Aims: To determine abundance of potential pathogenic microorganisms in pangasius and tilapia farms in five major fish-producing areas in Bangladesh by PCR approaches. Methodology and results: Important microbial water quality indicators were studied in water of 38 fish farms producing pangasius (Pangasianodon hypophthalmus) and tilapia (Oreochromis niloticus) in five major fish-producing areas of Bangladesh. The parameters included physicochemical data and PCR detection of total coliforms and E. coli, species of potentially pathogenic Vibrio, and cyanobacterial genes encoding the toxins microcystin and saxitoxin. Quantitative PCR showed that coliform bacteria occurred in all fish farms with densities from one to 2.2 × 105 per mL, while E. coli ranged from none to 5.0 × 104 per mL. Numbers of total coliforms and E. coli were higher in pangasius farms than in tilapia farms, and when high abundances occurred, coliform bacteria and E. coli bacteria co-varied. Detection of Vibrio-specific genes indicated presence of Vibrio species in 76% of the farms and included V. vulnificus and V. cholerae. The human pathogen type of V. cholerae (carrying the ctxA gene) and the fish pathogen V. parahaemolyticus were not detected. The microcystin-encoding mcyE gene ranged from undetectable to 2.6 × 105 copies per mL and tended to be highest in pangasius farms. The saxitoxin-encoding gene sxtA was not found in any of the farms. Conclusion, significance and impact of study Based on the high abundance of especially coliform bacteria and E. coli, we recommend more efficient water quality monitoring systems to improve detection and control of fecal coliforms and to reduce presence of microcystin-producing cyanobacteria in aquaculture farms in Bangladesh
Water Quality ; Tilapia ; Catfishes

For the investigation of the receptive field of the retinal neurons, the spatial and temporal properties of horizontal cells and the center-surround antagonisms of bipolar cells and the third-order neurons were studied using conventional intracellular recording techniques. Horizontal cells were hyperpolarized by the large annulus light stimuli (id: 3.5mm) and required at least 0.2 seconds of dark periods to respond enough. The amplitudes of the response of the ON-bipolar cell were decreased as the diameter of the spot stimuli was increased to 2.6mm and the responses were inverted at 2.6mm of inner diameter of the spreading annulus stimuli with fixed width. ON-sustained cell with spikes generated ON-sustained light responses by small annulus (1400-2100micrometer), but elicited OFF-sustained responses by large annulus (2100-2800micrometer). ON-sustained cell without spikes also showed surround antagonism. The spikes were generated at the spot of 490micrometer diameter and they were disappeared at the spot of 5600micrometer diameter. And, OFF-transient component of the ON-OFF transient cell was enhanced as annulus stimuli spread. The results suggest that the horizontal cells have large and monotonic receptive fields while the bipolar cells and the ON-sustained cells have large biphasic receptive fields in the catfish retina.
Catfishes* ; Neurons* ; Retina ; Retinal Neurons

The study aimed to assess the single and joint lethal toxicity, type of interaction and the extent to which simple mathematical model of concentration addition (CA), independent action (IA) and generalized concentration addition (GCA) could predict the joint toxicity of copper hydroxide and glyphosate mixture in Clarias gariepinus. Static bioassay were setup to determine the individual and combined (based on ratio 1:2) lethal concentrations (LCx) of the pesticides. Data from the static bioassays were then fitted into the synergistic ratio (SR), concentration-addition (toxicity unit; TU) and isobologram model to determine the type of interaction between the different classes of pesticides, while the CA, IA and GCA models were used to predicted the observed mixture effects. The estimated 24 h, 48 h, 72 h and 96 h LC50 for copper hydroxide were 198.66 mg/L, 167.51 mg/L, 138.64 mg/L, and 104.82 mg/L; glyphosate were 162.92 mg/L, 103.88 mg/L, 61.95 mg/L, and 52.6l mg/L; while the mixtures were 63.18 mg/L, 59.06 mg/L, 56.42 mg/L, and 50.67 mg/L, respectively. Glyphosate was 2 times more toxic than copper hydroxide to C. gariepinus when acting singly. The SR and RTU was <1 indicate that the interaction between the pesticides was synergistic. Synergism was also corroborated by the isobologram model. The interaction of the mixture of copper hydroxide and glyphosate followed the IA model while the CA and GCA model underestimated the observed mixture effects. The study showed that copper hydroxide was practically non-toxic, while glyphosate and the mixture were slightly toxic to C. gariepinus
Biological Assay ; Catfishes ; Copper ; Joints ; Models, Theoretical ; Pesticides

The study aimed to assess the single and joint lethal toxicity, type of interaction and the extent to which simple mathematical model of concentration addition (CA), independent action (IA) and generalized concentration addition (GCA) could predict the joint toxicity of copper hydroxide and glyphosate mixture in Clarias gariepinus. Static bioassay were setup to determine the individual and combined (based on ratio 1:2) lethal concentrations (LCx) of the pesticides. Data from the static bioassays were then fitted into the synergistic ratio (SR), concentration-addition (toxicity unit; TU) and isobologram model to determine the type of interaction between the different classes of pesticides, while the CA, IA and GCA models were used to predicted the observed mixture effects. The estimated 24 h, 48 h, 72 h and 96 h LC50 for copper hydroxide were 198.66 mg/L, 167.51 mg/L, 138.64 mg/L, and 104.82 mg/L; glyphosate were 162.92 mg/L, 103.88 mg/L, 61.95 mg/L, and 52.6l mg/L; while the mixtures were 63.18 mg/L, 59.06 mg/L, 56.42 mg/L, and 50.67 mg/L, respectively. Glyphosate was 2 times more toxic than copper hydroxide to C. gariepinus when acting singly. The SR and RTU was <1 indicate that the interaction between the pesticides was synergistic. Synergism was also corroborated by the isobologram model. The interaction of the mixture of copper hydroxide and glyphosate followed the IA model while the CA and GCA model underestimated the observed mixture effects. The study showed that copper hydroxide was practically non-toxic, while glyphosate and the mixture were slightly toxic to C. gariepinus
Biological Assay ; Catfishes ; Copper ; Joints ; Models, Theoretical ; Pesticides

The effects of r-aminobutyric acid(GABA) agonsits and antagonists were explored by the intracellular recording method to discern the preferential suppression of the ON component by GABA on the ON-OFF transient cell in the catfish (Ictalurus punctatus) retina. Experiments were performed in the superfused eyecup preparation. The animals were decapitated and pited before the eye, and the surrounding tissue was removed from the skull. The retina was exposed by excising the cornea, iris, and vitreous. This preparation rested on a wad of Ringer`s soaked cotton in contact with an Ag/Agcl reference electrode. Solutions were delivered through a manifold system that was connected to a pipette located near the absorbent wick. Electro-physiological recordings were made using standard intracellular electrodes filled with 2 M potassium acetate. The electrical signal was recorded with an amplifierand a penwriter, viewed on an oscilloscope, and stored on a data recorder. The light sources were red light-emitting-diode (LED) and the stimuli were full field illumination covering the cntire retina. GABA preferentially reduced ON light responses in ON-OFF transient cell. and GABA hyperpolarized bipolar cells, but the effects on ON bipolar cells were more sensitive than OFF bipolar cells. CACA and TACA, GABAc receptor agonist, did not act on bipolar cells. CACA and TACA, GABAc receptor agonists, hyperpolarized bipolar cells but the sensitivity deferences between ON and OFF bipolar cell were not observed. These results suggest that the preferential suppression of the ON component of the ON-OFF transient cell by GABA was resulted from the presynaptic mechanism that reduced bipolar cell input.
Animals ; Catfishes* ; Cornea ; Electrodes ; gamma-Aminobutyric Acid ; Iris ; Lighting ; Potassium Acetate ; Retina* ; Skull

A seven months old, tiger shovelnose catfish was referred to the veterinary medical teaching hospital of the college of veterinary medicine, Konkuk university because of suspecting a foreign body in the stomach. By physical and radiologic examinations, the catfish revealed abdominal enlargement, vomiting, inactivity and radiopaque foreign bodies in the stomach. Under general anesthesia with dilute isoflurane solution, celiotomy was performed. Stomach was atonic, and three foreign bodies were palpated in the stomach. In this process, three stones came out through mouth. Abdominal muscles were closed with a simple continuous suture pattern, and skin was closed with a simple mattress suture pattern. Sutured site was covered with glue and mucous taken from allogenic skin. On the second day after surgery, the patient recovered to normal condition, showing increased appetite and activity.
Animals ; Catfishes/*surgery ; Foreign Bodies/pathology/*surgery ; Gastroscopy/veterinary ; Stomach/*surgery

OBJECTIVES: This study aimed to estimate the effects of 4-nonylphenol (NP), a ubiquitously present surfactant in aquatic environments, on the anti-oxidant systems of the liver in the Far Eastern catfish Silurus asotus. METHODS: Changes in biochemical parameters involved in glutathione (GSH)-related and other anti-oxidant systems were analyzed following 4 weeks of 4-NP administration (0.1 and 1.0 mg/kg diet) via a formulated diet to catfish. RESULTS: 4-NP exposure induced an elevation in hepatic lipid peroxide levels and an accompanying decrease in reduced state GSH after 2 weeks, suggesting pro-oxidant effects of the chemical in catfish. This oxidative stress was associated with an inhibition of the GSH-utilizing enzyme glutathione peroxidase at the same time point. This inhibition was restored after 4 weeks. The activities of other anti-oxidant enzymes, i.e., glutathione reductase, superoxide dismutase and catalase were increased after 4 weeks. These enzyme increases occurred more strongly at the higher 4-NP concentration (1.0 mg/kg diet). CONCLUSIONS: 4-NP given to catfish at 0.1 to 1.0 mg/kg diet, concentrations relevant to environmental levels, depletes the endogenous anti-oxidant molecule GSH and temporarily inhibits GSH-related anti-oxidant enzymes. Such declines in anti-oxidant capacity and elevated oxidative stress seem to be compensated eventually by subsequent activation of various anti-oxidant enzyme systems.
Catalase ; Catfishes* ; Detergents* ; Diet ; Glutathione ; Glutathione Peroxidase ; Glutathione Reductase ; Liver ; Oxidative Stress ; Superoxide Dismutase

OBJECTIVES: This study aimed to estimate the effects of 4-nonylphenol (NP), a ubiquitously present surfactant in aquatic environments, on the anti-oxidant systems of the liver in the Far Eastern catfish Silurus asotus. METHODS: Changes in biochemical parameters involved in glutathione (GSH)-related and other anti-oxidant systems were analyzed following 4 weeks of 4-NP administration (0.1 and 1.0 mg/kg diet) via a formulated diet to catfish. RESULTS: 4-NP exposure induced an elevation in hepatic lipid peroxide levels and an accompanying decrease in reduced state GSH after 2 weeks, suggesting pro-oxidant effects of the chemical in catfish. This oxidative stress was associated with an inhibition of the GSH-utilizing enzyme glutathione peroxidase at the same time point. This inhibition was restored after 4 weeks. The activities of other anti-oxidant enzymes, i.e., glutathione reductase, superoxide dismutase and catalase were increased after 4 weeks. These enzyme increases occurred more strongly at the higher 4-NP concentration (1.0 mg/kg diet). CONCLUSIONS: 4-NP given to catfish at 0.1 to 1.0 mg/kg diet, concentrations relevant to environmental levels, depletes the endogenous anti-oxidant molecule GSH and temporarily inhibits GSH-related anti-oxidant enzymes. Such declines in anti-oxidant capacity and elevated oxidative stress seem to be compensated eventually by subsequent activation of various anti-oxidant enzyme systems.
Catalase ; Catfishes* ; Detergents* ; Diet ; Glutathione ; Glutathione Peroxidase ; Glutathione Reductase ; Liver ; Oxidative Stress ; Superoxide Dismutase

OBJECTIVE: The main objective of this study is to provide an assessment of the risks to human health associated with the exposure to heavy metal bioaccumulation in Manila Catfish (Arius dispar) from Laguna Lake.

METHODS: Manila Catfish (common name Kanduli) samples were collected in eight sampling stations in three major areas of the lake during the dry and wet seasons. Dry season samples were collected from May to June 2010 and wet season samples from September to November 2010. Coordinates of sampling locations were recorded using Global Positioning System to facilitate re-sampling activities and ensured that subsequent samples for the wet season were collected in the area as that of the wet season samples. Heavy metals analyses for cadmium, lead, arsenic, and chromium were conducted using Atomic Absorption Spectrophotometer and Mercury Analyzer for mercury. Estimates of health risks associated with Kanduli consumption were estimated based on non-carcinogenic health effects of heavy metals.

RESULTS: Non-carcinogenic Health Quotient (NHQ) values of the five heavy metals showed that lead is the most significant pollutant of concern in terms of adverse health effects from risks associated with Kanduli consumption from the lake.

CONCLUSION: From the point of view of disease prevention and control, long term consumption of Kanduli from Laguna Lake is expected to increase health risk due to lead contamination.

.humans ; Arsenic ; Mercury ; Cadmium ; Lakes ; Chromium ; Catfishes ; Seasons ; Geographic Information Systems ; Metals, Heavy ; Spectrophotometry, Atomic

The effects of GABA and glutamate on the horizontal cells were explored by an intracellular recording method to discern the mechanisms of receptive field formation by chemical coupling in the catfish outer retina. The results suggest that the horizontal cells of the catfish retina might use GABA as their transmitters and that the GABAergic system contributes to the formation of receptive fields of the horizontal cells. GABA|c receptors may be involved in a chemical coupling between horizontal cells and concerned with the depolarizing actions by GABA on horizontal cells in the catfish retina. Since the chloride equilibrium potential is more positive than the dark membrane potential in horizontal cells, GABA released from a horizontal cell may depolarize the neighboring horizontal cells. Thus a chemical coupling between horizontal cells may be formed. GABA|A receptors also may be involved in the negative feedback mechanism between photoreceptor and horizontal cell. And glutamate may be involved in connecting positive and negative feedback systems since it potentiated the GABA's actions. Therefore, it is presumed that large receptive fields in the catfish retina are formed not only by electrical coupling but also by chemical coupling between horizontal cells. And information travels laterally by pathways involving both electrical coupling composed of gap junctions and chemical coupling in the retinal network.
Catfishes* ; gamma-Aminobutyric Acid ; Gap Junctions ; Glutamic Acid ; Membrane Potentials ; Retina* ; Retinaldehyde