A Shift from Cellular to Humoral Responses Contributes to Innate Immune Memory in the Vector Snail Biomphalaria glabrata

International audienceDiscoveries made over the past ten years have provided evidence that invertebrate anti-parasitic responses may be primed in a sustainable manner, leading to the failure of a secondary encounter with the same pathogen. This phenomenon called " immune priming " or "innate immune memory" was mainly phenomenological. The demonstration of this process remains to be obtained and the underlying mechanisms remain to be discovered and exhaustively tested with rigorous functional and molecular methods, to eliminate all alternative explanations. In order to achieve this ambitious aim, the present study focuses on the Lophotrochozoan snail, Biomphalaria glabrata, in which innate immune memory was recently reported. We provide herein the first evidence that a shift from a cellular immune response (encapsulation) to a humoral immune response (biomphalysin) occurs during the development of innate memory. The molecular characterisation of this process in Biompha-laria/Schistosoma system was undertaken to reconcile mechanisms with phenomena

Pulsed light treatment as new method to maintain physical and nutritional quality of fresh-cut mangoes

International audienceThis study investigated the impact of pulsed light treatment on physical and nutritional quality of fresh-cut " Kent " mangoes. Pulsed light treatments were carried out using an automatic flash lamp system (Mulieribus, Claranor) composed of eight lamps situated all around the sample with a total fluence of 8 J cm −2. Firmness, colour, phenol, carotenoid, ascorbic acid contents and enzyme activities (Phenylalanineammonialyase, PAL and Polyphenoloxydase, PPO) were analysed. Pulsed light treatment maintained the firmness, the colour and the carotenoid content of fresh-cut mangoes. The treatment increased PPO activities after 3 days and maintained PAL activity. For the nutritional aspect, pulsed light maintained phenol and total ascorbic acid contents such as the control. Our results suggest that the application of pulsed light could be used with fresh-cut mangoes to improve physical quality and maintain nutritional properties. Industrial Relevance: Mango is one of the most important tropical fruit worldwide with an increasing demand for " ready to eat " products, because of convenience and fresh-like quality. However, fresh-cut mangoes suffer from browning and softening. Conventional thermal treatments decreased the browning but may contribute to the degradation of certain component. Nowadays, alternative nonthermal technologies are more and more studied such as Pulsed Light. In industry, Pulsed light is used to decontaminate surfaces, packaging or food (bread). No application is available on fruits and vegetables. This work estimated the feasibility of pulsed light treatment to improve the quality of fresh-cut mangoes. The results obtained are promising and could improve the use of pulsed light treatment to extend the shelf-life of fresh-cut products

La filière des farines infantiles produites localement dans 6 pays sahéliens

International audienc

Biodegradation of polyethylene by the bacterium Pseudomonas aeruginosa in acidic aquatic microcosm and effect of the environmental temperature

International audienceThe main problem about plastic packaging after their use is the fate of the plastic waste disposed of into the environment. This study was carried out in aquatic microcosm and aimed at assessing the impact of the temperature of an acidic environment on the polyethylene degradation by the bacterium Pseudomonas aeruginosa , as well as the electrical conductivity of the medium and the temporal abundance dynamics of cells involved. Sterilized pieces of polyethylene of 0.08 g in weight were immersed in sterile mineral solutions of pH 5 in glass flasks containing P. aeruginosa cells at concentration adjusted to 186.10 3 CFU/100 μL. The whole was incubated at 7 °C, 23 °C, 37 °C and 44 °C for 10 days, 20 days and 30 days. Analysis after incubations showed that electrical conductivity which was 3386 μS/cm at the initial moment increased with an increase in incubation period. Its highest value 5476 μS/cm was noted at 44 °C after 30 days. The pH of solutions decreased. Its lowest value 4.11 was noted at 7 °C after 10 and 20 days. The apparent degradation rates of polyethylene fragments varied from 8.10 − 5 g/10days (at 7 °C and 23 °C) to 2.10 − 4 g/10days (at 44 °C). The highest percentage of weight loss of the polyethylene was 6.25% registered after 30 days at 44 °C. The apparent changing rates in cell abundance varied with variation in incubation temperature. It was positive under 7 °C and 23 °C reflecting relative cell growth, and negative under 37 °C and 44 °C reflecting relative cell inhibition. The highest relative apparent cell growth rate was 1.831 CFU/10days recorded at 23 °C and the highest relative apparent cell inhibition rate was 7.831 CFU/10days recorded at 44 °C. In solutions, the pH, electrical conductivity and the weight of the fragments varied significantly from one incubation temperature to another and from one incubation period to another (P < 0.05). Cell abundances varied only from one incubation temperature to another (P < 0.05). The biodegradation process of polyethylene by P. aeruginosa under various environmental conditions and the impact of the products released on cells remains incompletely understood

CD28 deletion improves obesity-induced liver steatosis but increases adiposity in mice

International audienceLymphocytes have a critical role in visceral adipose tissue (AT) inflammation. The CD28 costimulatory molecule is required for lymphocyte activation and for the development of a functional regulatory T cells (Tregs) compartment; however, its role during obesity is unknown.During diet-induced obesity, we investigated the effects of selective interference with CD28 signaling using knockout mice (Cd28KO) and a CTLA4-Ig fusion protein inhibiting CD28-B7 interactions.Cd28 deficiency decreased pathogenic T cells and Treg content within AT without changing the macrophages number. Cd28KO epididymal but not subcutaneous fat was characterized by enlarged adipocytes, reduced levels of inflammatory cytokines and increased Glut4, adiponectin and lipogenic enzyme mRNA levels. This was associated with reduced inflammation, fat accumulation and enhanced glucose metabolism in liver. Weight gain and fasting glucose tolerance were not affected. CTLA4-Ig injections reduced the number of T cells in epididymal AT (epiAT) but not the inflammatory cytokines levels and failed to improve liver fat accumulation.Deletion of CD28 creates a new pro/anti-inflammatory balance in epiAT and liver and exerts a protective effect against hepatic steatosis

CD28 deletion improves obesity-induced liver steatosis but increases adiposity in mice

International audienceLymphocytes have a critical role in visceral adipose tissue (AT) inflammation. The CD28 costimulatory molecule is required for lymphocyte activation and for the development of a functional regulatory T cells (Tregs) compartment; however, its role during obesity is unknown.During diet-induced obesity, we investigated the effects of selective interference with CD28 signaling using knockout mice (Cd28KO) and a CTLA4-Ig fusion protein inhibiting CD28-B7 interactions.Cd28 deficiency decreased pathogenic T cells and Treg content within AT without changing the macrophages number. Cd28KO epididymal but not subcutaneous fat was characterized by enlarged adipocytes, reduced levels of inflammatory cytokines and increased Glut4, adiponectin and lipogenic enzyme mRNA levels. This was associated with reduced inflammation, fat accumulation and enhanced glucose metabolism in liver. Weight gain and fasting glucose tolerance were not affected. CTLA4-Ig injections reduced the number of T cells in epididymal AT (epiAT) but not the inflammatory cytokines levels and failed to improve liver fat accumulation.Deletion of CD28 creates a new pro/anti-inflammatory balance in epiAT and liver and exerts a protective effect against hepatic steatosis

Relative importance of the bacteria Brucella, Salmonella, Staphylococcus and other indicator bacteria in some mountain farm waters in West-Cameroon (Central Africa) and the potential role of some environmental factors

International audienceA bacteriological and physicochemical study was conducted in the waters of farms in mountainous regions of Cameroon. The different water samples were collected during two campaigns in December 2018 and February 2019. Ten stations representing the drinking water supply points in our study area were identified. The results showed that these waters contained both pathogenic and commensal fecal bacteria. The highest abundances reached 10x10 3 CFU/100mL for Salmonella sp., 72x10 3 CFU/100mL for Staphylococcus aureus, 102x10 3 CFU/100mL for Brucella suis and 40x10 3 CFU/100mL for Brucella abortus. These abundances were subject to space-time fluctuations. Water contamination by tweezers was not general and was present only in surface waters (rivers and ponds). The water in the ponds, rivers and wells analyzed were all basic, with low mineralization on average. The dissolved oxygen ranged from 37.5 to 70.6%, nitrate from 3.7 to 19.8 mg/L and iron from 0.01 to 3.5 mg/L. Most of the physicochemical parameters were relatively stable during the two campaigns. The degree of correlation between the physicochemical parameters and the abundance dynamics of the isolated bacteria was heterogeneous. This was clearly more pronounced with Salmonella sp. and Brucella suis. This would be due to the fraction of metabolically active cells present when the bacteria are exposed to unfavorable conditions. Correlations with the abiotic factors were less marked with Staphylococcus aureus and Brucella abortus; this would be due to their tolerance to environmental stresses

Minimum inhibition and bacterial concentrations of the plant Moringa Oleifera extracts against the bacteria Escherichia coli and Staphylococcus aureux

International audienceThis study aimed at assessing the MICs (Minimum Inhibitory Concentrations) and the MBCs (Minimum Bactericidal Concentrations) of the methanolic extracts from 4 different parts (leaves, seeds, stem, roots) of the plant Moringa oleifera against the bacteria E. coli and S. aureus. Phytochemical profile of each extract has been determined using LC/MS analyses. Microbial analyses were done using 96-wells plate method. Results showed that the four parts on the plants contain heterosides and glucosinolates. Iridoids were found in leaves, stem and roots. Flavonoids were found in leaves and stem. Phenolic acids were found only in leaves and carboxylic acids found only in stem. The abundance and the number of identified compounds of a given class varied from one part of plant to another. The MICs and MBCs varied with respect to the microorganism and the part of the plant. With E. coli, the MICs varied from 0.009 (leaves) to 1.25 mg/mL (seeds), and the MBCs varied from 0.156 (leaves) to 2.5 mg/mL (seeds and stem). With S. aureus, the MICs varied from 0.009 (stem and roots) to 0.039 mg/mL (leaves and roots), and the MBCs varied from 0.078 (leaves) to 4 mg/mL (stem). The bactericidal or bacteriostatic properties of the extracts varied depending on the part of the plant and the microorganism considered. Against E. coli, the leaves, stem and roots extracts were bacteriostatic whereas seeds extract was bactericidal. Against S. aureus, the seeds, stem and roots extracts were bacteriostatic whereas leaves extract was bactericidal

Role of <i>B</i>. <i>glabrata</i> plasmatic factors in innate immune memory response.

<p>A. 2D gel electrophoresis of plasma proteins. One gel of each plasma sample analysed was shown. Spot numbers of qualitative and quantitative differences were indicated. Four plasma samples were analysed from naïve (uninfected snails), 15DPPI and 25DPPI (recovered at 15 and 25 days after primo-infection) and 15DPC (recovered at 15 days after secondary challenge). B. Heat-Map of the qualitative and quantitative ratio versus naïve sample. Ratios were calculated using PDQuest software between all differentially regulated spots. Blue to red scale indicate ratio values from lower to higher represented spots. Four clusters are identified: Cluster 1: higher-represented proteins exclusively following secondary challenge (15 DPC). Cluster 2: sustained response: higher-represented proteins after the primo-infection and secondary infection. Cluster 3: higher-represented proteins at 15DPPI and thereafter down regulated at 25DPPI and 15DPC. Cluster 4: lower-represented proteins. C. Plasma transfer and effect on prevalence of <i>S</i>. <i>mansoni</i> infection. Four conditions were tested: untreated snails (Control group, n = 48); saline injected snails (control of injection, n = 25); naïve-plasma injected snails (n = 22); and primed-plasma injected snails (n = 25). For all the experimental groups, 15 days following injection, snails were infected with 10 miracidia of SmBRE. * indicated significant differences (P< 0.05).</p