Effects of Biological and Technical Factors on Brain and Muscle Cholinesterases in Nile Tilapia, Oreochromis niloticus: Implications for Biomonitoring Neurotoxic Contaminations

Abstract

Influence of body length, body weight, gender, sexual maturity, and tissue storage on brain and muscle cholinesterases (ChE) in Nile tilapia was evaluated considering its potential use in biomonitoring neurotoxic contaminations in tropical environments. Results show that ChE activities in both tissues decreased significantly with increased total length (4-24.5 cm) or body weight (1-186 g) of the fish and the relationships were curvilinear. Comparisons of the slopes and elevations of the regression lines of the logarithmic ChE and body size relationships of males with those of females indicated that gender had no significant effect on the body size-specific ChE activities. Response of the ChE of sexually mature males to chlorpyrifos exposure was similar to that of females. Gonadal maturity stage of this fish does not seem to influence ChE activities. Storage of tissues at -80 degrees C for 28 days had no significant effect on ChE activities in the control fish and the fish exposed to carbofuran. However, a partial reactivation of brain ChE activities was observed in the fish exposed to carbosulfan after 28 days of storage. The results emphasize the importance of consideration of body size of the fish and storage time of the tissues in order to formulate accurate conclusions about the neurotoxic chemical exposure when ChE of the fish is used in biomonitoring programs.

Use of biomarkers in Nile tilapia (Oreochromis niloticus) to assess the impacts of pollution in Bolgoda Lake, an urban water body in Sri Lanka

“…The results revealed that responses of brain and muscle ChE, hepatic EROD and GST activities, bile PAHs of Nile tilapia and hepatic MT can be used as biomarkers in assessing pollution status and pollution trends in water resources in Sri Lanka. In the present study, limited size range of Nile tilapia was used in biomarker studies as the body size could influence some biomarker measurements (Pathiratne et al 2008). Gender specific differences in the tested biomarkers in Nile tilapia were not evident in the present study.…”

“…ChE activities in the brain and muscle homogenates were determined at 25 • C following the method of Ellman et al (1961) as a kinetic assay as described earlier (Pathiratne et al 2008). The enzyme source was prepared by homogenizing the brain or muscle tissue of individual fish separately in ice-cold, 0.1 M pH 8 phosphate buffer (20 mg tissue in 1 mL of buffer).…”

Assessment of biological effects of pollutants in a hyper eutrophic tropical water body, Lake Beira, Sri Lanka using multiple biomarker responses of resident fish, Nile tilapia (Oreochromis niloticus)

“…Serum SDH activity was determined at 25°C as described by Gerlach (1983) using D-fructose as the substrate. The ChE activities in the brain and muscle homogenates of individual fish were determined at 25°C using acetylthiocholine iodide as the substrate following the method of Ellman et al (1961) as described earlier (Pathiratne et al 2008). Microsomal and cytosolic fractions of liver tissues were prepared by differential centrifugation (Pathiratne et al 2009).…”

In vitro and in vivo effects of cadmium on cholinesterases in Nile tilapia fingerlings: implications for biomonitoring aquatic pollution

“…The enzyme source was prepared by homogenizing the brain or muscle tissue of individual fish separately (unless otherwise stated) in ice-cold 0.1 M pH 8 phosphate buffer (20 mg tissue in 1 ml buffer). ChE activities in the tissue homogenates were determined colorimetrically, following the method of Ellman et al (1961) as a kinetic assay by using a recording spectrophotometer (GBC Cintra 10e) fitted with a thermostated cuvette holder as described previously (Pathiratne et al 2008). Proteins in the tissue homogenate were determined following Lowry's method (Lowry et al 1951).…”