CHAPTER-VI DIGESTIVE ENZYMES

Transcription

1 CHAPTER-VI DIGESTIVE ENZYMES INTRODUCTION: Carbohydrates, protein and lipids are the complex nutrients which constitute the diet of fish. There is a set of digestive enzymes which are capable of degrading each of these to the level of simple units that can be absorbed and subsequently metabolized. The complement of enzyme system is likely to vary among animal groups reflecting in a complex manner in adaptation to diet (Moitra and Das, 1967). Variations in the enzyme activity of the different regions of alimentary canal of several species of fishes and the relationship of enzyme activity with physiological status of fishes were revealed by Phillips (1969), Fange and Grove (1979). The enzyme action is more related to the structure and physiology of alimentary canal as well as to the rate of digestion of food. The study of enzyme system in the alimentary canal of fishes is of importance in understanding the specific dietary preferences. The enzyme activity of alimentary canal has relationship with feeding rate and composition of food. Enzyme activity in the digestive tract of teleosts has been initiated towards the end of 19* century (Sterling, 1884). The digestive enzymes of fishes is influenced by various factors like growth and development (Kitamichado and Tachino, 1960 a, b, c; Sinha, 1978; Das et al, 1987), time interval of feeding (Falge and Schipennk oh, 1976, Paul et al, 1990), Seasons (Kawashida, 1952; Anamichev, 1959; Chepik, 1966; Kuzmina 1980) and food and feeding habits (Vonslyke, 1927; Mehalanolis and Roy Choudry, 1950; Fish, 1960; Moitra and Roy 1960; Nagase, 1964; Nagayama and Saitro, 1968; Phillips, 1969; Kawai and Ikeda, 1971; Moitra and Bhattacharya, 1975; Ghosh, 1976; Preja 85

2 and Micczyslow, 1977; Tyagi et al, 1977; Ranganayki, 1980; Phadate and Srikar, 1988; Baskaran et.al, 1990; Ebanasar,1995; Kavitha, 2005; Sudha, 2005). Pollutants like heavy metals (Hota, 1995, Sesha Srinivas and Bala Parameswara Rao, 1996; Marasarrat Sultana and Lomte, 1999), Pesticides (Khillare, 1992; Anitasusan et.al, 1999), calcium (Shanmuga Priya, 2001; Kavitha, 2002) and detergents (Sastry and Agarwal, 1978) also influence digestive enzyme activity. Literature available on enzyme activity in the alimentary canal of murrels are scanty (Mehalanolis and Roy, Choudry, 1950; Sastry and Agarwal, 1978, Seshadri, 1967; Baskaran et.al, 1990; Gaur and Jaish, 1970; Goel, 1974; Ebanasar.1995). Azhar Baig et al, (1999) reported the influence of heavy metals on the enzyme activity of Channa punctatus. There are several reports to indicate the phenol induced alterations in enzymes and metabolites of various tissues in the fish models (Ito and Toshiro, 1980; Marinesco, et.al, 1980; Olowska, et.al, 1981; Verma, et.al, 1981a 1982; Dalela et.al, 1983; Gupta et.al, 1984; Ravichandran and Bemice, 1985; Gupta and Dalela, 1986; Tiedge, et.al, 1986; Smith et.al,). Reports reveal number of investigations on phenol induced effects in various fishes particularly devoted on the individual parameters like accumulatory patterns and the metabolism of phenolic compounds. Studies on the effect of phenols on the enzyme analysis are also available (Reddy et.al, 1993; Kristofferson et.al, 1974; Gupta and Dalela, 1984; Assem, et.al, 1989, Ravikumar and Nagaraj, 2003). As there are no literature on the effect of phenol and super phosphate on the digestive enzyme activity of Channa punctatus is available, the present investigation was planned and carried out. MATERIALS AND METHODS Channa punctatus was selected for the study for its easy availability and it responds well to aquarium conditions and can readily be kept under wide range of 86

3 environmental conditions. Healthy fishes were collected from the derelict ponds near Thanjavur and acclimatized to laboratory conditions in cement tanks. They were fed ad labitum of goat liver for 15 days. Murrels of uniform size ( g) were used for the experiment. The fishes were divided into seven groups of five each. Each weighed separately. Three groups of fishes were exposed to Ippm, 2 ppm and 3 ppm concentrations of phenol and the other three were exposed to the three doses of superphosphate solution. One group kept as control. The entire set were exposed to 24 hrs, 48 hrs, 72 hrs and 96 hrs. During the end of these exposure hours, the fishes were sacrificed by pitching and immediately and kept in a freezer. After noting their weight the abdomen were cut open and the following methods were utilized for the study. The samples of experimental fishes were taken in live and healthy condition and the gut was removed carefully and a homogenate was prepared in chilled phosphate buffer of ph 7. Saccharogenic assay (Henry and Chiamori, 1960) was used to assay amylase activity and the unit of amylase activity (AU) was calculated as mg maltose liberated at 10 minutes at 30 C. Casein digestion method of Kunitz (1947) was used to assay the protease activity and the unit of protease activity (PU) was calculated as mg of protein used inlo minutes at 30^ C. Lipase activity was assayed by using Bier's titrimetric method (Bier, 1962 ) and the unit of activity was calculated as the amount of N NaOH required to neutralize the fatty acid liberated during 3 hrs of incubation at 30 C. Each assay was repeated 5 times using fresh samples. The data on enzyme analysis of C. punctatus was subjected to analysis of varience using Minitab software and the significance is presented in the table: 87

4 RESULTS: Protease: The influence of phenol on the enzyme protease during different exposure times was presented in the table; 6; 1. This clearly indicates that phenol reduces the protease level. The influence of superphosphate on the enzyme protease was presented in the table: 6: 2. The results showed increased enzyme in all durations of the experiments. High protease activity of (Pu /g/hr) was recorded in S3 and least 120.5(Pu /g/hr) in P3.This reveals the inhibition of enzyme synthesis by phenol and enhances enzyme activity by superphosphate. Amylase: Influence of phenol on the enzyme amylase during different experimental periods was presented in the table: 6:3. The results showed decreased enzyme in all durations of the experiments. Influence of super phosphate on the enzyme amylase was presented in the table: 6: 4. The results showed increased enzyme activity in all durations of the experiments due to its exposure to superphosphate. Lipase: Changes of phenol on the enzyme lipase was presented in the table:6:5. The results showed decreased lipase enzyme in all the exposed durations due to the toxicity of phenol. Effect of superphosphate on the enzyme lipase was recorded in the table:6:6. The results of increasing activity was observed in all durations from 6.5 lu/ g/ hr to 7.93 lu/ g/ hr. 88

5 TABLE-6.1 Effect of three different sub-iethal dosages of phenol on digestive enzyme protease Pu/ g/ hr C ± ± ± ±12.7 PI ± ± ± ±11.6 P ± ± ±12.4 P ± ± ±16.4 *significant (P<0.1) TABLE - 6:2 Effect of three different sub-lethal dosages of super phosphate on digestive enenzyme protease-pu/g/hr C ± ± ± ±16.3 SI ± ± JLl ± 12.8 S ± ± ± ±16.3 S ± ± ± ± 17.9 * significant (P<0.1) 89'

6 TABLE Effect of three different sub-iethal dosages of phenol on digestive enzyme Amylase Au/ g/ hr C 48.2 ± ± ± ill-2 «PI ± ±_ M.5 P ± j^l.3 P ± ±_ :L0.6 *significant (P<0.1) TABLE-6:4 Effect of three different sub-lethal dosages of super phosphate on digestive enzyme -Amylase Au/ g/ hr C 48.4 ± ± ± 2.4 SI 52.5 ± ± ± ± 2,4 S ii ± ^4.2 S ii JL il JL 2.9 * significant (P<0.1) 90

7 TABLE Effect of three different sub-lethal dosages of phenol on digestive enzyme; Lipase lu/ g/ hr C 5.07 ± ± ± ±0.3 PI 4.91± ± ± ± 0.1 P ± ± ±0.8 P ± ± ± ±0.61 * significant (P<0.1) TABLE - 6:6 Effect of three different sub-lethal dosages of super phosphate on digestive enzyme- Lipase Au/ g/ hr C 6.5 HL ± ± ±0.3 SI 6.72 ± ± ± ±0.2 S ± ± ± ±0.9 S ± ±0.8 ol significant (P<0.1) 91

8 DISCUSSION: Digestive physiology of vertebrates have a significant dependence on the activity of digestive enzymes. Amylase, protease and lipase are of principal enzymes importance. Seasons, feeding habit and growth rate are the factors that influence the enzyme activity of the gut (Das, et al, 1987; Annamichev, 1959; Fish, 1960, Ebanasar,1995). Increased enzyme activity is much related to better utilization of feed and growth rate. In the present study, the digestive enzyme activity is found to decrease with increase in concentrations of phenol and in contrary it increased with increasing concentrations of superphosphate. The present study coincides the results of the several reports to indicate the phenol induced alterations in enzymes and metabolites of various tissues in the fish models (Ito and Toshiro, 1980; Marinesco, et.al, 1980; Olowska, et.al, 1981; Verma, et.al, 1981 a 1982; Dalela e?.a/., 1983; Gupta et.al, 1984; Ravichandran and 1990 Bemice, 1985; Gupta and Dalela, 1986; Tiedge, et.al, 1986; Smith et.al,). Report reveals number of investigations on phenol induced effects in various fishes particularly devoted on the individual parameters like accumulatory patterns and the metabolism of phenolic compounds. Studies on the effect of phenols on the enzyme analysis are also available (Reddy et.al, 1993; Kristofferson et.al, 1974; Gupta and Dalela, 1984; Assem, et.al, 1989, Ravikumar and Nagaraj, 2003). Quality of diet has significant influence on activity of enzyme of alimentary canal (Kawai and Ikeda, 1971, Phadate and Srikar, 1988; Baskaran et al, 1990; Ebanasar and Jayaprakas, 2003). The present study also reveals that the digestive enzyme activity in dependant on the nature of diet it takes and progression of life cycle. Ebanasar (1995) reported that the quality of diet and especially the biochemical composition of diet influences the digestive enzyme activity. Shanmugapriya (2001) and Ebanasar, et al, (2003) reported the Calcium enhanced digestive enzyme activity of carps. Likewise, Kavitha 92

9 (2003) reported the enhanced enzyme activity due to calcium in Oreochromis mossambicus. The results of the present investigation reveals that superphosphate enhances the digestive enzyme activity of C. punctatus and on the otherhand phenol suppresses the digestive enzyme activity. This reveals that the phenol adversely influences the fish by suppressing the digestion of fish which in turn may reflect in all the lively activities of fish. Likewise,superphosphate enhances the enzyme activity which may have the growth promoting effect. Hence, manuring with superphosphate in fish culture ponds or paddy fields with C. punctatus indirectly benefited by enhancing enzyme activity. 93