Preliminary Studies Of Starvation Stress On The Physiological And Biochemical Impact Of Juveniles Of Trachinotus Ovatus

Trachinotus ovatus was starved for12days when the water temperature was(25±0.5)℃and the salinity was (20±1), the effects of starvation on the physiology,biochemistry and histology of juvenile was studied, including survival, digestiveenzyme activity, antioxidant capacity, Na~+/K~+-ATPase activity, biochemicalcomposition and histological structure of digestive system. Tissue samples of thedigestive system were fixed and the digestive enzyme activity were determined on the0,3rd,6th,9th, and12th day of starvation, respectively; The total antioxidant capacity(T-AOC), superoxide dismutase (SOD) activity and malondialdehyde (MDA) levelsof the control and experimental group were measured in the7th day of starvation; TheNa~+/K~+-ATPase activity and biochemical composition of T. ovatus were determined ofthe control and experimental group in the8th day of starvation. The results showed asfollows:1. Effects of starvation stress on survial and the digestive enzyme activity injuveniles of T.ovatusIn this study, Trachinotus ovatus was starved for12days when the watertemperature was (25±0.5)℃and the salinity was (20±1), and the activities of protease,amylase and lipase in its digestive organs and the ratio of viscera weight to bodyweight were measured on the0,3rd,6th,9th, and12th day of starvation, respectively.The results showed that starvation had definite effects on the activities of all testenzymes and the ratio of viscera weight to body weight. The ratio of viscera weight tobody weight and the amylase activity were found to decrease gradually as thestarvation periods increased; the ratio of viscera weight to body weight had the fastestdecline from the0to6th days after starvation(P﹤0.01), and did not decreasedsignificantly after6days(P﹥0.05). The amylase activity decreased throughout theexperiment, and got significantly lower3days after starvation(P﹤0.01). With theprolongation of starvation, the protease activity was found to increase gradually, and was higher than that of the control(P﹤0.01). In general, the lipase activity decreasedfrom the0day to9th day, and increased significantly on the12th day of thestarvation(P﹤0.01). Mortality was observed on the8th day of the starvation, and thesurvival rate was64.67%on the12th day after starvation, indicating that the thresholdtime of death by starvation laid on the8th day after starvation.2. Effects of starvation stress on the total antioxidative capacity, the activity ofsuperoxide dismutase and the contents of malondialdehyde in juveniles ofT.ovatusThe effects of starvation have been studied with respect to antioxidant defense inthe branchial filament, liver and muscle of Trachinotus ovatus when the watertemperature was (25±0.5)℃and the salinity was (20±1). In the control, the resultsshowed the difference of total antioxidative eapability(T-AOC), activities ofsuperoxide dismutase(SOD) or malondialdehyde(MDA) levels among differentorgans and tissues. Among them the total antioxidative eapability is liver> musele>branchial filament. SOD activities and MDA levels are branchial filament> musele>liver. The T-AOC increased in the branchial filament and muscle after starvation,whereas decreased in the liver, compared with the control group had extremelysignificant difference(P﹤0.01). The activities SOD increased in the all tissues,compared with the control group had extremely significant difference in the branchialfilament and muscle (P﹤0.01), and had no significant difference in the liver(P>0.05).Fish deprived of food for7days showed a significant increase in lipid peroxidation(P﹤0.01), measured as MDA levels in the branchial filament and liver, but in themuscle have no statistical significant differences(P>0.05).3. Effects of starvation stress on Na~+/K~+-ATPase activity and biochemicalcomposition in juveniles of T. ovatusThe effects of starvation have been studied with respect to Na~+/K~+-ATPaseactivity in the branchial filament、liver and muscle and biochemical composition ofJuvenile Trachinotus ovatus when the water temperature was (25±0.5)℃and thesalinity was (20±1). In the control, The results showed the difference ofNa~+/K~+-ATPase activity among different organs and tissues. The Na~+/K~+-ATPaseactivity was musele﹤liver﹤branchial filament, in descending order. Fish deprivedof food for8days showed a significant increase in Na~+/K~+-ATPase activity in thebranchial filament(P<0.01), but in the muscle had no statistical significantdifferences(P>0.05), and showed a significant decrease in the liver (P<0.01). In the same period, contents of moisture in the whole body of Juvenile T. ovatus increasedwhile crude fat and crude protein, as well as the energy values, decreased greatlyduring starvation. And the relative loss rate of crude fat was bigger than crude protein,which indicated that the juvenile T. ovatus utilized fat as energy source in hunger early,and with the extension of the starvation, the protein would be consumed．4. Effects of starvation stress on the histological structure of the digestive systemin juveniles of T. ovatusUsing paraffin section technique and hematoxylin-eosin staining, the histologicalstructure of the the digestive system and their characteristics of changes afterstarvation in juveniles of T. ovatus were studied. The histology results show that theeffects on the digestive system were different with starvation time. The histologicalstructure of esophagus have no significant changes on the3rd day after starvation, thedamage was lesser compared with other gastrointestinal site from the3to9th daysafter starvation, and on12th days after starvation, the epithelial cells were arranged inirregular, the cell boundaries were blurred,most epithelial falled off and fractured.The effects of starvation were similar about the histological structure of the stomach,pyloric caeca and intestinal tract. S3were as well as the control, but S6and S9weredifferent that the mucosal cells were arranged in loose, the gaps of the cells werebigger, and some epithelium falled off. And S12were obviously different that mostepithelial falled off and fractured. The influence of hunger is most serious in thehepatopancreas, and the histological structure of hepatopancreas have significantchanges on the3rd day after starvation; the size of acinar cell and hepatic cellshrinked gradually, arranged in irregular, and the cell boundaries were blurred as thestarvation periods increased. The diameter of digestive tract, the heights of thegastrointestinal wall and the rugae, the size of goblet cells decreased gradually as thestarvation periods increased, and the degree were different in different tissues.