| To explore the effect of different diet on liver health of common carp(Cyprinus carpio),the common carp(492.6 ± 30g)was used as the research object in this experiment,270 experimental fish were randomly divided into three groups:earthworm group(A),mixed group(earthworm:duckweed=1:1,B)and duckweed group(C).Three repeats per group,and the formal experiment was conducted for 8 weeks.The results are as follows:1.Liver histological study of common carp feeding on different dietIn the mixed diet group,the liver tissue was relatively intact,spotty necrosis and vacuole degeneration was found in parts of liver cells of one experimental fish,but no observed fatty degeneration.Compared with the mixed diet group,the liver tissue in the earthworm group and duckweed group was incomplete.In earthworm group,vacuolar degeneration was found in all five fish,fatty degeneration was found in two fish and spotty necrosis was found in two fish.In duckweed group,vacuolar degeneration was found in 4 fish,spotty necrosis was observed in a few hepatocytes in 2 experimental fish,but no obvious fatty degeneration was observed.2.Liver enzymatic activities analysis of common carp feeding on different dietThe activities of trypsinase and lipase in liver of group B was significantly lower than those of group A(P<0.05),while the activities of α--amylase in group B was significantly higher than those of group A(P<0.05).The activities of superoxide dismutase(SOD)and glutathione transferase(GSH-Px)in group B were significantly higher than group A and C(P<0.05),and malondialdehyde(MDA)content in group B was significantly lower than that in group A(P<0.05).The activities of acid phosphatase(ACP)and alkaline phosphatase(AKP)in group B were significantly higher than those in group A and C(P<0.05).3.Liver differential expression analysis of mRNAs of common carp feeding on different dietThree experimental fish were randomly selected from each group for RNA-seq,with an average of 41,645,543 original sequences,261,934 new transcripts,123,729 variable splices,168,347 single nucleotide polymorphism(SNP)sites and 10,780 insertion or deletion(INDELs)sites obtained.By differential analysis,916 differentially expressed genes were identified in group A and group B,of which 18 were up-regulated and 898 were down-regulated.A total of 1296 differentially expressed genes were identified in group C and B,of which 49 were up-regulated and 1247 were down-regulated.There were 608 co-differentially expressed genes between group A and B and group C and B.By GO and KEGG Patway analysis,the differentially expressed genes between group A and group B were mainly enriched in 8 functional items.The differentially expressed genes between group C and group B were mainly enriched in 15 functional items.The "protein digestion and absorption","bile secretion","hematopoietic cell lineage","intestinal immune network producing IgA" and "cell adhesion molecule" pathways were significantly enriched both in groups A and B and C and B.4.Liver differential expression analysis of microRNAs of common carp feeding on different dietThree experimental fish were randomly selected from each group for miRNAseq,and subsequent analysis was performed after the removal of three samples whose sequence length was not dominated by 22nt.Using high-throughput sequencing technology,236 known microRNAs of common carp were identified in 6 microRNAs libraries.By differential analysis,nine differentially expressed microRNAs were identified in group A and group B,and 189 target genes were predicted.Eight differentially expressed microRNAs were identified in group C and group B,and 234 target genes were predicted.GO and Patway annotations of target genes showed that microRNAs were mainly involved in metabolic and apoptotic processes.The results showed that the mixed diet was more beneficial to the liver health of the common carp than the single type of diet. |
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