cumulée et du taux de rémission de la fusariose des plants de palmier plantés de 1990 à 2013 sur antécédents cocotiers et palmers fusariés. Ainsi, pour la première fois, nos résultats révèlent que les palmiers replantés sur antécédents cocotiers manifestent plus rapidement la fusariose que ceux plantés sur antécédents palmiers. Il est donc possible que les souches et les racines des cocotiers conservent le champignon pathogène de la première génération de palmiers fusariés constituant par conséquent une source d’inoculum lors des replantations.Conclusion et application des résultats : Les sites à antécédents culturaux cocotier ne constituent pas un environnement agro écologique favorable pour la culture des plants de palmiers à huile sensibles à la fusariose. Il est souhaitable d’utiliser des plants tolérants pour la mise en place de palmeraies industrielles.Mots clés : Palmier à huile, Cocotier, Fusarium oxysporum f.sp elaeidis, Clone, Antécédent cultural

Extinction time for some nonlinear heat equations

This paper concerns the study of the extinction time of the solution of the following initial-boundary value problem [left{% begin{array}{ll} hbox{$u_t=varepsilon Lu(x,t)-f(u)quad mbox{in}quad Omegatimesmathbb{R}_{+}$,} \ hbox{$u(x,t)=0quad mbox{on}quadpartialOmegatimesmathbb{R}_{+}$,} \ hbox{$u(x,0)=u_{0}(x)>0quad mbox{in}quad Omega$,} \ end{array}%right. ] where $Omega$ is a bounded domain in $mathbb{R}^{N}$ with smooth boundary $partialOmega$, $varepsilon$ is a positive parameter, $f(s)$ is a positive, increasing, concave function for positive values of s, $f(0)=0$, $int_{0}frac{ds}{f(s)}<+infty$, $L$ is an elliptic operator. We show that the solution of the above problem extincts in a finite time and its extinction time goes to that of the solution $alpha(t)$ of the following differential equation [alpha^{\u27}(t)=-f(alpha(t)),quad t>0,quad alpha(0)=M,] as $varepsilon$ goes to zero, where $M=sup_{xin Omega}u_{0}(x)$. We also extend the above result to other classes of nonlinear parabolic equations. Finally, we give some numerical results to illustrate our analysis