Biosorption of Pb(II) from contaminated water onto Moringa oleifera biomass: kinetics and equilibrium studies

Abstract

The present study aims at evaluating a batch scale biosorption potential of Moringa oleifera leaves (MOL) for the removal of Pb(II) from aqueous solutions. The MOL biomass was characterized by FTIR, SEM, EDX, and BET. The impact of initial concentrations of Pb (II), adsorbent dosage, pH, contact time, coexisting inorganic ions (Ca²⁺, Na⁺, K⁺, Mg²⁺, CO₃^2?, HCO₃^?, Cl^?), electrical conductivity (EC) and total dissolved salts (TDS) in water was investigated. The results revealed that maximum biosorption (45.83?mg/g) was achieved with adsorbent dosage 0.15?g/100?mL while highest removal (98.6%) was obtained at adsorbent biomass 1.0?g/100?mL and pH 6. The presence of coexisting inorganic ions in water showed a decline in Pb(II) removal (8.5% and 5%) depending on the concentrations of ions. The removal of Pb(II) by MOL decreased from 97% to 89% after five biosorption/desorption cycles with 0.3?M HCl solution. Freundlich model yielded a better fit for equilibrium data and the pseudo-second-order well described the kinetics of Pb(II) biosorption. FTIR spectra showed that –OH, C–H, –C–O, –C?=?O, and –O–C functional groups were involved in the biosorption of Pb(II). The change in Gibbs free energy (ΔG = ?28.10?kJ/mol) revealed that the biosorption process was favorable and thermodynamically driven. The results suggest MOL as a low cost, environment-friendly alternative biosorbent for the remediation of Pb(II) contaminated water.     

Characterisation of phytoplasma (16SrVI) associated with little leaf disease of Portulaca grandiflora – An in silico analysis

A new severe little leaf disease was observed on P. grandiflora, popular as Moss-rose Purslane, widely grown in temperate zones. Characteristic symptoms, ultrastructural studies, antibiotic response and amplification of 16S ribosomal DNA fragments (about 1.5 kb) by polymerase chain reaction (PCR) from infected samples, suspect the involvement of phytoplasma as a pathogen. Nested PCR product, 1.2 kb, with primer pairs R16F2n/R16R2 used for cloning and sequencing. Comparision of the 16S rRNA gene sequences showed that the causal, PLL phytoplasma, is very close (98%) to Indian brinjal little leaf (EF186820) and “Candidatus Phytoplasma trifolii” (AY390261), 16SrVI group phytoplasmas, previously reported from India and Canada respectively. Here, the status of PLL (EF651786) is verified by computer-simulated restriction fragment length polymorphism analysis of 16S rRNA genes of the F2n/R2 sequences of closely related strains of the 16SrVI group using 17 restriction enzymes.     

Peripheral Blood Cell Signatures of Plasmodium falciparum Infection during Pregnancy

Sequestration of Plasmodium falciparum-infected erythrocytes in placental intervillous spaces causes inflammation and pathology. Knowledge of the profiles of immune cells associated with the physiopathology of pregnancy-associated malaria (PAM) is scarce. We conducted a longitudinal, prospective study, both in Benin and Tanzania, including ∼1000 pregnant women in each site with systematic follow-up at scheduled antenatal visits until delivery. We used ex vivo flow cytometry to identify peripheral blood mononuclear cell (PBMC) profiles that are associated with PAM and anaemia, determining the phenotypic composition and activation status of PBMC in selected sub-groups with and without PAM both at inclusion and at delivery in a total of 302 women. Both at inclusion and at delivery PAM was associated with significantly increased frequencies both of B cells overall and of activated B cells. Infection-related profiles were otherwise quite distinct at the two different time-points. At inclusion, PAM was associated with anaemia, with an increased frequency of immature monocytes and with a decreased frequency of regulatory T cells (Treg). At delivery, infected women presented with significantly fewer plasmacytoid dendritic cells (DC), more myeloid DC expressing low levels of HLA-DR, and more effector T cells (Teff) compared to uninfected women. Independent associations with an increased risk of anaemia were found for altered antigen-presenting cell frequencies at inclusion, but for an increased frequency of Teff at delivery. Our findings emphasize the prominent role played by B cells during PAM whenever it arises during pregnancy, whilst also revealing signature changes in other circulating cell types that, we conclude, primarily reflect the relative duration of the infections. Thus, the acute, recently-acquired infections present at delivery were marked by changes in DC and Teff frequencies, contrasting with infections at inclusion, considered chronic in nature, that were characterized by an abundance of immature monocytes and a paucity of Treg in PBMC.     

High yield of cells committed to the photoreceptor-like cells from conjunctiva mesenchymal stem cells on nanofibrous scaffolds

Transplantation of stem cells using biodegradable and biocompatible nanofibrous scaffolds is a promising therapeutic approach for treating inherited retinal degenerative diseases such as retinitis pigmentosa and age-related macular degeneration. In this study, conjunctiva mesenchymal stem cells (CJMSCs) were seeded onto poly-l-lactic acid (PLLA) nanofibrous scaffolds and were induced to differentiate toward photoreceptor cell lineages. Furthermore, the effects of orientation of scaffold on photoreceptor differentiation were examined. Scanning electron microscopy (SEM) imaging, quantitative real time RT-PCR (qPCR) and immunocytochemistry were used to analyze differentiated cells and their expression of photoreceptor-specific genes. Our observations demonstrated the differentiation of CJMSCs to photoreceptor cells on nanofibrous scaffolds and suggested their potential application in retinal regeneration. SEM imaging showed that CJMSCs were spindle shaped and well oriented on the aligned nanofiber scaffolds. The expression of rod photoreceptor-specific genes was significantly higher in CJMSCs differentiated on randomly-oriented nanofibers compared to those on aligned nanofibers. According to our results we may conclude that the nanofibrous PLLA scaffold reported herein could be used as a potential cell carrier for retinal tissue engineering and a combination of electrospun nanofiber scaffolds and MSC-derived conjunctiva stromal cells may have potential application in retinal regenerative therapy.     

Analysis of Amblyomma sculptum haplotypes in an area endemic for Brazilian spotted fever

Amblyomma sculptum (Ixodida: Ixodidae) Berlese, 1888, a member of the Amblyomma cajennense complex, is the major vector of Brazilian spotted fever (BSF) in southeastern Brazil. In this study, the genetic diversity of A. sculptum populations in the state of Rio de Janeiro (RJ), Brazil, was investigated because genetic variability in tick populations may be related to vector competence. Samples of A. sculptum from 19 municipalities in 7 regions of RJ were subjected to DNA extraction, amplification and sequencing of D‐loop, cytochrome oxidase II and 12S rDNA mitochondrial genes. These sequences were used to map the genetic diversity of this tick. Amblyomma sculptum populations are genetically diverse in RJ, especially in the South Centre and Highland regions. Few unique haplotypes were observed in all populations, and the majority of genetic variation found was among ticks within each population. Phylogenetic reconstruction reinforced the assumption that all the haplotypes identified in RJ belong to A. sculptum. However, some RJ haplotypes are closer to A. sculptum from Argentina than to A. sculptum from elsewhere in Brazil. In RJ, A. sculptum has high genetic diversity, although little genetic differentiation. Observations also indicated a high level of gene flow among the studied populations and no evidence of population structure according to region in RJ.     

Prevalent mutations of human prion protein: a molecular modeling and molecular dynamics study

Point mutations in the human prion protein gene, leading to amino acid substitutions in the human prion protein contribute to conversion of PrPC to PrPSc and amyloid formation, resulting in prion diseases such as familial Creutzfeldt-Jakob disease (CJD), Gerstmann-Straussler-Scheinker disease (GSS), and fatal familial insomnia. We have investigated impressions of prevalent mutations including Q217R, D202N, F198S, on the human prion protein and compared the mutant models with wild types. Structural analyses of models were performed with molecular modeling and molecular dynamics simulation methods. According to our results, frequently occurred mutations are observed in conserved and fully conserved sequences of human prion protein and the most fluctuation values occur in the Helix 1 around residues 144-152 and C-terminal end of the Helix 2. Our analysis of results obtained from MD simulation clearly shows that this long-range effect plays an important role in the conformational fluctuations in mutant structures of human prion protein. Results obtained from molecular modeling such as creation or elimination of some hydrogen bonds, increase or decrease of the accessible surface area and molecular surface, loss or accumulation of negative or positive charges on specific positions, and altering the polarity and pKa values, show that amino acid point mutations, though not urgently change the stability of PrP, might have some local impacts on the protein interactions which are required for oligomerization into fibrillar species.     

Molecular dynamics study of the dominant-negative E219K polymorphism in human prion protein

Human prion diseases are associated with misfolding or aggregation of the Human Prion Protein (HuPrP). Missense mutations in the HuPrP gene, contribute to conversion of HuPrP^C to HuPrP^Sc and amyloid formation. Based on our previous comprehensive study, three missense mutations, from two different functional groups, i.e. disease-related mutations, and protective mutations, were selected and extensive molecular dynamics simulations were performed on these three mutants to compare their dynamics and conformations with those of the wildtype HuPrP. In addition to simulations of monomeric forms of mutants, in order to study the dominant-negative effect of protective mutation (E219K), 30-ns simulations were performed on E219K-wildtype and wildtype-wildtype dimeric forms. Our results indicate that, although after 30-ns simulations the global three-dimensional structure of models remain fairly intact, the disease-related mutations (V210I and Q212P) introduce local structural changes, i.e. close contact changes and secondary structure changes, in addition to global flexibility changes. Furthermore, our results support the loss of hydrophobic interaction due to the mutations in hydrophobic core that has been reported by previous NMR and computational studies. On the other hand, this protective mutation (E219K) results in helix elongation, and significant increases of overall flexibility of E219K mutant during 30-ns simulation. In conclusion, the simulations of dimeric forms suggest that the dominant-negative effect of this protective mutation (E219K) is due to the incompatible structures and dynamics of allelic variants during conversion process.     

Enzyme-linked immunosorbent assay for the diagnosis of Wuchereria bancrofti infection using urine samples and its application in Bangladesh

In Sri Lanka, urine ELISA showed high sensitivity and specificity in detecting filaria-specific IgG4. It also produced much higher positive rates than antigen tests in prevalence studies with young children. In this study, we have confirmed the usefulness of urine ELISA in the field of Bangladesh. The ELISA detected 89 of 105 (85%) ICT antigen test positive subjects in endemic areas. With both ICT and microfilaria positives, the sensitivity was 97% (30/31). All of 104 ICT negative people in a non-endemic area were ELISA negative (100% specificity). In a prevalence study with 319 young children (5–10 years) from a low endemic area after five rounds of MDA, seven (2.2%) were detected by the present urine test, but only one (0.3%) by ICT (P = 0.075). The satisfactorily high sensitivity, 100% specificity and effective case detection among young ages along with scope for analyzing the titers will indicate urine ELISA to be an effective tool in the post-MDA surveys to confirm elimination or to detect resurgence in Bangladesh.