Denghua Yin

Bio: Denghua Yin is an academic researcher from Shanghai Ocean University. The author has contributed to research in topics: Coilia nasus & Biology. The author has an hindex of 3, co-authored 8 publications receiving 25 citations.

The intestinal microbiota of lake anchovy varies according to sex, body size, and local habitat in Taihu Lake, China.

Abstract: Lake anchovy (Coilia ectenes taihuensis) is a sedentary, dominant fish species that forms an unmanaged fishery in Taihu Lake, eastern China. The environment and developmental stage of lake anchovy are likely important drivers of their gut microbiome, which is linked to host health and development. To investigate the relationship between the gut microbiome and three defined factors (fish sex, fish body size, and the local habitat), high-throughput sequencing of the 16S ribosomal RNA gene was used to study the microorganisms of 184 fish samples and four water samples collected in Taihu Lake. Four dominant bacterial phyla (Proteobacteria, Firmicutes, Planctomycetes, and Cyanobacteria) were present in all fish samples. We compared the microbial communities of males and females and found that the relative abundance of Corynebacteriaceae was significantly higher in males than in females, while the opposite trend was detected for Sphingomonadaceae. We also discovered that the relative abundance of Firmicutes was positively correlated with fish body size and that the proportions of Proteobacteria and Tenericutes were lower in larger fish than in fish of other sizes. Finally, we found that the difference in microbial richness between eastern and northern Taihu Lake was the most marked. Lake anchovy was rich in Lactobacillus and Clostridium in the eastern site, while those in the northern site had the highest abundance of Sphingomonas and Methylobacterium, suggesting that the local habitat may also influence the intestinal microbiome. These findings will not only help researchers understand the community composition of the intestinal microflora of lake anchovy but also contribute to the protection of fish resources in Lake Taihu and the sustainable use of lake anchovy.

Digestive enzyme activity of the Japanese grenadier anchovy Coilia nasus during spawning migration: influence of the migration distance and the water temperature.

Abstract: In this study, we investigated the activity levels of two major digestive enzymes (pepsin and lipase) in the commercially important Japanese grenadier anchovy Coilia nasus during its upstream migration to analyse the digestive physiological responses to starvation and to analyse the influence of the water temperature on enzyme activity. Water temperature had a significant effect on pepsin activity, while long-term starvation resulted in a significant decrease in pepsin activity. As starvation continued, however, a slight increase in pepsin activity between the Wuhu (440 river km) and Anqing (620 river km) regions may indicate that C. nasus had refeeding behaviour due to its large expenditure of energy reserves. In contrast, lipase activity was not significantly affected by the water temperature but the effect of fasting increased as much as 13% of lipase activity from the Chongming region (20 river km) to Anqing region, suggesting that the stored lipids of grenadier anchovy were mobilised to meet energy requirements of upstream migration activity and gonad development. Lipid mobilisation activated lipoprotein lipase (LPL; proteins with lipase activity) to hydrolyse triacylglycerides (TAG), which is the first step of lipid assimilation and obtained energy from fatty acids under fasting conditions. Therefore, the increased lipase activity is attributed mainly to the lipase that is involved in endogenous lipid hydrolysis. Grenadier anchovy appears to adapt to long-term starvation during migration and the increased lipase activity may indicate a crucial effect on lipid metabolism. This study demonstrated that distinct alterations occur in pepsin and lipase activities during the spawning migration of grenadier anchovy due to exogenous nutrition and endogenous metabolism. Furthermore, it provides a basis for further research on the digestive physiology and energy metabolism in this species.

Insights into response to food intake in anadromous Coilia nasus through stomach transcriptome analysis

Abstract: Coilia nasus is a valuable commercial migratory fish species with ecological and economic importance in China. To explore the molecular mechanisms underlying the response to food intake, the stomach transcriptomes of feeding and non‐feeding C. nasus were analysed via RNA‐seq. A total of 610,640,864 clean reads were obtained, and annotation to six databases identified 63,567 unigenes. Comparative analysis of the gene expression in feeding and non‐feeding C. nasus identified 1,968 differentially expressed genes (p < .05), including 1,180 up‐regulated and 788 down‐regulated genes. Our results showed that stomach distention activated the vagal afferent neurons, resulting in satiation. Several of the most relevant appetite genes (e.g. leptin receptor [LepR], somatostatin [SS], nucleobindin‐2 [NUCB2], 5‐hydroxytryptamine receptor [5‐HTR], growth hormone receptor [GHR]) were also involved in the regulation of food intake and led to the termination of feeding. Furthermore, significant differences were observed in the genes encoding key enzymes involved in metabolism such as the tricarboxylic acid cycle (TCA) pathways, fatty acid synthesis and glycolysis, indicating that C. nasus utilizes food for its energy and nutrient contents to support life and gonadal development. These findings provide valuable insights into the mechanisms underlying appetite and metabolic regulation in anadromous fish and create a foundation for further research on C. nasus artificial breeding and migration energetics.

Effects of temperature on feeding and digestive processes in fish.

Abstract: As most fish are ectotherms, their physiology is strongly affected by temperature. Temperature affects their metabolic rate and thus their energy balance and behavior, including locomotor and feeding behavior. Temperature influences the ability/desire of the fish to obtain food, and how they process food through digestion, absorb nutrients within the gastrointestinal tract, and store excess energy. As fish display a large variability in habitats, feeding habits, and anatomical and physiological features, the effects of temperature are complex and species-specific. The effects of temperature depend on the timing, intensity, and duration of exposure as well as the speed at which temperature changes occur. Whereas acute short-term variations of temperature might have drastic, often detrimental, effects on fish physiology, long-term gradual variations might lead to acclimation, e.g. variations in metabolic and digestive enzyme profiles. The goal of this review is to summarize our current knowledge on the effects of temperature on energy homeostasis, with specific focus on metabolism, feeding, digestion, and how fish are often able to "adapt" to changing environments through phenotypic and physiological changes.

Disruption of gut integrity and permeability contributes to enteritis in a fish-parasite model: a story told from serum metabolomics.

Abstract: In the animal production sector, enteritis is responsible for serious economic losses, and intestinal parasitism is a major stress factor leading to malnutrition and lowered performance and animal production efficiency. The effect of enteric parasites on the gut function of teleost fish, which represent the most ancient bony vertebrates, is far from being understood. The intestinal myxozoan parasite Enteromyxum leei dwells between gut epithelial cells and causes severe enteritis in gilthead sea bream (Sparus aurata), anorexia, cachexia, growth impairment, reduced marketability and increased mortality. This study aimed to outline the gut failure in this fish-parasite model using a multifaceted approach and to find and validate non-lethal serum markers of gut barrier dysfunction. Intestinal integrity was studied in parasitized and non-parasitized fish by immunohistochemistry with specific markers for cellular adhesion (E-cadherin) and tight junctions (Tjp1 and Cldn3) and by functional studies of permeability (oral administration of FITC-dextran) and electrophysiology (Ussing chambers). Serum samples from parasitized and non-parasitized fish were analyzed using non-targeted metabolomics and some significantly altered metabolites were selected to be validated using commercial kits. The immunodetection of Tjp1 and Cldn3 was significantly lower in the intestine of parasitized fish, while no strong differences were found in E-cadherin. Parasitized fish showed a significant increase in paracellular uptake measured by FITC-dextran detection in serum. Electrophysiology showed a decrease in transepithelial resistance in infected animals, which showed a diarrheic profile. Serum metabolomics revealed 3702 ions, from which the differential expression of 20 identified compounds significantly separated control from infected groups in multivariate analyses. Of these compounds, serum inosine (decreased) and creatine (increased) were identified as relevant and validated with commercial kits. The results demonstrate the disruption of tight junctions and the loss of gut barrier function, a metabolomic profile of absorption dysfunction and anorexia, which further outline the pathophysiological effects of E. leei.

Symbiotic Bacterial Metabolites Regulate Gastrointestinal Barrier Function via the Xenobiotic Sensor PXR and Toll-like Receptor 4

Abstract: Intestinal microbial metabolites are conjectured to affect mucosal integrity through an incompletely characterized mechanism. Here we showed that microbial-specific indoles regulated intestinal barrier function through the xenobiotic sensor, pregnane X receptor (PXR). Indole 3-propionic acid (IPA), in the context of indole, is a ligand for PXR in vivo, and IPA downregulated enterocyte TNF-α while it upregulated junctional protein-coding mRNAs. PXR-deficient (Nr1i2(-/-)) mice showed a distinctly \"leaky\" gut physiology coupled with upregulation of the Toll-like receptor (TLR) signaling pathway. These defects in the epithelial barrier were corrected in Nr1i2(-/-)Tlr4(-/-) mice. Our results demonstrate that a direct chemical communication between the intestinal symbionts and PXR regulates mucosal integrity through a pathway that involves luminal sensing and signaling by TLR4.

Energy Acquisition and Allocation to Egg Production in Relation to Fish Reproductive Strategies

Abstract: Oogenesis in fishes follows a universal plan; yet, due to differences in the synchrony and rate of egg development, spawning frequency varies from daily to once in a lifetime. Some species spawn and feed in separate areas, during different seasons, by storing energy and drawing on it later for reproduction (i.e. capital breeding). Other species spawn using energy acquired locally, throughout a prolonged spawning season, allocating energy directly to reproduction (i.e. income breeding). Capital breeders tend to ovulate all at once and are more likely to be distributed at boreal latitudes. Income breeding allows small fish to overcome allometric constraints on egg production. Income breeders can recover more quickly when good-feeding conditions are re-established, which is a benefit to adults regarding bet-hedging spawning strategies. Many species exhibit mixed capital- and income-breeding patterns. An individual's position along this capital–income continuum may shift with ontogeny or in relation to environmental conditions, so breeding patterns are a conditional reproductive strategy. Poor-feeding environments can lead to delayed maturation, skipped spawning, fewer spawning events per season or fewer eggs produced per event. In a few cases, variations in feeding environments appear to affect recruitment variability. These flexible processes of energy acquisition and allocation allow females to prioritize their own condition over their propagules' condition at any given spawning opportunity, thereby investing energy cautiously to maximize lifetime reproductive value. These findings have implications for temporal and spatial sampling designs, for measurement and interpretation of fecundity, and for interpreting fishery and ecosystem assessments.