Indoor environment, physiological factors, and diet as predictors of halogenated flame retardant levels in stool and plasma of children from a Canadian cohort.

Exposure to halogenated flame retardants (HFRs) has been associated with various adverse effects on human health. Human exposure to HFRs mainly occurs through diet, ingesting contaminated dust, and inhaling contaminated air. Understanding and characterizing the variables linked to these exposure pathways is essential for developing effective risk assessment and mitigation strategies. We investigated indoor environment quality, physiological factors, and diet as potential predictors of HFRs concentration in children's plasma and stool. A selected number of HFRs, including polybrominated diphenyl ethers (PBDEs), Dechlorane-like compounds, and emerging halogenated flame retardants, were measured in children from eastern Quebec (Canada). Information on indoor environment quality, physiological factors, and diet was obtained through self-report questionnaires. Our results show that lower brominated compounds, which are more volatile, were primarily correlated to indoor environment quality. Notably, the use of air purifiers was associated with lower BDE47 and BDE100 levels in blood and newer residential buildings were associated with higher concentrations of BDE47. A significant seasonal variation was found in stool samples, with higher levels of lower brominated PBDEs (BDE47 and BDE100) in samples collected during summer. No association between household income or maternal education degree and HFRs was found. Among emerging compounds, Dec602 and Dec603 were associated with the most variables, including the use of air dehumidifiers, air conditioning, and air purifiers, and the child's age and body fat percentage.

Complementarity of plasma and stool for the characterization of children's exposure to halogenated flame retardants: Update on analytical methods and application to a Canadian cohort.

Sixteen halogenated flame retardants including Polybrominated diphenyl ethers (PBDEs), Dechlorane-like compounds, and emerging halogenated flame retardants were measured in stool and plasma samples from children aged 8.9-13.8 years old. Samples were obtained from a Canadian cohort investigating the effect of contaminants on children's neurodevelopment in the Estrie region, Québec, Canada. The method for stool analysis developed for this study showed good recovery for all targeted compounds (73%-93%) with associated relative standard deviation (RSD) in the range of 16.0%-30.7% for most compounds except for the thermosensitive BDE209, OBTMBI, and BTBPE, which showed slightly higher RSD, i.e., 49.3%, 37.2%, and 34.9% respectively. Complementarity investigation of stool and blood samples allowed us to better characterize human exposure to these halogenated flame retardants. Exposure patterns differed significantly between stool and blood, notably in the relative abundance of BDE47, BDE100, BDE99, and BDE153 and the detection frequencies of BDE209, syn-DP, anti-DP, and DBDPE. There was no correlation between the two matrices' PBDEs concentration levels except for BDE153 (rho = 0.44, p < 0.01). Our results indicate that future epidemiological studies may benefit from the use of stool as a complementary matrix to blood, especially investigations into chemical impacts on the gut microbiome. Results also revealed that children from the GESTE cohort, an Eastern Canadian semi-rural cohort, are exposed to both historical and emergent flame retardants.

Pulcherriminic acid modulates iron availability and protects against oxidative stress during microbial interactions.

Siderophores are soluble or membrane-embedded molecules that bind the oxidized form of iron, Fe(III), and play roles in iron acquisition by microorganisms. Fe(III)-bound siderophores bind to specific receptors that allow microbes to acquire iron. However, certain soil microbes release a compound (pulcherriminic acid, PA) that, upon binding to Fe(III), forms a precipitate (pulcherrimin) that apparently functions by reducing iron availability rather than contributing to iron acquisition. Here, we use Bacillus subtilis (PA producer) and Pseudomonas protegens as a competition model to show that PA is involved in a peculiar iron-managing system. The presence of the competitor induces PA production, leading to precipitation of Fe(III) as pulcherrimin, which prevents oxidative stress in B. subtilis by restricting the Fenton reaction and deleterious ROS formation. In addition, B. subtilis uses its known siderophore bacillibactin to retrieve Fe(III) from pulcherrimin. Our findings indicate that PA plays multiple roles by modulating iron availability and conferring protection against oxidative stress during inter-species competition.

Characterization of childhood exposure to environmental contaminants using stool in a semi-urban middle-class cohort from eastern Canada.

Children are exposed to various environmental organic and inorganic contaminants with effects on health outcomes still largely unknown. Many matrices (e.g., blood, urine, nail, hair) have been used to characterize exposure to organic and inorganic contaminants. The sampling of feces presents several advantages; it is non-invasive and provides a direct evaluation of the gut microbiome exposure to contaminants. The gut microbiome is a key factor in neurological development through the brain-gut axis. Its composition and disturbances can affect the neurodevelopment of children. Characterization of children exposure to contaminants is often performed on vulnerable populations (e.g., from developing countries, low-income neighborhoods, and large urban centers). Data on the exposure of children from middle-class, semi-urban, and mid-size populations to contaminants is scarce despite representing a significant fraction of the population in North America. In this study, 73 organics compounds from different chemical classes and 22 elements were analyzed in 6 years old (n = 84) and 10 years old (n = 119) children's feces from a middle-class, semi-urban, mid-size population cohort from Eastern Canada. Results show that 67 out of 73 targeted organics compounds and all elements were at least detected in one child's feces. Only caffeine (97% & 80%) and acetaminophen (28% & 48%) were detected in more than 25% of the children's feces, whereas all elements besides titanium were detected in more than 50% of the children.

Screening of polymer types and chemical weathering in macro- and meso-plastics found on lake and river beaches using a combined chemometric approach.

In the environment, synthetic polymers, commonly known as "plastics", are well-known to undergo various chemical weathering processes, which modify their surface chemistry by introducing new functional groups. Such changes are important to monitor, as they can severely influence the toxicity caused by plastic debris. Therefore, in this study, two chemometric models are proposed to accelerate the chemical classification of macro- and meso-plastics found in the environment. For this purpose, principal component analysis (PCA) and hierarchical cluster analysis (HCA) were applied on preprocessed infrared spectra of 83 plastic fragments found on public lake and river beaches. HCA associated all beach samples with a known plastic, whereas PCA enabled the association of only 39.8% (33 out of 83) of the beach samples with a known plastic. However, both techniques agreed on 93.9% of the samples identified. According to PCA and HCA results, polypropylene and polyethylene were the most frequently identified polymers in the samples. PCA turned out to be a very promising tool for fast screening of weathered plastics, since the distance of samples from the polypropylene cluster in the PCA plot was correlated with weathering. This was later confirmed by employing other characterization techniques such as micro-Raman, X-ray photoelectron spectroscopy and scanning electron microscopy. Finally, future experiments should focus on the applicability of the proposed combined chemometric approach for very small microplastics (<100 µm), as they have more important effects than larger plastics on aquatic ecosystems.

In Utero Exposure to Caffeine and Acetaminophen, the Gut Microbiome, and Neurodevelopmental Outcomes: A Prospective Birth Cohort Study.

Pregnant individuals are exposed to acetaminophen and caffeine, but it is unknown how these exposures interact with the developing gut microbiome. We aimed to determine whether acetaminophen and/or caffeine relate to the childhood gut microbiome and whether features of the gut microbiome alter the relationship between acetaminophen/caffeine and neurodevelopment. Forty-nine and 85 participants provided meconium and stool samples at 6-7, respectively, for exposure and microbiome assessment. Fecal acetaminophen and caffeine concentrations were quantified, and fecal DNA underwent metagenomic sequencing. Caregivers and study staff assessed the participants' motor and cognitive development using standardized scales. Prenatal exposures had stronger associations with the childhood microbiome than concurrent exposures. Prenatal acetaminophen exposure was associated with a trend of lower gut bacterial diversity in childhood [ß = -0.17 Shannon Index, 95% CI: (-0.31, -0.04)] and was marginally associated with differences in the relative abundances of features of the gut microbiome at the phylum (Firmicutes, Actinobacteria) and gene pathway levels. Among the participants with a higher relative abundance of Proteobacteria, prenatal exposure to acetaminophen and caffeine was associated with lower scores on WISC-IV subscales. Acetaminophen during bacterial colonization of the naïve gut is associated with lasting alterations in childhood microbiome composition. Future studies may inform our understanding of downstream health effects.

Hydroxypyridinones in nitrogen-fixing bacterial cultures: a metal buffer for molybdenum and simulation of natural conditions.

Organic matter regulates the availability of important trace elements in aquatic and terrestrial ecosystems by acting as a source and container for microbes. To overcome the limitation of trace elements, nitrogen-fixing bacteria, e.g. release low-molecular-weight chelators (metallophores), which scavenge the essential cofactors of the nitrogenase, iron, and molybdenum (Mo), via complexation and subsequent uptake. The formation of metallophores is triggered by limiting conditions, which must be replicated in the laboratory in order to study metallophores as a mediator in metal cycling. While ethylenediaminetetraacetic acid (EDTA)-based buffer systems for metal cations are well established, there is limited knowledge regarding the buffering of oxoanions such as molybdate in a bacterial growth medium. To mimic the availability of molybdenum in nature under laboratory conditions, this study created a Mo-buffer system for bacterial growth media of the model organisms Azotobacter vinelandii and Frankia sp. CH37. We investigated selected hydroxypyridinones (HPs) as potential molybdenum-chelating agents, determining the amount required for efficient molybdenum complexation by calculating speciation plots of the various candidate complexes in artificial growth media at various pH values. The Mo-maltol system was identified as an ideal, nontoxic molybdenum-buffer system. In the presence of the Mo-maltol system, the growth of Frankia sp. was limited under diazotrophic conditions, whereas A. vinelandii could acquire molybdenum through the release of protochelin and subsequent molybdenum uptake. The study paves the way for unravelling molybdenum recruitment and homeostasis under limiting conditions in bacteria.

Unraveling global and diazotrophic bacteriomes of boreal forest floor feather mosses and their environmental drivers at the ecosystem and at the plant scale in North America.

Feather mosses are abundant cryptogams of the boreal forest floor and shelter a broad diversity of bacteria who have important ecological functions (e.g., decomposition, nutrient cycling). In particular, nitrogen (N2-) fixation performed by feather moss-associated diazotrophs constitutes an important entry of nitrogen in the boreal forest ecosystem. However, the composition of the feather moss bacteriome and its environmental drivers are still unclear. Using cDNA amplicon sequencing of the 16S rRNA and nifH genes and cyanobacterial biomass quantification, we explored the active global and diazotrophic bacterial communities of two dominant feather moss species (i) at the ecosystem scale, along a 500-km climatic and nutrient deposition gradient in the North American boreal forest, and (ii) at the plant scale, along the moss shoot senescence gradient. We found that cyanobacteria were major actors of the feather moss bacteriome, accounting for 33% of global bacterial communities and 65% of diazotrophic communities, and that several cyanobacterial and methanotrophic genera were contributing to N2-fixation. Moreover, we showed that bacteria were occupying ecological niches along the moss shoot, with phototrophs being dominant in the apical part and methanotrophs being dominant in the basal part. Finally, climate (temperature, precipitation), environmental variables (moss species, month, tree density) and nutrients (nitrogen, phosphorus, molybdenum, vanadium, iron) strongly shaped global and diazotrophic bacteriomes. In summary, this work presents evidence that the feather moss bacteriome plays crucial roles in supporting moss growth, health, and decomposition, as well as in the boreal forest carbon and nitrogen cycles. This study also highlights the substantial effects of climate and nutrients on the feather moss bacteriome, suggesting the importance of understanding the impacts of global change on moss-associated bacterial growth and activity.

Association of Prenatal Acetaminophen Exposure Measured in Meconium With Adverse Birth Outcomes in a Canadian Birth Cohort.

Background: The small number of studies examining the association of prenatal acetaminophen with birth outcomes have all relied on maternal self-report. It remains unknown whether prenatal acetaminophen exposure measured in a biological specimen is associated with birth outcomes. Objectives: To investigate the association of acetaminophen measured in meconium with birthweight, gestational age, preterm birth, size for gestational age, gestational diabetes, preeclampsia, and high blood pressure. Methods: This birth cohort from Sherbrooke, QC, Canada, included 773 live births. Mothers with no thyroid disease enrolled at their first prenatal care visit or delivery. Acetaminophen was measured in meconium for 393 children at delivery. We tested associations of prenatal acetaminophen with birthweight, preterm birth, gestational age, small and large for gestational age, gestational diabetes, preeclampsia, and high blood pressure. We imputed missing data via multiple imputation and used inverse probability weighting to account for confounding and selection bias. Results: Acetaminophen was detected in 222 meconium samples (56.5%). Prenatal acetaminophen exposure was associated with decreased birthweight by 136 g (ß = -136; 95% CI [-229, -43]), 20% increased weekly hazard of delivery (hazard ratio = 1.20; 95% CI [1.00, 1.43]), and over 60% decreased odds of being born large for gestational age (odds ratio = 0.38; 95% CI [0.20, 0.75]). Prenatal acetaminophen was not associated with small for gestational age, preterm birth, or any pregnancy complications. Conclusion: Prenatal acetaminophen was associated with adverse birth outcomes. Although unobserved confounding and confounding by indication are possible, these results warrant further investigation into adverse perinatal effects of prenatal acetaminophen exposure.

In Vivo Temperature Dependency of Molybdenum and Vanadium Nitrogenase Activity in the Heterocystous Cyanobacteria Anabaena variabilis.

The reduction of atmospheric dinitrogen by nitrogenase is a key component of terrestrial nitrogen cycling. Nitrogenases exist in several isoforms named after the metal present within their active center: the molybdenum (Mo), the vanadium (V), and the iron (Fe)-only nitrogenase. While earlier in vitro studies hint that the relative contribution of V nitrogenase to total BNF could be temperature-dependent, the effect of temperature on in vivo activity remains to be investigated. In this study, we characterize the in vivo effect of temperature (3-42 °C) on the activities of Mo nitrogenase and V nitrogenase in the heterocystous cyanobacteria Anabaena variabilis ATTC 29413 using the acetylene reduction assay by cavity ring-down absorption spectroscopy. We demonstrate that V nitrogenase becomes as efficient as Mo nitrogenase at temperatures below 10-15 °C. At temperatures above 22 °C, BNF seems to be limited by O2 availability to respiration in both enzymes. Furthermore, Anabaena variabilis cultures grown in Mo or V media achieved similar growth rates at temperatures below 20 °C. Considering the average temperature on earth is 15 °C, our findings further support the role of V nitrogenase as a viable backup enzymatic system for BNF in natural ecosystems.

Impact of Pharmaceutical Compounds in the Bioremediation of Municipal Biosolids by the White-Rot-Fungi Trametes hirsuta.

The potential of microorganisms for the treatment of municipal biosolids is continuously growing. The present studies evaluated the potency of Trametes hirsuta for the reduction in biosolid mass, production of extracellular enzymes, and removal of pharmaceutical compounds (PhACs) in biosolid slurry in the presence and absence of spiked PhACs [5 non-steroidal anti-inflammatories (NSAIs) and 2 psychoactive compounds (PACs)]. Toxicity after 35 days of fungal treatment was also assessed. Results showed that the growth of T. hirsuta is limited above 25% and wholly inhibited above 50% of biosolids in the slurry. At 12% of biosolid concentration, biosolid mass was reduced by 90%, NSAIs were entirely removed, but PACs' removal was only ~20%. Increasing biosolid content to 25% did not markedly affect biosolid reduction but significantly enhanced the removal of PACs (>50%). Results also showed that both PhACs and biosolids induced the production of oxidative enzymes. In 12% biosolids in the slurry, the oxidative potential measured by the ABTS assay (OABTS) reached 5,000 mM of OABTS in the presence of PhACs, and 2,500 mM of OABTS without PhACs, as compared to 1,200 mM of OABTS in control culture. Finally, we report that white rot fungi (WRF) treatment significantly decreased the toxicity of the biosolids.

Assessing pesticides exposure effects on the reproductive performance of a declining aerial insectivore.

In the context of increasing global environmental changes, it has become progressively important to understand the effects of human activity on wildlife populations. Declines in several avian populations have been observed since the 1970s, especially with respect to many farmland and grassland birds, which also include some aerial insectivores. Changes in farming practices referred to as agricultural intensification coincide with these major avian declines. Among those practices, increased pesticide use is hypothesized to be a key driver of avian population declines as it can lead to both toxicological and trophic effects. While numerous laboratory studies report that birds experience acute and chronic effects upon consuming pesticide treated food, little is known about the effects of the exposure to multiple pesticides on wildlife in natural settings. We monitored the breeding activities of Tree Swallows (Tachycineta bicolor) on 40 farms distributed over a gradient of agricultural intensification in southern Québec, Canada, to evaluate the presence of pesticides in their diet and quantify the exposure effects of those compounds on their reproductive performance between 2013 and 2018. We first assessed the presence of 54 active agents (or derivatives) found in pesticides in 2,081 food boluses (insects) delivered to nestlings by parents and documented their spatial distribution within our study area. Second, we assessed the effect of pesticide exposure through food (number of active agents detected and number of contaminated boluses on a given farm for a given year, while controlling for sampling effort) on clutch size as well as hatching and fledging successes and nestling's mass upon fledging. Pesticides were ubiquitous in our study system and nearly half (46%) of food boluses were contaminated by at least one active agent. Yet we found no relationship between our proxies of food contamination by pesticides and Tree Swallow reproductive performance. More studies are needed to better understand the putative role of pesticides in the decline of farmland birds and aerial insectivores as potential sublethal effects of pesticides can carry over to later life stages and impact fitness.

Efficiencies of selected biotreatments for the remediation of PAH in diluted bitumen contaminated soil microcosms.

Unconventional oils such as diluted bitumen from oil sands differs from most of conventional oils in terms of physiochemical properties and PAHs composition. This raises concerns regarding the effectiveness of current remediation strategies and protocols originally developed for conventional oil. Here we evaluated the efficiency of different biotreatment approaches, such as fungi inoculation (bioaugmentation), sludge addition (bioaugmentation/biostimulation), perennial grasses plantation (phytoremediation) and their combinations as well as natural attenuation (as control condition), for the remediation of soil contaminated by synthetic crude oil (a product of diluted bitumen) in laboratory microcosms. We specifically monitored the PAHs loss percentage (alkylated PAHs and unsubstituted 16 EPA Priority PAHs), the residue of PAHs and evaluated the ecotoxicity of soil after treatment. All treatments were highly efficient with more than ~ 80% of ∑PAHs loss after 60 days. Distinctive loss efficiencies between light PAHs (≤ 3 rings, ~ 96% average loss) and heavy PAHs (4-6 rings, ~ 29% average loss) were observed. The lowest average PAHs residue (0.10 ± 0.02 mg·kg-1, for an initial concentration of 0.29 ± 0.12 mg·kg-1) was achieved with the "sludge-plants (grasses)" combination. Sludge addition was the only treatment that achieved significantly lower ecotoxicity (3% ± 4% of growth inhibition of L. sativa) than the control (natural attenuation, 13% ± 4% of inhibition). Sludge addition, grasses plantation and "sludge-fungi combination" treatments could result in lower PAH exposure (than other treatments) in post-treated soil when using the Canadian Soil Quality Guidelines for the protection of environmental and human health for potentially carcinogenic and other PAHs.

Vegetation drives the structure of active microbial communities on an acidogenic mine tailings deposit.

Plant-microbe associations are increasingly recognized as an inextricable part of plant biology and biogeochemistry. Microbes play an essential role in the survival and development of plants, allowing them to thrive in diverse environments. The composition of the rhizosphere soil microbial communities is largely influenced by edaphic conditions and plant species. In order to decipher how environmental conditions on a mine site can influence the dynamics of microbial communities, we characterized the rhizosphere soil microbial communities associated with paper birch, speckled alder, and spruce that had naturally colonized an acidogenic mine tailings deposit containing heavy metals. The study site, which had been largely undisturbed for five decades, had highly variable vegetation density; with some areas remaining almost barren, and others having a few stands or large thickets of mature trees. Using Illumina sequencing and ordination analyses (redundancy analysis and principal coordinate analysis), our study showed that soil bacterial and fungal community structures correlated mainly with vegetation density, and plant species. Tailings without any vegetation were the most different in bacterial community structure, compared to all other areas on the mine site, as well as an adjacent natural forest (comparison plot). The bacterial genera Acidiferrobacter and Leptospirillum were more abundant in tailings without vegetation than in any of the other sites, while Bradyrhizobium sp. were more abundant in areas of the tailings deposit having higher vegetation density. Frankia sp. is equally represented in each of the vegetation densities and Pseudomonas sp. present a greater relative abundance in boreal forest. Furthermore, alder rhizosphere showed a greater relative abundance of Bradyrhizobium sp. (in comparison with birch and spruce) as well as Haliangium sp. (in comparison with birch). In contrast, fungal community structures were similar across the tailings deposit regardless of vegetation density, showing a greater relative abundance of Hypocrea sp. Tailings deposit fungal communities were distinct from those found in boreal forest soils. Alder rhizosphere had greater relative abundances of Hypocrea sp. and Thelephora sp., while birch rhizosphere were more often associated with Mollisia sp. Our results indicate that, with increasing vegetation density on the mine site, the bacterial communities associated with the individual deciduous or coniferous species studied were increasingly similar to the bacterial communities found in the adjacent forest. In order to properly assess and restore disturbed sites, it is important to characterize and understand the plant-microbe associations that occur since they likely improve plant fitness in these harsh environments.

Association of Prenatal Acetaminophen Exposure Measured in Meconium With Risk of Attention-Deficit/Hyperactivity Disorder Mediated by Frontoparietal Network Brain Connectivity.

Importance: Despite evidence of an association between prenatal acetaminophen exposure and attention-deficit/hyperactivity disorder (ADHD) in offspring, the drug is not contraindicated during pregnancy, possibly because prior studies have relied on maternal self-report, failed to quantify acetaminophen dose, and lacked mechanistic insight. Objective: To examine the association between prenatal acetaminophen exposure measured in meconium (hereinafter referred to as meconium acetaminophen) and ADHD in children aged 6 to 7 years, along with the potential for mediation by functional brain connectivity. Design, Setting, and Participants: This prospective birth cohort study from the Centre Hospitalier Université de Sherbrooke in Sherbrooke, Québec, Canada, included 394 eligible children, of whom 345 had meconium samples collected at delivery and information on ADHD diagnosis. Mothers were enrolled from September 25, 2007, to September 10, 2009, at their first prenatal care visit or delivery and were followed up when children were aged 6 to 7 years. When children were aged 9 to 11 years, resting-state brain connectivity was assessed with magnetic resonance imaging. Data for the present study were collected from September 25, 2007, to January 18, 2020, and analyzed from January 7, 2019, to January 22, 2020. Exposures: Acetaminophen levels measured in meconium. Main Outcomes and Measures: Physician diagnosis of ADHD was determined at follow-up when children were aged 6 to 7 years or from medical records. Resting-state brain connectivity was assessed with magnetic resonance imaging; attention problems and hyperactivity were assessed with the Behavioral Assessment System for Children Parent Report Scale. Associations between meconium acetaminophen levels and outcomes were estimated with linear and logistic regressions weighted on the inverse probability of treatment to account for potential confounders. Causal mediation analysis was used to test for mediation of the association between prenatal acetaminophen exposure and hyperactivity by resting-state brain connectivity. Results: Among the 345 children included in the analysis (177 boys [51.3%]; mean [SD] age, 6.58 [0.54] years), acetaminophen was detected in 199 meconium samples (57.7%), and ADHD was diagnosed in 33 children (9.6%). Compared with no acetaminophen, detection of acetaminophen in meconium was associated with increased odds of ADHD (odds ratio [OR], 2.43; 95% CI, 1.41-4.21). A dose-response association was detected; each doubling of exposure increased the odds of ADHD by 10% (OR, 1.10; 95% CI, 1.02-1.19). Children with acetaminophen detected in meconium showed increased negative connectivity between frontoparietal and default mode network nodes to clusters in the sensorimotor cortices, which mediated an indirect effect on increased child hyperactivity (14%; 95% CI, 1%-26%). Conclusions and Relevance: Together with the multitude of other cohort studies showing adverse neurodevelopment associated with prenatal acetaminophen exposure, this work suggests caution should be used in administering acetaminophen during pregnancy. Research into alternative pain management strategies for pregnant women could be beneficial.

Bacillus subtilis Modulates Its Usage of Biofilm-Bound Iron in Response to Environmental Iron Availability.

Iron (Fe) is one of the most important micronutrients for most life forms on earth. While abundant in soil, Fe bioavailability in oxic soil is very low. Under environmental conditions, bacteria need to acquire sufficient Fe to sustain growth while limiting the energy cost of siderophore synthesis. Biofilm formation might mitigate this Fe stress, since it was shown to accumulate Fe in certain Gram-negative bacteria and that this Fe could be mobilized for uptake. However, it is still unclear if, and to what extent, the amount of Fe accumulated in the biofilm can sustain growth and if the mobilization of this local Fe pool is modulated by the availability of environmental Fe (i.e., Fe outside the biofilm matrix). Here, we use a nondomesticated strain of the ubiquitous biofilm-forming soil bacterium Bacillus subtilis and stable Fe isotopes to precisely evaluate the origin of Fe during growth in the presence of tannic acid and hydroxides, used as proxies for different environmental conditions. We report that this B. subtilis strain can accumulate a large quantity of Fe in the biofilm, largely exceeding Fe associated with cells. We also report that only a fraction of biofilm-bound Fe is available for uptake in the absence of other sources of Fe in the vicinity of the biofilm. We observed that the availability of environmental Fe modulates the usage of this pool of biofilm-bound Fe. Finally, our data suggest that consumption of biofilm-bound Fe relates to the efficacy of B. subtilis to transport Fe from the environment to the biofilm, possibly through siderophores.IMPORTANCE Recent pieces of evidence suggest that Fe bound to the biofilm could assume at least two important functions, a local source of Fe for uptake and a support to extracellular metabolism, such as extracellular electron transfer. Our results show that B. subtilis can use biofilm-bound Fe for uptake only if it does not compromise Fe homeostasis of the biofilm, i.e., maintains a minimum Fe concentration in the biofilm for extracellular purposes. We propose a theoretical framework based on our results and recent literature to explain how B. subtilis manages biofilm-bound Fe and Fe uptake in response to environmental Fe availability. These results provide important insights into the management of biofilm-bound and environmental Fe by B. subtilis in response to Fe stress.

Targeting Infectious Agents as a Therapeutic Strategy in Alzheimer's Disease.

Alzheimer's disease (AD) is the most prevalent dementia in the world. Its cause(s) are presently largely unknown. The most common explanation for AD, now, is the amyloid cascade hypothesis, which states that the cause of AD is senile plaque formation by the amyloid ß peptide, and the formation of neurofibrillary tangles by hyperphosphorylated tau. A second, burgeoning theory by which to explain AD is based on the infection hypothesis. Much experimental and epidemiological data support the involvement of infections in the development of dementia. According to this mechanism, the infection either directly or via microbial virulence factors precedes the formation of amyloid ß plaques. The amyloid ß peptide, possessing antimicrobial properties, may be beneficial at an early stage of AD, but becomes detrimental with the progression of the disease, concomitantly with alterations to the innate immune system at both the peripheral and central levels. Infection results in neuroinflammation, leading to, and sustained by, systemic inflammation, causing eventual neurodegeneration, and the senescence of the immune cells. The sources of AD-involved microbes are various body microbiome communities from the gut, mouth, nose, and skin. The infection hypothesis of AD opens a vista to new therapeutic approaches, either by treating the infection itself or modulating the immune system, its senescence, or the body's metabolism, either separately, in parallel, or in a multi-step way.

Methylparaben in meconium and risk of maternal thyroid dysfunction, adverse birth outcomes, and Attention-Deficit Hyperactivity Disorder (ADHD).

BACKGROUND: Parabens, which are used as a preservative in foods and personal care products, are detected in nearly 100% of human urine samples. Exposure to parabens is associated with DNA damage, male infertility, and endocrine disruption in adults, but the effects of prenatal exposure are unclear. In part, this is due to inadequate assessment of exposure in maternal urine, which may only reflect maternal rather than fetal exposure. To address this gap, we examined the association of prenatal methylparaben measured in meconium with preterm birth, gestational age, birthweight, maternal thyroid hormones, and child Attention-Deficit Hyperactivity Disorder (ADHD) at 6-7 years. DESIGN: Data come from the GESTation and the Environment (GESTE) prospective observational pregnancy cohort in Sherbrooke, Quebec, Canada. Participants were 345 children with data on ADHD among 394 eligible pregnancies in women age ≥18 years with no known thyroid disease before pregnancy and meconium collected at delivery. Methylparaben was measured in meconium. Birthweight, gestational age, and maternal thyroid hormones at <20 weeks gestation were measured at the Centre Hospitalier Universitaire de Sherbrooke. Preterm birth was defined as vaginal birth before the 37th week of gestation. Physician diagnosis of ADHD was determined at a scheduled cohort follow-up when children were 6-7 years old or from medical records. Associations between meconium methylparaben and outcomes were estimated with logistic and linear regressions weighted on the inverse probability of exposure to account for potential confounders, including child sex, familial income, maternal education, pre-pregnancy body mass index, age, and smoking and alcohol consumption during pregnancy. RESULTS: Methylparaben was detected in 65 meconium samples (19%), 33 children were diagnosed with ADHD (10%), and 13 children were born preterm (4%). Meconium methylparaben was associated with preterm birth (odds ratio [OR] = 4.81; 95% CI [2.29, 10.10]), decreased gestational age (beta [ß] = -0.61 weeks; 95% CI [-0.93, -0.29]) and birthweight (ß = -0.12 kg; 95% CI [-0.21, -0.03]), altered maternal TSH (relative concentration [RC] = 0.76; 95% CI [0.58, 0.99]), total T3 (RC = 0.84; 95% CI [0.75, 0.96]) and total T4 (RC = 1.10; 95% CI [1.01, 1.19]), maternal hypothyroxinemia (OR = 2.50, 95% CI [1.01, 6.22]), and child ADHD at age of 6-7 (OR = 2.33, 95% CI [1.45, 3.76]). The effect of meconium methylparaben on ADHD was partially mediated by preterm birth (20% mediation) and birthweight (13% mediation). CONCLUSIONS: Meconium methylparaben was associated with preterm birth, decreased gestational age and birthweight, maternal thyroid hormone dysfunction, and child ADHD. Parabens are a substantial health concern if causally related to these adverse outcomes.

Differences in elemental composition of tailings, soils, and plant tissues following five decades of native plant colonization on a gold mine site in Northwestern Québec.

Mining activities have significant environmental impacts, such as the production of acid mine drainage and the typical absence of vegetation on mine tailings whose absence can facilitate the migration of metals to adjacent ecosystems. We investigated the metal and metalloid composition of plants and substrates on, and near a former gold mine site to understand elemental dynamics in such environments. A mine tailings deposit rich in Mo and As in Northwestern Québec was studied following the natural colonization of the deposit by boreal plant species. The site and surrounding forest were categorized into 6 vegetation density classes (VDC) to determine if and how vegetation density, and plant elemental composition, and soil properties were linked. Macroelemental composition of plant tissues (P, K and Ca) was relatively stable, despite differences in macroelemental levels of substrates between different VDC (with lower macronutrient levels associated with less dense areas), indicating the adaptability of the three species studied (Alnus incana spp. rugosa, Betula papyrifera and Picea spp.). Results showed that across a wide range of substrate properties, it was plant species and density that explained metal and metalloid composition in plant tissues (leaves, stems, and roots), while the main environmental determinants for this were VDC, pH, Ca and Cu. Increasing vegetation density was associated with decreasing As and Mo concentrations in substrates. This study sheds light on the plasticity of alder, spruce and birch growing on mine sites, allowing us to better understand elemental dynamics on such sites, and ultimately improve their management.

Quantification of Moss-Associated Cyanobacteria Using Phycocyanin Pigment Extraction.

In the boreal forest, cyanobacteria can establish associations with feather moss and realize the biological nitrogen fixation (BNF) reaction, consisting in the reduction of atmospheric dinitrogen into bioavailable ammonium. In this ecosystem, moss-associated cyanobacteria are the main contributors to BNF by contributing up to 50% of new N input. Current environmental changes driven by anthropogenic activities will likely affect cyanobacteria activity (i.e., BNF) and populations inhabiting mosses, leading to potential important consequences for the boreal forest. Several methods are available to efficiently measure BNF activity, but quantifying cyanobacteria biomass associated with moss is challenging because of the difficulty to separate bacteria colonies from the host plant. Attempts to separate cyanobacteria by shaking or sonicating in water were shown to be poorly efficient and repeatable. The techniques commonly used, microscopic counting and quantitative PCR (qPCR) are laborious and time-consuming. In aquatic and marine ecosystems, phycocyanin (PC), a photosynthesis pigment produced by cyanobacteria, is commonly used to monitor cyanobacteria biomass. In this study, we tested if PC extraction and quantification can be used to estimate cyanobacteria quantity inhabiting moss. We report that phycocyanin can be easily extracted from moss by freeze/thaw disturbance of cyanobacteria cells and can be quickly and efficiently measured by spectrofluorometry. We also report that phycocyanin extraction is efficient (high recovery), repeatable (relative SD < 13%) and that no significant matrix effects were observed. As for aquatic systems, the main limitation of cyanobacteria quantification using phycocyanin is the difference of cellular phycocyanin content between cyanobacteria strains, suggesting that quantification can be impacted by cyanobacteria community composition. Nonetheless, we conclude that phycocyanin extraction and quantification is an easy, rapid, and efficient tool to estimate moss-associated cyanobacteria number.