الفهرس 
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Abstract
This study was done in Department of Physiology, Faculty of Veterinary Medicine (Moshtohor) Zagazig University (Benha). In
cooperation with Cell Biology Department, National Res. Centre, Dokki, Cairo
The study aimed to clarify the effect of malathion and dimethoate on some physiological and cytogenetic processes of tilapia fish
(Oreochromis niloticus), also study the residues of these pesticides and the recovery of them after 15 days.
The study included four groups each group included thirty adult mature fishes.
1-The first group, put in aquaria free from pesticides used as control group.
2-The second group was exposed to malathion in concentration 0.44 mg/L for seven days.
3-The third group was exposed to malathion in concentration 0.1 mg/L for seven days.
4-The fourth group was exposed to dimethoate in concentration 0.49mg/L for seven days.
Techniques were used for determination of ALAT and ASAT (aminotransaminases enzymes) and examination of the electrophoresis pattern of fish. They were used as an index for physiological processes. Chromosomal aberration and micronuclei tests were used as an index to evaluate the relationship between the genetic processes and the effect of water pollution with pesticides. Detection of pesticides residues after seven days and examination the recovery from the residues after 15 days
in water free from the pesticides.
The following results were obtained
A- The effect of pollutants on enzymes:
1. In the control group, the mean values of the activity of ALAT were 10.43 U/L, 27.84 U/g/ min and 35.18 U/g/min in plasma, muscles and liver respectively.
2-The exposure of fish for malathion and dimethoate caused significant increase in the activity of ALAT in plasma, muscles and liver except the exposure for malathion in lower concentration, the activity of ALAT was non significant increase in the liver. However the activity of ALAT in dimethoate exposed group was higher than malathion exposed groups in plasma and liver.
3-In the control group the mean values of the activity were 9.59U/L/min, 19.67, and 26.4 U/g/min in plasma, muscles and liver respectively.
4- The exposure of fish for both malathion and dimethoate caused significant increase in the activity of ASAT in plasma, muscles and< liver except the exposure for malathion in lower concentration, the
activity of ASAT was non significant increase in theplasma. However the activity of ASAT in dimethoate exposed group was higher than malathion exposed groups.
B- Effect of pollutants on serum proteins :
1-The electrophoretic pattern of serum protein of Oreochromis nilotica showed that the major serum protein fractions separated in control group were 11 fractions, whereas in low concentration of malathion exposed group were 14 fractions and in higher concentration of malathion and dimethoate exposed groups, the serum protein fractions were 12 fractions.
2-The malathion and dimethoate exposure caused significant decrease in fraction 1, also dimethoate exposure caused significant decrease in fraction 2 and 3 compared to control. The exposure for lower concentration of malathion caused significant increase in fractions 10 and 11.
3-In the control group, the mean value of y globulin was 17.72 °A , 13 globulin 14.26 %, cc globulin 16.66% of total serum protein. While the mean value of total globulin was 48.64%. The mean value of total albumin was 51.01% of total serum protein.
SUMMARY
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4- The exposure of fish for malathion and dimethoate caused significant decrease in the percentage of 7 globulin and total globulin compared with control group.
C- Effect of pollutants on chromosomes and cylogenetic :
1-The normal screening of chromosomes of Oreochromis niloticus showed that the normal diploid number of chromosomes was
2n=44.
2-The exposure of fish for malathion and dimethoate caused an increase in the frequency of chromosomal aberrations but the frequency in high concentration of malathion exposed group was higher than in low concentration of malathion exposed group and than in
dimethoate exposed group.
3-The types of aberrations observed in this study were structural chromosomal aberrations (gap, break, fragment, deletion, ring, centromeric attenuation and centric fusion), numerical chromosomal aberrations (aneuploidy and polyploidy) and other type (condensation or stickness).
4-The predominant types of aberrations by exposure to high concentration of malathion were centromeric attenuation, gap, fragments, aneuploidy and The predominant types of aberrations by exposure to low concentration of malathion exposed group were centromeric attenuation and
condensation.
6-The predominant types of aberration by exposure to dimethoate were gap, break, deletion, centromeric attenuation, centric fusion,
polyploidy and condensation.
7-The malathion and dimethoate reduced the rate of cell division (mitotic index) when compared to that of control.
8-The exposure of fish for malathion and dimethoate caused a significant increase in the frequency of micronuclei but the frequency is highest in dimethoate exposed group.
D- The pollutants residues :
1-The mean values of the residues of malathion were 0.00, 0.012 and 0.0036 mg/kg in control, high concentration of malathion exposed group and low concentration of malathion exposed group
respectively.
2-While the mean values of dimethoate were 0.00 and 0.038 mg/kg in control and dimethoate exposed group respectively.
3-When pre-exposed the fish put in water free from the pesticide, the residues are not detected in the tissues of the recovered fish.
SUMMARY
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It could be concluded that the pollution with pesticides (malathion and dimethoate) caused marked changes in aminutransaminases (ALAT and ASAT), serum protein fractions and chromosomes in Tilapia niloticus fish. These physiological and chromosomal parameters could also be used as criteria for pollution intensity which can be used to avoid its toxic effect on aquatic environment. In addition, the results of this study advice that the micronucleus test as the most easy method used as indicator for pollution in fish. Also these results advise to put fish which found in areas polluted with these pesticides in clean water free from pesticides for period not less than 15 days before marketing.