Cutin-Derived Oligomers Induce Hallmark Plant Immune Responses.

The cuticle constitutes the outermost defensive barrier of most land plants. It comprises a polymeric matrix - cutin, surrounded by soluble waxes. Moreover, the cuticle constitutes the first line of defense against pathogen invasion, while also protecting the plant from many abiotic stresses. Aliphatic monomers in cutin have been suggested to act as immune elicitors in plants. This study analyses the potential of cutin oligomers to activate rapid signaling outputs reminiscent of pattern-triggered immunity (PTI) in the model plant Arabidopsis. Cutin oligomeric mixtures led to Ca2+ influx and MAPK activation. Comparable responses were measured for cutin, which was also able to induce a reactive oxygen species (ROS) burst. Furthermore, cutin oligomer treatment resulted in a unique transcriptional reprogramming profile, having many archetypal features of PTI. Targeted spectroscopic and spectrometric analyses of the cutin oligomers suggest that the elicitors compounds consist mostly of two up to three 10,16-dihydroxyhexadecanoic acid monomers linked together through ester bonds. This study demonstrates that cutin breakdown products can act as inducers of early plant immune responses, which underlying mechanisms of perception and potential use in agriculture warrant further investigation.

Bringing up to date the toolkit for the catabolism of aromatic compounds in fungi: The unexpected 1,2,3,5-tetrahydroxybenzene central pathway.

Saprophytic fungi are able to catabolize many plant-derived aromatics, including, for example, gallate. The catabolism of gallate in fungi is assumed to depend on the five main central pathways, i.e., of the central intermediates' catechol, protocatechuate, hydroxyquinol, homogentisate and gentisate, but a definitive demonstration is lacking. To shed light on this process, we analysed the transcriptional reprogramming of the growth of Aspergillus terreus on gallate compared with acetate as the control condition. Surprisingly, the results revealed that the five main central pathways did not exhibit significant positive regulation. Instead, an in-depth analysis identified four highly expressed and upregulated genes that are part of a conserved gene cluster found in numerous species of fungi, though not in Aspergilli. The cluster comprises a monooxygenase gene and a fumarylacetoacetate hydrolase-like gene, which are recognized as key components of catabolic pathways responsible for aromatic compound degradation. The other two genes encode proteins with no reported enzymatic activities. Through functional analyses of gene deletion mutants in Aspergillus nidulans, the conserved short protein with no known domains could be linked to the conversion of the novel metabolite 5-hydroxydienelatone, whereas the DUF3500 gene likely encodes a ring-cleavage enzyme for 1,2,3,5-tetrahydroxybenzene. These significant findings establish the existence of a new 1,2,3,5-tetrahydroxybenzene central pathway for the catabolism of gallate and related compounds (e.g. 2,4,6-trihydroxybenzoate) in numerous fungi where this catabolic gene cluster was observed.

Purification of archetypal soybean root suberin mostly comprising alka(e)noic acids using an ionic liquid catalyst.

Soybean (Glycine max) is an increasingly relevant crop due to its economic importance and also a model plant for the study of root symbiotic associations with nodule forming rhizobia. Plant polyesters mediate plant-microbe interactions with both pathogenic and beneficial microbes; suberin has been hypothesized to play a key role during the early steps of rhizobia attachment to the root. The downside is that suberin chemistry in soybean root is still scarcely studied. This study addresses this outstanding question by reporting a straightforward workflow for a speedy purification of suberin from soybean root and for its subsequent detailed chemical analysis. To purify suberin, cholinium hexanoate (an ionic liquid) was used as the catalyst. The ensuing suberin is highly esterified as observed by a precise Nuclear Magnetic Resonance quantification of each ester type, discriminating between primary and acylglycerol esters. Moreover, the composing hydrolysable monomers detected through GC-MS revealed that hexadecanoic acid is the most abundant monomer, similar to that reported before by others. Overall, this study highlights the adequacy of the ionic liquid catalyst for the isolation of suberin from soybean roots, where the polymer natural abundance is low, and builds new knowledge on the specificities of its chemistry; essential to better understand the biological roles of suberin in roots.

Finding a Needle in a Haystack: Producing Antimicrobial Cutin-Derived Oligomers from Tomato Pomace.

Agro-industrial residues comprise a rich diversity of plant polymers and bioactive compounds, constituting promising sources for the development of materials, including bioplastics, and food supplements, among other applications. In particular, the polyester cutin is abundant in fruit peel, a plentiful constituent of pomace agro-industrial residues. The potential of diverse fruit pomaces as a source for the development of cutin-derived materials/products has been extensively sought out. This study expands the established knowledge: it sets proof of concept for the production of antimicrobial oligomers from cutin-rich materials isolated in a single step from tomato pomaces generated by two remote agro-industries. Specifically, it first analyzed how the chemical signature (nuclear magnetic resonance (NMR) and gas chromatography-mass spectrometry (GC-MS)) of a pomace (and of its major constituents) mirrors that of the corresponding cutin-rich material isolated using an ionic liquid extractant. The cutin-rich materials were then deconstructed (using mild hydrolyses), and the resultant mixtures were chemically characterized and screened for bactericidal activity against Escherichia coli and Staphylococcus aureus. The presence of esterified structures, linear and/or branched, likely comprising dioic acids as a major building block (but not exclusively) is a prerequisite for activity against E. coli but not against S. aureus that was susceptible to monomers as well. Further studies are required to optimize the production of broad bactericidal oligomers from any cutin-rich pomace source, moving ahead toward their circular usage.

The Vacinómetro® initiative: an eleven-year monitorization of influenza vaccination coverage rates among risk groups in Portugal.

Annual vaccination is fundamental for individual and group protection against seasonal influenza infection. International and Portuguese healthcare organizations have established influenza vaccination coverage rate (VCR) targets for risk groups, namely 75% in people ≥ 65 years old. The Vacinómetro® initiative has been monitoring influenza VCR among target risk groups in Portugal since 2009,: Group 1, ≥ 65 years old; Group 2, patients with chronic conditions; Group 3, healthcare workers in direct contact with patients; and Group 4, 60-64 years old. Besides VCR, social-demographic and health-related variables have been evaluated. During the study period (2009/2010 - 2019/2020), the VCR increased in the 4 target risk groups: from 58.6% to 76.0% in Group 1 (reaching the WHO target); 33.3% to 72.0% in Group 2; 25.0% to 58.9% in Group 3; and 36.6% to 42.8% in Group 4. "Physician recommendation" was the main driver for vaccination whereas "lack of habit" was the main barrier to vaccination. Vacinómetro® data demonstrate that free-of-charge vaccination has a positive impact on VCR. The observed positive trends in influenza VCR demonstrate that public health measures implemented in Portugal to facilitate access to influenza vaccine result in increased vaccine uptake. Strategies to promote population literacy and the physician's awareness should be continued and reinforced. Free-of-charge vaccination criteria extended to more risk groups would also contribute to higher influenza VCR in Portugal.

Quantification of Structure-Property Relationships for Plant Polyesters Reveals Suberin and Cutin Idiosyncrasies.

Polyesters, as they exist in planta, are promising materials with which to begin the development of "green" replacements. Cutin and suberin, polyesters found ubiquitously in plants, are prime candidates. Samples enriched for plant polyesters, and in which their native backbones were largely preserved, were studied to identify "natural" structural features; features that influence critical physical properties. Quantitative nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC), and X-ray scattering methods were used to quantify structure-property relationships in these polymeric materials. The degree of esterification, namely, the presence of acylglycerol linkages in suberin and of secondary esters in cutin, and the existence of mid-chain epoxide groups defining the packing of the aliphatic chains were observed. This packing determines polymer crystallinity, the resulting crystal structure, and the melting temperature. To evaluate the strength of this rule, tomato cutin from the same genotype, studying wild-type plants and two well-characterized mutants, was analyzed. The results show that cutin's material properties are influenced by the amount of unbound aliphatic hydroxyl groups and by the length of the aliphatic chain. Collectively, the acquired data can be used as a tool to guide the selection of plant polyesters with precise structural features, and hence physicochemical properties.

Protective effects of silymarin in broiler feed contaminated by mycotoxins: growth performance, meat antioxidant status, and fatty acid profiles.

The aim of this study was to determine whether the inclusion of silymarin in broiler feed was able to mitigate the adverse effects of mycotoxin on growth performance, health status, liver oxidative stress, and meat fatty acid profiles. A completely randomized design with four treatments, four repetitions, and 15 chicks per repetition was used, with the following groups: (a) feed without additives (NoMyc-NoSil), (b) feed supplemented with silymarin (NoMyc-Sil), (c) feed contaminated with mycotoxin (Myc-NoSil), and (d) feed contaminated with mycotoxin and supplemented with silymarin (Myc-Sil). Growth performance, intestinal and liver health, and meat quality were assessed. The consumption of feed contaminated with mycotoxin delayed weight gain and increased the feed conversion ratio; however, the addition of silymarin prevented these adverse effects on the chicken industry. Serum ALT activity was higher in Myc-NoSil broilers than in other groups. Intake of silymarin in healthy birds increased serum globulin concentration and reduced albumin concentration and ALT and AST serum activities compared to the Myc-NoSil group. The NoMyc-Sil birds had greater villus heights and crypt depths. Luminosity and water loss by cooking were affected by mycotoxin ingestion, changes that did not occur in the meat of birds that were supplemented with silymarin. The sum of saturated and monounsaturated fatty acids in the meat did not change among treatments, unlike the sum of polyunsaturated fatty acids higher in the meat of birds that consumed silymarin. We conclude that silymarin is a potential additive in broiler feed; it reduces impairment of growth performance at the end of the productive cycle, prevents oxidative stress, improves meat quality, and increases polyunsaturated fatty acids.

An Ionic Liquid Extraction That Preserves the Molecular Structure of Cutin Shown by Nuclear Magnetic Resonance.

The biopolyester cutin is ubiquitous in land plants, building the polymeric matrix of the plant's outermost defensive barrier, the cuticle. Cutin influences many biological processes in planta; however, due to its complexity and highly branched nature, the native structure remains partially unresolved. Our aim was to define an original workflow for the purification and systematic characterization of the molecular structure of cutin. To purify cutin we tested the ionic liquids cholinium hexanoate and 1-butyl-3-methyl-imidazolium acetate. The ensuing polymeric materials are highly esterified, amorphous, and have a typical monomeric composition as demonstrated by solid-state NMR, complemented by spectroscopic, thermal, and x-ray scattering analyses. We performed a systematic study by solution-state NMR of cryogenically milled cutins extracted from tomatoes (Solanum lycopersicum 'Micro-Tom'; the wild type and the GLYCEROL-3-PHOSPHATE ACYLTRANSFERASE [GPAT6] and CUTIN SYNTHASE [CUS1] mutants). We resolved their molecular structures, relative distribution of ester aliphatics, free acid end-groups and free hydroxyl groups, differentiating between those derived from primary and secondary esters. Our data demonstrate the existence of free hydroxyl groups in cutin and provide insight into how the mutations affect the esterification arrangement of cutin. The usage of ionic liquids for studying plant polyesters has advantages over conventional approaches, since simple modifications can be applied to recover a biopolymer carrying distinct types/degrees of modifications (e.g. preservation of esters or cuticular polysaccharides), which in combination with the solution NMR methodologies developed here, constitutes essential tools to fingerprint the multifunctionality and the structure of cutin in planta.

Ionic Liquids Chemical Stress Triggers Sphingoid Base Accumulation in Aspergillus nidulans.

Understanding stress responses and signaling pathways in fungi became a fundamental need for the discovery of new specific antifungal targets for fighting emerging life-threatening pathogens and drug resistance. Ionic liquids constitute a unique class of chemicals, which structural diversity and tunable physical and chemical properties can provide a great diversity of stimuli. In this study, we propose the use of ionic liquids as tools to unravel signaling of stress responses in the filamentous fungus Aspergillus nidulans. We assessed how three ionic liquids with distinct effects over the cell wall and plasma membrane affect the biosynthesis of sphingolipids and accumulation of free sphingoid bases in this fungus. The stress imposed by each ionic liquid triggered the sphingolipid biosynthetic pathway and led to distinct profiles of sphingoid bases accumulation. Dodecyltributylphosphonium chloride and 1-decyl-3-methylimidazolium chloride induced the accumulation of sphingosine and of a yet unknown sphingoid base, respectively, while cholinium decanoate did not seem to accumulate any of these intermediates. This study brings further light to the roles of sphingoid bases in A. nidulans. In particular, sphingosine as a possible response mediator to cell wall damage induced by dodecyltributylphosphonium chloride, and involvement of an unknown sphingoid base in the response to plasma membrane permeabilization caused by 1-decyl-3-methylimidazolium chloride. In addition, we completed the genetic assignment of the glucosylceramide pathway in A. nidulans through the identification of the sphingolipid Δ4-desaturase gene (AN4405). The knowledge established reinforces the idea of targeting sphingolipids biosynthesis in the search of improved antifungal compounds.

Equine infectious anaemia in equids of Southern Pantanal, Brazil: seroprevalence and evaluation of the adoption of a control programme / Anemia infecciosa equina em equídeos do Pantanal Sul, Brasil: soroprevalência e avaliação da adoção de um programa de controle

The working equid population in Corumbá, Southern Pantanal, is very large and has a crucial role in the main economic activity of the State of Mato Grosso do Sul, the beef cattle industry. The aim of the present study was to estimate the prevalence of equine infectious anaemia (EIA) in working equids of ranches in the municipality of Corumbá, by the official agar gel immunodiffusion (AGID) test, and evaluate the adoption of the Programme for the Prevention and Control of Equine Infectious Anaemia proposed by Embrapa Pantanal and official entities in the 1990s. From September to November 2009, forty ranches distributed through the area of the municipality were visited, and serum samples were obtained from 721 equines and 232 mules. According to previous publications and the present data, it was concluded that the prevalence of EIA in this population has increased from 18.17% to 38.60%, which represents at this time approximately 13,000 infected animals. There was no significant difference between the apparent prevalence of equines and mules. It was also verified that the control programme was not known by the greater part of the interviewed ranch owners, managers and foremen and, in their perception, EIA is not a primary threat to address. Among the studied variables, the serologic testing practice significantly reduced the risk for the presence of EIA seropositivity, as well as the separation of riding equipment and segregation of seropositives.(AU)

A população de equídeos de serviço em Corumbá, Pantanal Sul, é muito numerosa e tem um papel crucial na principal atividade econômica do estado de Mato Grosso do Sul, a pecuária de corte extensiva. O objetivo deste trabalho foi estimar a prevalência atual da anemia infecciosa equina (AIE) em equídeos de serviço em fazendas do município de Corumbá, pelo teste oficial de imunodifusão em gel de ágar (IDGA), e avaliar a adoção do Programa de Prevenção e Controle da Anemia Infecciosa Equina proposto pela Embrapa Pantanal e entidades oficiais nos anos 1990. De setembro a novembro de 2009, quarenta fazendas distribuídas na área do município foram visitadas, e amostras de soro obtidas de 721 equinos e 232 muares. De acordo com publicações anteriores e os dados obtidos neste trabalho, concluiu-se que a prevalência da AIE nesta população aumentou de 18.17% para 38,60%, o que representa atualmente cerca de 13.000 animais infectados. Não houve diferença significativa entre as prevalências aparentes de equinos e muares. Verificou-se, também, que o programa de controle era desconhecido pela maior parte dos produtores, gerentes e capatazes entrevistados e, na percepção dos mesmos, a AIE não é uma ameaça importante a ser enfrentada. Dentre as variáveis estudadas, a prática da realização de testes sorológicos reduziu significantemente o risco para a presença de soropositividade para AIE, assim como a separação dos equipamentos de montaria e a segregação dos soropositivos.(AU)

A common matrix metalloproteinase (MMP)-2 polymorphism affects plasma MMP-2 levels in subjects environmentally exposed to mercury.

Mercury (Hg) exposure is associated with disease conditions, including cardiovascular problems. Although the mechanisms implicated in these complications have not been precisely defined yet, matrix metalloproteinases (MMPs) may be involved. The gene encoding MMP-2 presents genetic polymorphisms which affect the expression and activity level of this enzyme. A common polymorphism of MMP-2 gene is the C(-1306)T (rs 243865), which is known to disrupt a Sp1-type promoter site (CCACC box), thus leading to lower promoter activity associated with the T allele. This study aimed at examining how this polymorphism affects the circulating MMP-2 levels and its endogenous inhibitor, the tissue inhibitor of metalloproteinase-2 (TIMP-2) in 210 subjects environmentally exposed to Hg. Total blood and plasma Hg concentrations were determined by inductively coupled plasma-mass spectrometry (ICP-MS). MMP-2 and TIMP-2 concentrations were measured in plasma samples by gelatin zymography and ELISA, respectively. Genotypes for the C(-1306)T polymorphism were determined by Taqman® Allele Discrimination assay. We found a positive association (p=0.0057) between plasma Hg concentrations and MMP-2/TIMP-2 (an index of net MMP-2 activity). The C(-1306)T polymorphism modified MMP-2 concentrations (p=0.0465) and MMP-2/TIMP-2 ratio (p=0.0060) in subjects exposed to Hg, with higher MMP-2 levels been found in subjects carrying the C allele. These findings suggest a significant interaction between the C(-1306)T polymorphism and Hg exposure, possibly increasing the risk of developing diseases in subjects with the C allele.

O ciclo da vesícula sináptica, espinhos dendríticos e a transdução de sinal / Synaptic vesicle cycle, dendritic spines and signal transduction

No sistema nervoso, a sinapse é a estrutura que permite a um neurônio passar um sinal elétrico ou químico a outro neurônio ou outra célula (muscular ou glandular). A palavra sinapse vem de "synaptein", palavra que Sir Charles Scott Sherrington e seus colegas acunharam do grego "syn" (junto) e "haptein"(afivelar). As sinapses podem ser separadas entre elétricas e químicas, porém a maior parte da transmissão sináptica é realizada através das sinapses químicas. Apesar das sinapses químicas terem uma resposta mais lenta que as elétricas, elas possuem a vantagem da amplificação do sinal gerada através de uma cascata de segundos mensageiros. As sinapses químicas podem ser excitatórias ou inibitórias e são caracterizadas por um terminal pré-sináptico (onde estão presentes as vesículas que contêm os neurotransmissores) em contato com um terminal pós-sináptico (onde estão presentes os receptores ionotrópicos e metabotrópicos para esses neurotransmissores) separados pela fenda sináptica. As sinapses típicas acontecem sobre axônios (axo-axônicas), sobre dendritos (axo-dendríticas), sobre o soma de outro neurônio (axo-somáticas) e sobre os espinhos dendríticos...

In the nervous system, the synapse is the structure that allows a neuron pass an electrical or chemical signal to another neuron or another cell (muscle or glandular). The word synapse comes from "synaptein" that Sir Charles Scott Sherrington and his colleagues minted from the Greek "syn" (together) and "haptein"(buckling). Most part of the synaptic transmission is performed through chemical synapses. Chemical synapses have a slower response than the electric ones; they have the advantage of amplifying the signal generated through a cascade of second messengers. Chemical synapses can be excitatory or inhibitory and are characterized by a presynaptic terminal (where there are vesicles that contain the neurotransmitters) in contact with a postsynaptic terminal (where there are the ionotropic and metabotropic receptors) separated by the synaptic cleft. Synapses can occur on axons (axo-axonal), on dendrites (axodendritic), on soma (axo-somatic) and on dendritic spines...

Neurotransmissão glutamatérgica e plasticidade sináptica: aspectos moleculares, clínicos e filogenéticos / Glutamatergic neurotransmission and synaptic plasticity: molecular, clinical, and phylogenetic aspects

A comunicação entre neurônios é passível de constantes modificações, até mesmo no encéfalo adulto. Esta capacidade de circuitos neuronais fortalecerem ou enfraquecerem suas interações sinápticas específicas (fenômeno conhecido como plasticidade sináptica) pode ocorrer de acordo com as diferentes demandas ambientais, o que favorece a noção de que alterações dinâmicas na comunicação entre neurônios estão na base da flexibilidade comportamental (i.e., processos de aprendizagem e memória). Nas últimas décadas, o avanço das neurociências tem permitido uma melhor compreensão a respeito da plasticidade sináptica, especialmente a plasticidade de sinapses glutamatérgicas, cujos processos moleculares de modificação sináptica parecem estar entre os mais comuns de todo o sistema desse progresso na ciência básica tem contribuído para uma melhor compreensão acerca dos processos patológicos envolvendo as sinapses glutamatérgicas, como a doença de Alzheimer. Além disso, a crescente compreensão sobre o funcionamento da comunicação glutamatérgica tem ajudado a esclarecer como as sinapses, em geral, teriam se originado e evoluído na escala filogenética do reino animal (Metazoa)...

Communication between neurons is subject to constant changes, even in the adult brain. This ability of neural circuits to strengthen or weaken their specific synaptic interactions (a phenomenon known assynaptic plasticity) may occur according to different environmental demands, which favors the idea that dynamic changes in the communication between neurons underlie behavioral flexibility (i.e., learning and memory processes). In recent decades, advances in neuroscience has allowed a better understanding of synaptic plasticity, specially the plasticity of glutamatergic synapses, whose molecular processes of synaptic change appear to be among the most common throughout the central nervous system.Much of this progress in basic science has contributed to a better understanding of pathological processes involving the glutamatergic synapses, such as Alzheimer's disease. Furthermore, the growing understanding about the physiology of glutamatergic communication has helped explain how synapses, in general, would have originated and evolved in the phylogenetic scale of the Metazoa...

A functional matrix metalloproteinase (MMP)-9 polymorphism modifies plasma MMP-9 levels in subjects environmentally exposed to mercury.

Mercury (Hg) exposure causes health problems including cardiovascular diseases. Although precise mechanisms have not been precisely defined yet, matrix metalloproteinases (MMPs) may be involved. The gene encoding MMP-9 presents genetic polymorphisms which affect the expression and activity level of this enzyme. Two polymorphisms in the promoter region [C(-1562)T and (CA)(n)] are functionally relevant, and are implicated in several diseases. This study aimed at examining how these polymorphisms affect the circulating MMP-9 levels and its endogenous inhibitor, the tissue inhibitor of metalloproteinase-1 (TIMP-1) in 266 subjects environmentally exposed to Hg. Blood and plasma Hg concentrations were determined by inductively coupled plasma-mass spectrometry (ICP-MS). MMP-9 and TIMP-1 concentrations were measured in plasma samples by gelatin zymography and ELISA, respectively. Genotypes for the C(-1562)T and the microsatellite (CA)(n) polymorphisms were determined. We found a positive association (P<0.05) between plasma Hg concentrations and MMP-9/TIMP-1 ratio (an index of net MMP-9 activity). When the subjects were divided into tertiles with basis on their plasma Hg concentrations, we found that the (CA)(n) polymorphism modified MMP-9 concentrations and MMP-9/TIMP-1 ratio in subjects with the lowest Hg concentrations (first tertile), with the highest MMP-9 levels being found in subjects with genotypes including alleles with 21 or more CA repeats (H alleles) (P<0.05). Conversely, this polymorphism had no effects on subjects with intermediate or high plasma Hg levels (second and third tertiles, respectively). The C(-1562)T polymorphism had no effects on MMP-9 levels. These findings suggest a significant interaction between the (CA)(n) polymorphism and low levels of Hg exposure, possibly increasing the risk of developing diseases in subjects with H alleles.

Environmental exposure to methylmercury is associated with a decrease in nitric oxide production.

Some studies have recently suggested that mercury (Hg)-exposed populations face increased risks of cardiovascular diseases, and experimental data indicate that such risks might be due to reductions in nitric oxide bioavailability. However, no previous study has examined whether Hg exposure affects plasma nitrite concentrations in humans as an indication of nitric oxide production. Here, we investigated whether there is an association between circulating nitrite and Hg concentrations in whole blood, plasma and hair from an exposed methylmercury (MeHg) population. Hair and blood samples were collected from 238 persons exposed to MeHg from fish consumption. Hg concentrations in plasma (PHg), whole blood (BHg) and hair Hg (HHg) were determined by inductively coupled plasma-mass spectrometry. Mean BHg content was 49.8 +/- 35.2 microg/l, mean PHg was 7.8 +/- 6.9 microg/l and HHg 14.6 +/- 10.6 microg/g. Mean plasma nitrite concentration was 253.2 +/- 105.5 nM. No association was found between plasma nitrite concentration and BHg or HHg concentrations in a univariate model. However, multiple regression models adjusted for gender, age and fish consumption showed a significant association between plasma nitrite and plasma Hg concentration (beta = -0.1, p < 0.001). Our findings constitute preliminary clinical evidence that exposure to MeHg may cause inhibitory effects on the production of endothelial nitric oxide.

Mercury exposure increases circulating net matrix metalloproteinase (MMP)-2 and MMP-9 activities.

Mercury (Hg) exposure causes health problems that may result from increased oxidative stress and matrix metalloproteinase (MMP) levels. We investigated whether there is an association between the circulating levels of MMP-2, MMP-9, their endogenous inhibitors (the tissue inhibitors of metalloproteinases; TIMPs) and the circulating Hg levels in 159 subjects environmentally exposed to Hg. Blood and plasma Hg were determined by inductively coupled plasma-mass spectrometry (ICP-MS). MMP and TIMP concentrations were measured in plasma samples by gelatin zymography and ELISA respectively. Thiobarbituric acid-reactive species (TBARS) were measured in plasma to assess oxidative stress. Selenium (Se) levels were determined by ICP-MS because it is an antioxidant. The relations between bioindicators of Hg and the metalloproteinases levels were examined using multivariate regression models. While we found no relation between blood or plasma Hg and MMP-9, plasma Hg levels were negatively associated with TIMP-1 and TIMP-2 levels, and thereby with increasing MMP-9/TIMP-1 and MMP-2/TIMP-2 ratios, thus indicating a positive association between plasma Hg and circulating net MMP-9 and MMP-2 activities. These findings provide a new insight into the possible biological mechanisms of Hg toxicity, particularly in cardiovascular diseases.

Trace element levels in whole blood of riparian villagers of the Brazilian Amazon.

Monitoring the nutritional status of essential elements is of critical importance in human health. However, trace element concentrations in biological fluids are affected by environmental and physiological parameters, and therefore considerable variations can occur between specific population subgroups. Brazil is a large country with much food diversity. Moreover, dietary habits differ from north to south. As an example, the traditional populations of the Brazilian Amazon basin are heavily dependent on fish, fruits, vegetables and manioc for their daily sustenance. However, very few studies have examined to what extent these diets reflect adequate nutritional status for essential elements. Then, in the present study we have evaluated the levels of some trace elements (Cu, Co, Zn Sr, and Rb) in the whole blood of a riparian Brazilian Amazonian population and estimated the influence of age and gender on levels and inter-element interactions in the same population. For this, 253 subjects, aged 15 to 87, from 13 communities situated on the banks of the Tapajós, one of the major tributaries of the Amazon, were randomly selected. The values found for cobalt, copper and strontium in whole blood are in the same range as in other populations. On the other hand, the levels of rubidium and zinc may be considered higher. Moreover, gender was shown to influence Zn and Cu levels while age influenced the concentrations of Sr and Rb in men and Cu in women. Given the scarcity of studies examining nutritional status in traditional communities of the Amazon, our study is the first to provide relevant insight into trace element values in this region and inter-element interactions. This paper is also of particular importance for future studies looking at the possible protective effects of traditional Amazon riparian diets against mercury intake from fish consumption.

Biomarkers of selenium status in the Amazonian context: blood, urine and sequential hair segments.

Selenium (Se) is an essential element and deficit or excess of dietary Se is associated with health disorders. Relatively elevated Se levels have been reported in the Brazilian Amazon, where there are also important annual variations in the availability of different foods. The present study was conducted among six riparian communities of the Tapajós River to evaluate seasonal variations in blood and sequential hair cm Se concentrations, and to examine the relationships between Se in blood and hair, and blood and urine. Two cross-sectional studies were conducted, at the descending water (DWS, n=259) and the rising water (RWS, n=137) seasons, with repeated measures for a subgroup (n=112). Blood Se (B-Se), hair Se (H-Se) and urine Se (U-Se) were determined. Match-paired analyses were used for seasonal comparisons and the method of best fit was used to describe the relationships between biomarkers. B-Se levels presented a very large range (142-2447 microg/l) with no overall seasonal variation (median 284 and 292 microg/l, respectively). Sequential analysis of 13 cm hair strands showed significant variations over time: Se concentrations at the DWS were significantly lower compared with the rising water season (medians: 0.7 and 0.9 microg/g; ranges: 0.2-4.3 microg/g and 0.2-5.4 microg/g, respectively). At both seasons, the relationships between B-Se and H-Se were linear and highly significant (r(2)=67.9 and 63.6, respectively), while the relationship between B-Se and U-Se was best described by a sigmoid curve. Gender, age, education and smoking did not influence Se status or biomarker relationships. Variations in H-Se suggest that there may be seasonal availability of Se sources in local food. For populations presenting a large range and/or elevated Se exposure, sequential analyses of H-Se may provide a good reflection of variations in Se status.

Human mercury exposure and adverse health effects in the Amazon: a review.

This paper examines issues of human mercury (Hg) exposure and adverse health effects throughout the Amazon region. An extensive review was conducted using bibliographic indexes as well as secondary sources. There are several sources of Hg (mining, deforestation, reservoirs), and exposure takes place through inhalation or from fish consumption. There is a wide range of exposure, with mean hair-Hg levels above 15 microg/g in several Amazonian communities, placing them among the highest reported levels in the world today. Dietary Hg intake has been estimated in the vicinity of 1-2 microg/kg/day, considerably higher than the USEPA RfD of 0.1 microg/kg/day or the World Health Organization recommendation of 0.23 microg/kg/day. Neurobehavioral deficits and, in some cases, clinical signs have been reported both for adults and children in relation to Hg exposure in several Amazonian countries. There is also some evidence of cytogenetic damage, immune alterations, and cardiovascular toxicity. Since fish provide a highly nutritious food source, there is an urgent need to find realistic and feasible solutions that will reduce exposure and toxic risk, while maintaining healthy traditional dietary habits and preserving this unique biodiversity.

Evaluation of the use of human hair for biomonitoring the deficiency of essential and exposure to toxic elements.

Monitoring the nutritional status of essential elements and assessing exposure of individuals to toxic elements is of great importance for human health. Thus, the appropriate selection and measurement of biomarkers of internal dose is of critical importance. Due to their many advantages, hair samples have been widely used to assess human exposure to different contaminants. However, the validity of this biomarker in evaluating the level of trace elements in the human body is debatable. In the present study, we evaluated the relationship between levels of trace elements in hair and whole blood or plasma in a Brazilian population. Hair, blood and plasma were collected from 280 adult volunteers for metal determination. An ICP-MS was used for sample analysis. Manganese, copper, lead and strontium levels in blood varied from 5.1 to 14.7, from 494.8 to 2383.8, from 5.9 to 330.1 and from 11.6 to 87.3 microg/L, respectively. Corresponding levels in hair varied from 0.05 to 6.71, from 0.02 to 37.59, from 0.02 to 30.63 and from 0.9 to 12.6 microg/g. Trace element levels in plasma varied from 0.07 to 8.62, from 118.2 to 1577.7 and from 2.31 to 34.2 microg/L for Mn, Cu and Sr, respectively. There was a weak correlation (r=0.22, p<0.001) between lead levels in hair and blood. Moreover, copper and strontium levels in blood correlate with those levels in plasma (r=0.64 , p<0.001 for Cu) and (r=0.22, p<0.05 for Sr). However, for Cu, Mn and Sr there was no correlation between levels in hair and blood. Our findings suggest that while the idea of measuring trace elements in hair is attractive, hair is not an appropriate biomarker for evaluating Cu, Mn and Sr deficiency or Pb exposure.