Lutte contre les ravageurs des stocks de céréales et de légumineuses au Sénégal et en Afrique occidentale : synthèse bibliographique

Controlling pests of cereals and legumes in Senegal and West Africa: a review. Post-harvest losses of cereals and legumes are a major problem in Senegal and West Africa. The solutions to eliminate insects, major pests of stored products were mainly chemical. However, due to pollution associated with pesticides use, selection of resistant strains, environmental pollution, poisoning, the search for alternatives is needed. It is reported on different methods of protecting stocks performed alternatively or in combination with pesticides. The major pest species encountered, particularly Prostephanus truncatus (Horn), insect emerging in Senegal, could be controlled by alternative methods including specially the use of insecticide plants. Different aspects related to this alternative way to chemical pesticides are reviewed herein

Efficiency of Traditional Maize Storage and Control Methods in Rural Grain Granaries: a Case Study from Senegal

Maize storage and pest control method as practiced in traditional clay granaries in the Kédougou region in eastern Senegal were evaluated under rural conditions during two successive years. Three storage modes, i.e. maize cobs, winnowed and non-winnowed maize grains, were tested in seven granaries where the insecticidal plants Hyptis spicigera or H. suaveolens were either incorporated in the store structure or deposited as layers intermittently with maize. At the beginning of the storage period, all granaries were artificially infested with 7 pairs Tribolium castaneum and Sitophilus zeamais. No damage, losses or live insects were observed during 7 months of storage when maize cobs were placed between layers of H. spicigera. Compared with the control, incorporation of insecticidal plants within the granary bottom had no significant effect on the damage and loss level irrespective of the storage mode. Non-winnowed maize always suffered less damage and losses than the winnowed variant. In all granaries depredation, insect abundance and moisture content were highest toward the end of storage period between June and July

Optimization of extracellular catalase production from Aspergillus phoenicis K30 by a linear regression method using date flour as single carbon source and purification of the enzyme

Aspergillus phoenicis K30 is the selected mutant which produces an amount of extracellular catalase. To amplify the extracellular catalase production by the strain, a fermentation optimization was performed. To select the factors affecting the production, nine active variables (factors) consisting of 12 experiments were analyzed by Plackett-Burman design. Each variable was tested at two levels, a higher and a lower level. The studies of the effect of each variable and the establishment of a correlation between the response of enzyme activity and variables revealed that the link is a multiple linear regression form. The optimization was carried out through a simplex algorithm. The amount of extracellular catalase produced by the strain in the optimized medium was about four times higher than that obtained in non optimized medium corresponding to 3820 mg/L of extracellular proteins including 59500 U/L of extracellular catalase activity after 96 h of fermentation. The steps of purification were allowed to improve enzyme activity by 305-fold. From an analytical gel electrophoresis under native conditions, an apparent molecular mass of 158 kDa was determined suggesting that the enzyme is a homodimer. The isoelectric point of the protein was found to be 5 ± 0.1 as determined by a Pharmacia Phast-system.Keywords: Aspergillus phoenicis, extracellular catalase purification, dates flour, optimization, multiple linear regression.African Journal of Biotechnology Vol. 12(19), pp. 2646-265

Earthworms Use Odor Cues to Locate and Feed on Microorganisms in Soil

Earthworms are key components of temperate soil ecosystems but key aspects of their ecology remain unexamined. Here we elucidate the role of olfactory cues in earthworm attraction to food sources and document specific chemical cues that attract Eisenia fetida to the soil fungi Geotrichum candidum. Fungi and other microorganisms are major sources of volatile emissions in soil ecosystems as well as primary food sources for earthworms, suggesting the likelihood that earthworms might profitably use olfactory cues to guide foraging behavior. Moreover, previous studies have documented earthworm movement toward microbial food sources. But, the specific olfactory cues responsible for earthworm attraction have not previously been identified. Using olfactometer assays combined with chemical analyses (GC-MS), we documented the attraction of E. fetida individuals to filtrate derived from G. candidum colonies and to two individual compounds tested in isolation: ethyl pentanoate and ethyl hexanoate. Attraction at a distance was observed when barriers prevented the worms from reaching the target stimuli, confirming the role of volatile cues. These findings enhance our understanding of the mechanisms underlying key trophic interactions in soil ecosystems and have potential implications for the extraction and collection of earthworms in vermiculture and other applied activities

Rotavirus NSP1 Inhibits NFκB Activation by Inducing Proteasome-Dependent Degradation of β-TrCP: A Novel Mechanism of IFN Antagonism

Mechanisms by which viruses counter innate host defense responses generally involve inhibition of one or more components of the interferon (IFN) system. Multiple steps in the induction and amplification of IFN signaling are targeted for inhibition by viral proteins, and many of the IFN antagonists have direct or indirect effects on activation of latent cytoplasmic transcription factors. Rotavirus nonstructural protein NSP1 blocks transcription of type I IFNα/β by inducing proteasome-dependent degradation of IFN-regulatory factors 3 (IRF3), IRF5, and IRF7. In this study, we show that rotavirus NSP1 also inhibits activation of NFκB and does so by a novel mechanism. Proteasome-mediated degradation of inhibitor of κB (IκBα) is required for NFκB activation. Phosphorylated IκBα is a substrate for polyubiquitination by a multisubunit E3 ubiquitin ligase complex, Skp1/Cul1/F-box, in which the F-box substrate recognition protein is β-transducin repeat containing protein (β-TrCP). The data presented show that phosphorylated IκBα is stable in rotavirus-infected cells because infection induces proteasome-dependent degradation of β-TrCP. NSP1 expressed in isolation in transiently transfected cells is sufficient to induce this effect. Targeted degradation of an F-box protein of an E3 ligase complex with a prominent role in modulation of innate immune signaling and cell proliferation pathways is a unique mechanism of IFN antagonism and defines a second strategy of immune evasion used by rotaviruses

Control of the induction of type I interferon by Peste des petits ruminants virus.

Peste des petits ruminants virus (PPRV) is a morbillivirus that produces clinical disease in goats and sheep. We have studied the induction of interferon-β (IFN-β) following infection of cultured cells with wild-type and vaccine strains of PPRV, and the effects of such infection with PPRV on the induction of IFN-β through both MDA-5 and RIG-I mediated pathways. Using both reporter assays and direct measurement of IFN-β mRNA, we have found that PPRV infection induces IFN-β only weakly and transiently, and the virus can actively block the induction of IFN-β. We have also generated mutant PPRV that lack expression of either of the viral accessory proteins (V&C) to characterize the role of these proteins in IFN-β induction during virus infection. Both PPRV_ΔV and PPRV_ΔC were defective in growth in cell culture, although in different ways. While the PPRV V protein bound to MDA-5 and, to a lesser extent, RIG-I, and over-expression of the V protein inhibited both IFN-β induction pathways, PPRV lacking V protein expression can still block IFN-β induction. In contrast, PPRV C bound to neither MDA-5 nor RIG-I, but PPRV lacking C protein expression lost the ability to block both MDA-5 and RIG-I mediated activation of IFN-β. These results shed new light on the inhibition of the induction of IFN-β by PPRV

Negative Regulation of Interferon-β Gene Expression during Acute and Persistent Virus Infections

The production of type I interferons (IFNs) in response to viral infections is critical for antiviral immunity. However, IFN production is transient, and continued expression can lead to inflammatory or autoimmune diseases. Thus, understanding the mechanisms underlying the negative regulation of IFN expression could lead to the development of novel therapeutic approaches to the treatment of these diseases. We report that the transcription factor IRF3 plays a central role in the negative regulation of interferon-β (IFNβ) expression during both acute and persistent (chronic) virus infections. We show that the degradation of IRF3 during acute infections, rather than the activation of transcriptional repressors, leads to the down regulation of IFNβ expression. We also show that the block to IFNβ expression in mouse embryonic fibroblasts that are persistently infected with Sendai virus (SeV) correlates with the absence of transcriptionally active IRF3. Remarkably, ongoing protein synthesis and viral replication are required to maintain repression of the IFNβ gene in persistently infected cells, as the gene can be activated by the protein synthesis inhibitor cycloheximide, or by the antiviral drug ribavirin. Finally, we show that the SeV V protein inhibits IRF3 activity in persistently infected cells. Thus, in conjunction with the known interference with STAT1 by the SeV C protein, both IFN activation and its signaling pathways are blocked in persistently infected cells. We conclude that the transcription factor IRF3 is targeted for turnover and inactivation through distinct mechanisms from both the host cells and virus, leading to the inhibition of IFNβ gene expression during acute and persistent viral infections. These observations show that IRF3 plays a critical role, not only in the activation of the IFNβ gene, but also in the controlling the duration of its expression. (284 words

Trappin-2/Elafin Modulate Innate Immune Responses of Human Endometrial Epithelial Cells to PolyI∶C

BACKGROUND: Upon viral recognition, innate and adaptive antiviral immune responses are initiated by genital epithelial cells (ECs) to eradicate or contain viral infection. Such responses, however, are often accompanied by inflammation that contributes to acquisition and progression of sexually transmitted infections (STIs). Hence, interventions/factors enhancing antiviral protection while reducing inflammation may prove beneficial in controlling the spread of STIs. Serine antiprotease trappin-2 (Tr) and its cleaved form, elafin (E), are alarm antimicrobials secreted by multiple cells, including genital epithelia. METHODOLOGY AND PRINCIPAL FINDINGS: We investigated whether and how each Tr and E (Tr/E) contribute to antiviral defenses against a synthetic mimic of viral dsRNA, polyinosine-polycytidylic acid (polyI:C) and vesicular stomatitis virus. We show that delivery of a replication-deficient adenovector expressing Tr gene (Ad/Tr) to human endometrial epithelial cells, HEC-1A, resulted in secretion of functional Tr, whereas both Tr/E were detected in response to polyI:C. Moreover, Tr/E were found to significantly reduce viral replication by either acting directly on virus or through enhancing polyI:C-driven antiviral protection. The latter was associated with reduced levels of pro-inflammatory factors IL-8, IL-6, TNFα, lowered expression of RIG-I, MDA5 and attenuated NF-κB activation. Interestingly, enhanced polyI:C-driven antiviral protection of HEC-Ad/Tr cells was partially mediated through IRF3 activation, but not associated with higher induction of IFNβ, suggesting multiple antiviral mechanisms of Tr/E and the involvement of alternative factors or pathways. CONCLUSIONS AND SIGNIFICANCE: This is the first evidence of both Tr/E altering viral binding/entry, innate recognition and mounting of antiviral and inflammatory responses in genital ECs that could have significant implications for homeostasis of the female genital tract

Adsorption of essential oil components of Lavandula angustifolia on sodium modified bentonite from Nador (North-East Morocco)

The analysis of essential oil has basically one technical goal: to achieve the best possible separation performance by using the most effective, available and current technology of chromatography. The present work aimed to study the formulation created by the adsorption of active components of Lavandula angustifolia essential oil on sodium modified bentonite. Essential oils were obtained from dried leaves of L. angustifolia; they were extracted by hydro distillation and were analyzed by gas chromatography-mass spectrometry (GC-MS) and gas chromatography flame ionization detector (GC-FID). The retention indices (RI) were calculated for each detected component. Besides, the characterization of the individual components making up the oils was performed with the use of a mass spectrometry (MS) library. The quantitative analysis was made by GC-FID. The identified components accounted for more than 95% for each essential oil. The results of these studies show that organic contaminant adsorption is dependent, to some degree, on solid-liquid ratio and the competition system of mixture. The adsorption amount of terpenics and the others components could be the results of many factors. The selectivity was affected by the abundance of each component in the crude essential dependent on the particle size fractions; the finer fractions adsorbed higher amounts. The selectivity of adsorption was affected by the polarity of terpenic components.Keywords: Clays, bentonite, essential oil, adsorption, Lavande angustifolia.African Journal of Biotechnology, Vol 13(31) 3413-342

L'ylang-ylang [Cananga odorata (Lam.) Hook. f. & Thomson] : une plante à huile essentielle méconnue dans une filière en danger

Ylang-ylang [Cananga odorata (Lam.) Hook. f. & Thomson]: a barely known essential oil plant in an industry at risk. Cananga odorata is a tropical tree from the Annonaceae family, native of Indonesia. Only the forma genuina can be called ylang-ylang. Nowadays, it is mainly cultivated in the Indian Ocean Islands in order to extract the ylang-ylang essential oil for the cosmetic industry. Ylang-ylang develops on many types of soils, under high temperatures and average precipitations of 1,500 mm per year. The pollarding, the maintenance, the elimination of water sprouts and the weeding must be performed to insure a high flower yield and facilitate harvesting. Flower harvest takes place all year long but flowers and essential oils yields are higher during the dry season. Mature and fresh flowers are then distillated and fractionated to obtain essential oil. Generated incomes are important for the economy of the three main producers: Union of Comoros, Madagascar and Mayotte. However, this plant is still poorly known despite its great economic value. This lack of information is a bottleneck for solving the ylang-ylang industry problems which endanger it. Moreover, there is no improvement program of this plant despite the high added value of its essential oil, probably due to the fact that its reproduction biology is far from being known. A thorough study of the plant and its essential oil could generate information necessary to solve the aforementioned problems, maintain and develop the ylang-ylang industry