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

Transcriptome Analysis Reveals the Molecular Mechanism Involved in Carotenoid Absorption and Metabolism in the Ridgetail White Prawn Exopalaemon carinicauda

Astaxanthin plays a vital role in pigmentation, immune function, reproduction, and antioxidation in aquatic species. To clarify the molecular mechanism of astaxanthin utilization in Exopalaemon carinicauda (E. carinicauda), we conducted a comparative transcriptome analysis on the intestine, hepatopancreas, and muscle of E. carinicauda, fed with an astaxanthin diet and a normal diet. A total of 144 differentially expressed genes (DEGs) were identified in three tissues between the two groups. Genes related to absorption and transport, such as LDLR and the vitellogenin receptor, were upregulated in the intestine after astaxanthin supplementation, while the ileal sodium/bile acid cotransporter-like gene was downregulated. In the hepatopancreas, genes involved in lipid storage and degradation were significantly altered at the transcriptional level, including Kruppel 1-like, ACSBG2, δ(7)-sterol 5(6)-desaturase-like, and PNLIPRP2. In the muscle, the expression of the FABP gene was significantly upregulated, while several actin and troponin genes were significantly downregulated. Furthermore, GSEA analysis on the transcriptomes of three tissues revealed that astaxanthin supplementation influenced the expression of genes related to antioxidation and growth, indicating that astaxanthin may have a positive impact on the growth, development, and resistance of organisms. The data from this research provide valuable insights into elucidating the molecular mechanisms underlying astaxanthin absorption and metabolism and also offer guidance for the application of astaxanthin in the aquaculture of economically important crustaceans.

Dietary Phaffia rhodozyma-Synthesized 3S, 3'S-Astaxanthin Promotes Body Coloration and Muscle Quality in Pacific White Shrimp Litopenaeus vannamei

The focus of people on the yield of aquatic products has gradually shifted to superior quality. Astaxanthin is well-known for its superior antioxidant capacity, while research on its regulatory effect on muscle quality is limited. This study aims to investigate whether dietary Phaffia rhodozyma-synthesized 3S, 3'S-astaxanthin (L-AST) could promote the body coloration and muscle quality of Litopenaeus vannamei. Experimental diets with L-AST levels of 0, 30, 60, and 90 mg/kg were fed to L. vannamei (IBW: 2.72 ± 0.03 g) for 8 weeks. The results revealed that the shrimp fed L-AST diets presented better body coloration with decreased L ∗ values whereas increased a∗ values and possessed higher levels of muscle astaxanthin. Dietary supplementation with 60 mg/kg L-AST significantly enhanced muscle texture (hardness, chewiness, resilience, and gumminess), which could be attributed to an increase in alkaline-insoluble collagen content and a decrease in myofiber diameter. Interestingly, dietary supplementation with 60 or 90 mg/kg L-AST markedly increased the content of glycine (a sweet amino acid) and total flavor amino acid (glutamic acid, aspartate, alanine, glycine). Further study showed that dietary supplementation with 60 or 90 mg/kg L-AST significantly improved free fatty acid profile by increasing contents of some monounsaturated fatty acids (C17:1n7, C18:1n9t and C24:1n9) and polyunsaturated fatty acids (C20:02 and C22:6n3). Taken together, dietary P. rhodozyma-synthesized L-AST considerably promoted muscle quality in L. vannamei by promoting histological and texture properties, elevating alkaline-insoluble collagen content while improving the profile of free amino acids and fatty acids.

Multi-Omics Integrative Analysis to Reveal the Impacts of Shewanella algae on the Development and Lifespan of Marine Nematode Litoditis marina

Understanding how habitat bacteria affect animal development, reproduction, and aging is essential for deciphering animal biology. Our recent study showed that Shewanella algae impaired Litoditis marina development and lifespan, compared with Escherichia coli OP50 feeding; however, the underlying mechanisms remain unclear. Here, multi-omics approaches, including the transcriptome of both L. marina and bacteria, as well as the comparative bacterial metabolome, were utilized to investigate how bacterial food affects animal fitness and physiology. We found that genes related to iron ion binding and oxidoreductase activity pathways, such as agmo-1, cdo-1, haao-1, and tdo-2, were significantly upregulated in L. marina grown on S. algae, while extracellular structural components-related genes were significantly downregulated. Next, we observed that bacterial genes belonging to amino acid metabolism and ubiquinol-8 biosynthesis were repressed, while virulence genes were significantly elevated in S. algae. Furthermore, metabolomic analysis revealed that several toxic metabolites, such as puromycin, were enriched in S. algae, while many nucleotides were significantly enriched in OP50. Moreover, we found that the "two-component system" was enriched in S. algae, whereas "purine metabolism" and "one-carbon pool by folate" were significantly enriched in E. coli OP50. Collectively, our data provide new insights to decipher how diet modulates animal fitness and biology.

Integrative Application of Transcriptomics and Metabolomics Provides Insights into Unsynchronized Growth in Sea Cucumber (Stichopus monotuberculatus)

Ever-increasing consumer demand for sea cucumbers mainly leads to huge damage to wild sea cucumber resources, including Stichopus monotuberculatus, which in turn exerts negative impacts on marine environments due to the lack of ecological functions performed by sea cucumbers. Aquaculture of sea cucumbers is an effective way to meet consumer demand and restore their resources. Unsynchronous growth is a prominent problem in the aquaculture of sea cucumbers which has concealed unelucidated molecular mechanisms until now. In this study, we carried out an integrative analysis of transcriptomics and metabolomics on fast-growing (SMF) and slow-growing (SMS) groups of S. monotuberculatus cultured in the same environmental conditions. The results revealed that a total of 2054 significantly differentially expressed genes (DEGs) were identified, which are mainly involved in fat digestion and absorption, histidine metabolism, arachidonic acid metabolism, and glutathione metabolism. 368 differential metabolites (DMs) were screened out between the SMF group and the SMS group; these metabolites are mainly involved in glycerophospholipid metabolism, purine metabolism, biosynthesis of unsaturated fatty acids, pyrimidine metabolism, arachidonic acid metabolism, and other metabolic pathways. The integrative analysis of transcriptomics and metabolomics of S. monotuberculatus suggested that the SMF group had a higher capacity for lipid metabolism and protein synthesis, and had a more frequent occurrence of apoptosis events, which are likely to be related to coping with environmental stresses. The results of this study provide potential values for the aquaculture of sea cucumbers which may promote their resource enhancement.

Antioxidant, Transcriptomic and Metabonomic Analysis of Hepatopancreatic Stress Resistance in Exopalaemon carinicauda Following Astaxanthin Feeding

Astaxanthin (Axn) is a xanthophyll carotenoid that has previously been shown to suppress hepatic inflammation, reduce oxidative liver damage, and improve metabolic profiles. 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. In this study, dietary Axn can significantly decreased MDA content, T-AOC and significantly increased SOD, GSH and CAT activities in shrimp hepatopancreas. Moreover, transcriptome and metabolome of E. carinicauda after Axn feeding were investigated to identify the mechanism of the effect of Axn on E. carinicauda. The transcriptomic data revealed that a total 99 different expression genes (DEGs) were identified between the Axn and control groups, of which 47 and 52 were upregulated and downregulated, respectively. DEGs of E. carinicauda such as catherpsin, actin and PARP after Axn feeding were associated with apoptosis and immune system. The metabolomic analysis revealed that A total of 73 different expression metabolites (DEMs) were identified in both metabolites, including 30 downregulated metabolites and 43 upregulated metabolites. And Axn participate in metabolism processes in hepatopancreas of E. carinicauda, including the TCA cycle, amino acid metabolism and lipid metabolism. The multiple comparative analysis implicated that Axn can improve the antioxidant capacity of hepatopancreas and the energy supply of hepatopancreas mitochondria, and then improve the ability of anti-apoptosis. Collectively, all these results will greatly provide new insights into the molecular mechanisms underlying tolerance of adverse environment in E. carinicauda.