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Jun 2023 DOI 10.14302/issn.2377-2549.jndc-23-4615
Manickum ThavrinCorresponding author
A literature review was undertaken with a focus on 1) identifying the research gaps regarding CECs, 2) identifying the most common ones, and 3) identifying the typical analytical methods/technologies employed, for their analysis. A total of 214 papers were noted, with a total of 21 review articles (9.8%). Of this total, a surprisingly high number were from South Africa alone: 117 (54.7%), of which 44 (20.6%) reports were associated with South Africa’s Water Research Commission (WRC). The top three CECs research gaps were (decreasing rank: Number of “gaps”, %): 1) Toxicity/Risk/Impact (260, 21.5%), 2) Analysis/Tests/Methods (118, 9.8%) and 2) Future research/studies (118, 9.8%), and 3) Monitoring (89, 7.4%). The common classes of CECs that were reported on, were : (i) Chemical: pharmaceuticals, personal care products, steroids, chlorinated and brominated contaminants, PAHs, PCBs, phthalates, alkyl phenols, herbicides, organochlorine pesticides, engineered nanomaterials and (ii) “Microbiological”: antibiotic resistance genes, human enteric bacteria and viruses, microbial pathogens (e.g., E Coli, rotavirus, Crypto, etc.), infectious biological water contaminants (e.g., E Coli isolates), cyanobacterial blooms (Microcystis). Common test methods used for analysis of the chemical contaminants were found to be chromatography (gas, liquid)-mass spectrometry; for the microbial contaminants, they were culture-based methods, ELISA, fluorescence microscopy, qPCR, RT-qPCR, gel electrophoresis, Raman spectroscopy, and also chromatography (largely liquid)-mass spectrometry, were also used. Some proposals were additionally made to address the very common, significant research gaps noted in CECs research, especially the standardization of analytical chemical test methods, based on chromatography-mass spectrometry, for quantification.
May 2020 DOI 10.14302/issn.2641-4538.jphi-20-3338
Chibueze Izah SylvesterCorresponding author
Department of Microbiology, Faculty of Science, Bayelsa Medical University, Yenagoa, Bayelsa State, Nigeria
This study investigated the acute toxicity of Clariasgariepinusfingerlings. The fingerlings of Clariasgariepinuswere acclimatized for 1 week before the range-finding test was carried out at varying concentrations. Sublethal concentration (viz: 0.00ppm, 10.80 ppm, 18.00 ppm, 25.20 ppm, 32.40 ppm and 39.60 ppm of the 2,4-D Dimethylamine salt) were made in a rectangular aquarium. Each experimental concentration was carried out in triplicate with 10 fish each. The media were renewed at every 24 hours throughout the experimental duration viz: 96 hours. When the fish were introduced into the aquarium containing the toxicants, they exhibited some behavioural changes including opercular movement, air gulping and irregular swimming pattern. The mortality rate significantly increased as the concentration of the 2,4-D Dimethylamine salt increased for each of the exposure duration. The LC50 values at 24, 48, 72 and 96 were 86.15 ppm, 36.28 ppm, 18.72 ppm and 15.68 ppm, respectively. From the findings of this study, there is a need for exercise caution in the use of 2,4-D Dimethylamine salt based herbicides close to the aquatic ecosystem.
May 2019 DOI 10.14302/issn.2637-6075.jpae-19-2779
Chibueze Izah SylvesterCorresponding author
Department of Biological Sciences, Bayelsa Medical University, Yenagoa, Bayelsa State, Nigeria.
This study evaluated the behavioural response and toxicity of paraquat dichloride to fingerlings of Clariasgariepinus. The fishes were acclimatized for 14 days and exposed to sublethal concentration of 0.00 ppm, 16.56 ppm, 22.08 ppm, 27.60 ppm, 33.12 ppm and 38.64 ppm. A 24 hours’ renewal bioassay was adopted in this study. Results showed that the fishes exhibited change in swimming, opercular movement, body pigmentation, surfacing and air gulping. Mortality rate increased significantly at p<0.05 as the concentration of the toxicant increased as well as the exposure period. LC50 values at 24, 48, 72 and 96 were 59.95, 47.59, 38.12 and 26.18ppm, respectively. Based on the results, Paraquat dichloride users need to discard the remains of empty cans properly to avoid contamination. Also there is need to exercise caution when using paraquat dichloride based herbicides in agricultural fields close to surface water resources.
May 2018 DOI 10.14302/issn.2832-5311.jpcd-18-2077
Farkaš VladimírCorresponding author
Institute of Chemistry, Centre for Glycomics, Slovak Academy of Sciences, 84538 Bratislava, Slovakia
Polysaccharide transglycosylases (PTGs) are a unique group of glycoside hydrolases playing important roles in the formation and modification of plant and fungal cell walls. Their action involves cutting the molecule of the polysaccharide substrate at the glycosidic bond, followed by transfer of the newly formed reducing-end fragment to the non-reducing end of another polysaccharide molecule, with the formation of a new glycosidic bond. As there is no net increase in the number of reducing ends in the system, conventional reductometric methods used to assess the activity of glycoside hydrolases are ineffective. Since the PTGs participate in vital processes, such as the elaboration of cell walls in plants and fungi, and are not present in animal cells, they are considered as possible targets for future specific fungicides and herbicides. Biochemical studies of PTGs, as well as the search for their inhibitors, require the availability of convenient and efficient methods for their assay. In this review we briefly describe the principles of methods used to detect and to determine the activity of this important group of enzymes.