Infiltrating Lobular Breast Cancer Presenting as Isolated Gastric Metastasis: a Case Report

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Molecular and clinical spectra of FBXL4 deficiency

Abstract

F-box and leucine-rich repeat protein 4 (FBXL4) is a mitochondrial protein whose exact function is not yet known. However, cellular studies have suggested that it plays significant roles in mitochondrial bioenergetics, mitochondrial DNA (mtDNA) maintenance, and mitochondrial dynamics. Biallelic pathogenic variants in FBXL4 are associated with an encephalopathic mtDNA maintenance defect syndrome that is a multisystem disease characterized by lactic acidemia, developmental delay, and hypotonia. Other features are feeding difficulties, growth failure, microcephaly, hyperammonemia, seizures, hypertrophic cardiomyopathy, elevated liver transaminases, recurrent infections, variable distinctive facial features, white matter abnormalities and cerebral atrophy found in neuroimaging, combined deficiencies of multiple electron transport complexes, and mtDNA depletion. Since its initial description in 2013, 36 different pathogenic variants in FBXL4 were reported in 50 affected individuals. In this report, we present 37 additional affected individuals and 11 previously unreported pathogenic variants. We summarize the clinical features of all 87 individuals with FBXL4-related mtDNA maintenance defect, review FBXL4 structure and function, map the 47 pathogenic variants onto the gene structure to assess the variants distribution, and investigate the genotype-phenotype correlation. Finally, we provide future directions to understand the disease mechanism and identify treatment strategies.

This article is protected by copyright. All rights reserved

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Endonucleolytic cleavage in the expansion segment 7 of 25S rRNA is an early marker of low-level oxidative stress in yeast. [Cell Biology]

The ability to detect and respond to oxidative stress is crucial to the survival of living organisms. In cells, sensing of increased levels of reactive oxygen species (ROS) activates many defensive mechanisms that limit or repair damage to cell components. The ROS-signaling responses necessary for cell survival under oxidative stress conditions remain incompletely understood, especially for the translational machinery. Here, we found that drug treatments or a genetic deficiency in the thioredoxin system that increase levels of endogenous hydrogen peroxide in the yeast Saccharomyces cerevisiae promote site-specific endonucleolytic cleavage in 25S ribosomal RNA (rRNA) adjacent to the c-loop of the expansion segment 7 (ES7), a putative regulatory region located on the surface of the 60S ribosomal subunit. Our data also show that ES7c is cleaved at early stages of the gene expression program that enables cells to successfully counteract oxidative stress, and is not a prerequisite or consequence of apoptosis. Moreover, the 60S subunits containing ES7c-cleaved rRNA cofractionate with intact subunits in sucrose gradients and repopulate polysomes after a short starvation-induced translational block, indicating their active role in translation. These results demonstrate that ES7c cleavage in rRNA is an early and sensitive marker of increased ROS levels in yeast cells and suggest that changes in ribosomes may be involved in the adaptive response to oxidative stress.

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Myristoylation of Src kinase mediates Src induced and high fat diet accelerated prostate tumor progression in mice [Molecular Bases of Disease]

Exogenous fatty acids provide substrates for energy production and the biogenesis of the cytoplasmic membrane, but they also enhance cellular signaling during cancer cell proliferation. However, it remains controversial whether dietary fatty acids are correlated with tumor progression. In this study, we demonstrate that increased Src kinase activity is associated with high fat diet accelerated progression of prostate tumors and that Src kinases mediate this pathological process. Moreover, in the in vivo prostate regeneration assay, host SCID mice carrying Src(Y529F) transduced regeneration tissues were fed with a low fat diet or a high fat diet and treated with vehicle or dasatinib. The high fat diet not only accelerated Src induced prostate tumorigenesis in mice, but also compromised the inhibitory effect of the anticancer drug dasatinib on Src kinase oncogenic potential in vivo. We further show that myristoylation of Src kinase is essential to facilitate Src induced and high fat diet accelerated tumor progression. Mechanistically, metabolism of exogenous myristic acid increased the biosynthesis of myristoyl CoA and myristoylated Src, and promoted Src kinase mediated oncogenic signaling in human cells. Of the fatty acids tested, only exogenous myristic acid contributed to increased intracellular myristoyl CoA levels. Our results suggest that targeting Src kinase myristoylation, which is required for Src kinase association at the cellular membrane, blocks dietary fat accelerated tumorigenesis in vivo. Our findings uncover a molecular basis of how the metabolism of myristic acid stimulates high fat diet mediated prostate tumor progression.

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Human Rab small GTPase- and class V myosin-mediated membrane tethering in a chemically defined reconstitution system [Cell Biology]

Membrane tethering is a fundamental process essential for compartmental specificity of intracellular membrane trafficking in eukaryotic cells. Rab-family small GTPases and specific sets of Rab-interacting effector proteins, including coiled-coil tethering proteins and multisubunit tethering complexes, have been reported to be responsible for membrane tethering. However, whether and how these key components directly and specifically tether subcellular membranes still remains enigmatic. Using chemically defined proteoliposomal systems reconstituted with purified human Rab proteins and synthetic liposomal membranes to study the molecular basis of membrane tethering, we established here that Rab-family GTPases have a highly conserved function to directly mediate membrane tethering, even in the absence of any types of Rab effectors such as the so-called tethering proteins. Moreover, we demonstrate that membrane tethering mediated by endosomal Rab11a is drastically and selectively stimulated by its cognate Rab effectors, class V myosins (Myo5A and Myo5B), in a GTP-dependent manner. Of note, Myo5A and Myo5B exclusively recognized and cooperated with the membrane-anchored form of their cognate Rab11a to support membrane tethering mediated by trans-Rab assemblies on apposing membranes. Our findings support the novel concept that Rab-family proteins provide a bona fide membrane tether to physically and specifically link two distinct lipid bilayers of subcellular membranes. They further indicate that Rab-interacting effector proteins, including class V myosins, can regulate these Rab-mediated membrane tethering reactions.

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Plasma membrane phosphatidylinositol 4-phosphate and 4,5-bisphosphate determine the distribution and function of K-Ras4B but not H-Ras proteins [Signal Transduction]

Plasma membrane (PM) localization of Ras proteins is crucial for transmitting signals upon mitogen stimulation. Posttranslational lipid modification of Ras proteins plays an important role in their recruitment to the PM. Electrostatic interactions between negatively charged PM phospholipids and basic amino acids found in K-Ras4B (K-Ras) but not in H-Ras are important for permanent K-Ras localization to the PM. Here, we investigated how acute depletion of negatively charged PM polyphosphoinositides (PPIns) from the PM alters the intracellular distribution and activity of K- and H-Ras proteins. PPIns depletion from the PM was achieved either by agonist-induced activation of phospholipase C β or with a rapamycin-inducible system in which various PI phosphatases were recruited to the PM. Redistribution of the two Ras proteins was monitored with confocal microscopy or with a recently developed bioluminescent energy transfer (BRET)-based approach involving fusion of the Ras C-terminal targeting sequences or the entire Ras proteins to Venus fluorescent protein. We found that PM PPIns depletion caused rapid translocation of K-Ras but not H-Ras from the PM to the Golgi. PM depletion of either phosphatidylinositol 4-phosphate (PtdIns4P) or PtdIns(4,5)P2, but not PtdIns(3,4,5)P3, was sufficient to evoke K-Ras translocation. This effect was diminished by deltarasine, an inhibitor of the Ras-phosphodiesterase interaction, or by simultaneous depletion of the Golgi PtdIns4P. The PPIns depletion decreased incorporation of [3H]-Leucine in K-Ras-expressing cells, suggesting that Golgi-localized K-Ras is not as signaling competent as its PM-bound form. We conclude that PPIns in the PM are important regulators of K-Ras mediated signals.

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Phosphomimetic S3D-Cofilin Binds But Only Weakly Severs Actin Filaments [Enzymology]

Many biological processes, including cell division, growth, and motility, rely on rapid remodeling of the actin cytoskeleton and on actin-filament severing by the regulatory protein cofilin. Phosphorylation of vertebrate cofilin at serine 3 (Ser-3) regulates both actin binding and severing. Substitution of serine with aspartate at position 3 (S3D) is widely used to mimic cofilin phosphorylation in cells and in vitro. The S3D substitution weakens cofilin binding to filaments, and it is presumed that subsequent reduction in cofilin occupancy inhibits filament severing, but this hypothesis has remained untested. Here, using time-resolved phosphorescence anisotropy, electron cryomicroscopy, and all-atom molecular dynamics simulations, we show that S3D-cofilin indeed binds filaments with lower affinity, but also with a higher cooperativity than wild-type cofilin, and severs actin weakly across a broad range of occupancies. We found that three factors contribute to the severing deficiency of S3D-cofilin. First, the high cooperativity of S3D-cofilin generates fewer boundaries between bare and decorated actin segments where severing occurs preferentially. Second, S3D-cofilin only weakly alters filament bending and twisting dynamics and therefore does not introduce the mechanical discontinuities required for efficient filament severing at boundaries. Third, Ser-3 modification (i.e. substitution with Asp or phosphorylation) undocks and repositions the cofilin N-terminus away from the filament axis, which compromises S3D-cofilins ability to weaken longitudinal filament subunit interactions. Collectively, our results demonstrate that, in addition to inhibiting actin binding, Ser-3 modification favors formation of a cofilin binding mode that is unable to sufficiently alter filament mechanical properties and promote severing.

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Translesion synthesis DNA polymerases promote error-free replication through the minor-groove DNA adduct 3-deaza-3-methyl adenine [DNA and Chromosomes]

N3-methyladenine (3-MeA) is formed in DNA by reaction with S-adenosyl methionine, the reactive methyl donor, and by reaction with alkylating agents. 3-MeA protrudes into the DNA minor groove and strongly blocks synthesis by replicative DNA polymerases (Pols). However, the mechanisms for replicating through this lesion in human cells remain unidentified. Here we analyzed the roles of translesion synthesis (TLS) Pols in the replication of 3-MeA-damaged DNA in human cells. Because 3-MeA has a short half-life in vitro, we used the stable 3-deaza analog, 3-deaza-3-methyl adenine (3-dMeA), which blocks the DNA minor groove similarly to 3-MeA. We found that replication through the 3-dMeA adduct is mediated via three different pathways, dependent upon Polι/Polκ, Polθ, and Polζ. As inferred from biochemical studies, in the Polι/Polκ pathway, Polι inserts a nucleotide (nt) opposite 3-dMeA and Polκ extends synthesis from the inserted nt. In the Polθ pathway, Polθ carries out both the insertion and extension steps of TLS opposite 3-dMeA, and in the Polζ pathway, Polζ extends synthesis following nt insertion by an as yet unidentified Pol. Steady-state kinetic analyses indicated that Polι and Polθ insert the correct nt T opposite 3-dMeA with a much reduced catalytic efficiency and that both Pols exhibit a high propensity for inserting a wrong nt opposite this adduct. However, in spite of their low fidelity of synthesis opposite 3-dMeA, TLS opposite this lesion replicates DNA in a highly error-free manner in human cells. We discuss the implications of these observations for TLS mechanisms in human cells..

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Bacterial DnaB helicase interacts with the excluded strand to regulate unwinding [Molecular Biophysics]

Replicative hexameric helicases are thought to unwind duplex DNA by steric exclusion (SE), where one DNA strand is encircled by the hexamer and the other is excluded from the central channel. However, interactions with the excluded strand on the exterior surface of hexameric helicases have also been shown to be important for DNA unwinding, giving rise to the steric exclusion and wrapping (SEW) model. For example, the archaeal SsoMCM helicase has been shown to unwind DNA via a SEW mode to enhance unwinding efficiency. Using single molecule FRET (smFRET), we now show that the analogous E. coli DnaB helicase also interacts specifically with the excluded DNA strand during unwinding. Mutation of several conserved and positively-charged residues on the exterior surface of EcDnaB resulted in increased interaction dynamics and states compared to wild-type. Surprisingly, these mutations also increased the DNA unwinding rate, suggesting that electrostatic contacts with the excluded strand act as a regulator for unwinding activity. In support, experiments neutralizing charge of the excluded strand with a morpholino substrate instead of DNA also dramatically increased the unwinding rate. Of note, although the stability of the excluded strand was nearly identical for EcDnaB and SsoMCM, these enzymes are from different superfamilies and unwind DNA with opposite polarities. These results support the SEW model of unwinding for EcDnaB that expands on the existing SE model of hexameric helicase unwinding to include contributions from the excluded strand to regulate the DNA unwinding rate.

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Interaction between the AAA+ ATPase p97 and its cofactor ataxin3 in health and disease: Nucleotide-induced conformational changes regulate cofactor binding [Protein Structure and Folding]

p97 is an essential ATPase associated with various cellular activities (AAA+) that functions as a segregase in diverse cellular processes, including the maintenance of proteostasis. p97 interacts with different cofactors that target it to distinct pathways; an important example is the deubiquitinase ataxin3, which collaborates with p97 in endoplasmic reticulum associated degradation (ERAD). However, the molecular details of this interaction have been unclear. Here, we characterized the binding of ataxin3 to p97, showing that ataxin3 binds with low-micromolar affinity to both wild-type p97 and mutants linked to degenerative disorders known as multisystem proteinopathy 1 (MSP1); we further showed that the stoichiometry of binding is one ataxin3 molecule per p97 hexamer. We mapped the binding determinants on each protein, demonstrating that ataxin3's p97/VCP-binding motif (VBM) interacts with the inter-lobe cleft in the N-domain of p97. We also probed the nucleotide dependence of this interaction, confirming that ataxin3 and p97 associate in the presence of ATP and in the absence of nucleotide, but not in the presence of ADP. Our experiments suggest that an ADP-driven downward movement of the p97 N-terminal domain dislodges ataxin3 by inducing a steric clash between the D1-domain and ataxin3's C-terminus. In contrast, MSP1 mutants of p97 bind ataxin3 irrespective of their nucleotide state, indicating a failure by these mutants to translate ADP binding into a movement of the N-terminal domain. Our model provides a mechanistic explanation for how nucleotides regulate the p97-ataxin3 interaction and why atypical cofactor binding is observed with MSP1 mutants.

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PLEIOTROPHIN, A MULTIFUNCTIONAL CYTOKINE AND GROWTH FACTOR, INDUCES LEUKOCYTE RESPONSES THROUGH THE INTEGRIN MAC-1 [Protein Structure and Folding]

Pleiotrophin (PTN) is a multifunctional, cationic, glycosaminoglycan-binding cytokine and growth factor involved in numerous physiological and pathological processes, including tissue repair and inflammation-related diseases. PTN has been shown to promote leukocyte responses by inducing their migration and expression of inflammatory cytokines. However, the mechanisms through which PTN mediates these responses remain unclear. Here, we identified the integrin Mac-1 (αMβ2, CD11b/CD18) as the receptor mediating macrophage adhesion and migration to PTN. We also found that expression of Mac-1 on the surface of human embryonic kidney (HEK) 293 cells induced their adhesion and migration to PTN. Accordingly, PTN promoted Mac-1-dependent cell spreading and initiated intracellular signaling manifested in phosphorylation of Erk1/2. While binding to PTN, Mac-1 on Mac-1-expressing HEK293 cells appear to cooperate with cell-surface proteoglycans, since both anti-Mac-1 function-blocking mAb and heparin were required to block adhesion. Moreover, biolayer interferometry and NMR indicated a direct interaction between the αMI domain, the major ligand-binding region of Mac-1, and PTN. Using peptide libraries, we found that in PTN, the αMI domain bound sequences enriched in basic and hydrophobic residues, indicating that PTN conforms to the general principle of ligand-recognition specificity of the αMI domain toward cationic proteins/peptides. Finally, using recombinant PTN-derived fragments, we show that PTN contains two distinct Mac-1-binding sites in each of its constitutive domains. Collectively, these results identify PTN as a ligand for the integrin Mac-1 on the surface of leukocytes and suggest that this interaction may play a role in inflammatory responses.

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Dopamine Transporter Phosphorylation Site Threonine 53 is Stimulated by Amphetamines and Regulates Dopamine Transport, Efflux, and Cocaine Analog Binding [Neurobiology]

The dopamine transporter (DAT) controls the spatial and temporal dynamics of dopamine neurotransmission through reuptake of extracellular transmitter and is a target for addictive compounds such as cocaine, amphetamine (AMPH), and methamphetamine (METH). Reuptake is regulated by kinase pathways and drug exposure, allowing for fine-tuning of clearance in response to specific conditions, and here we examine the impact of transporter ligands on DAT residue Thr53, a proline-directed phosphorylation site previously implicated in AMPH-stimulated efflux mechanisms. Our findings show that Thr53 phosphorylation is stimulated in a transporter-dependent manner by AMPH and METH in model cells and rat striatal synaptosomes, and in striatum of rats given subcutaneous injection of METH. Rotating disc electrode voltammetry revealed that initial rates of uptake and AMPH-induced efflux were elevated in phosphorylation-null T53A DAT relative to WT and charge-substituted T53D DATs, consistent with functions related to charge or polarity. These effects occurred without alterations of surface transporter levels, and mutants also showed reduced cocaine analog binding affinity that was not rescued by Zn2+. Together these findings support a role for Thr53 phosphorylation in regulation of transporter kinetic properties that could impact DAT responses to amphetamines and cocaine.

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Erratum to: BMC Public Health, Vol. 18

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Early emergence of negative regulation of the tyrosine kinase Src by the C-terminal Src kinase [Signal Transduction]

Stringent regulation of tyrosine kinase activity is essential for normal cellular function. In humans, the tyrosine kinase Src is inhibited via phosphorylation of its C-terminal tail by another kinase, C-terminal Src kinase (Csk). While Src and Csk orthologs are present across holozoan organisms, including animals and protists, the Csk-Src negative regulatory mechanism appears to have evolved gradually. For example, in choanoflagellates, Src and Csk are both active, but the negative regulatory mechanism is reportedly absent. In filastereans, a protist clade closely related to choanoflagellates, Src is active but Csk is apparently inactive. In this study, we use a combination of bioinformatics, in vitro kinase assays and yeast-based growth assays to characterize holozoan Src and Csk orthologs. We show that, despite appreciable differences in domain architecture, Csk from Corallochytrium limacisporum, a highly diverged holozoan marine protist, is active and can inhibit Src. However, in comparison with other Csk orthologs, Corallochytrium Csk displays a broad substrate specificity and inhibits Src in an activity independent manner. Furthermore, in contrast to previous studies, we show that Csk from the filasterean Capsaspora owczarzaki is active and that the Csk-Src negative regulatory mechanism is present in Csk and Src proteins from Capsaspora owczarzaki and the choanoflagellate Monosiga brevicollis. Our results suggest that negative regulation of Src by Csk is more ancient than previously thought and that it might be conserved across all holozoan species.

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Thioredoxin-1 maintains mTOR function during oxidative stress in cardiomyocytes [Signal Transduction]

Thioredoxin 1 (Trx1) is a 12 kDa oxidoreductase that catalyzes thiol-disulfide exchange reactions to reduce proteins with disulfide bonds. As such, Trx1 helps protect the heart against stresses, such as ischemia and pressure overload. Mechanistic target of rapamycin (mTOR) is a serine/threonine kinase that regulates cell growth, metabolism and survival. We have previously shown that mTOR activity is increased in response to myocardial ischemia-reperfusion injury. However, whether Trx1 interacts with mTOR to preserve heart function remains unknown. Using a substrate-trapping mutant of Trx1 (Trx1C35S), we here show that mTOR is a direct interacting partner of Trx1 in the heart. In response to H2O2 treatment in cardiomyocytes, mTOR exhibited a high molecular weight shift in non-reducing SDS-PAGE in a 2-mercaptoethanol sensitive manner, suggesting that mTOR is oxidized and forms disulfide bonds with itself or other proteins. The mTOR oxidation was accompanied by reduced phosphorylation of endogenous substrates, such as S6 kinase (S6K) and 4E-Binding Protein 1 (4EBP1) in cardiomyocytes. Immune complex kinase assays disclosed that the H2O2 treatment diminished mTOR kinase activity, indicating that mTOR is inhibited by oxidation. Of note, Trx1 overexpression attenuated both H2O2-mediated mTOR oxidation and inhibition, whereas Trx1 knockdown increased mTOR oxidation and inhibition. Moreover, Trx1 normalized H2O2- induced downregulation of metabolic genes and stimulation of cell death, and an mTOR inhibitor abolished Trx1-mediated rescue of gene expression. H2O2-induced oxidation and inhibition of mTOR were attenuated when Cys1483 of mTOR was mutated to phenylalanine. These results suggest that Trx1 protects cardiomyocytes against stress by reducing mTOR at Cys1483, thereby preserving the activity of mTOR and inhibiting cell death.

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Casein kinase 2-mediated phosphorylation of Brahma-related gene 1 controls myoblast proliferation and contributes to SWI/SNF complex composition [DNA and Chromosomes]

Transcriptional regulation is modulated in part by chromatin remodeling enzymes that control gene accessibility by altering chromatin compaction or nucleosome positioning. Brahma-related gene 1 (Brg1), a catalytic subunit of the mammalian SWI/SNF chromatin remodeling enzymes, is required for both myoblast proliferation and differentiation, and the control of Brg1 phosphorylation by calcineurin, PKCβ1, and p38 regulates the transition to differentiation. However, we hypothesized that Brg1 activity might be regulated by additional kinases. Here, we report that Brg1 is also a target of Casein Kinase 2 (CK2), a serine/threonine kinase, in proliferating myoblasts. We found that CK2 interacts with Brg1, and mutation of putative phosphorylation sites to non-phosphorylatable (Ser to Ala, SA) or phosphomimetic residues (Ser to Glu, SE) reduced Brg1 phosphorylation by CK2. While BRG1-deleted myoblasts that ectopically express the SA-Brg1 mutant proliferated similarly to the parental cells or cells ectopically expressing wildtype (WT) Brg1, ectopic expression of the SE-Brg1 mutant reduced proliferation and increased cell death, similar to observations from cells lacking Brg1. Moreover, pharmacological inhibition of CK2 increased myoblast proliferation. Furthermore, the Pax7 promoter, which controls expression of a key transcription factor required for myoblast proliferation, was in an inaccessible chromatin state in the SE-Brg1 mutant, suggesting that hyperphosphorylated Brg1 cannot remodel chromatin. WT-, SA-, and SE-Brg1 exhibited distinct differences in interacting with and affecting expression of the SWI/SNF subunits Baf155 and Baf170 and displayed differential sub-nuclear localization. Our results indicate that CK2-mediated phosphorylation of Brg1 regulate myoblast proliferation and provide insight into one mechanism by which composition of the mammalian SWI/SNF enzyme complex is regulated.

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Spatial distribution of metals within the liver acinus and their perturbation by PCB126

Abstract

Animal studies show that exposure to the environmental pollutant 3,3′,4,4′,5-pentachlorobiphenyl (PCB126) causes alterations in hepatic metals as measured in acid-digested volume-adjusted tissue. These studies lack the detail of the spatial distribution within the liver. Here we use X-ray fluorescence microscopy (XFM) to assess the spatial distribution of trace elements within liver tissue. Liver samples from male Sprague Dawley rats, treated either with vehicle or PCB126, were formalin fixed and paraffin embedded. Serial sections were prepared for traditional H&E staining or placed on silicon nitride windows for XFM. With XFM, metal gradients between the portal triad and the central vein were seen, especially with copper and iron. These gradients change with exposure to PCB126, even reverse. This is the first report of how micronutrients vary spatially within the liver and how they change in response to toxicant exposure. In addition, high concentrations of zinc clusters were discovered in the extracellular space. PCB126 treatment did not affect their presence, but did alter their elemental makeup suggesting a more general biological function. Further work is needed to properly evaluate the gradients and their alterations as well as classify the zinc clusters to determine their role in liver function and zinc homeostasis.

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Applicability and efficacy of diatom indices in water quality evaluation of the Chambal River in Central India

Abstract

Diatom indices have gained considerable popularity in estimation of the trophic state and degree of pollution in lotic ecosystems. However, their applicability and efficacy have rarely been tested in Indian streams and rivers. In the present study, benthic diatom assemblages were sampled at 27 sites along the Chambal River in Central India. PCA revealed three groups of sites, namely, heavily polluted (HVPL), moderately polluted (MDPL), and least polluted (SANT). A total of 100 diatom taxa belonging to 40 genera were identified. Brachysira vitrea (Grunow) was the most abundant species recorded from the least polluted sites with an average relative abundance of 29.52. Nitzschia amphibia (Grunow) was representative of heavily polluted sites (average relative abundance 31.71) whereas moderately polluted sites displayed a dominance of Achnanthidium minutissimum (Kϋtzing) with an average relative abundance of 26.33. CCA was used to explore the relationship between diatom assemblage composition and environmental variables. Seventeen different diatom indices were calculated using diatom assemblage data. The relationship between measured water quality variables and index scores was also investigated. Most of the diatom indices exhibited strong correlations with water quality variables including BOD, COD, conductivity, and nutrients, particularly phosphate. Best results were obtained for TDI and IPS indices which showed a high level of resolution with respect to discrimination of sites on the basis of pollution gradients. Water quality maps for the Chambal River were hence prepared in accordance with these two indices. However, satisfactory results with respect to water quality evaluation were also obtained by the application of EPI-D and IGD indices. The present study suggests that TDI and IPS are applicable for biomonitoring of rivers of Central India. Diatom indices, which are simpler to use such as IGD, may be considered, at least for a coarser evaluation of water quality.

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An investigation of the health effects caused by exposure to arsenic from drinking water and coal combustion: arsenic exposure and metabolism

Abstract

Few studies have been conducted to compare arsenic exposure, metabolism, and methylation in populations exposed to arsenic in drinking water and from coal combustion. Therefore, arsenic concentrations in the environment and arsenic speciation in the urine of subjects exposed to arsenic as a consequence of coal combustion in a rural area in Shaanxi province (CCA) and in drinking water in a rural area in Inner Mongolia (DWA) were investigated. The mean arsenic concentrations in drinking water, indoor air, and soil in CCA were 4.52 μg/L, 0.03 mg/m³, and 14.93 mg/kg, respectively. The mean arsenic concentrations in drinking water and soil in DWA were 144.71 μg/L and 10.19 mg/kg, respectively, while the level in indoor air was lower than the limit of detection. The total daily intakes of arsenic in DWA and CCA were 4.47 and 3.13 μg/day·kg, respectively. The mean urinary concentrations of inorganic arsenic (iAs), monomethylarsonic acid (MMA), dimethylarsenic acid (DMA), and total arsenic (TAs) for subjects with skin lesions in DWA were 50.41, 47.01, 202.66, and 300.08 μg/L. The concentrations for subjects without skin lesions were 49.76, 44.20, 195.60, and 289.56 μg/L, respectively. The %iAs, %MMA, and %DMA in the TAs in the urine of subjects from CCA were 12.24, 14.73, and 73.03%, while the corresponding values from DWA were 17.54, 15.57, and 66.89%, respectively. The subjects in DWA typically had a higher %iAs and %MMA, and a lower %DMA, and primary and secondary methylation index (PMI and SMI) than the subjects in CCA. It was concluded that the arsenic methylation efficiency of subjects in DWA and CCA was significantly influenced by chronic exposure to high levels of arsenic in the environment. The lower PMI and SMI values in DWA revealed lower arsenic methylation capacity due to ingestion of arsenic in drinking water. However, it remained unclear if the differences in arsenic metabolism between the two groups were due to differences in exposure levels or in exposure route.

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Vinegar production from fruit concentrates: effect on volatile composition and antioxidant activity

Abstract

Vinegar stands as a highly appreciated fermented food product due to several functional properties and multiple applications. This work focuses on vinegar production from fruit wines derived from fruit concentrates, to attain a food product with nutritional added value. Four fruit vinegars (orange, mango, cherry and banana), were produced and characterized, with total acidities of 5.3 ± 0.3% for orange, 5.6 ± 0.2% for mango, 4.9 ± 0.4% for cherry and 5.4 ± 0.4% for banana. Acetification showed impact on aroma volatiles, mainly related to oxidative reactions. Minor volatiles associated with varietal aroma were identified, monoterpenic alcohols in orange vinegar, esters in banana vinegar, C₁₃-norisoprenoids in cherry vinegar and lactones in mango vinegar, indicating fruit vinegars differentiated sensory quality. Total antioxidant activity analysis by FRAP, revealed fruit vinegars potential to preserve and deliver fruit functional properties. Antioxidant activity of fruit vinegars, expressed as equivalents of Fe₂SO₄, was of 11.0 ± 1.67 mmol L⁻¹ for orange, 4.8 ± 0.5 mmol L⁻¹ for mango, 18.6 ± 2.33 mmol L⁻¹ for cherry and 3.7 ± 0.3 mmol L⁻¹ for banana. Therefore, fruit vinegars presented antioxidant activity close to the reported for the corresponding fruit, and between 8 and 40 folds higher than the one found in commercial cider vinegar, demonstrating the high functional potential of these novel vinegar products.

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