Antioxidant, Transcriptome and the Metabolome Response to Dietary Astaxanthin in Exopalaemon carinicauda

Abstract

Astaxanthin (Axn), a feed additive, is becoming increasingly important for modulating the metabolism, growth, development, and reproduction of aquatic organisms in aquaculture. In this study, Exopalaemon carinicauda (E. carinicauda) is an economically important fishery species in China that has been found to exhibit increased body weight following Axn feeding as compared to a standard diet. The antioxidant, transcriptomic, and metabolomic analyses of the response of E. carinicauda after Axn feeding were investigated. Axn could reduce the content of malondialdehyde and increase the activities of various antioxidant enzymes, which also proved that axn can improve the antioxidant capacity Transcriptomic analysis suggested that synthesis and secretion of immune proteins, cytoskeleton structure, and apoptosis signaling were altered after Axn feeding. The metabolic response to axn mainly includes the up regulation of different amino acids and the change of unsaturated fatty acids. Combined transcriptomic and metabolomic data indicated that amino acid metabolic pathways were upregulated in the muscles after Axn feeding. For good measure, energy metabolism pathways were upregulated in the muscles to improve ATP and unsaturated fatty acid production. This study provides key information to increase our understanding of the effects of Axn in shrimp.

Keywords: Exopalaemon carinicauda; antioxidant; astaxanthin; metabolome; transcriptome.

FIGURE 1

Malondialdehyde (MDA) and antioxidant enzyme activity. (A) MDA (B) T-AOC (C) SOD (D) GSH, and (E) CAT. Data are expressed as means ± SD (n = 3). *<0.05, ^**<0.01 compared to the control group.

FIGURE 2

(A) Differential expression of Exopalaemon carinicauda following Axn feeding. Significantly upregulated and downregulated genes are, respectively, shown in blue and gray. (B) The most enriched Gene Ontology (GO) term analysis and function classifications of the transcriptomic responses for Exopalaemon carinicauda after feeding Axn. (C) Kyoto Encyclopedia of Genes and Genomes pathway analysis of the transcriptomic responses for E. carinicauda after feeding Axn.

FIGURE 3

Quality analysis of metabolomic data. (A) OPLS-DA (orthogonal partial least-squares-discriminant analysis) score diagram for the positive ion mode. (B) OPLS-DA score diagram for the negative ion mode. (C) OPLS-DA permutation test for the positive ion mode. (D) OPLS-DA permutation test for the negative ion mode.

FIGURE 4

Kyoto Encyclopedia of Genes and Genomes pathways analysis of differentially expressed metabolites in response to Axn. The ordinate represents the top 20 KEGG terms significantly enriched by the DEMs, the abscissa indicates the rich factor between two sampling datasets.

FIGURE 5

(A) Kyoto Encyclopedia of Genes and Genomes pathways analysis of association analysis between transcriptome and metabolome in the positive ion mode. (B) Kyoto Encyclopedia of Genes and Genomes pathways analysis of association analysis between transcriptome and metabolome in the negative ion mode. (C) Correlation map of genes and metabolites regulated by Axn feeding in the muscle of Exopalaemon carinicauda. The altered genes and metabolites are shown by marking the names in red (upregulated) or green (downregulated).

FIGURE 6

Comparison of gene expression data between RNA sequencing (RNA-Seq) and quantitative real-time reverse transcription PCR (qRT-PCR). Data are presented as mean ± standard deviation (SD) of three replicates.