Source to tap investigation of natural organic matter in non-disinfected drinking water distribution systems

Despite being reduced by treatment, natural organic matter (NOM) is ubiquitous in drinking water distribution systems (DWDSs) from sources to consumers' taps where it can potentially have negative impacts on drinking water quality. While a few studies have investigated its behaviour in disinfected and NOM-rich DWDSs, its dynamics in non-disinfected systems, characterized by low NOM content, have not yet been explored. In this study, we monitored the NOM variations occurring between groundwater sources and consumers' taps of a non-disinfected DWDS, including three drinking water treatment plants, using both fluorescence and absorbance, selected due to their increasing adoption by water utilities. PARAFAC analysis of fluorescence data, combined with absorbance indices, highlighted how NOM characteristics in groundwater vary due to the combination of multiple factors (e.g., well depth, pumping rate), especially in the case of shallower aquifers. The treatment processes display different effects on NOM when monitored by fluorescence and absorbance, due to the differences among fluorophores and between fluorescent and chromophoric molecules. Variations of the NOM characteristics between the treatment plant outlets and sampling locations within the network were detected only in few locations, suggesting the importance of the processes occurring in specific sections of the network and the last meter before consumption. These findings highlight the overall stability of water quality within non- disinfected NOM-poor DWDSs, but they stress the importance of (i) properly selecting the analytical method to be used for monitoring and (ii) localized water quality variations mainly related to pipe materials, suggesting several implications for DWDS monitoring and management

Data for discriminating dead/live bacteria in homogenous cell suspensions and the effect of insoluble substrates on turbidimetric measurements

Estimation of bacterial growth by rapid traditional methods such as spectrophometric measurements at 600 nm (OD600) is not applicable for cultures containing insoluble particles in the growth media. Colony counts are the only suitable alternative but these are laborious and not high-throughput. The data presented in this article is related to the research article entitled “Two-colour fluorescence fluorimetric analysis for direct quantification of bacteria and its application in monitoring bacterial growth in cellulose degradation systems” (Duedu and French, 2017) [1]. This data article presents original primary data describing the discrimination of dead/live bacteria in homogenous cell suspensions and how the presence of insoluble substrates affect the turbidity of the suspensions

Modulation of poly-N-acetylglucosamine accumulation within mature Staphylococcus epidermidis biofilms grown in excess glucose

PNAG is a major component of Staphylococcus epidermidis biofilms involved in intercellular adhesion as well as in the interaction of the biofilm with components of the host immune response. Synthesis of PNAG has been found to be regulated by several environmental factors. In the present study, the effect of glucose metabolism-dependent culture medium acidification in PNAG accumulation was evaluated. Established S. epidermidis biofilms were allowed to grow in excess glucose with or without maintained pH conditions. PNAG accumulation in these biofilms was determined by flow cytometry and fluorescence microscopy using wheat germ agglutinin as a fluorescent probe. Biofilms grown in maintained pH conditions presented significantly higher amounts of this polymer as well as higher icaA expression than biofilms grown in acidic pH conditions. Moreover, PNAG accumulation in biofilms grown in non-maintained pH conditions occurred in association with cell death. Overall, we show that glucose metabolism by decreasing the culture pH affects biofilm physiology in respect to PNAG production and cell death. The reported in vitro modulation of PNAG accumulation within S. epidermidis biofilms further highlights the role of environment on determining the biofilm physiological state.(undefined

Ligand engagement of Toll-like receptors regulates their expression in cortical microglia and astrocytes

BACKGROUND: Toll-like receptor (TLR) activation on microglia and astrocytes are key elements in neuroinflammation which accompanies a number of neurological disorders. While TLR activation on glia is well-established to up-regulate pro-inflammatory mediator expression, much less is known about how ligand engagement of one TLR may affect expression of other TLRs on microglia and astrocytes. METHODS: In the present study, we evaluated the effects of agonists for TLR2 (zymosan), TLR3 (polyinosinic-polycytidylic acid (poly(I:C)), a synthetic analogue of double-stranded RNA) and TLR4 (lipopolysaccaride (LPS)) in influencing expression of their cognate receptor as well as that of the other TLRs in cultures of rat cortical purified microglia (>99.5 %) and nominally microglia-free astrocytes. Elimination of residual microglia (a common contaminant of astrocyte cultures) was achieved by incubation with the lysosomotropic agent L-leucyl-L-leucine methyl ester (L-LME). RESULTS: Flow cytometric analysis confirmed the purity (essentially 100 %) of the obtained microglia, and up to 5 % microglia contamination of astrocytes. L-LME treatment effectively removed microglia from the latter (real-time polymerase chain reaction). The three TLR ligands robustly up-regulated gene expression for pro-inflammatory markers (interleukin-1 and interleukin-6, tumor necrosis factor) in microglia and enriched, but not purified, astrocytes, confirming cellular functionality. LPS, zymosan and poly(I:C) all down-regulated TLR4 messenger RNA (mRNA) and up-regulated TLR2 mRNA at 6 and 24 h. In spite of their inability to elaborate pro-inflammatory mediator output, the nominally microglia-free astrocytes (>99 % purity) also showed similar behaviours to those of microglia, as well as changes in TLR3 gene expression. LPS interaction with TLR4 activates downstream mitogen-activated protein kinase and nuclear factor-κB signalling pathways and subsequently causes inflammatory mediator production. The effects of LPS on TLR2 mRNA in both cell populations were antagonized by a nuclear factor-κB inhibitor. CONCLUSIONS: TLR2 and TLR4 activation in particular, in concert with microglia and astrocytes, comprise key elements in the initiation and maintenance of neuropathic pain. The finding that both homologous (zymosan) and heterologous (LPS, poly(I:C)) TLR ligands are capable of regulating TLR2 gene expression, in particular, may have important implications in understanding the relative contributions of different TLRs in neurological disorders associated with neuroinflammation

Source to taps investigation of natural organic matter in non-disinfected drinking water distribution systems

Despite being reduced by treatment, natural organic matter (NOM) is ubiquitous in drinking water distribution systems (DWDSs) from sources to consumers taps where it can potentially have negative impacts on drinking water quality. While few studies have studied its behavior in disinfected and NOM-rich DWDSs, its dynamics in non-disinfected systems, characterized by low NOM content, have not been explored yet. In this study, we monitored the NOM variations occurring between sources and consumers taps of a non-disinfected DWDS using both absorbance and fluorescence, selected due to their increasing adoption by water utilities. PARAFAC analysis of fluorescence data, combined with absorbance indices, highlighted how NOM characteristics in groundwater can vary likely due to the combination of multiple factors, especially in case of shallower aquifers. The treatment processes acted differently on fluorescent components and absorbance likely due to the differences among fluorophores and between fluorescent and chromophoric molecules. Within the distribution network, variations were detected only at selected sampling locations suggesting the importance of the “last meter” factor, especially for sampling locations located within buildings. These findings remark the overall stability of water quality within non-disinfected DWDSs, but they stress the importance of localized water quality variations, suggesting several implications for DWDS monitoring and management

Rapid flow cytometric immunodetection of bacteria to monitor aquatic environments

International audienceno abstrac

Rapid flow cytometric immunodetection of bacteria to monitor aquatic environments

International audienceno abstrac

Isolation and characterization of two cyclin cDNAs from Pisum sativum L.

In order to investigate the role of cell division in plant development, we isolated two plant genes which encode homologues of animal and yeast cell cycle regulators known as cyclins. Through the use of degenerate primers and the polymerase chain reaction (PCR) we isolated a Pisum sativum sequence which showed homology to the ‘cyclin box°s functional domain found within cyclin proteins. Using this sequence as probe we isolated two different cyclin cDNAs, Pissa;CycA3;1 and Pissa;CycB1;3 from a Pisum sativum L. root tip cDNA library. The deduced amino acid sequences of both cDNAs showed the highest sequence similarity with mitotic cyclins. Analyses of Pissa;CycA3;1 and Pissa;CycB1;3 expression in different tissues, by reverse transcription-polymerase chain reaction (RT-PCR) using primers corresponding to unique regions of their cDNAs, showed their differential expression in relation to cell cycle activity. Furthermore, RT-PCR was used to analyze synchronized root tip cells; results revealed that Pissa;CycA3;1 is preferentially expressed in mid-S (SM) and during late S-G2 (Sl- G2) transition, whereas Pissa;CycB1;3 mRNA is only detectable in Sl and G2 phases

Radioanalytical Techniques in Studies of Trace Metals in Renal Insufficiency and Dialytic Treatment

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