Correlation between some environmental variables and abundance of Almophrya mediovacuolata (Ciliophora: Anoplophryidae) endocommensal ciliate of an anecic earthworms (Oligochaeta: Annelida) in Bambui (North-West Cameroon)

This study was devoted to accessing the influence of some soil physico-chemical parameters on the abundance of Almophrya mediovacuolata Ngassam, 1983, astome ciliate of the digestive tract of earthworms (EW) of the species Alma nilotica collected along “Fa’a ntsa” stream in Bambui. The survey primarily involved soil samples collection from the same spots of EW collection and preparation for physico-chemical analysis; evaluation in situ of the volumic density (VD) of worms (number /dm3 soil), their dissection, isolation and counting of ciliates with respect to different portion of EW’s gut (fore, mid and hindgut). Furthermore, correlation analysis between soil physico-chemical parameters and biological responses (EW volumic density and ciliate abundance) were performed. The results reveal that EW abundance was positively and significantly correlated with the following physico-chemical parameters: Cation Exchange Capacity CEC (p <0.01) and Mg2+ (p <0.05). A positive and significant correlation was found between Almophrya mediovacuolata and the pH of KCl in the foregut and midgut (p <0.01) while a negative and significant correlation was found between the abundance of Almophrya mediovacuolata and Ca2+ in the foregut (p <0.05). Almophrya mediovacuolata were found mostly in the foregut. This result shows that each portion of the digestive tract of Alma nilotica can be considered as a set of natural microhabitat in which a number of physico-chemical factors generate ecological niches suitable for the survival of different species of microorganisms among which ciliated protozoa. The fore and midgut was noticed to be the preferential zones of Almophrya mediovacuolata.Keywords: Biotic parameters, ciliated protozoa, microhabitat, soil physico-chemical parameters

Assessment of the potential effect of some streams properties on the isolated Aeromonas hydrophila strains susceptibility against some β-Lactams and Sulfamids

The isolation and characterization of A. hydrophila strains were carried out a given stream located in the equatorial zone in Cameroon (Central Africa), during the mild rainy season and the mild dry season. The water physicochemical parameters measured were temperature, pH, electrical conductivity, color, turbidity and suspended solids. It has been noted that bacterial abundances as well as the values of physicochemical parameters undergoes temporal variations. Antimicrobial susceptibility tests showed that the means diameters of inhibition with Oxacillin, Ceftriazone, Penicellin, Sulfamethoxazol-trimethoprim, Chloramphenicol, Imipenem, Amoxicillin-Clavulanic acid and Cefazolin were 6.44, 21, 6.63, 9.58, 15.37, 22.18, 14.29 and 10.26 mm respectively. 100% of strains tested were resistant to Penicillin, 89.47 % resistant to Oxacillin, 68.42% resistant to Sulphamethoxazole-trimetroprim and 63.15% were resistant to Cefazolin. There were 54.60% cases of antibiotic resistance, 24.34 % of intermediate sensitivity and 21.05% of sensitive strains against the tested antibiotics. The encoded redundancy analysis indicates that the percentage of the variation explained on the canonical axes is of 47.8% for the F1 axis and 25.9% for the F2 axis, for an accumulated percentage of 73.7%. The suspended solids, the Ceftriazon and Chloramphenicol are correlated to the F1 axis in positive coordinates, and the Temperature and Amoxicillin-Clavulanic acid in negative coordinates. The correlation test between the water physicochemical characteristics and the inhibition diameters of antibiotics showed some significant correlations (P<0.05). The regulation of bacterial genes would be regulated by complex mechanisms. Although many factors implied are linked to the bacterial cell, others may belong to the closed environment

Actin-interacting and flagellar proteins in Leishmania spp.: Bioinformatics predictions to functional assignments in phagosome formation

Several motile processes are responsible for the movement of proteins into and within the flagellar membrane, but little is known about the process by which specific proteins (either actin-associated or not) are targeted to protozoan flagellar membranes. Actin is a major cytoskeleton protein, while polymerization and depolymerization of parasite actin and actin-interacting proteins (AIPs) during both processes of motility and host cell entry might be key events for successful infection. For a better understanding the eukaryotic flagellar dynamics, we have surveyed genomes, transcriptomes and proteomes of pathogenic Leishmania spp. to identify pertinent genes/proteins and to build in silico models to properly address their putative roles in trypanosomatid virulence. In a search for AIPs involved in flagellar activities, we applied computational biology and proteomic tools to infer from the biological meaning of coronins and Arp2/3, two important elements in phagosome formation after parasite phagocytosis by macrophages. Results presented here provide the first report of Leishmania coronin and Arp2/3 as flagellar proteins that also might be involved in phagosome formation through actin polymerization within the flagellar environment. This is an issue worthy of further in vitro examination that remains now as a direct, positive bioinformatics-derived inference to be presented

Molecular Phylogeny and Evolution of Parabasalia with Improved Taxon Sampling and New Protein Markers of Actin and Elongation Factor-1α

BACKGROUND: Inferring the evolutionary history of phylogenetically isolated, deep-branching groups of taxa-in particular determining the root-is often extraordinarily difficult because their close relatives are unavailable as suitable outgroups. One of these taxonomic groups is the phylum Parabasalia, which comprises morphologically diverse species of flagellated protists of ecological, medical, and evolutionary significance. Indeed, previous molecular phylogenetic analyses of members of this phylum have yielded conflicting and possibly erroneous inferences. Furthermore, many species of Parabasalia are symbionts in the gut of termites and cockroaches or parasites and therefore formidably difficult to cultivate, rendering available data insufficient. Increasing the numbers of examined taxa and informative characters (e.g., genes) is likely to produce more reliable inferences. PRINCIPAL FINDINGS: Actin and elongation factor-1α genes were identified newly from 22 species of termite-gut symbionts through careful manipulations and seven cultured species, which covered major lineages of Parabasalia. Their protein sequences were concatenated and analyzed with sequences of previously and newly identified glyceraldehyde-3-phosphate dehydrogenase and the small-subunit rRNA gene. This concatenated dataset provided more robust phylogenetic relationships among major groups of Parabasalia and a more plausible new root position than those previously reported. CONCLUSIONS/SIGNIFICANCE: We conclude that increasing the number of sampled taxa as well as the addition of new sequences greatly improves the accuracy and robustness of the phylogenetic inference. A morphologically simple cell is likely the ancient form in Parabasalia as opposed to a cell with elaborate flagellar and cytoskeletal structures, which was defined as most basal in previous inferences. Nevertheless, the evolution of Parabasalia is complex owing to several independent multiplication and simplification events in these structures. Therefore, systematics based solely on morphology does not reflect the evolutionary history of parabasalids

Impact of two disinfectants on detachment of Enterococcus faecalis from polythene in aquatic microcosm

After cell adhesion processes in microcosm, the impact of sodium hypochlorite (NaOCl) and hydrogen peroxide (H2O2) on the detachment of Enterococcus faecalis from polythene fragments immersed in water under stationary and dynamic conditions was assessed. The abundance of planktonic cells was also evaluated. The density of E. faecalis adhered in absence of disinfectant fluctuated between 2 and 4 units (Log CFU/cm2). After living in disinfected water, the density of E. faecalis remained adhered to polythene sometimes reached 2 units (Log CFU/Cm2). This highest abundance of cells remained adhered was recorded with cells coming from the lag, exponential and stationary growth phases in water treated with 0.5‰ NaOCl. In H2O2 disinfected water, the highest value was recorded at all cells growth phases with 5‰ H2O2 concentration. Adhered E. faecalis cells have been sometimes completely or partially decimated respectively by NaOCl and H2O2 treated water. Considering separately each experimental condition, it was noted that increasing the concentration of disinfectant caused a significant decrease (P≤0.01) in abundance of cells stay adhered after living in water disinfected by the two disinfectants. Changes in disinfectant concentrations in different experimental conditions had an impact on the detachment of E. faecalis cells from the substrates.Â

Révision de la sous-famille des Metaracoelophryinae de Puytorac 1972 (Oligohymenophora : Hoplytophryida : Hoplytophryidae), ciliés astomes du tube digestif d’oligochètes terricoles d’Afrique : description de cinq espèces nouvelles

Cinq nouvelles espèces de ciliés astomes, présentes dans le tube digestif de vers oligochètes du genre Alma du Cameroun, ont été décrites. Les techniques utilisées sont : l’observation vitale, la coloration au DAPI, la microscopie électronique à balayage et les imprégnations argentiques selon Fernandez Galiano, 1966. Ce travail confirme la présence des genres Paracoelophrya et Dicoelophrya dans le tube digestif des oligochètes du genre Alma du Gabon et du Cameroun ; il permet de faire une synthèse récapitulative de la sous-famille des Metaracoelophryinae. De plus, est confirmée l’homogénéité de ce groupe, et est reposée la question de la parenté phylogénétique des Hoplitophryida

Révision de la sous-famille des Metaracoelophryinae de Puytorac 1972 (Oligohymenophora : Hoplytophryida : Hoplytophryidae), ciliés astomes du tube digestif d’oligochètes terricoles d’Afrique : description de cinq espèces nouvelles

Cinq nouvelles espèces de ciliés astomes, présentes dans le tube digestif de vers oligochètes du genre Alma du Cameroun, ont été décrites. Les techniques utilisées sont : l’observation vitale, la coloration au DAPI, la microscopie électronique à balayage et les imprégnations argentiques selon Fernandez Galiano, 1966. Ce travail confirme la présence des genres Paracoelophrya et Dicoelophrya dans le tube digestif des oligochètes du genre Alma du Gabon et du Cameroun ; il permet de faire une synthèse récapitulative de la sous-famille des Metaracoelophryinae. De plus, est confirmée l’homogénéité de ce groupe, et est reposée la question de la parenté phylogénétique des Hoplitophryida

Biofilms in hospital effluents as a potential crossroads for carbapenemase-encoding strains

International audienceBacterial resistance to carbapenem, which is mainly due to the successful dissemination of carbapenemase-encoding genes, has become a major health problem. Few studies have aimed to characterize the level of resistance in the environment, notably in hospital wastewater, which is a likely hotspot for exchange of antibiotic resistance genes.In this work, we looked for the presence of imipenem-resistant bacteria and imipenem in the effluent of the teaching hospital of Clermont-Ferrand, France. Selective growth of bacteria from 14-day old biofilms formed in the pipe sewer showed that 22.1% of the isolates were imipenem-resistant and identified as Aeromonas (n = 23), Pseudomonas (n = 10), Stenotrophomonas (n = 4) and Acinetobacter (n = 1). Fifteen of these strains harbored acquired carbapenemase-encoding genes blaVIM (n = 11), blaOXA-48 (n = 2), blaGES (n = 1), blaNDM (n = 1). All isolates also harbored associated resistances to aminoglycosides, fluoroquinolones and/or tetracyclin. S1-nuclease pulsed-field gel electrophoresis analysis of eight selected isolates showed that four of them harbored one to two plasmids of molecular weight between 48.5 Kb and 194 Kb. In vitro transformation assays evidenced the presence of blaVIM and blaNDM on plasmids with the blaVIM harboring 80 Kb plasmid having conjugative capacity.The predicted environmental concentration of imipenem in the hospital effluent was 3.16 μg/L, suggesting that biofilm bacteria are subjected to sub-MICs of imipenem within the effluent. However, no imipenem molecule was detected in the hospital effluent, probably owing to its instability: in vitro assays indicated that imipenem's biological activity was no longer detectable after 45 h of storage. However, the predictive value of the hazard quotient relative to the development of resistance was >1.0 (HQr = 28.9 ± 1.9), which indicates a possible risk.The presence of carbapenemase-encoding genes in hospital effluent biofilm strains and their ability to transfer are therefore a potential hazard that should not be neglected and points to the need for monitoring antibiotic resistance in hospital wastewater

Variations morphologiques de l’appareil nucléaire chez les ciliés Astomes Almophrya bivacuolata et A. mediovacuolata (Protozoa : Ciliophora) endocommensaux d’oligochètes terricoles du Cameroun

L’imprégnation argentique complétée par la coloration nucléaire de Feulgen et la coloration au DAPI nous ont permis d’étudier les variations morphologiques de l’appareil nucléaire chez deux espèces de ciliés Astomes, Almophrya bivacuolata (de Puytorac et Dragesco, 1968) et A. mediovacuolata (Ngassam, 1983) endocommensaux. Nous avons mis en évidence d’importantes digitations et la présence de bandes sombres dans la structure du macronoyau en “H” des petits types cellulaires ainsi que la présence de formes intermédiaires entre “H” et “X” dans ces deux espèces