In this study, the substrate specificity and the inhibition kinetics of various types of insecticides to the acetylcholinesterase (AChE) from a local fish; Puntius schwanenfeldii were investigated. The substrate specificity determination was done using three thiocholine substrates, which were ATC, PTC and BTC. The results showed that he partially purified cholinesterase from Puntius schwanenfeldii that preferred ATC is a true AChE. The Km and Vmax values of AChE for these substrates were 16.61 mmol and 286.5 U/mg for ATC, 19.92 mmol and 245.3 U/mg for PTC, and 48.64 mmol and 219.6 U/mg for BTC, respectively. The IC50 values for the carbamates bendiocarb, carbaryl, propoxur, carbofuran and methomyl were 0.838, 7.045, 29.441, 1.411 and 8.335 mg/L, respectively, which were comparable to the IC50 values for carbamates from several AChE from fish.
This study reports on the characterization of a purified AChE from Oreochromis mossambica
brain extract. The purification protocol involved the application of custom-synthesized affinity
chromatography gel (Edrophonium–Sephacryl S-400) and the use of high performance liquid
chromatography system (HPLC). Soluble AChE was partially purified 27.9 fold with a highest
specific activity around 73.1 × 103 U/mg proteins. The partially purified AChE higher capability
to hydrolyse acetylthiocholine (ATC) and shows less degradation against propionylthiocholine
(PTC) and also butyrylthiocholine (BTC). Based on enzyme kinetic analysis, the partially
purified AChE exhibits the apparent Michaelis constants Km, for ATC, PTC and BTC in the
range of 125, 260 and 600 μM and the maximum velocities Vmax were 276, 59 and 36
μmol/min/mg protein, respectively. The apparent inhibition constant (ki) values of eserine,
propidium and carbofuran were 0.24 μM-1min-1, 65 μM-1min-1 and 0.41 μM-1min-1 μM-1min-1,
respectively. The purified enzyme is apparently an AChE since it capable to hydrolyzes ATC at a
higher rate compared to other synthetic substrates, at pH 7.0 and 25ºC, and is inhibited by it
specific inhibitor which is eserine but not by iso-OMPA.
Observations on the effects of copper on the liver proteome of Puntius javanicus based on the
one dimensional PAGE was carried out. The liver was dissected from each fish, which was
separately treated with different concentrations of copper sulfate ranging from 0.1 to 5.0 mg/L.
The livers were extracted and one dimensional PAGE was performed under nonreducing
(native) and reducing (SDS)-PAGE. Several bands were resolved in the native PAGE with
probable candidates for the effect of copper observed showing an increased in the expression
and downregulation strongly associated with increasing copper concentrations. This study
showed that high concentrations of copper significantly alters P. javanicus liver at the proteome
level, and preliminary screening based on one dimensional PAGE is considered rapid and
simple to assess the toxicity effect of copper before more advanced and extensive assesment
with a second dimensional PAGE is carried out.
Recently, the contamination of heavy metals towards the environment especially in aquatic system has drastically increased. Heavy metals are able to transform into persistent metallic compound in which it can be accumulated within the organisms’ body system, disrupting the food chain and eventually threatened the human life. The occurrence of heavy metals spillage in the rivers and lakes are due to the careless disposal of excess heavy metals used for human activities. The accumulation of heavy metals in water system will affect all aquatic organisms especially fish. The toxicity of copper in fish can be determined by several changes in the fish under treatment with heavy metals sub-lethal concentration, LC50 within 96-hours period of acute exposure. Therefore, fish can be considered as a high potential biomarker for monitoring heavy metals pollution in aquatic system. Several selective organs are highly sensitive to the xenobiotic pollution and express changes to the exposure. One of the most potential biomarker is the biochemical biomarker of cholinesterase (ChE) inhibition by heavy metals in fish has been well studied in pollution monitoring recently. Thus, this paper gives an overview of the manipulation of fish as a biomarker of heavy metals through enzymatic reaction which have proven to be very useful in the environmental pollution monitoring.
Bioremediation is a new green economic approach in providing solutions for cleaning up
contaminated sites. Phytoremediation uses plants as a tool for remediation purposes. The usage
of plant species offers higher potential solution to remediate heavy metal contaminated sites.
This study aimed on screening potential plant species for phytoremediation of heavy metal
contaminated water. The potential of three aquatic macrophytes species (Eichorrnia crassipes,
Pistia stratiotes and Ipomoea aquatica) for chromium and nickel phytoremediations was tested.
The plants were exposed for 10 days under hydroponic conditions in heavy metal contaminated
water. E. crassipes showed the highest chromium and nickel concentrations in its biomass, 1.60
and 2.40 μg/L respectively. Meanwhile, P. stratiotes had chromium and nickel concentrations
detected at 0.89 and 0.081 μg/L, respectively; chromium and nickel concentrations of I.
aquatica detected were, 0.49 and 0.08 μg/L, respectively. The ability of these plants to
accumulate heavy metals and survived throughout the experiment demonstrates the potential of
these plants to remediate metal-enriched water. Among the three tested aquatic plants, E.
crassipes was proven to be the most suitable plant species that can phytoremediate heavy metal
contaminated water followed by P. stratiotes and I. aquatica.
Investigation on in vivo effects of copper (Cu) on the ultrastructure of P. javanicus liver was
carried out using transmission electron microscopy (TEM). The addition of sublethal
concentration of 5 mg/L of Cu caused abnormalities on the bile canaliculi (BC) including
dilation and elongation compared to control and at lower concentrations of copper with a normal
round shape form. Findings from this study support an alternative histological assessment of the
effects of Cu concentration on P. javanicus liver.