Evaluation of toxicity of an organophosphate pesticide (Nogos) on behavior of the walking catfish (Clarias batrachus ) and it’s translocation in rice-fish ecosystem

The Present study investigated the toxic effects of the pesticide Nogos on the walking catfish Clarias batrachus, and its translocation and residual accumulation in a pesticide administrated rice-fish ecosystem under laboratory conditions. The experiment was conducted in aquaria containing soil collected from the paddy. Nogos was applied at five concentrations such as 0.085 ppm. 0.170 ppm, 0.255 ppm, 0.340 ppm, 0.510 ppm and 0.595ppm. A control was maintained without Nogos. An LC50 was obtained at a concentration of 0.31 ppm Nogos. Nogos at a concentration of 0.595 ppm showed LC100 to the fish while lower concentrations of 0.085 ppm did not induce any mortality. Some behavioral changes noticed were: rapid opercular movement, jumping, jerking, erratic and circular movement, loss of equilibrium, leaching of mucous through anus, immobility and resting on the corners of the test aquarium, development of red spots on the dorsal surface, white spots on the abdomen. Maximum radioactivity was observed in water on day 2 (1.1 µg/g) of application of the pesticide. Soil sample showed peak radioactivity 0.55 µg/g on day 12 of application and thereafter declined slowly to background level by day 90 of pesticide application. Paddy root and shoot showed highest activity on day 24 (0.24 µg/g) and day 24 (0.20 µg/g), respectively.

S30. SCHIZOPHRENIA IN A FISH: EFFECTS OF NMDA ANTAGONISM ON LOCOMOTOR BEHAVIOR AND SOCIAL INTERACTION IN ZEBRAFISH

Background Applying cross-species approaches in animal preclinical studies of psychiatric disorders can minimize the overinterpretations often generated using specific strains or species in animal models of human conditions. Zebrafish is a model organism widely used in neuroscience research as an alternative to rodents, but protocols relevant to the symptoms and neurobiology of schizophrenia have not been fully established and validated in this species. MK-801, an NMDA receptor antagonist, is frequently used to recapitulate schizophrenia symptoms in rodent models. We thus aimed to evaluate the effects of a concentration curve of MK-801 on locomotor activity, social interaction, and neurochemical parameters related to oxidative stress in adult zebrafish. Methods Wild-type male and female zebrafish (50:50 ratio) were randomly allocated to 4 groups: control; 1 µM MK-801; 5 µM MK-801 or 10 µM MK-801 (n = 12). In the locomotor activity test animals were individually and sequentially placed in (1) a beaker with 200 mL of water for 20 min, (2) test aquarium for 30 min to assess basal locomotor activity, (3) beaker with water or MK-801 at the different concentrations for 20 min, and (4) test aquarium for 60 min. Locomotor and exploratory parameters (total distance traveled and upper zone time) were automatically analyzed using ANY-Maze software. In the social interaction test animals were individually exposed to water or MK-801 for 20 min and then placed for 7 min in a tank flanked by two identical tanks either empty or containing 10 zebrafish serving as social stimuli. Distance traveled was automatically tracked while social interaction time was manually and blindly scored using Boris software; only the last 5 minutes were analyzed. Oxidative damage in the brain was assessed by the levels of thiobarbituric acid reactive substances (TBARS). Data were analyzed by ANOVA followed by Tukey post hoc test. Results Exposure to 5 µM MK-801 decreased the total distance traveled in the locomotor activity test. In the social interaction test, exposure to 5 and 10 µM MK-801 significantly increased the total distance traveled while reduced the time of social interaction with the stimulus animals. No differences in TBARS levels were found between the groups. Discussion Unlike what is observed in rodents after MK-801 administration, zebrafish did not show hyperlocomotion at the concentrations tested. Other studies point to the context-dependent effect of this drug, as an increase in locomotor activity is only observed when animals are tested in a novel environment. In the social interaction test, on the other hand, animals were tested in a novel context with social stimulus and zebrafish exhibited hyperlocomotion and decreased social interaction, similar to what is observed in rodents. In contrast to chronic animal models and patients with schizophrenia, there were no differences in TBARS levels after acute exposure to MK-801. These preliminary results reinforce that zebrafish is an alternative model organism useful to the study of psychotic disorders. More behavioral and biochemical tests are needed to achieve reproducible tests and models to study multiple schizophrenia domains in zebrafish.

UVC Light for Antifouling

Biofouling, the accumulation of biomass on submerged surfaces, has been a problem in the marine world for centuries. On the hull of ships, it creates an increase in drag, it can block water inlets for cooling or firefighting operations, and it can severely reduce the efficiency of heat exchangers. Because of this, many different technologies are in use. However, most of them have severe drawbacks, such as pollution of the environment, or a limited effectiveness when the object is stationary in the water.In this article, we present a novel approach, based on the use of ultraviolet (UV) light, to keep surfaces free from biofouling. The fundamental idea is to have a type of coating, which emits light outward from the surface. Experimental trials have been conducted with test samples in a number of environments, ranging from a test aquarium to open waters in various places around the world. The results are very consistent; surfaces are kept completely free from fouling for prolonged periods, regardless of location or circumstances. This is achieved at very low power levels at the surface, in the order of 1 mW of UV light per square meter.It is concluded that the fundamental principle of emitting UV light outward from a surface is a successful and promising new approach, which can possibly be applied on many different surfaces in many different application areas.<graphic href="MTS51210fx01.tif"/>

Activity determination of Na+ K+ - ATPase and Mg++ - ATPase enzymes in the gill of Poecilia vivipara (Osteichthyes, Cyprinodontiformes) in different salinities

This work aimed to know the tolerance mechanisms through the salinity variation by Na+ K+ - ATPase and Mg++ - ATPase and enzymes encountered in the gills of Poecilia vivipara. In field, the presence of this species was observed in salinities of 0 and 28‰. In laboratory, these fish were maintained in aquarium with mean salinity of 30‰ and positive responses were obtained. Some adult specimens, collected in a lagoon of the Coqueiros Beach, were utilized as matrixes. In the experiments the specimens used were those born in the test aquarium. For each salinity studied three replicates were made with three specimens for each one. The alevins were maintained in salinities of 5, 10, 15, 20, 25, 30 and 35‰ during a month for adaptation. Gills were extracted in appropriate buffer for isolation of plasma membrane and used for specific dosage of the total enzymatic activity of Na+ K+ - ATPase and Mg++ - ATPase. The relation of alevins to their adaptation towards the salinity variation was also studied. The activity of the two enzymes showed a different result. The major expression of Na+ K+ - ATPase was observed in 20‰ (35 µmoles Pi.mg protein.h-1), the best salinity to cultivate P. vivipara.

BLIND MEXICAN CAVE FISH (ASTYANAX HUBBSI) RESPOND TO MOVING VISUAL STIMULI

In apparatus for measuring optomotor behaviour, blind Mexican cave fish, Astyanax hubbsi, increase their swimming velocity upon rotation of a striped cylinder, i.e. in response to a solely visual stimulus. The fish follow the movements of the stripes at (i) rotation velocities between 60 degrees s-1 and 80 degrees s-1, (ii) light intensities of less than 20 lx and, (iii) stimulus widths subtending an angle of less than 1 &deg;. Extirpation of the vestigial eye structures does not affect the response to the moving visual stimulus, which indicates that the response is mediated by extra-ocular photoreceptors. An optomotor response can be reliably evoked in a round test aquarium. Fish do not respond when the test aquarium contains environmental cues, such as bars on the wall or when a section of the round aquarium is divided off. This indicates that the fish obtain information about their environment from different sensory sources and that the visual stimulus is effective only when no other means of orientation are available. We suggest a modified theory of the optomotor response, which emphasizes the crucial role of the environment in eliciting the response and which permits behaviours more complex than just following the stimulus.