Abstract We describe the toxicity of multiwalled carbon nanotubes (MWCNTs) in two aquatic species: Danio rerio and Artemia salina. Fish were exposed to 25 mg L-1, 50 mg L-1, and 100 mg L-1 MWCNTs for 7 days. After exposure, the gills from D. rerio showed lamellar fusion and epithelial lifting in the secondary lamellae, and vasodilation in the primary lamellae. In the gills, heat shock protein 70 and Bax (pro apoptotic member) were stained more intensely in the treated groups than in the control group. The nauplii of A. salina were exposed to 25 µg L-1, 50 µg L-1, and 100 µg L-1 MWCNTs for 96 h. After exposure, the nauplii from the control group presented 20 % mortality, whereas the 25 µg mL-1, 50 µg mL-1, and 100 µg L-1 groups had 46.7 %, 70 %, and 100 % mortality, respectively. The nauplii exposed to 25 µg mL1 and 50 µg mL1 MWCNTs had black aggregates in the intestine because of the uptake of nanomaterials. In addition, the 25 µg mL-1 and 50 µg mL-1 MWCNT groups had black aggregates attached onto the body surface, appendages of the second pair, and mandibles.The results revealed the toxic effects of MWCNTs on the two aquatic organisms, and both species showed great potential for toxicological evaluation of MWCNTs in aquatic environments.

Abstract Pesticides, as Temephos and Roundup, and surfactants, like Sodium Dodecyl Sulfate (SDS), when discharged into the environment, are harmful to non-target wildlife, especially fish. To evaluate the effects of those chemicals alone and their binary combinations, we assessed the histological alterations in Danio rerio gills after 15 days of exposure to Temephos (1ppm), Roundup (10ppm), SDS (2ppm), SDS plus Temephos (2ppm+1ppm), SDS plus Roundup (2ppm+10ppm) and Temephos plus Roundup (1ppm+10ppm). Hyperplasia, a regressive change, was significant in all exposed groups. The progressive change, complete fusion of lamellae, was significantly intensive in Roundup plus Temephos group. Regarding circulatory disturbances, vascular congestion was significant intensive in SDS group, while severe aneurysm was observed in Roundup group. Although xenobiotics in the blend are biologically complex, mainly for long periods, combinatorial exposure incremented only complete fusion of lamellae. Our results reinforce the rationalization of indiscriminate use of those compounds alone or in combination.

Abstract Herein we evaluated the histopathological alterations and expression patterns of multixenobiotic resistence (MXR) and autophagic proteins in liver samples of fish chronically exposed to anthropogenic contaminants in a highly polluted river, and then again after they had been transferred to good quality water. Two groups were established: euthanized on the day of capture (0 h), and maintained for 30 days in a tank (30 d). The fish of 0 h presented liver with vacuolated and hypertrophic hepatocytes. Also, it was observed strong immunostaining of cathepsin-D, LC3-II and P-gp. Necrosis and apoptosis were also observed throughout the liver. Conversely, the second group (30 d) showed recovery of the liver normal histology and weak immunoreaction of the studied proteins. So, our results indicated that there was a hepatic recovery in the fish kept in good quality water, as showed by the decreased expression of cathepsin-D, LC3-II, and the MXR (P-gp). Therefore, the alterations here observed could be proposed as potential biomarkers to be tested for following the impacts of remediation or mitigation measures to environmental impacts.

Lophiosilurus alexandri é um peixe endêmico da bacia do rio São Francisco, Brasil. O objetivo do trabalho foi induzir L. alexandri à desova e obter dados sobre várias variáveis reprodutivas para esta espécie. Para desova induzida, adultos foram submetidos ao homogeneizado de hipófise de Cyprinus carpio (HHC). Nove das 12 fêmeas (75%) responderam positivamente ao tratamento. A extrusão dos ovócitos aconteceu 8,4 h após a segunda dose de HHC com a temperatura da água mantida a 26ºC. O número de ovócitos liberados por grama de ova foi de 74 ± 5 ovócitos g-1 e a média do diâmetro ovocitário foi de 3,1 ± 0,2 e 3,6 ± 0,2 mm, antes e depois da hidratação, respectivamente. Os ovócitos foram opacos, amarelo-castanho, demersais, altamente adesivos e revestidos por capa gelatinosa. A fecundidade total apresentou 4.534 ± 671 ovócitos e a taxa de fertilização foi de 59%. As fertilidades inicial e final foram de 2.631 ± 740 e 1.542 ± 416 embriões, respectivamente. A eclosão das larvas aconteceu até 56 h após a fertilização e as larvas tiveram comprimento total de 8,4 ± 0,1 mm. Este trabalho fornece informações biológicas importantes para L. alexandri, que podem ser utilizadas para o manejo e conservação desta espécie.

Lophiosilurus alexandri is an endemic fish from the São Francisco River basin, Brazil. The aim of this study was to induce L. alexandri to spawn and to obtain data on several reproductive variables for this species. For induced spawning, adults were submitted to Cyprinus carpio pituitary homogenate (CPH). Nine of the 12 females (75%) responded positively to the treatment. The stripping of oocytes was performed 8.4 h after the second dose of CPH with the water temperature maintained at 26ºC. The number of stripped oocytes per gram of ova was 74 ± 5 oocytes g-1, and the mean oocyte diameter was 3.1 ± 0.2 and 3.6 ± 0.2 mm, before and after hydration, respectively. The oocytes were opaque, yellowish, demersal, highly adhesive, and covered by a gelatinous coat. The total fecundity was 4,534 ± 671 oocytes, and the fertilization rate was 59%. The initial and final fertilities were 2,631 ± 740 and 1,542 ± 416 embryos, respectively. Larval hatching occurred up to 56 h after fertilization, and the larvae had a total length of 8.4 ± 0.1 mm. This work provides important biological information for L. alexandri that can be used for management and conservation of this species.