INFLUENCE DES PARAMETRES DE REPRODUCTION SUR LA PRODUCTIVITE DES HYBRIDES F2 NAIN X NAIN

<p>The objective of this study was to evaluate some production parameters for the identification of elite Nain. Twenty-seven coconut trees, spread over 2 plots, were selected. A control, Malay Yellow Dwarf (NJM), was added to each plot. The study of the relationship between five variables revealed highly significant correlations between them. The multivariate analyses made it possible to identify among the genotypes, the type 7 individuals as being the most efficient. Individuals of type 7 had the highest averages for number of flowers at bag laying (NFP), number of flowers at bag removal (NFE), number of knotted flowers (NFN) and number of nuts harvested (NNR) compared to types 4, 5 and 6. Pollen germination rates in type 1 (Control) individuals were significantly higher than those of the other four types that did not differ significantly between them. The tests for the prediction of the number of nuts harvested indicated that 48.31% of the fluctuations of seed nuts reaching maturity are attributable to the number of female flowers counted at the installation of the bag, that of the female flowers counted at the bag removal and that of the female flowers tied. The predicted values for the number of mature seed nuts are: Nnoirec = -1.12 – 0.007*Nflepose + 0.012*Nflenlev + 0.408*Nflnou +0.014TG. Individuals of type 7 likely to be elite broodstock can be used in programs of genetic improvement of the coconut for better performance.</p><p><br> </p&gt

Evaluation of the interaction between insecticide resistance-associated genes and malaria transmission in Anopheles gambiae sensu lato in central Côte d'Ivoire

BACKGROUND: There is evidence that the knockdown resistance gene (Kdr) L1014F and acetylcholinesterase-1 gene (Ace-1R) G119S mutations involved in pyrethroid and carbamate resistance in Anopheles gambiae influence malaria transmission in sub-Saharan Africa. This is likely due to changes in the behaviour, life history and vector competence and capacity of An. gambiae. In the present study, performed as part of a two-arm cluster randomized controlled trial evaluating the impact of household screening plus a novel insecticide delivery system (In2Care Eave Tubes), we investigated the distribution of insecticide target site mutations and their association with infection status in wild An. gambiae sensu lato (s.l.) populations. METHODS: Mosquitoes were captured in 40 villages around Bouaké by human landing catch from May 2017 to April 2019. Randomly selected samples of An. gambiae s.l. that were infected or not infected with Plasmodium sp. were identified to species and then genotyped for Kdr L1014F and Ace-1R G119S mutations using quantitative polymerase chain reaction assays. The frequencies of the two alleles were compared between Anopheles coluzzii and Anopheles gambiae and then between infected and uninfected groups for each species. RESULTS: The presence of An. gambiae (49%) and An. coluzzii (51%) was confirmed in Bouaké. Individuals of both species infected with Plasmodium parasites were found. Over the study period, the average frequency of the Kdr L1014F and Ace-1R G119S mutations did not vary significantly between study arms. However, the frequencies of the Kdr L1014F and Ace-1R G119S resistance alleles were significantly higher in An. gambiae than in An. coluzzii [odds ratio (95% confidence interval): 59.64 (30.81-131.63) for Kdr, and 2.79 (2.17-3.60) for Ace-1R]. For both species, there were no significant differences in Kdr L1014F or Ace-1R G119S genotypic and allelic frequency distributions between infected and uninfected specimens (P > 0.05). CONCLUSIONS: Either alone or in combination, Kdr L1014F and Ace-1R G119S showed no significant association with Plasmodium infection in wild An. gambiae and An. coluzzii, demonstrating the similar competence of these species for Plasmodium transmission in Bouaké. Additional factors including behavioural and environmental ones that influence vector competence in natural populations, and those other than allele measurements (metabolic resistance factors) that contribute to resistance, should be considered when establishing the existence of a link between insecticide resistance and vector competence

Investigation of a Large Collection of <i>Pseudomonas aeruginosa</i> Bacteriophages Collected from a Single Environmental Source in Abidjan, Côte d’Ivoire

<div><p>Twenty two distinct bacteriophages were isolated from sewage water from five locations in the city of Abidjan, Côte d'Ivoire over a two-year period, using a collection of <i>Pseudomonas aeruginosa</i> strains with diverse genotypes. The phages were characterized by their virulence spectrum on a panel of selected <i>P</i>. <i>aeruginosa</i> strains from cystic fibrosis patients and by whole genome sequencing. Twelve virions representing the observed diversity were visualised by electron microscopy. The combined observations showed that 17 phages, distributed into seven genera, were virulent, and that five phages were related to temperate phages belonging to three genera. Some showed similarity with known phages only at the protein level. The vast majority of the genetic variations among virulent phages from the same genus resulted from seemingly non-random horizontal transfer events, inside a population of <i>P</i>. <i>aeruginosa</i> phages with limited diversity. This suggests the existence of a single environmental reservoir or ecotype in which continuous selection is taking place. In contrast, mostly point mutations were observed among phages potentially capable of lysogenisation. This is the first study of <i>P</i>. <i>aeruginosa</i> phage diversity in an African city and it shows that a large variety of phage species can be recovered in a limited geographical site at least when different bacterial strains are used. The relative temporal and spatial stability of the Abidjan phage population might reflect equilibrium in the microbial community from which they are released.</p></div

Electron microscopy examination of nine phages representative of the different genera observed in the present phage collection.

<p>Scale bar represents 100 nm.</p

Minimum spanning tree representation of PAK_P1-like phages genomes.

<p>The numbers indicated on each branch represent the number of SNPs making this branch. A total of 12125 SNPs were identified and the tree size is 19714 indicating a high level of homoplasia. Homoplasia might result from independent HGT events with unknown phages infecting other <i>Pseudomonas</i> species. Colors indicate the phages country of origin.</p

Minimum spanning tree representation of KPP10-like phages genome.

<p>The numbers indicated on each branch are the number of SNPs constituting this branch. A total of 9097 SNPs were identified and the tree size was 12233 indicating a significant level of homoplasia. Colors indicate the phages country of origin.</p

Host-range of representative Abidjan and Pyo-Phage-derived phages.

<p>* slow growing strain</p><p>°continuous release of prophage</p><p>c: clear plaque; c+: maximum growth; t: turbid plaques</p><p>Host-range of representative Abidjan and Pyo-Phage-derived phages.</p

Genomic organization of N4-like phage Ab09.

<p>The different ORFs are colored according to their putative function: yellow, unknown; grey, transcription; green, morphogenesis; blue, DNA replication; purple, lysis.</p

Genomic organization of LUZ24-like phage Ab22.

<p>The different ORFs are colored according to their putative function: yellow, unknown; red, biosynthesis; green, morphogenesis; blue, DNA replication; purple, lysis. Vertical arrows indicate the position of single-strand DNA interruptions.</p

Characteristics of the new phages.

<p>^a according to [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0130548#pone.0130548.ref030" target="_blank">30</a>]</p><p>^b showing only a few SNPs</p><p>Characteristics of the new phages.</p