Metals and arsenic in marine fish commercialized in the NE Brazil: Risk to human health

Abstract

Arsenic, cadmium, lead, and mercury in fish is the result of long-term biomagnification in the food chain and is of public concern, due to the toxicity they engender. The objective of this research was to determine the concentrations of arsenic, cadmium, lead, and mercury in 13 species of marine fish broadly commercialized in Aracaju, SE, Brazil and to evaluate the risks of fish consumption associated with these trace elements, using the Target Hazard Quotient (THQ). As, Cd, and Pb levels were measured with inductively coupled plasma mass spectrometry (ICP-MS), and mercury was analyzed via cold vapor atomic absorption spectrometry. The results indicate a large variability in concentrations for arsenic (0.07–2.03?mg kg^–1) and mercury (0.01–1.44?mg kg^–1), associated with the animal dietary category. Cadmium (0.04–0.19?mg kg^–1) and lead (<0.01–0.45?mg kg^–1), on the other hand showed a mild variability. None of the evaluated specimens had As, Cd, and Pb THQ values higher than 1. The THQ values for mercury were higher but indicated no consumption risk, except for amberjack, and snook fish. Overall THQ indicates lower risk of consumption in fish that are at the base of the food chain, than in those that are top predators.     

In vivo measurements of electrical conductivity of porcine organs at low frequency: New method of measurement

Calculations of the induced currents created in the human body by external electromagnetic fields would be more accurate provided that more realistic experimental values of the electrical properties of the body were available. The purpose of this work is to experimentally obtain values for the conductivity of living organs in conditions close to the real situation. Two‐electrode in vivo measurements of the bioimpedance of some porcine organs have been performed. From these measurements and taking into account geometrical considerations, the electrical conductivity for the kidney, liver, heart, and spinal cord has been obtained and were found to be higher than the values reported in the literature. Furthermore, a new experimental procedure is proposed where the conductivity is determined from the values of the electrical potential and currents that are induced by an external electromagnetic field created by a coil placed close to the organ under study. Bioelectromagnetics 33:612–619, 2012. © 2012 Wiley Periodicals, Inc.     

The surface free energy of Leishmania mexicana amazonensis.

Surface charge of Leishmania mexicana amazonensis was investigated by direct zeta-potential determination and ultrastructural cytochemistry, and its surface tension was studied by measurements of the advancing contact angle formed by the parasite monolayers with drops of liquids of different polarities. Both virulent and avirulent promastigotes exhibited negatively charged surfaces with a zeta-potential of about -15 mV. Treatment of these cells with trypsin, alkaline phosphatase, or phospholipase C rendered their surfaces less negatively charged, whereas neuraminidase did not alter the parasite negativeness. Cytochemically, we could observe a reduction in the cationized ferritin binding after the parasite treatment with each of the former enzymes, but not with neuraminidase. The surface free energy of parasites was calculated by taken to account the London dispersion, the Keeson dipole-dipole, and the Debye dipole-induced forces, as well as the surface polarity of the parasites and their zeta-potentials, by considering their adhesion to polystyrene surfaces. The delta G values of -6.4 and -18.1 mJ.m-2 were obtained for avirulent and virulent promstigotes, respectively.     

Comparison of RAPD and RFLP genetic markers in determining genetic similarity among Brassica oleracea L. genotypes

Genetic similarity among 45 Brassica Oleracea genotypes was compared using two molecular markers, random amplified polymorphic DNA (RAPD) and restriction fragment length polymorphisms (RFLPs). The genotypes included 37 broccolis (var. italica), five cauliflowers (var. botrytis) and three cabbages (var. capitata) which represented a wide range of commercially-available germplasm, and included open-pollinated cultivars, commercial hybrids, and inbred parents of hybrid cultivars. Fifty-six polymorphic RFLP bands and 181 polymorphic RAPD bands were generated using 15 random cDNA probes and 62 10-mer primers, respectively. The objectives were to compare RFLP and RAPD markers with regard to their (1) sampling variance, (2) rank correlations of genetic distance among sub-samples, and (3) inheritance. A bootstrap procedure was used to generate 200 random samples of size n (n=2,3,5,... 55) independently from the RAPD and RFLP data sets. The coefficient of variance (CV) was estimated for each sample. Pooled regressions of the coefficient of variance on bootstrap sample size indicated that the rate of decrease in CV with increasing sample size was the same for RFLPs and RAPDs. The rank correlation between the Nei-Li genetic similarity values for all pairs of genotypes (990) based on RFLP and RAPD data was 0.745. Differences were observed between the RFLP and RAPD dendrograms of the 45 genotypes. Overlap in the distributions of rank correlations between independent sub-samples from the RAPD data set, compared to correlations between RFLP and RAPD sub-samples, suggest that observed differences in estimation of genetic similarity between RAPDs and RFLPs is largely due to sampling error rather than due to DNA-based differences in how RAPDs and RFLPs reveal polymorphisms. A crossing algorithm was used to generate hypothetical banding patterns of hybrids based on the genotypes of the parents. The results of this study indicate that RAPDs provide a level of resolution equivalent to RFLPs for detemination of the genetic relationships among genotypes.     

Effect of replacing [NTf2] by [PF6] anion on the [BMIm][NTf2] ionic liquid confined by gold

The effect of replacing bis(trifluoromethylsulphonyl)imide ([NTf₂]) by hexafluorophosphate ([PF₆]) in room temperature ionic liquid (IL) 1-butyl-3-methylimidazolium bis(trifluoromethylsulphonyl)imide ([BMIm][NTf₂]) confined between two gold interfaces is herein reported through molecular dynamics simulations using all-atom non-polarisable force-fields. Five systems were studied ranging from pure [BMIm][NTf₂] to pure [BMIm][PF₆], with [PF₆] molar fractions of 0, 0.125, 0.25, 0.375 and 0.5. Special attention was drawn to investigate the impact of the [PF₆] anion on the IL, in particular on the first layers of the liquid in close contact with the solid gold surface.     

Robustness of a meta-network to alternative habitat loss scenarios

Studying how habitat loss affects the tolerance of ecological networks to species extinction (i.e. their robustness) is key for our understanding of the influence of human activities on natural ecosystems. With networks typically occurring as local interaction networks interconnected in space (a meta-network), we may ask how the loss of specific habitat fragments affects the overall robustness of the meta-network. To address this question, for an empirical meta-network of plants, herbivores and natural enemies we simulated the removal of habitat fragments in increasing and decreasing order of area, age and connectivity for plant extinction and the secondary extinction of herbivores, natural enemies and their interactions. Meta-network robustness was characterized as the area under the curve of remnant species or interactions at the end of a fragment removal sequence. To pinpoint the effects of fragment area, age and connectivity, respectively, we compared the observed robustness for each removal scenario against that of a random sequence. The meta-network was more robust to the loss of old (i.e. long-fragmented), large, connected fragments than of young (i.e. recently fragmented), small, isolated fragments. Thus, young, small, isolated fragments may be particularly important to the conservation of species and interactions, while contrary to our expectations larger, more connected fragments contribute little to meta-network robustness. Our findings highlight the importance of young, small, isolated fragments as sources of species and interactions unique to the regional level. These effects may largely result from an unpaid extinction debt, whereby younger fragments are likely to lose species over time. Yet, there may also be more long-lasting effects from cultivated lands (e.g. water, fertilizers and restricted cattle grazing) and network complexity in small, isolated fragments. Such fragments may sustain important biological diversity in fragmented landscapes, but maintaining their conservation value may depend on adequate restoration strategies.     

Hsp70 protein levels and thermotolerance in Drosophila subobscura: a reassessment of the thermal co-adaptation hypothesis

Theory predicts that geographic variation in traits and genes associated with climatic adaptation may be initially driven by the correlated evolution of thermal preference and thermal sensitivity. This assumes that an organism's preferred body temperature corresponds with the thermal optimum in which performance is maximized; hence, shifts in thermal preferences affect the subsequent evolution of thermal-related traits. Drosophila subobscura evolved worldwide latitudinal clines in several traits including chromosome inversion frequencies, with some polymorphic inversions being apparently associated with thermal preference and thermal tolerance. Here we show that flies carrying the warm-climate chromosome arrangement O(3+4) have higher basal protein levels of Hsp70 than their cold-climate O(st) counterparts, but this difference disappears after heat hardening. O(3+4) carriers are also more heat tolerant, although it is difficult to conclude from our results that this is causally linked to their higher basal levels of Hsp70. The observed patterns are consistent with the thermal co-adaptation hypothesis and suggest that the interplay between behaviour and physiology underlies latitudinal and seasonal shifts in inversion frequencies.     

E-NTPDase and E-ADA activities are altered in lymphocytes of patients with indeterminate form of Chagas' disease

Trypanosoma cruzi infection triggers a chronic inflammatory process in human host and purinergic system ecto-enzymes play an important role in modulating the inflammatory and immune responses. In this study, it was investigated ecto-nucleoside triphosphate diphosphohydrolase (E-NTPDase; EC 3.6.1.5; CD39) and ecto-adenosine deaminase (E-ADA; EC 3.5.4.4) activities in lymphocytes from patients with indeterminate form of Chagas' disease (IFCD). Twenty-five IFCD patients and 25 healthy subjects (control group) were selected. The peripheral lymphocytes were isolated and E-NTPDase and E-ADA activities were determined. Adenine nucleotides and adenosine levels were determined in serum by HPLC and the E-NTPDase1 expression in lymphocytes by Western blot analysis. E-NTPDase (ATP and ADP as substrates) and E-ADA (adenosine as substrate) activities were decreased in lymphocytes from IFCD patients (P<0.05 and P<0.01, respectively), while the E-NTPDase1 expression presented no changes in these patients. Serum ATP levels showed to be decreased (P<0.05) and both AMP (P<0.01) and adenosine (P<0.001) levels were increased in the IFCD group. The enzymatic alterations observed are in agreement with the immune response against T. cruzi infection in IFCD patients, since the decreased extracellular ATP and the increased adenosine levels trigger a Th2 anti-inflammatory response, which it is associated to adaptation of host to parasite, preventing clinical progress of disease.