Biomedical subjects

M Niamat Ali

Publications and source records attributed to M Niamat Ali.

5 recordsLinked to original sources

PubMed2004

Studies on lethal concentrations and toxicity stress of some xenobiotics on aquatic organisms.

Three widely used xenobiotics pentachlorophenol (PCP), 2,4-dichlorophenoxyacetic acid (2,4-D) and 2-chloro-2,6-diethyl-N-(butoxymethyl) acetanilide (Butachlor) are evaluated for acute toxicity and stress behavior on freshwater fish (Heteropneustes fossilis, Clarias batrachus, Channa punctatus) and mosquito larvae (Culex pipiens fatigans). The experiment was carried out by medium treatment using intermittent flow-through system. Median lethal concentrations (LC50) were calculated by probit analysis. The LC50 values and 95% confidence intervals showed variable range for tested chemicals. Mosquito larvae generally appeared resistant than fish, while H. fossilis was found to be most sensitive. Stress signs in the form of behavioral changes are also observed. Both types of organisms are recommended as good bioindicator for the risk assessment of aquatic environment due to chemicals tested.

2,4-Dichlorophenoxyacetic Acid↗

PubMed2003

Evaluation of genotoxicity of PCP and 2,4-D by micronucleus test in freshwater fish Channa punctatus.

An in vivo study on the genotoxic effects of pentachlorophenol (PCP) and 2,4-dichlorophenoxyacetic acid (2,4-D) was carried out with freshwater air-breathing fish Channa punctatus. The fish were exposed to three sublethal doses of PCP (0.2, 0.4, and 0.6 ppm) and 2,4-D (25, 50, and 75 ppm) by medium treatment. Micronucleated erythrocytes were sampled at intervals of 48, 72, and 96 h post-treatment. Student's t test revealed significant increases in micronucleus (MN) frequency. Maximum incidence of MN was recorded at highest concentrations and durations for both chemicals. A time- and dose-dependent response of the MN frequency for both chemicals was confirmed. PCP-treated groups had 8-10 MN per cell, specifically at higher concentrations and duration. Echinocytes were recorded at higher concentrations of 2,4-D. The study confirmed the genotoxicity of PCP and 2,4-D in this organism. PCP was found to be more toxic than 2,4-D in terms of MN induction. This assay has further potential for detecting genotoxic compounds in aquatic ecosystems.

2,4-Dichlorophenoxyacetic Acid↗

PubMed2002

Induction of micronuclei and erythrocyte alterations in the catfish Clarias batrachus by 2,4-dichlorophenoxyacetic acid and butachlor.

The micronucleus test (MNT) in fish erythrocytes has increasingly been used to detect the genotoxic effects of environmental mutagens and its frequency is considered to reflect the genotoxic damage to cells, mainly the chromosomes. Besides, morphologically altered erythrocyte is taken as an index of cytotoxicity. Both parameters were used in the present study by two herbicides, 2,4-dichlorophenoxyacetic acid (2,4-D, in 25, 50 and 75ppm concentrations) and 2-chloro-2,6-diethyl-N-(butoxymethyl) acetanilide (butachlor, in 1, 2 and 2.5ppm concentrations) for genotoxic and cytotoxic endpoints. The study was carried out by an in vivo method on peripheral erythrocytes of catfish Clarias batrachus using multiple sampling times (48, 72 and 96h). Cytogenetic preparations were made by haematoxylin-eosin staining technique. Pycnotic and granular micronuclei (MN) were consistently observed irrespective of chemical tested. A wide range of altered cells was also observed. Echinocytes accompanied by altered nuclei and vacuoles were prominent feature of 2,4-D, whereas, anisochromasia and anisocytosis of erythrocytes were characteristic of butachlor. Increase in MN as well as altered cells frequencies were significant. A positive dose-response relationship in all exposures and sampling times was observed. Herbicides used were found to be genotoxic as well as cytotoxic in this fish. The suitability of the adopted parameters for the screening of the aquatic genotoxicants is discussed.

2,4-Dichlorophenoxyacetic Acid↗

PubMed2002

Clastogenicity of pentachlorophenol, 2,4-D and butachlor evaluated by Allium root tip test.

The meristematic mitotic cells of Allium cepa is an efficient cytogenetic material for chromosome aberration assay on environmental pollutants. For assessing genotoxicity of pentachlorophenol (PCP), 2,4-dichlorophenoxyacetic acid (2,4-D) and 2-chloro-2,6-diethyl-N-(butoxymethyl) acetanilide (butachlor), 50% effective concentration (EC(50)), c-mitosis, stickiness, chromosome breaks and mitotic index (MI) were used as endpoints of genotoxicity. EC(50) values for PCP and butachlor are 0.73 and 5.13 ppm, respectively. 2,4-D evidently induced morphological changes at higher concentrations. Some changes like crochet hooks, c-tumours and broken roots were unique to 2,4-D at 5-20 ppm. No such abnormalities were found in PCP and butachlor treated groups, however, root deteriorated and degenerated at higher concentrations (<3 ppm) in PCP. MI in 2,4-D showed a low average of 14.32% followed by PCP (19.53%), while in butachlor it was recorded 71.6%, which is near to the control value. All chemicals induced chromosome aberrations at statistically significant level. The highest chromosome aberration frequency (11.90%) was recorded in PCP at 3 ppm. Large number of c-mitotic anaphases indicated that butachlor acts as potent spindle inhibitor, whereas, breaks, bridges, stickiness and laggards were most frequently found in PCP showing that it is a potent clastogen.

2,4-Dichlorophenoxyacetic Acid↗

PubMed2002

Computerized automated morphometric assay including frequency estimation of pentachlorophenol induced nuclear anomalies (micronucleus) in catfish Heteropneustes fossilis.

An in vivo study of the effects of pentachlorophenol was carried out with a pre-acclimatized fish species, Heteropneustes fossilis, using four sub-lethal concentrations, 0.1, 0.2, 0.3 and 0.4 ppm, and three sampling times, 48, 72 and 96 h. Cytogenetic preparations were stained by the haematoxylin-eosin technique. The incidence of micronuclei was scored by a manual and an automated method. Small-sized micronuclei appeared in the cytoplasm in addition to the main nucleus. The frequency of micronucleated erythrocytes peaked at 4 days (96 h) exposure. The percentage of single micronuclei increased with longer exposures. The Mann-Whitney U test showed all micronuclei frequencies were significantly different from control (P<0.05). No statistical difference was observed between scores obtained by the manual and automated methods. A linear relationship between the percentage of micronucleated erythrocytes and dose was confirmed at all levels. Computer image analysis of morphological variations of erythrocytes indicated a 1:5 ratio of micronuclei and main nucleus accompanied by a reduction in cell volume by 600 dot units. Pentachlorophenol-mediated genotoxicity was confirmed in this fish for the first time. Possible consequences of genotoxicity and cytotoxicity are discussed.

Animals↗