Membrane Lipid Microenvironment Modulates Thermodynamic Properties of the Na+-K+-ATPase in Branchial and Intestinal Epithelia in Euryhaline Fish In vivo

The Phospholipid Molecular Species Profile of Apostichopus japonicus Tissues Modifies through Exposure to n-3 Polyunsaturated Fatty Acid-Deficient Diet

The sea cucumber Apostichopus japonicus, being a target species of commercial fisheries and aquaculture, is also used as a source of biologically active compounds with high pharmacological potential. By the methods of high-performance liquid chromatography with high resolution mass spectrometry, we analyzed the major structural phospholipids (PL)—glycerophosphoethanolamines (PE), glycerophosphocholines (PC), glycerophosphoserines (PS), and glycerophosphoinositols (PI)—in tissues of wild and cultured sea cucumbers. The intestines of the wild and cultured animals differed from the other tissues by an elevated content of molecular species of PE, PC, and PS with 22:6n-3 fatty acid. The respiratory trees of the studied animals contained a high level of odd-chain PI and PI with 20:4n-6. The exposure to n-3 PUFA-deficient diet resulted in substantial changes in the molecular species profile of PL of the wild and cultured animals. The cultured sea cucumbers showed a significant decrease in the 20:5n-3 content in all four studied PL classes. A replacement of 20:5n-3 by 20:4n-6 occurred in PE, PC, and PI. The decrease in the level of molecular species of PS with 20:5n-3 was compensated by an increase in the level of monounsaturated long-chain PS. The diet of cultured sea cucumbers is a crucial factor for enhancing the nutritional properties of the product obtained from them.

Diet, Immunity, and Microbiota Interactions: An Integrative Analysis of the Intestine Transcriptional Response and Microbiota Modulation in Gilthead Seabream (Sparus aurata) Fed an Essential Oils-Based Functional Diet

Essential oils (EOs) are promising alternatives to chemotherapeutics in animal production due to their immunostimulant, antimicrobial, and antioxidant properties, without associated environmental or hazardous side effects. In the present study, the modulation of the transcriptional immune response (microarray analysis) and microbiota [16S Ribosomal RNA (rRNA) sequencing] in the intestine of the euryhaline fish gilthead seabream (Sparus aurata) fed a dietary supplementation of garlic, carvacrol, and thymol EOs was evaluated. The transcriptomic functional analysis showed the regulation of genes related to processes of proteolysis and inflammatory modulation, immunity, transport and secretion, response to cyclic compounds, symbiosis, and RNA metabolism in fish fed the EOs-supplemented diet. Particularly, the activation of leukocytes, such as acidophilic granulocytes, was suggested to be the primary actors of the innate immune response promoted by the tested functional feed additive in the gut. Fish growth performance and gut microbiota alpha diversity indices were not affected, while dietary EOs promoted alterations in bacterial abundances in terms of phylum, class, and genus. Subtle, but significant alterations in microbiota composition, such as the decrease in Bacteroidia and Clostridia classes, were suggested to participate in the modulation of the intestine transcriptional immune profile observed in fish fed the EOs diet. Moreover, regarding microbiota functionality, increased bacterial sequences associated with glutathione and lipid metabolisms, among others, detected in fish fed the EOs supported the metabolic alterations suggested to potentially affect the observed immune-related transcriptional response. The overall results indicated that the tested dietary EOs may promote intestinal local immunity through the impact of the EOs on the host-microbial co-metabolism and consequent regulation of significant biological processes, evidencing the crosstalk between gut and microbiota in the inflammatory regulation upon administration of immunostimulant feed additives.