Sublethal Effects of Profenofos on Locomotor Behavior and Gill Architecture of the Mosquito Fish, Gambusia affinisby J. Venkateswara Rao, Ghousia Begum, N. M. Jakka, K. Srikanth, R. Nageswara Rao

Drug and Chemical Toxicology

Text

Drug and Chemical Toxicology, 29:255–267, 2006

Copyright © Taylor & Francis Group, LLC

ISSN: 0148-0545 print

DOI: 10.1080/01480540600651543

LDCT0148-05451525 6014Drug and Chemical Toxicology, Vol. 29, No. 03, March 2006: pp. 0–0Sublethal Effects of Profenofos on Locomotor Behavior and Gill

Architecture of the Mosquito

Fish,Gambusia affinis

Effect of Profenofos on Behavior and Gill of FishVenkateswara Rao et al.

J. Venkateswara Rao,1 Ghousia Begum,1 N. M. Jakka,1

K. Srikanth,1 and R. Nageswara Rao2 1Toxicology Unit, Biology Division, Indian Institute of Chemical Technology, Hyderabad, India 2Analytical Division, Indian Institute of Chemical Technology, Hyderabad, India

Subacute studies of profenofos on mosquito fish, Gambusia affinis, were carried out for 20 days to assess the locomotor behavior and structural integrity of gill in relation to bioaccumulation and targeted enzyme acetylcholinesterase (AChE; EC 3.1.1.7). The sublethal concentration of 0.13 mg/L (1/5 of LC50) altered locomotor behavior such as distance traveled and swimming speed in exposed fish. This could be due to inhibition in the activity of acetylcholinesterase and deformities in the primary and secondary lamella of gill. The bioaccumulation values indicated that the accumulation of profenofos was highest in viscera followed by head and body. The average bioconcentration factor values are 254.83, 6.18, and 2.52 μg/g for viscera, head, and body. The findings revealed that profenofos is highly toxic even at sublethal concentrations to the mosquito fish, Gambusia affinis.

Keywords AChE, Behavior, Bioaccumulation, Fish, Gill, Profenofos.

INTRODUCTION

Synthetic pesticides are fairly well recognized as a cost-effective method of controlling pests, but these chemicals are toxic to aquatic species, particularly fish. There is a growing concern worldwide over the indiscriminate use of such chemicals, resulting in environmental pollution and toxicity risk to nontargeted organisms (Coppage and Bradeich, 1976; Venkateswara Rao, 2004a).

Responses of aquatic organisms are broad-ranged depending on the toxic compound, exposure time, water quality, and the species (Eisler, 1970; Fisher,

Address correspondence to J. Venkateswara Rao, Scientist, Toxicology Unit, Biology

Division, Indian Institute of Chemical Technology, Hyderabad 500 007, India; Fax: +91 (40) 2719 3227; E-mail: jv@india.com; jv@iict.res.in

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Fo r p er so na l u se o nl y. 256 Venkateswara Rao et al. 1991; Dutta and Richmonds, 1992). Pesticides are either directly applied to soil to control soil-borne pests or are deposited on soil as runoff from foliar applications.

As a result, fish are intermittently exposed to comparatively low concentrations of pesticides affecting their behavioral responses. Our previous studies revealed that profenofos is highly toxic to fish (Venkateswara Rao et al., 2003a), and there are several instances of fish mortality that have occurred in the United States due to aerial spraying with profenofos (USEPA, 1998).

There is a growing interest in the development of behavioral markers to assess the sublethal effects of toxicant. Behavior is considered a promising tool in ecotoxicology (Drummond and Russom, 1990; Scherrer, 1992; Cohn and

MacPhail, 1996) and is becoming prominent in toxicity assessments in unicellular organisms (Tadehl and Häder, 2001), insects (Scherer and Harrison, 1979; Martin, 2003), and fish (Hansen et al., 1999, Beauvais et al, 2000,

Scholz et al., 2000, Venkateswara Rao et al., 2003b, 2005a, 2005b). Locomotion has been found to be a consistently sensitive measure of toxic stress for a wide range of environmental contamination (Little and Finger, 1990). Diverse methods have already been developed and used to measure the locomotor activity of exposed organisms (Gotz, 1980). Time-lapse video techniques have been successfully used to facilitate the documentation of behaviors of normal and stressed organisms (Healing et al., 1997). With the recent development of computer-assisted electronics, video-camera tracking systems have been greatly improved (Ethovision: Noldus, Wegeningen, The Netherlands) and used extensively in quantification of locomotor behavior with a high degree of precision (Lucas et al., 2002; Martin, 2003; Schuder et al., 2004).

In the current study, we have made an attempt to evaluate the sublethal toxicity of profenofos (O-(4-bromo-2-chlorophenyl) O-ethyl-S-propyl phosphorothioate) on the fish, Gambusia affinis, chosen as an experimental model because of its wide availability and suitability to evaluate the toxicity of xenobiotics (Cengiz et al., 2001, 2002; Hassanein, 2002). The work focused mainly on study of the perturbation of locomotor behavior (distance traveled per unit time in m/min and swimming speed in cm/s) and alterations in gill morphology with special emphasis on target enzyme, acetylcholinesterase, and bioaccumulation of profenofos in different parts of the fish.

MATERIALS AND METHODS

All the reagents used in the current study were of analytical grade and were used without further purification. The test compound profenofos, synthesized at Indian Institute of Chemical Technology, was of 99% purity. The fish species Gambusia affinis (Order: Cyprinodontiformes; Family: Poeciliidae) was obtained from Andhra Pradesh Fisheries Department, Medchal (Hyderabad); the fish were transported in oxygenated polythene bags to the laboratory and immediately transferred into a glass aquarium of 100-L capacity containing

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Fo r p er so na l u se o nl y.

Effect of Profenofos on Behavior and Gill of Fish 257 well-aerated unchlorinated groundwater. Fish weighing 125 ± 5 mg were transferred to a 40-L glass aquarium (60 × 30 × 30 cm) for 7 days and fed commercial dry feed pellets (Hello Fish Dry Pellets; CVM Products, Beijing,