Transcriptomic responses to yam ( Dioscorea oppositifolia L .) extract dietary supplementation in rainbow trout ( Oncorhynchus mykiss ) liver

Abstract

Infectious diseases in rainbow trout (Oncorhynchus mykiss) have been seen in rainbow trout farming industry. Yam (Dioscorea oppositifolia L.) has a functional impact upon anti‐disease and strengthens immunity. Understanding the molecular mechanisms which occur in rainbow trout in response to yam will be useful to decrease disease‐related morbidity and mortality. In the present study, we conducted transcriptome analysis of liver in rainbow trout fed diets including yam extract (0, 0.2% and 0.4%), to identify yam extract‐induced genes and pathways. Over 451 million clean reads were obtained from nine liver libraries. Two comparisons were separately implemented between yam extract groups and control group. Using |log2Fold‐change|>1 and p‐value < .05 as the threshold, a total of 2,693 differentially expressed unigenes (DEGs) were identified, including 1599 up‐regulated and 1,094 down‐regulated unigenes. The RNA‐Seq results were verified by RT‐qPCR. DEGs were classified into three categories by GO annotation and functional enrichment analysis: biological process (23 subclasses), cellular component (16 subclasses) and molecular function (16 subclasses). KEGG annotation and classifications of DEGs indicated endocrine system, immune system, lipid metabolism, carbohydrate metabolism and signal transduction pathways include a large number of DEGs. In addition, 526 overlap DEGs in two comparisons were annotated to 174 pathways in KEGG analysis, 7 top significantly enriched pathway terms include chemokine signalling pathway, platelet activation, progesterone‐mediated oocyte maturation, insulin signalling pathway, FoxO signalling pathway, cGMP‐PKG signalling pathway and sphingolipid signalling pathway. These findings provide valuable information for further analysis of the disease resistance mechanisms of rainbow trout fed yam.

Effects of Chinese yam ( Dioscorea oppositifolia L .) dietary supplementation on intestinal microflora, digestive enzyme activity and immunity in rainbow trout ( Oncorhynchus mykiss )

“…Yam has been used as therapeutic agent for a long time in China. In fact, it is currently known that dietary yam supplementation can enhance gastrointestinal function and regulate the non‐specific immune response (Chen et al., 2015; Jeon et al., 2006; Meng et al., 2019; Shin et al., 2006; Thankappan & Morawala‐Patell, 2011; Wang et al., 2020). However, no study is available on the effect of dietary yam supplementation on digestion and non‐specific immunity of cold water fish.…”

“…According to the research results of yam extract as feed additive in related animals (Jeon et al., 2006), the powder was added to the basal diet (control) at the rate of 0.1%, 0.2% and 0.4% (w/w) to produce three different diets. The formula of basic feed is the same as our previous report (Wang et al., 2020) and also shown in Table . Feed pellet making process was as follows: all the ingredients are crushed into fine powder, then evenly stirred into dough with cold water, and then granulated into 2‐mm diameter and 5‐mm length pellets, finally air‐dried and stored in the refrigerator.…”

“…It contains many ingredients, such as steroidal saponins including dioscin, gracillin, furostanol, starch, mucopolysaccharides, dioscorin as a storage protein, amino acids and phenanthrene derivatives (Jeon et al., 2006; Wu, Zhu, Zheng, & Sheng, 2011). The results of pharmacological studies showed that yam has certain beneficial effects on certain vertebrates, such as promoting digestion, immunomodulation, antioxidant defence and anti‐inflammation (Meng et al., 2019; Qiao, Zhang, & Li, 2010; Shin et al., 2006; Wang, Liu, Wang, Chen, & Meng, 2020; Zhang et al., 2020). However, few studies on the effect of yam on aquatic animals were reported.…”

“…Also, Wang et al. (2020) have reported that transcriptome analysis of the liver of rainbow trout ( Oncorhynchus mykiss ) fed Chinese yam.…”

Long-term regulation of fat sensing in rainbow trout (Oncorhynchus mykiss) fed a vegetable diet from the first feeding: focus on free fatty acid receptors and their signalling

“…The binding of free FA on free FA receptors could activate the receptors, resulting in an increase in intracellular Ca concentrations. One of the first actors in this Ca-signalling pathway is plcb , which plays a role in G protein-coupled receptor-mediated signal transduction in RT (48) and in the feeding response. The regulation of the three plcb isoforms followed the same trend: they were upregulated 4 h after the meal compared with 20 min in RT fed the C diet.…”