| Channel catfish,Ictalurus punctatus,is the leading aquatic economic species in China,Southeast Asia and North America,but the healthy development of its aquaculture industry has been hindered due to the rise in the price of feed raw materials.Therefore,the search for low-priced and high-quality soybean raw materials is of great significance to the development of the channel catfish farming industry.As the world’s most widely grown crops and high-quality plant protein,transgenic soybean had been allowed to be processed and utilized for commercial purposes in many countries and regions,but their safety has also received widespread attention,so it is extremely important to study the safety of aquatic animals feed by using genetically modified soybeans.In this trial,transgenic soybean 10048(double-resistant herbicide-tolerant soybean,inserted cp4-epsps and pat genes),10702(insect-resistant herbicide-tolerant soybean,vip3 Aa and pat genes inserted),three conventional soybean varieties(Dongsheng 3,Dongsheng 7 and Dongsheng 9)and their non-transgenic counterpart parent control group JACK were used as the main protein source(soybean flour mass content of 45% pellet feed),and were fed to juvenile channel catfish for eight weeks indoor.By comparing the survival rate,growth performance,antioxidant enzyme activity,expression of relative m RNA levels of genes and the effect of intestinal microflora to evaluate the safety of transgenic soybean fed to the channel catfish,and the study provided theoretical abasis and reference value for the application of transgenic soybean feed in aquaculture.The experimental results are showed as follows:Firstly,the feeding of transgenic soybean feed had no significant effect on the survival rate,weight gain rate,feed conversion ratio,feeding rate,specific growth rate and body index of each group of channel catfish(P > 0.05).After 8 weeks,the survival rate of channel catfish was maintained at 83.33% to 87.50%,and there were no significant differences between the weight gain rate,specific growth rate,feed conversion,feeding rate and feed conversion ratio and the control(P > 0.05).The results of the body index showed that the hepatosomatic index,the viscerosomatic index and the condition factor were not affected by different feed types,although the VSI of the transgenic soybean 10048 group was 12.35%,and higher than that of the control group(11.11%),but the value was in the range of10.90% to 12.50% of the VSI value of the six groups,indicating that the VSI value remained in the normal ranges.Secondly,the results of antioxidant enzyme activity(LDH,T-AOC,GOT and GPT)determination of head kidney,liver and spleen tissues showed that there was no significant difference in the activity of transgenic soybean and control(P > 0.05),and the LDH activity level in head kidney,liver and spleen tissues was consistent;There was no significant difference between the transgenic soybean group and control(P >0.05),the T-AOC activity level in liver and spleen was consistent and higher than that in the head kidney,but there was no significant difference between the transgenic soybean and control(P > 0.05).And the GOT activity in the head kidney and liver was consistent,it was both higher than the GOT level in the spleen,and there was no significant difference between the transgenic soybean and control.The GPT activity in the liver tissue was higher than that in the head kidney and spleen,but there was no significant difference between the groups(P > 0.05).The expression of spleen immune factors(TNFα,MHC-II,IL1β and IL8)was detected and the results showed that the expression of TNFα was not affected by transgenic soybean fed,and there was no significant difference between the groups(P > 0.05);The expression of IL1βwas consistent between the each group,and no significant difference was observed(P> 0.05);the expression of MHC-II and IL8 was the highest in the transgenic soybean group 10702,but there was no difference between the transgenic soybean group and the control(P > 0.05)Thirdly,the results of intestinal 16 S r RNA gene sequencing showed that there were 201,215 and 730 OTU in the control group,transgenic soybean10048 and10702 group,respectively.The dominant intestinal flora at the phylum level was Fusobacterium,and the dominant flora cetebacterium at the genus level was not significantly different from that of the control group(P>0.05).The results of this experiment show that insect-resistant and herbicide-resistant transgenic soybean 10048 and 10702 have no significant negative effects on the survival rate,growth performance,antioxidant capacity,expression of genes and composition of intestinal flora,and have certain biosafety.This study provides an experimental basis for the safe use of transgenic soybeans 10048 and 10702 in aquatic organisms. |
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