The effects of cadmium (Cd) and arsenic (As), dosed alone or in combination have been poorly investigated in crustaceans. Besides, it is not known if dietary supplementation of exogenous antioxidants, like lipoic acid (LA), might prevent or even reverse toxic effects of Cd and As. The objective of the present study was to evaluate the role of lipoic acid in modulating biochemical responses after Cd and As exposures in Litopenaeus vannamei. Muscle from shrimp exposed to Cd alone or Cd+As showed a decrease in glutathione (GSH) levels, while the pre-treatment with LA reversed this situation. In this tissue, the pre-treatment with LA also induced an increase in glutathione-S-transferase (GST) activity in all groups. In hepatopancreas it was observed a marked accumulation of Cd and As, a decrease in the reactive oxygen species (ROS) concentration in response to Cd exposure alone (-LA); concomitant in the same group it was observed an increment of metallothionein-like content. As exposure induced an increase in GSH levels but LA reversed this increase. Also, LA showed to increase the GST activity in all groups treated. Besides, in this organ LA showed to augment total antioxidant competence. Obtained results indicate that LA can be used as a chemo-protectant against oxidative insults in shrimp.

Recently, it has been suggested that the mitochondrial oligomycin A-sensitive F0-ATPase subunit is an uncoupling channel linked to apoptotic cell death, and as such, the toxicological inhibition of mitochondrial F0-ATP hydrolase can be an interesting mitotoxicity-based therapy under pathological conditions. In addition, carbon nanotubes (CNTs) have been shown to offer higher selectivity like mitotoxic-targeting nanoparticles. In this work, linear and nonlinear classification algorithms on structure−toxicity relationships with artificial neural network (ANN) models were set up using the fractal dimensions calculated from CNTs as a source of supramolecular chemical information. The potential ability of CNT-family members to induce mitochondrial toxicity-based inhibition of the mitochondrial H + -F0F1-ATPase from in vitro assays was predicted. The attained experimental data suggest that CNTs have a strong ability to inhibit the F0-ATPase active-binding site following the order oxidized−CNT (CNT−COOH > CNT−OH) > pristine−CNT and mimicking the oligomycin A mitotoxicity behavior. Meanwhile, the performance of the ANN models was found to be improved by including different nonlinear combinations of the calculated fractal scanning electron microscopy (SEM) nanodescriptors, leading to models with excellent internal accuracy and predictivity on external data to classify correctly CNT-mitotoxic and nonmitotoxic with specificity (Sp > 98.9%) and sensitivity (Sn > 99.0%) from ANN models compared with linear approaches (LNN) with Sp ≈ Sn > 95.5%. Finally, the present study can contribute toward the rational design of carbon nanomaterials and opens new opportunities toward mitochondrial nanotoxicology-based in silico models.

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BackgroundNematodes are used in many different fields of science, including environmental and biomedical research. Counting and/or estimating nematode numbers is required during research. Although being one of the most common procedures, this apparently simple task is a time-consuming process, prone to errors and concerns regarding procedure, reliability, and accuracy. When an estimate is necessary, there is a traditional manual counting procedure that in this study it will be called as “drop method” (DM). This popular method that extrapolates an animal count from a small drop of fluid shows a high coefficient of variation. To solve this problem, the present study used the free-living nematode Caenorhabditis elegans to develop a new estimation procedure that was based on a relationship between area and volume of a larger sample.ResultsThe new method showed a low coefficient of variation and a close relationship between estimated and real counts of the total number of nematodes in large C. elegans suspensions. Reactive oxygen concentration was measured as an example of method application and to allow comparison between methods.ConclusionThe proposed method is accurate, facile and reproducible, requiring simple, inexpensive materials that make it an excellent alternative to the DM manual counting procedure. Although the DM is faster, its estimates are not as accurate or as precise as those of the new proposed method.Electronic supplementary materialThe online version of this article (10.1186/s12575-018-0089-2) contains supplementary material, which is available to authorized users.

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