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The increase in pesticide use in response to agricultural demands poses a risk to non-target organisms, including fish. Integrated analysis of biochemical, histopathological and genetic parameters in fish exposed to Malathion insecticide provide information on the toxicity mechanisms of this pesticide, which is classified as a probable carcinogen for humans. The present study assessed the biological responses of Colossoma macropomum after exposure to Malathion. We started determining the lethal concentration, which is the concentration capable of killing 50% of the subjects in an acute toxicity test (LC 50 -96 h), which was 15.77 ± 3.30 mgL -1 . The fish were, then, exposed to Malathion during 96 h at a sublethal concentration, 7.30 mgL -1 . Overall, we observed an increased activity of biotransformation and antioxidant enzymes, which reduced production of mitochondrial reactive oxygen species after 96 h exposure, as well as kept constant the mitochondrial respiration, Acetylcholinesterase activity and DNA damage. However, fish exposed to insecticide presented severe gill histopathological damage and increased expression of proto-oncogene ras. Taken together, the results suggest that, after four days of exposure to the Malathion, C. macropomum efficiently activates its defense mechanisms, suggesting that the basal response mechanisms are responsive. On the other hand, histopathologic damages evidenced the adverse effects of Malathion on fish, since it promoted gill necrosis and increased the expression of ras oncogene that is directly related to tumorigenesis events., (Copyright © 2020 Elsevier Inc. All rights reserved.)

The present work aimed to investigate the effects of acute (12, 24, 48 and 96 h) and subchronic (168 and 336 h) exposure of seahorse, Hippocampus reidi to water-accommodated fraction (WAF) of diesel fuel on biotransformation parameters, antioxidant defenses and DNA integrity. In addition, a recovery experiment was performed, where the organisms remained in absence of the contaminant for 336 h, after WAF exposure for 168 h (totaling 504 h). At the end of each experimental protocol, the concentration of pyrene-, benzo(a)pyrene- and naphthalene-type metabolites in bile, hepatic activity of glutathione-S-transferase (GST), superoxide dismutase (SOD), and catalase (CAT), as well as lipid peroxidation (LPO) levels in hepatocytes, were analyzed, in addition to the DNA damage and the micronucleus (MN) test in the peripheral blood. It was observed that both acute and subchronic WAF exposure affected the investigated parameters in different ways. In general, the exposed groups presented higher mean values for the investigated parameters if compared with their respective controls. After the recovery experiment, the mean values of PAH metabolites, LPO, DNA damage and MN frequency were significantly lower than those of animals exposed for 168 h, indicating that the recovery period was appropriately long for the evaluated biomarkers return to the control levels. The results indicated that the selected H. reidi biomarkers proved to be adequate and complementary tools in determining the first impacts of acute and subchronic exposure caused by WAF of diesel fuel in fish, as well as their recovery in clean water., (Copyright © 2019. Published by Elsevier B.V.)

Colossoma macropomum, or tambaqui, is the largest native Characiform species found in the Amazon and Orinoco river basins, yet few resources for genetic studies and the genetic improvement of tambaqui exist. In this study, we identified a large number of single-nucleotide polymorphisms (SNPs) for tambaqui and constructed a high-resolution genetic linkage map from a full-sib family of 124 individuals and their parents using the genotyping by sequencing method. In all, 68,584 SNPs were initially identified using minimum minor allele frequency (MAF) of 5%. Filtering parameters were used to select high-quality markers for linkage analysis. We selected 7,734 SNPs for linkage mapping, resulting in 27 linkage groups with a minimum logarithm of odds (LOD) of 8 and maximum recombination fraction of 0.35. The final genetic map contains 7,192 successfully mapped markers that span a total of 2,811 cM, with an average marker interval of 0.39 cM. Comparative genomic analysis between tambaqui and zebrafish revealed variable levels of genomic conservation across the 27 linkage groups which allowed for functional SNP annotations. The large-scale SNP discovery obtained here, allowed us to build a high-density linkage map in tambaqui, which will be useful to enhance genetic studies that can be applied in breeding programs.

The increment in crude oil exploitation over the last decades has considerably increased the risk of polycyclic aromatic hydrocarbon (PAH) contamination to Amazonian aquatic environments, especially for the black water environments such as the Rio Negro. The present work was designed to evaluate the acute toxicity of the Urucu crude oil (CO), the chemically dispersed Urucu crude oil (CO + D), and the dispersant alone (D) to the Amazonian fish Colossoma macropomum. Acute toxicity tests were performed, using a more realistic approach, where fish were acclimated to both groundwater (GW), used as internal control, and natural Rio Negro water (RNW) and exposed to CO, CO + D and D. Then, biomarkers such as ethoxyresorufin-O-deethylase (EROD), superoxide dismutase (SOD), lipid peroxidation (LPO), serum sorbitol dehydrogenase (s-SDH) in liver, DNA damage in blood cells, and the presence of the benzo[a]pyrene-type, pyrene-type, and naphthalene-type metabolites in fish bile were assessed. Fish exposed to CO and CO + D, at both water types tested, presented increased biomarker responses and higher PAH-type metabolites in the bile. However, fish exposed to these treatments after the acclimation to RNW increased the levels of LPO, s-SDH (hepatotoxicity), DNA damage in blood cells (genotoxicity), and benzo[a]pyrene-type metabolites when compared to fish in GW. Our data suggests that some physicochemical properties of Rio Negro water (i.e., presence of natural organic matter (NOM)) might cause mild chemical stress responses in fish, which can make it more susceptible to oxidative stress following exposure to crude oil, particularly to those chemically dispersed.

Prochilodus nigricans, locally known as curimatã, is an Amazonian commercial fish that endures adverse environmental conditions, in particular low dissolved oxygen, during its migration. Poorer environmental conditions are expected in the near future. Prochilodus nigricans overcomes current seasonal and diurnal changes in dissolved oxygen by adjusting erythrocytic levels of ATP and GTP, modulators of Hb-O2 affinity. Will this fish species be endangered under more extreme environmental conditions as hypoxia and acidification tend to occur in a shorter period of time? As P. nigricans does not exhibit any apparent morphological alterations to exploit the air-water interface, it must rely on fast adjustments of blood properties. To investigate this aspect, basic hematology indices, pHe, pHi, plasma lactate, erythrocytic levels of ATP and GTP and functional properties of the hemolysate of P. nigricans were analyzed over a period of 6h in hypoxia and subsequent recovery in normoxia. The levels of erythrocytic GTP were four times higher than ATP and were reduced to ¼ of the original level after 3h under hypoxia. Erythrocytic levels of ATP were unaffected over the experimental period. All other analyzed blood parameters exhibited a time-course change in animals under hypoxia and returned to normoxic levels. Considering the hemolysate functional properties and the ability to regulate the above mentioned blood characteristics, P. nigricans is able to endure short-term changes in dissolved oxygen., (Copyright © 2015 Elsevier Inc. All rights reserved.)

The copper sensitivity of 10 wild ornamental fish from Rio Negro, an ion-poor river in the Amazon, was analyzed in the absence of dissolved organic carbon (DOC). No mortality was observed at concentrations up to 700mug Cul(-1) for two species exposed to CuCl(2).2H(2)O dissolved in standard EPA-USA water. Copper sensitivity of fish was also tested in INPA groundwater, which is similar to that of the Rio Negro, but lacking typical DOC of Rio Negro water. In these experiments, all four characid fish species were more sensitive to copper than the catfish and the cichlids. LC(50) values ranged from 12.8mug Cul(-1) for the characid Hemigrammus rhodostomus to 74.1mug Cul(-1) for the callichtyid Dianema urostriatum. Copper sensitivity of Hyphessobrycon socolofi was 52-fold lower in EPA (1405.5mug Cul(-1)) than in INPA water (26.8mugCul(-1)). The differences in values of LC(50) may be related to species-specific physiological abilities to ion-regulate under the original conditions of the habitat of the analyzed species.

Hemoglobin electrophoretic pattern, whole blood Bohr effect, intraerythrocytic phosphates and some hematological parameters were determined and compared between lotic and lentic Hypostomus regani specimens. The electrophoretic patterns of specimens from both kinds of environments showed four anodic fractions. The relative concentration of the fraction I (the most anodal) is significantly different between specimens from lotic and lentic ambients. Both lentic and lotic specimens presented a low Bohr effect: phi = -0.012 to lentic habitat and phi = -0.187 to lotic one. ATP/GTP ratio are higher than 1.0 for lotic environment specimens and lower than 1.0 for lentic ones.

The electrophoretic patterns of hemoglobin (Hb) and the functional properties of blood of seven migratory fish species, in two different kinds of habitat during both the rainy and dry seasons, were studied. All species showed multiple hemoglobins and very similar electrophoretic patterns except for Schizodon nasutus, which showed two cathodal components. The functional properties of blood reflect those electrophoretic patterns, since all species showed very little or no Bohr effect during each situation studied. Data on Leporinus obtusidens blood (during the rainy season), from both lotic and lentic environments, showed a normal Bohr effect (phi = -0.073). Similarly, Schizodon nasutus and Leporinus friderici from a lotic environment during the dry season were compared and showed a reverse Bohr effect (phi = 0.042). In the other 14 situations, only Leporinus elongatus from a lentic environment during the rainy season showed a statistically significant difference in log P50 values from the other fishes.

Electrophoretic patterns of hemoglobins, red blood cell phosphates, Bohr effect of blood and stripped hemoglobin, ATP and GTP modulation of Hb-O2 affinity of two species belonging to the genus Semaprochilodus (S. insignis and S. taeniurus--jaraquis), captured at two different locations in Rio Negro, near Manaus (Amazonas), are described. High Bohr effect values were found in these two species and in jaraqui-açu (a possible hybrid between them). In S. insignis a higher Bohr effect for migrating individuals was observed, while S. taeniurus showed the reverse. The main erythrocytic phosphates found in these two species are ATP and GTP. They have a large influence on the O2-Hb binding properties in both species. The GTP/ATP ratio showed large differences between catching places. The two species have different electrophoretic patterns. Semaprochilodus insignis showed four anodal components which showed quantitative variation between catching places; S. taeniurus had three anodal components and a similar quantitative variation.

Red blood cell soluble phosphates from Semaprochilodus taeniurus, S. insignis and a possible hybrid jaraqui-açu, from Amazon basin, were studied by column chromatography. The Semaprochilodus school and the jaraqui-açu shows an intermediate percentage of total phosphorus content as GTP but not as ATP. GTP/ATP ratio for jaraqui-açu and S. taeniurus were 1.5 and for S. insignis, 3.0.