Evaluation of Organochlorine Pesticide Residues in Fish and Water from Lake Geriyo in Yola North Local Government Area of Adamawa State, Nigeria

Pesticides usage in agricultural fields to control pests is extremely toxic to non-target organisms like fish and affects fish health through deterioration of metabolism, and sometimes leading to death. The present study was carried out to determine the level of organochlorine (OC) pesticide residues in, water and fish (Catfish and Tilapia) from Lake Geriyo, in Adamawa State, Nigeria, in order to find out the extent of pesticide contamination and accumulation in the lake. Soxhlet extraction process was used for the extraction of fish using a mixture of hexane and acetone, while water sample was extracted using dichloromethane liquid- liquid extraction method. The extracts were cleaned-up and analyzed using a gas chromatograph mass spectrometer (GC-MS). The result shows that organochlorine pesticides residues such as endrin, aldrin, dieldrin, heptachlor were detected in the water and the fish samples of the study area. Dieldrin was the predominant residue in all the fish samples analysed, at the concentration range of 0.36mg/kg to 0.57mg/kg and 0. 051mg/kg to 0.047mg/kg in Tilapia and catfish respectively, while Lindane was of  higher concentration in water samples, (0.33mg/L) in point p1 upstream and 0.27mg/L in point p2 downstream.  The lowest levels of OC pesticides were related to Endrin, Aldrin and Heptachlor in which Endrin and Heptachor were not found in water samples. The result of the investigation shows that matured fish contain higher concentration of the OC pesticide residues than the immature fish. Dieldrin and Lindane were found to be the predominant pesticide residues in all the analysed water and fish samples. Therefore the result indicates that Lake Gariyo is contaminated by pesticide from the nearby vegetable gardens which affects the water quality and non target organisms like fishes thereof. Keywords: Organochlorine, Pesticides, Lake Geriyo, Adamawa State, Fish and Water DOI: 10.7176/CMR/11-2-0

Structure Prediction, Molecular Dynamics Simulation and Docking Studies of D-Specific Dehalogenase from Rhizobium sp. RC1

Currently, there is no three-dimensional structure of D-specific dehalogenase (DehD) in the protein database. We modeled DehD using ab initio technique, performed molecular dynamics (MD) simulation and docking of D-2-chloropropionate (D-2CP), D-2-bromopropionate (D-2BP), monochloroacetate (MCA), monobromoacetate (MBA), 2,2-dichloropropionate (2,2-DCP), d,l-2,3-dichloropropionate (d,l-2,3-DCP), and 3-chloropropionate (3-CP) into the DehD active site. The sequences of DehD and D-2-haloacid dehalogenase (HadD) from Pseudomonas putida AJ1 have 15% sequence similarity. The model had 80% of the amino acid residues in the most favored region when compared to the crystal structure of DehI from Pseudomonas putida PP3. Docking analysis revealed that Arg107, Arg134 and Tyr135 interacted with D-2CP, and Glu20 activated the water molecule for hydrolytic dehalogenation. Single residue substitutions at 25–30 °C showed that polar residues of DehD were stable when substituted with nonpolar residues and showed a decrease in activity within the same temperature range. The molecular dynamics simulation of DehD and its variants showed that in R134A variant, Arg107 interacted with D-2CP, while in Y135A, Gln221 and Arg231 interacted with D-2CP. It is our emphatic belief that the new model will be useful for the rational design of DehDs with enhanced potentials

Determination of Heavy Metals and Anti-nutrient Residues in Selected Organs of Bovines Commonly Slaughtered in Federal Polytechnic Mubi, Adamawa State, Nigeria

This study was conducted to determine the concentrations of heavy metals (Lead, Chromium, Copper, Cadmium and Zinc) and anti-nutrients residues (phytate and oxalate) in cattle (bovines) organs slaughtered at Federal Polytechnic Mubi, Nigeria slaughterhouse. Different organs (kidney, liver, lungs, heart and spleen) were collected randomly from five different bovines as samples from slaughterhouse and were brought to the laboratory for analysis. All of the heavy metals analyzed were detected with Lead presenting 293.07 ± 163.53 mg/kg in lung, 2.97 ± 0.39 mg/kg Zinc in heart, 0.632 + 0,3724 mg/kg Cadmium, 1.53 + 1.48 2.972 2.97 ± 0.39 mg/kg Copper, 4.0E-4 ± 2.0E-4 mg/kg Chromium in liver, while highest concentration 0.63 ± 0.37 mg/kg of Cadmium and 1.53 ± 1.48 mg/kg Copper was found in spleen. The concentrations of Lead, Zinc, Copper, Cadmium and Chromium detected exceeds the recommended maximum acceptable levels proposed by the World Health Organization (WHO) which are Cadmium 0.5 mg/kg, Lead 0.30 mg/kg, Zinc 0.2 mg/kg, Chromium 1.00 mg/kg, Copper 0.1- 0.50 mg/kg. The results from this study indicate that heavy metal toxicity could result from the consumption of organs of bovines (cows) feed within contaminated areas of Federal Polytechnic Mubi, Adamawa State, Nigeria. Keywords: Anti-nutrient, Bovines, Heavy metals, Organs, Slaughte

Interactions of non-natural halogenated substrates with D-specific dehalogenase (DehD) mutants using in silico studies

The D-2-haloacid dehalogenase of D-specific dehalogenase (DehD) from Rhizobium sp. RC1 catalyses the hydrolytic dehalogenation of D-haloalkanoic acids, inverting the substrate-product configuration and thereby forming the corresponding L-hydroxyalkanoic acids. Our investigations were focused on DehD mutants: R134A and Y135A. We examined the possible interactions between these mutants with haloalkanoic acids and characterized the key catalytic residues in the wild-type dehalogenase, to design dehalogenase enzyme(s) with improved potential for dehalogenation of a wider range of substrates. Three natural substrates of wild-type DehD, specifically, monochloroacetate, monobromoacetate and D,L-2,3-dichloropropionate, and eight other non-natural haloalkanoic acids substrates of DehD, namely, L-2-chloropropionate; L-2-bromopropionate; 2,2-dichloropropionate; dichloroacetate; dibromoacetate; trichloroacetate; tribromoacetate; and 3-chloropropionate, were docked into the active site of the DehD mutants R134A and Y135A, which produced altered catalytic functions. The mutants interacted strongly with substrates that wild-type DehD does not interact with or degrade. The interaction was particularly enhanced with 3-chloropropionate, in addition to monobromoacetate, monochloroacetate and D,L-2,3-dichloropropionate. In summary, DehD variants R134A and Y135A demonstrated increased propensity for binding haloalkanoic acid and were non-stereospecific towards halogenated substrates. The improved characteristics in these mutants suggest that their functionality could be further exploited and harnessed in bioremediations and biotechnological application

REGULATION SYSTEMS OF POWER SUPPLY SOURCES WITH CHANGED EXTERNAL CHARACTERISTICS FOR TECHNOLOGICAL PLANTS

The work covers the semiconductor converters for technological plants. The aim of the work is to create the methods, new algorithms, structures and concrete control devices of the power supply sources the static external characteristics of which can be formed according to the free regularities. The new control algorithms and procedures of constructing power supply sources with changed external characteristics have been proposed; the methods for solution of the analysis and synthesis problems of the regulation systems of the rectifier converters for large deviations of the regulated value have been proposed. The proposed procedures, devices and control algorithms of the rectifier converters and also the analysis and synthesis methods of the regulation systems can be used at design of the new converters. The control system of the electric drive in the test stand for investigation of the methods and aids decreasing the noise of the pipe-line systems has been introducedAvailable from VNTIC / VNTIC - Scientific & Technical Information Centre of RussiaSIGLERURussian Federatio

Structure prediction, molecular dynamics simulation and docking studies of d-specific dehalogenase from rhizobium sp. Rc1

Currently, there is no three-dimensional structure of D-specific dehalogenase (DehD) in the protein database. We modeled DehD using ab initio technique, performed molecular dynamics (MD) simulation and docking of D-2-chloropropionate (D-2CP), D-2-bromopropionate (D-2BP), monochloroacetate (MCA), monobromoacetate (MBA), 2,2-dichloropropionate (2,2-DCP), D,L-2,3-dichloropropionate (D,L-2,3-DCP), and 3-chloropropionate (3-CP) into the DehD active site. The sequences of DehD and D-2-haloacid dehalogenase (HadD) from Pseudomonas putida AJ1 have 15% sequence similarity. The model had 80% of the amino acid residues in the most favored region when compared to the crystal structure of DehI from Pseudomonas putida PP3. Docking analysis revealed that Arg107, Arg134 and Tyr135 interacted with D-2CP, and Glu20 activated the water molecule for hydrolytic dehalogenation. Single residue substitutions at 25-30 °C showed that polar residues of DehD were stable when substituted with nonpolar residues and showed a decrease in activity within the same temperature range. The molecular dynamics simulation of DehD and its variants showed that in R134A variant, Arg107 interacted with D-2CP, while in Y135A, Gln221 and Arg231 interacted with D-2CP. It is our emphatic belief that the new model will be useful for the rational design of DehDs with enhanced potentials

D-specific dehalogenases, a review

Bacterial dehalogenases cleave carbon-halogen bonds with different stereo-configurations. Rhizobium sp. RC1 produces a D-haloalkanoic-specific dehalogenase (DehD) that can cleave the carbon-halogen bond of halogenated organic pollutants. The sequence identity for DehD and HadD from Pseudomonas putida AJ1 is 27%, and 20 amino acid residues are highly conserved in these two enzymes. Therefore, DehD and HadD may have active sites that contain the same charged catalytic residues. The activity of DehD rapidly increases with increasing pH and is optimum at pH 9.5. It also has lower Km values and higher kcat values for various substrates than do other D-specific dehalogenases. Because DehD catalyzes the hydrolytic dehalogenation of D-haloalkanoic acids with inversion around the chiral carbon, it has potential industrial applications. Site-directed mutagenesis of DehD can be exploited for industrial production of chemicals, pharmaceutical and medical applications, and in environmental remediation