Effects Of Phenol On Digestive Function Of Moina Macrocopa

Phenol is one of the important organic materials. Penol and its derivatives are widely used in industries and they cause serious environment pollution. To understand the toxicity of phenol in digestive system, water flea Moina macrocopa was used to study the impact of penol on digestive enzyme activity, intestinal microvilli, fat metabolism and amino acid composition under the stress of phenol.Moina macrocopa was treated with different concentrations of phenol (0.25,0.75,1.25,1.75 and 2.25mg/L, respectively) for different time (24 and 48 hours respectively). Using spectrophotometric method, level of free fatty acids (FFA), content of triglyceride (TG), activity of lipoprotein lipase (LPL), composition of amino acid and the antivity of digestive enzymes related to fat metabolism including amylase, lipase, trypsin and protease were assayed. Using histological methods, microstructure and submicroscopic structure of intestinal tract of M. macrocopa were observed.The results demonstrated that:(1) Moina macrocopa was 0.83～1.20mm in length with the shape of wide egg. Whole body was transparent. There were 90.92g water,6.38g crude protein,1.11g crude fat and 0.67g ash respectively in 100g wet samples.17 amino acids occupied 54.44%of total protein.(2) In control group striated border of intestinal epithelial were smooth, columnar epithelial cells were tightly packed, which had a round nucleus. Cell boundaries are distinct. In low concentration (0.25mg/L) of phenol, striated border of intestinal epithelial became little rough. As the concentration of phenol treatment increased, striated border of intestinal epithelial became rough, and the emergence of the phenomenon of cell separation, cells loosely arranged cells gradually blurred boundaries, cell shape is not regular. Under transmission electron microscopy, microvilli of control intestinal epithelial cell exhibit finger-like protrusions, arranged in orderly parallel, and single hexagonal microvilli were almost of even thickness, while the microvilli of small were closely packed. At low phenol concentration (0.25mg/L), microvilli of intestinal were slightly irregularly arranged. At phenol concentration (1.25mg/L) some microvilli were lost, rupted and sparsely arranged. At high phenol concentration of 2.25mg/L treated, microvilli exhibited a messy arrangement, reduced in the number, the gap increased, the thickness varies irregularly shaped.(3) With the increase in phenol concentration and the treatment time, the activity changes in the four digestive enzymes in M. macrocopa were different. Lipase level increased significantly when M. macrocopa treated with 0.25mg/L and 0.75mg/L (P<0.05) for 24 hours; trypsin level changed significantly both for 24 and 48 hours with the significant increasing in 0.75 mg/L phenol for 48 hours (P<0.05); protease level showed to increase and then decrease when increase of the con centration of phenol; protease level was found to increase highly significantly when M. macrocopa treated with 0.75mg/L phenol for 48 hours (P<0.01). No significant change in activity was observed for amylase.(4) Increasing phenol concentration significantly decreased the level of free fatty acids and triglyceride (P<0.05). Lipoprotein lipase activity was shown to increase and then decrease significantly when M. macrocopa was treated with 0.75 mg/L phenol for 24 hours or 1.25 mg/L phenol for 48 hours (P<0.05). In addition, no significant difference was found in amino acid content when M. macrocopa was treated with different concentration of phenol (0.25,1.25 and 2.25mg/L).Conclusions:(1) Moina macrocopa rich in protein content was an excellent bait for fish.(2) Midgut is an important site for digestion and absorption in M. macrocopa. Phenol exposure can cause microvilli of intestinal tract irreversible damage and affect the digestive function and growth of M. macrocopa.(3) Assimilation was inhibited in M. macrocopa under the stress of phenol. M. macrocopa need to enhance digestion of the mgested food to maintain the energy needed for normal metabolism. Digestive enzyme activity can be used as a potential biochemical index to reflect M. macrocopa in phenol environment.(4) Fat metabolism disorder affects energy metabolism and inhibits growth and reproduction of M. macrocopa. In the long run, it will affect growth of M. macrocopa population.