| T-2 toxin(T-2) is one kinds of secondary metabolites produced by fungi and is often found in cereal grains. T-2 can appear in the food chain because of fungal infection of crops, either by being consumed directly by humans or used as livestock feed. T-2 is a potential health hazard for both humans and animals for the metabolism of ingested T-2could result in T-2 accumulation in different organs or tissues, entering into the food chain through meat, milk, or eggs.This study tried to estimated the damage effect of T-2 toxin on shrimp’s growth index,digestive enzymes and histological. The results showed shrimps fed T-2 feed diet showed significantly lower growth performance, compared to the control. With the increase of concentration of T-2, the activity of protease, amylase in intestinal tract and the activity of lipase and aminopherase in hepatopancreas were decreased. In addition, the activity of protease, amylase and aminopherase in hepatopancreas and intestinal lipase in 0.5, 0.5 to4.8, 0.5 to 1.2, 0.5 to 4.8 mg·kg-1 were higher than the controls respectively, but in the high dose the enzyme activity is lower. On the strength of the dose-effect curve of T-2 and digestive enzyme,the NOAEL and EC50 of intestinal proteases are minimum, so intestinal proteases is most sensitive to T-2 and it could be used as a non-specific biomarker to shrimp exposed to T-2 toxin. On account of the histopathologic changes of hepatopancreas,intestinal and muscle, we found that T-2 has damage on shrimp’s histopathologic and histopathological effects were dose-dependent. In a word, feeding with T-2 caused body weight gain, digestive enzyme activities reducing and lesions in histopathology of shrimp.Different non-specific immunity in blood and hepatopancreas were observed, the results indicated that content of serum albumin, lysozyme activity and antibacterial activity have negatively correlated with the dose of T-2 in feed. Serum albumin content is significantly decreasing in the groups fed with various concentrations of T-2, and it could be used as a non-specific biomarker to shrimp exposed to T-2 toxin. The EC50 of albumin content induced by T-2 is 1.28 mg·kg-1, which caculated from the dose-effect curve of T-2concentraction and albumin content, but no NOAEL. Homesis appeared in the total protein content, cohesion, hemolysin activity and acid phosphatase of serum includedhepatopancreas acid phosphatase by fed various level of T-2(0.5 to 4.8, 1.2 to 2.4, 0.5, 0.5to 4.8, 0.5 to 1.2 mg·kg-1 respectively). Nevertheless, in high dose(12.2 mg·kg-1) all the indexes were inhibited. In hepatopancreas ATPase expressed disorder, energy metabolism and ion dysregulation induced by T-2 in feed. So, T-2 injured the immune system of shrimp and most measuring indexes were increased in low dose, inhibited in high dose.To evaluated the toxic effects of T-2 and its masked residues in shrimp on mice,various dose of T-2 infected shrimp which has no detectable level of free T-2 and then administered to adult KM mice, the weight gain rate, organ coefficients, blood routine,serum biochemical parameter and the genetic toxicity were observed. The results exhibited that low doses T-2 infected shrimp has no effect on mice. However, high dose T-2 infected shrimp caused decreasing of weigh gain rate and organ coefficients. Moreover, a significant increase in neutrophils and experimental mice symptoms such as mild anemia or bone marrow hematopoietic function was hindered. Serum biochemical parameter was significant different(p < 0.05) in high dose T-2 infected shrimp groups which also have significant(p < 0.05) genetic toxicity on mice. From what has been discussed above,although T-2 infected shrimp has no free T-2, it has some injury in mice and the results indirectly proved T-2 in feed could transformed into masked T-2 toxins(m T-2s) by shrimp after ingesting.In order to find the best methods to disintegrated the masked T-2 toxins, different tissues of infected by T-2 in feed for 20 d were treated with high pressure, different content and p H value HCl or Na OH, artificial intestinal juice and gastric juice, then using LC-MS/MS and MTT test to evaluate disintegrated effects. The results revealed artificial intestinal juice treatment is the optimal way to disintegrated m T-2s in shrimps MTT test.After hydrolysis by artificial intestinal juice, T-2 was detected in head, hepatopancreas and blood by LC-MS/MS which indirectly illustrated that m T-2s mainly residule in those organs. Moreover, it existed a positive correlation between the dose of T-2 and m T-2s concentration. Also in blood, highest content(5.23 ng·g-1) were qualified, which showed that hepatopancreas is mainly repository of m T-2s. The distribution of m T-2s in shrimp is:blood > head > muscle > hepatopancreas, and T-2 is no detected in hepatopancreas in all diets except 12.2 groups with 0.17 ng·g-1 after hydrolysis.When RAW 264.7 cells incubated with T-2 and m T-2s for 24 h, the m RNA expression of IL-6, IL-1β, TNF-α, the critical signal molecules in JAK/STAT including JAK1-3, STAT1-3, and SOCSs were decteded by q RT-PCR. It was showed that the toxicity of T-2 was higher than m T-2s and the toxicity was different with different m T-2s,the immune toxicity molecular markers in JAK/STAT of T-2 was IL-6, JAK3, STAT3 andof m T-2s was IL-6 and STAT2. |
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