PRR-Mediated Immune Response and Intestinal Flora Profile in Soybean Meal-Induced Enteritis of Pearl Gentian Groupers, Epinephelus fuscoguttatus♀ × Epinephelus lanceolatus♂

Abstract

Pattern recognition receptors (PRRs) can recognize microbial-specific pathogen-associated molecular patterns, initiate signal cascade transduction, activate the expressions of host immunity and proinflammatory genes, and, ultimately, trigger an immune response against identified pathogens. The present study focused on two outcomes of feeding pearl gentian groupers with high levels of soybean meal (SBM): (1) growth performance and (2) the intestinal environment, including tissue structure, flora profile, and immune responses. Some 720 groupers were randomly divided into three groups (n = 4): (1) controls, fed a 50% fish meal feed (FM), (2) with 20% of the FM substituted with SBM (SBM20), and (3) 40% of the FM substituted with SBM (SBM40). The fish were fed these iso-nitrogenous and iso-lipidic diets for 10 weeks. They were kept in containers with 1 m3 of water under natural light and temperature levels. The experimental results demonstrate that the SBM diets significantly degraded growth performance and intestinal physiology. Typical enteritis characteristics and immune fluctuations appeared, as reflected by the enzyme activities of total superoxide dismutase and lysozyme, and the contents of immunoglobulin M, complement 3, and complement 4. 16SrDNA high-throughput sequencing showed that the intestinal flora was significantly affected, with the abundance of harmful bacteria, such as Vibrio and Streptococcus, increasing with dietary SBM level. Based on “3 + 2” full-length transcriptome sequencing, three triggered PRRs were found in the intestine: the RIG-like receptor, NOD-like receptor, and Toll-like receptor signaling pathways. The intestinal flora variations were significantly correlated with the activation of the three PRR signaling pathways by canonical correlation analysis. These culminated in the transcriptome activation of NF-κB, IRFs, and costimulatory molecules, ultimately promoting the expressions of proinflammatory cytokines, interferons (IFNs), chemokines, and other molecules vital to the innate and/or adaptive immune responses. This study provides new information for diagnosing and preventing SBMIE in aquaculture fish.

Effects of Fishmeal Replacement by Clostridium Autoethanogenum Protein Meal on Cholesterol Bile Acid Metabolism, Antioxidant Capacity, Hepatic and Intestinal Health of Pearl Gentian Grouper (Epinephelus Fuscoguttatus ♀ × Epinephelus Lanceolatus ♂)

“…Pearl gentian grouper ( Epinephelus fuscoguttatus ♀ × Epinephelus lanceolatus ♂), with the heterosis of fast growth and strong disease resistance, is farmed in large quantities in China [ 1 ]. It is a predatory fish which requires about 45% fishmeal in the diet [ 2 ].…”

Effects of indole-3-butyric acid supplementation in diets containing high soybean meal on growth, intestinal inflammation, and intestinal flora of pearl gentian grouper (Epinephelus fuscoguttatus ♀ × Epinephelus lanceolatu♂)

“…However, some studies found that feeding soybean meal replacing sh meal to certain sh species can result in a signi cant reduction in growth performance. Replacing 40% of the sh meal in the diet with soybean meal reduces the growth performance of juvenile pearl gentian grouper (Zhang et al 2022b). Studies on Oncorhynchus mykiss, Epinephelus lanceolatus, Lates calcarifer, Lateolabrax japonicus, and Tinca tinca similarly found that the optimal percentage of soybean to replace sh meal in diets suitable for sh growth was less than 40% (Tantikitti et ANFs, including trypsin inhibitor, phytic acid, soybean lectins, and soybean saponin.…”

Tryptophan metabolism and gut flora profile in different soybean protein induced enteritis of pearl gentian groupers

“…The experimental feeds were offered from 8:00 a.m. to 4:00 p.m. every day for 10 weeks, with four replicates. The uneaten feeds were siphoned to calculate the weight of the intake feeds, and the feed consumption ratio was determined ( 27 ). The feeding experiment was conducted within inner cultural systems belonging to the Marine Biological Research Base of Zhanjiang City (Guangdong, China).…”