Evaluation of genotoxicity and effects on reproduction of nonylphenol in Oreochromis niloticus (Pisces: cichlidae)

Abstract

Nonylphenol ethoxylate (NPE) is widely used as a component of detergents, paints, pesticides, and many other products. In the aquatic environment NPE breakdown to 4-nonylphenol (NP), which is more stable and persistent. NP is estrogenic in fish, avian, and mammals and is described as an environmental pollutant with endocrine disruptor characteristics. The genotoxicity of NP was evaluated through micronuclei assay and single cell gel electrophoresis (Comet assay) in peripheral erythrocytes of Oreochromis niloticus exposed in vivo. The study on reproductive development was also carried out in male and female gonads of O. niloticus. Lethal concentration (LC 50%) of 0.032 ml l -1 was previously determined. We ran assays with O. niloticus exposed to concentrations of 1.0, 10.0, and 16.0 ll l -1 of NP diluted in water. Our results showed that NP was not genotoxic. However, 3-day exposure to NP in concentrations of 1.0, 10.0, and 16.0 ll l -1 of water increased the frequency of reproductive stages in males and females. The histology of the reproductive tract of the treated fish was significantly altered in females treated with 16.0 ll l -1 of water when compared to controls. Analogous estrogenic effects were observed, such as accelerated maturation of oocytes and spermatogenesis. These results showed that the O. niloticus reproductive system is sensitive to NP estrogenicity.

Cytogenetic toxicity and gonadal effects of 17 α-methyltestosterone in Astyanax bimaculatus (Characidae) and Oreochromis niloticus (Cichlidae)

“…This assay was performed as described by (Singh et al, 1988), with some modifications for fish as previously reported by Rivero et al (2008), as described below. The cell suspension placed in the microtube was mixed with 120 µL low-melting agarose (37°C).…”

“…It is a valuable tool for population monitoring, for example, in assessing mechanisms of mutagenesis, genotoxicity and ecological monitoring, and for investigating DNA damage and repair in different cell types in response to a range of DNA-damaging agents, among others (Dusinska and Collins, 2008;McKenna et al, 2008;Collins, 2009). Thus, the micronucleus (MN) test, assessment of nuclear abnormalities (NA) (da Silva and Fontanetti, 2006) and the comet assay are excellent techniques used in vivo to test the genotoxicity of environmental pollutants such as EDC (al-Sabti and Metcalfe, 1995;Grisolia and Starling, 2001;Pacheco and Santos, 2002;Bolognesi et al, 2006;Kim and Hyun, 2006;Rivero et al, 2008).…”

Lack of genotoxicity in Astyanax bimaculatus and Oreochromis niloticus of 17α-methyltestosterone used in fish hatcheries to produce male monosex populations

“…This assay was performed as described by Singh et al (1988), with some modifications for fish as previously reported by Rivero et al (2008), as described below. The cell suspension sampled in the microtubule was mixed with 120 µL low melting agarose (37°C).…”

Effects of 4-Nonylphenol on reproduction of exposed females during puberty

“…NP is present in the environment mainly after degradation of nonylphenol ethoxylates (NPE; Soares et al, 2008). NPE is an alkylphenol widely utilized in the non-ionic surfactant industry, lubricants, antioxidants, detergents, paints, insecticides and herbicides, and also used as a stabilizer in plastic polymers (Oliveira-Filho et al, 2005;Rivero et al, 2008). Many studies show the presence of this pollutant in sewage, sediments, rivers and drinking water (Tsuda et al, 2000;Berryman et al, 2004;Shao et al, 2005).…”

“…Estrogenic action of NP is described for diverse animals, including birds (Razia et al, 2006), fish (Rivero et al, 2008) and mammals (Chapin et al, 1999;Tagaki et al, 2004). The median lethal dose of NP in male adult mice is 170 mg/kg body weight (b.w.)…”