Adverse effects of 2,4-D dimethylammonium based-herbicide on Acetylcholinesterase expression in Nile tilapia (Oreochromis niloticus).

In this study, the evaluation of a 2,4-D dimethylammonium based-herbicide impacted on Nile tilapia was done. The effects focus on Acetylcholinesterase (AChE) expression in the brain, gill, muscle, and plasma using antibody techniques. Our findings revealed a decrease in AChE expression with prolonged exposure. For these, AChE was purified using hydroxyapatite column chromatography. Moreover, the isolated protein was characterized as AChE by Polyclonal Ab specific to AChE through the Western blot. For interpretation at the cellular and molecular level, we employed two analytical techniques, histology, and optical coherence tomography (OCT). Alterations in the gill, liver, and muscle were observed to increase with increased exposure time. Field study concludes that AChE could serve as a biomarker to detect herbicide contamination in water and its accumulation in aquatic animals. This study may aid in surveillance and strategy formulation for managing contamination from such substances in various water sources.

Development of an antibody technique for acetylcholinesterase expression detection in the gill of Nile tilapia (Oreochromis niloticus) as a glyphosate-based herbicide biomarker.

Widely used glyphosate-based herbicides can remain in agricultural fields or be spread into the surrounding environment. This study aimed to develop an antibody technique for assessing acetylcholinesterase (AChE) expression in Nile tilapia (Oreochromis niloticus) after glyphosate exposure in the assessed tissues consisting of plasma, muscle, gills, and liver. Results showed that the cumulative mortality of fish exposed to glyphosate increased with exposure time and glyphosate concentration. The LC50 was evaluated using probit analysis. A sub-lethal concentration of 2 µL L-1 glyphosate-based herbicide altered behavioural and physiological appearances. AChE expression decreased compared to that in the control group with increasing glyphosate exposure time. The 71 kDa AChE was consecutively expressed in plasma, muscle, gill, and liver under laboratory and field conditions, as detected by dot blot and Western blot analysis. Furthermore, laboratory and field studies of the gills showed positive immunohistochemical results. Although this study could detect AChE expression in many tissues, using gills to assess AChE exposure allowed the fish not to be sacrificed compared with other organ studies, and this technique can be used in both laboratory and field conditions. In conclusion, the antibody technique can be applied to measure AChE expression in the gill tissue to assess glyphosate-based herbicide exposure.

Acetylcholinesterase (AChE) polyclonal antibody from hybrid catfish (C. macrocephalus × C. gariepinus): Specification, sensitivity and cross reactivity.

AChE (acetylcholinesterase) is generally classified as a specific biomarker of pesticide exposure. The aim of this study was to produce AChE polyclonal antibody from hybrid catfish that were exposed to commercial glyphosate. The hybrid catfish was exposed to glyphosate (0.75 mL/L) for 24 h. After that, the fish brain was dissected, AChE was extracted and purified by hydroxyapatite column chromatography and eluted with 0.2 M potassium phosphate buffer pH 6.8. This protocol gave 70% yield. Then, the brain extract was characterized using 10% SDS-PAGE and Western blot probed with commercial polyclonal antibody specific to AChE (PAb-AChE). The protein, 71 kDa, was then used as an antigen to immunize mice for antibody production. The polyclonal antibody (PAb) was characterized using dot blot, Western blot and immunohistochemistry for immunolocalization of AChE in hybrid catfish exposed to glyphosate. We found that the appropriate dilution of antibody for both dot blot and Western blot was 1:3500, and 1:2500 for immunohistochemistry. Cross reactivity testing showed that PAb-AChE can be used with AChE from striped snakehead fish at the same dilution as used with AChE from hybrid catfish. It was concluded that PAb specific to hybrid catfish AChE from this work was highly specific and sensitive, and can cross-react with striped snakehead fish AChE. Thus, this polyclonal antibody may be used in monitoring glyphosate exposure in hybrid catfish and striped snakehead fish.