Treating Cattle to Protect People? Impact of Footbath Insecticide Treatment on Tsetse Density in Chad

Background

In Chad, several species of tsetse flies (Genus: Glossina ) transmit African animal trypanosomoses (AAT), which represents a major obstacle to cattle rearing, and sleeping sickness, which impacts public health. After the failure of past interventions to eradicate tsetse, the government of Chad is now looking for other approaches that integrate cost-effective intervention techniques, which can be applied by the stake holders to control tsetse-transmitted trypanosomoses in a sustainable manner. The present study thus attempted to assess the efficacy of restricted application of insecticides to cattle leg extremities using footbaths for controlling Glossina m. submorsitans, G . tachinoides and G . f . fuscipes in southern Chad.

Methodology/Principal Findings

Two sites were included, one close to the historical human African trypanosomiasis (HAT) focus of Moundou and the other to the active foci of Bodo and Moissala. At both sites, a treated and an untreated herd were compared. In the treatment sites, cattle were treated on a regular basis using a formulation of deltamethrin 0.005% (67 to 98 cattle were treated in one of the sites and 88 to 102 in the other one). For each herd, tsetse densities were monthly monitored using 7 biconical traps set along the river and beside the cattle pen from February to December 2009. The impact of footbath treatment on tsetse populations was strong (p < 10^-3) with a reduction of 80% in total tsetse catches by the end of the 6-month footbath treatment.

Conclusions/Significance

The impact of footbath treatment as a vector control tool within an integrated strategy to manage AAT and HAT is discussed in the framework of the “One Health” concept. Like other techniques based on the treatment of cattle, this technology should be used under controlled conditions, in order to avoid the development of insecticide and acaricide resistance in tsetse and tick populations, respectively.     

A unigene catalogue of 5700 expressed genes in cassava

Two economically important characters, starch content and cassava bacterial blight resistance, were targeted to generate a large collection of cassava ESTs. Two libraries were constructed from cassava root tissues of varieties with high and low starch contents. Other libraries were constructed from plant tissues challenged by the pathogen Xanthomonas axonopodis pv.manihotis. We report here the single pass sequencing of 11 954 cDNA clones from the 5’ ends, including 111 from the 3’ ends. Cluster analysis permitted the identification of a unigene set of 5700 sequences. Sequence analyses permitted the assignment of a putative functional category for 37% of sequences whereas ~ 16% sequences did not show any significant similarity with other proteins present in the database and therefore can be considered as cassava specific genes. A group of genes belonging to a large multigene family was identified. We characterize a set of genes detected only in infected libraries putatively involved in the defense response to pathogen infection. By comparing two libraries obtained from cultivars contrasting in their starch content a group of genes associated to starch biosynthesis and differentially expressed was identified. This is the first large cassava EST resource developed today and publicly available thus making a significant contribution to genomic knowledge of cassava.     

Enantiopure Ti(IV) amino triphenolate complexes as NMR chiral solvating agents

Enantiopure Ti(IV) complexes bearing pseudo-C(3) amino triphenolate ligands have been synthesized and characterized. The complexes bearing ortho phenyl groups act as (1)H NMR chiral solvating agent (CSA) for the stereochemical analysis of a series of sulfoxides. The coordination of a Lewis base coligand (sulfoxide) and the presence of aromatic rings are the key structural factors for the efficiency of the CSA.     

Genome analyses highlight the different biological roles of cellulases

Cellulolytic enzymes have been the subject of renewed interest owing to their potential role in the conversion of plant lignocellulose to sustainable biofuels. An analysis of ～1,500 complete bacterial genomes, presented here, reveals that ～40% of the genomes of sequenced bacteria encode at least one cellulase gene. Most of the bacteria that encode cellulases are soil and marine saprophytes, many of which encode a range of enzymes for cellulose hydrolysis and also for the breakdown of the other constituents of plant cell walls (hemicelluloses and pectins). Intriguingly, cellulases are present in organisms that are usually considered as non-saprophytic, such as Mycobacterium tuberculosis, Legionella pneumophila, Yersinia pestis and even Escherichia coli. We also discuss newly emerging roles of cellulases in such non-saprophytic organisms.     

Genetic mapping of a dominant gene conferring resistance to cassava mosaic disease

Cassava mosaic disease (CMD) is the most-important disease of cassava (Manihot esculenta) in Africa, and is a potential threat to Latin American (LA) cassava production. Although this viral disease is still unknown in LA, its vector - the whitefly - has recently been found. The disease is best controlled through host-plant resistance, which was first found in third backcross derivatives of an interspecific cross between cassava and Manihot glaziovii, and is thought to be polygenic. Recently, high levels of resistance were also found in several Nigerian cassava landraces. Classical genetic analysis and molecular genetic-mapping of the landraces showed that a major dominant gene confers this resistance. Bulk segregant analysis (BSA) was used to quickly identify a simple sequence repeat (SSR) marker linked to the CMD-resistance gene. The marker, SSRY28, is located on linkage group R of the male-parent-derived molecular genetic map. The gene, designated as CMD2, is flanked by the SSR and RFLP marker GY1 at 9 and 8 cM, respectively. To our knowledge, this is the first report of qualitative virus resistance in cassava, and of molecular markers that tag CMD resistance in cassava. We discuss the use of markers linked to CMD2 for marker-assisted breeding of CMD resistance in Latin America and for increasing the cost-effectiveness of resistance breeding in Africa.     

Dryoptkirbioside,A New Fructofuranoside Glycerol,and Other Constituents from Dryopteris kirbi Hook et Grav Rhizomes

A new fructofuranoside glycerol, dryoptkirbioside ( 1 ), along with thirteen known compounds ( 2 - 14 ), was isolated from the MeOH extract of Dryopteris kirbi rhizomes by silica gel column chromatography, Sephadex LH-20 column chromatography, and semipreparative HPLC. The structure of the new compound was determined by analyses of its spectroscopic data including nuclear magnetic resonance (NMR), and high-resolution electrospray ionisation mass spectrometry (HR-ESI-MS) and chemical conversions. The hexane-soluble portion and the EAF_A fraction showed strong activities against lung (A549), breast (MCF-7), and cervical (HeLa) human cancer cell lines (IC₅₀ values ranging from 4.0 to 8.8 μg/mL). Aspidinol P ( 5 ) and aspidinol B ( 6 ) exhibited moderate to low cytotoxicity on the three cell lines (IC₅₀ values ranging from 20.4 to 58.7 μM). The MeOH extract and hexane-soluble portion had excellent activities against Staphylococcus aureus and Bacillus subtilis (MICs 11.7 and 23.4 μg/mL), whereas the AcOEt- and BuOH-soluble portions were significantly active on S. aureus (MICs 46.9 and 93.8 μg/mL). The main fractions EAF_B, EAF_C and nBF_B displayed excellent activity against S. aureus (MICs 11.7 and 23.4 μg/mL). Aspidinol B ( 6 ) had significant activity, while aspidinol P ( 5 ) was moderately active against S. aureus and B. subtilis (MICs 42.0 and 89.5 μM).     

Simple sequence repeat (SSR) markers survey of the cassava (Manihot esculenta Crantz) genome: towards an SSR-based molecular genetic map of cassava

The development of PCR-based, easily automated molecular genetic markers, such as SSR markers, are required for realistic cost-effective marker-assisted selection schemes. This paper describes the development and characterization of 172 new SSR markers for the cassava genome. The placement of 36 of these markers on the existing RFLP framework map of cassava is also reported. Two similar enrichment methods were employed. The first method yielded 35 SSR loci, for which primers could be designed, out of 148 putative DNA clones. A total of 137 primer pairs could be designed from 544 putative clones sequenced for the second enrichment. Most of the SSRs (95%) were di-nucleotide repeats, and 21% were compound repeats. A major drawback of these methods of SSR discovery is the redundancy – 20% duplication; in addition, primers could not be designed for many SSR loci that were too close to the cloning site – 45% of the total. All 172 SSRs amplified the corresponding loci in the parents of the mapping progeny, with 66% of them revealing a unique allele in at least one of the parents, and 26% having unique alleles in both of the parents. Of the 36 SSRs that have been mapped, at least 1 was placed on 16 out of the 18 linkage groups of the framework map, indicating a broad coverage of the cassava genome. This preliminary mapping of the 36 markers has led to the joining of a few small groups and the creation of one new group. The abundance of allelic bridges as shown by these markers will lead to the development of a consensus map of the male- and female-derived linkage groups. In addition, the relatively higher number of these allelic bridges, 30% as against 10% for RFLPs in cassava, underscores SSR as the marker of choice for cassava. The 100% primer amplification obtained for this set of primers also confirms the appropriateness of SSR markers for use in cassava genome analysis and the transferability of the technology as a low-cost approach to increasing the efficiency of cassava breeding. Current efforts are geared towards the generation of more SSR markers to attain a goal of 200 SSR markers, or 1 SSR marker every 10 cM. Received: 15 November 1999 / Accepted: 14 April 2000     

Differential pathogenesis of closely related 2018 Nigerian outbreak clade III Lassa virus isolates

Nigeria continues to experience ever increasing annual outbreaks of Lassa fever (LF). The World Health Organization has recently declared Lassa virus (LASV) as a priority pathogen for accelerated research leading to a renewed international effort to develop relevant animal models of disease and effective countermeasures to reduce LF morbidity and mortality in endemic West African countries. A limiting factor in evaluating medical countermeasures against LF is a lack of well characterized animal models outside of those based on infection with LASV strain Josiah originating form Sierra Leone, circa 1976. Here we genetically characterize five recent LASV isolates collected from the 2018 outbreak in Nigeria. Three isolates were further evaluated in vivo and despite being closely related and from the same spatial / geographic region of Nigeria, only one of the three isolates proved lethal in strain 13 guinea pigs and non-human primates (NHP). Additionally, this isolate exhibited atypical pathogenesis characteristics in the NHP model, most notably respiratory failure, not commonly described in hemorrhagic cases of LF. These results suggest that there is considerable phenotypic heterogeneity in LASV infections in Nigeria, which leads to a multitude of pathogenesis characteristics that could account for differences between subclinical and lethal LF infections. Most importantly, the development of disease models using currently circulating LASV strains in West Africa are critical for the evaluation of potential vaccines and medical countermeasures.     

Discovery of nucleotide polymorphisms in the Musa gene pool by Ecotilling

Musa (banana and plantain) is an important genus for the global export market and in local markets where it provides staple food for approximately 400 million people. Hybridization and polyploidization of several (sub)species, combined with vegetative propagation and human selection have produced a complex genetic history. We describe the application of the Ecotilling method for the discovery and characterization of nucleotide polymorphisms in diploid and polyploid accessions of Musa. We discovered over 800 novel alleles in 80 accessions. Sequencing and band evaluation shows Ecotilling to be a robust and accurate platform for the discovery of polymorphisms in homologous and homeologous gene targets. In the process of validating the method, we identified two single nucleotide polymorphisms that may be deleterious for the function of a gene putatively important for phototropism. Evaluation of heterozygous polymorphism and haplotype blocks revealed a high level of nucleotide diversity in Musa accessions. We further applied a strategy for the simultaneous discovery of heterozygous and homozygous polymorphisms in diploid accessions to rapidly evaluate nucleotide diversity in accessions of the same genome type. This strategy can be used to develop hypotheses for inheritance patterns of nucleotide polymorphisms within and between genome types. We conclude that Ecotilling is suitable for diversity studies in Musa, that it can be considered for functional genomics studies and as tool in selecting germplasm for traditional and mutation breeding approaches.     

The Proto-oncogene PKCι regulates the alternative splicing of Bcl-x pre-mRNA

Two splice variants derived from the Bcl-x gene via alternative 5' splice site selection (5'SS) are proapoptotic Bcl-x(s) and antiapoptotic Bcl-x(L). Previously, our laboratory showed that apoptotic signaling pathways regulated the alternative 5'SS selection via protein phosphatase-1 and de novo ceramide. In this study, we examined the elusive prosurvival signaling pathways that regulate the 5'SS selection of Bcl-x pre-mRNA in cancer cells. Taking a broad-based approach by using a number of small-molecule inhibitors of various mitogenic/survival pathways, we found that only treatment of non-small cell lung cancer (NSCLC) cell lines with the phosphoinositide 3-kinase (PI3K) inhibitor LY294002 (50 μmol/L) or the pan-protein kinase C (PKC) inhibitor G?6983 (25 μmol/L) decreased the Bcl-x(L)/(s) mRNA ratio. Pan-PKC inhibitors that did not target the atypical PKCs, PKCι and PKCζ, had no effect on the Bcl-x(L)/(s) mRNA ratio. Additional studies showed that downregulation of the proto-oncogene, PKCι, in contrast to PKCζ, also resulted in a decrease in the Bcl-x(L)/(s) mRNA ratio. Furthermore, downregulation of PKCι correlated with a dramatic decrease in the expression of SAP155, an RNA trans-acting factor that regulates the 5'SS selection of Bcl-x pre-mRNA. Inhibition of the PI3K or atypical PKC pathway induced a dramatic loss of SAP155 complex formation at ceramide-responsive RNA cis-element 1. Finally, forced expression of Bcl-x(L) "rescued" the loss of cell survival induced by PKCι siRNA. In summary, the PI3K/PKCι regulates the alternative splicing of Bcl-x pre-mRNA with implications in the cell survival of NSCLC cells.