Adsorption behavior and mechanism of Lead (Pb2+) by sulfate polysaccharide from Enteromorpha prolifera

Lead (Pb²⁺) pollution poses severe healthy and ecological risks to humans. In this work, sulfate polysaccharide from Enteromorpha prolifera (SPE) was utilized for Pb²⁺ adsorption from simulated intestinal fluid. In order to evaluate its adsorption behaviors comprehensively, batch adsorption of Pb²⁺ was investigated under different conditions. Results showed that SPE presents high adsorption ability for Pb²⁺ through chemical adsorption process and the maximum adsorption capacity for Pb²⁺ was 278.5 mg/g. And SPE exhibited higher removal efficiency (≥60%) for trace Pb²⁺ (<10 mg/L) compared to that of other adsorbents based on polysaccharide. Besides, its adsorption can be described by Langmuir isotherm and pseudo-second-order kinetic models. Further, XRD, FTIR, and XPS were used to characterize the possible interaction of Pb²⁺ with SPE, and the results showed that carboxyl and hydroxyl groups in SPE play more important role than that of sulfate group. Our work represents the first assessment of Pb²⁺ adsorption properties of SPE. This investigation highlights the potential application of SPE to protect the body from hazard of food-derived heavy metals.

Remarkably high Pb2+ binding capacity of a novel, regenerable bioremediator Papiliotrema laurentii RY1: Functional in both alkaline and neutral environments

The ability of P. laurentii strain RY1 to remediate lead (Pb²⁺) from water was investigated in batch and column studies. The lead removal ability of non-viable biomass, non-viable biomass immobilised on agar-agar (biobeads) and agar-agar at different pH was compared in batch studies. It was found that among the three, biobeads have maximum ability to remove Pb²⁺ followed by biomass and agar-agar beads. Maximum and almost equal lead removal by biobeads was observed at both neutral and alkaline pH making it a novel and more applicable bioremediator as all other reported bioremediators have a single pH for optimum activity. Studies were performed to determine the optimum conditions for lead removal from aqueous solutions for biobeads. The physical and chemical characterization of the biobeads before and after Pb²⁺ biosorption was done by using S.E.M. and F.T.I.R. respectively. The adsorption of Pb²⁺ on biobeads obeyed the Langmuir adsorption isotherm and pseudo first order kinetics. These mean that the Pb²⁺ binding sites are identical, located on the surface of the adsorbant and the rate of Pb²⁺ removal from aqueous solution is directly proportional to the number of Pb²⁺ binding sites on the biobeads. The thermodynamics of the biosorption process is also investigated. The binding capacity of the biobeads in batch study was found to be 52.91mg/gm which is higher in comparison to other reported yeast bioremediators. The used biobeads can be desorbed using 0.1(M) CaCl₂. The desorbed biobeads can be used subsequently for several cycles of lead removal making it cost-effective. Column studies were also performed for biobeads with the help of Thomas model for examining its suitability for industrial application. Maximum specific lead uptake of the biobeads when applied in the column was found to be 58.26mg/gm which being promising makes it suitable for application in industries involved in the treatment of wastewater contaminated with high amounts of lead. The high mass transfer co-efficient indicate that small sized column can be used effectively to remove high amounts of lead which makes the bioremediation process by the biobeads more economical and advantageous for industrial application. Several factors like effectiveness of the biobeads in Pb²⁺removal at both neutral and alkaline pH, reusability, high mass transfer co-efficient, regenerability and high binding capacity makes it a novel versatile, cost-effective and high utility bioremediator.

Developmental exposure to Pb2+ induces transgenerational changes to zebrafish brain transcriptome

Lead (Pb2+) is a major public health hazard for urban children, with profound and well-characterized developmental and behavioral implications across the lifespan. The ability of early Pb2+ exposure to induce epigenetic changes is well-established, suggesting that Pb2+-induced neurobehavioral deficits may be heritable across generations. Understanding the long-term and multigenerational repercussions of lead exposure is crucial for clarifying both the genotypic alterations behind these behavioral outcomes and the potential mechanism of heritability. To study this, zebrafish (Danio rerio) embryos (<2 h post fertilization; EK strain) were exposed for 24 h to waterborne Pb2+ at a concentration of 10 μM. This exposed F0 generation was raised to adulthood and spawned to produce the F1 generation, which was subsequently spawned to produce the F2 generation. Previous avoidance conditioning studies determined that a 10 μM Pb2+ dose resulted in learning impairments persisting through the F2 generation. RNA was extracted from control- and 10 μM Pb2+-lineage F2 brains, (n = 10 for each group), sequenced, and transcript expression was quantified utilizing Quant-Seq. 648 genes were differentially expressed in the brains of F2 lead-lineage fish versus F2 control-lineage fish. Pathway analysis revealed altered genes in processes including synaptic function and plasticity, neurogenesis, endocrine homeostasis, and epigenetic modification, all of which are implicated in lead-induced neurobehavioral deficits and/or their inheritance. These data will inform future investigations to elucidate the mechanism of adult-onset and transgenerational health effects of developmental lead exposure.

Role of the mitochondrial Ca²⁺ uniporter in Pb²⁺-induced oxidative stress in human neuroblastoma cells

Lead (Pb(2+)) has been shown to induce cellular oxidative stress, which is linked to changes in intracellular calcium (Ca(2+)) concentration. The mitochondrial Ca(2+) uniporter (MCU) participates in the maintenance of Ca(2+) homeostasis in neurons, but its role in Pb(2+)-induced oxidative stress is unclear. To address this question, oxidative stress was induced in human neuroblastoma SH-SY5Y cells and in newborn rats by Pb(2+) treatment. The results showed that the production of reactive oxygen species is increased in cells upon treatment with Pb(2+) in a dose-dependent manner, while glutathione and MCU expression were reduced. Moreover, neuronal nitric oxide synthase protein expression was elevated in rats exposed to Pb(2+) during gestation, while MCU expression was decreased. Application of the MCU activator spermine or MCU overexpression reversed Pb(2+)-induced oxidative stress and inhibition of mitochondrial Ca(2+) uptake, while the MCU inhibitor Ru360 and MCU knockdown potentiated the effects of Pb(2+). These results indicate that the MCU mediates the Pb(2+)-induced oxidative stress response in neurons through the regulation of mitochondrial Ca(2+) influx.