Transcriptome Profiling and Molecular Pathway Analysis of Genes in Association with Salinity Adaptation in Nile Tilapia Oreochromis niloticus

Abstract

Nile tilapia Oreochromis niloticus is a freshwater fish but can tolerate a wide range of salinities. The mechanism of salinity adaptation at the molecular level was studied using RNA-Seq to explore the molecular pathways in fish exposed to 0, 8, or 16 (practical salinity unit, psu). Based on the change of gene expressions, the differential genes unions from freshwater to saline water were classified into three categories. In the constant change category (1), steroid biosynthesis, steroid hormone biosynthesis, fat digestion and absorption, complement and coagulation cascades were significantly affected by salinity indicating the pivotal roles of sterol-related pathways in response to salinity stress. In the change-then-stable category (2), ribosomes, oxidative phosphorylation, signaling pathways for peroxisome proliferator activated receptors, and fat digestion and absorption changed significantly with increasing salinity, showing sensitivity to salinity variation in the environment and a responding threshold to salinity change. In the stable-then-change category (3), protein export, protein processing in endoplasmic reticulum, tight junction, thyroid hormone synthesis, antigen processing and presentation, glycolysis/gluconeogenesis and glycosaminoglycan biosynthesis—keratan sulfate were the significantly changed pathways, suggesting that these pathways were less sensitive to salinity variation. This study reveals fundamental mechanism of the molecular response to salinity adaptation in O. niloticus, and provides a general guidance to understand saline acclimation in O. niloticus.

Comparative transcriptome analysis reveals molecular strategies of oriental river prawn Macrobrachium nipponense in response to acute and chronic nitrite stress

“…Little research revealed the function of extracellular matrix-receptor interaction under stressed conditions. Transcriptome analysis of tilapia Oreochromis niloticus reported that extracellular matrix-receptor interactions were down-regulated under salinity stress [67], which is consistent with this study, inferring the common functions of extracellular matrix-receptor interaction under the stress on M. nipponense. Besides, glycosphingolipid biosynthesis -lacto and neolacto series and glycosphingolipid biosynthesis -ganglio series which commit to cell adhesion/recognition and signal transduction [68] were depressed by environmental acute nitrite stress.…”

Significant association of SNP polymorphism in the tilapiaenhancer of polycomb homolog 1gene with salt tolerance

“…In tilapia, some osmoregulation associated genes have been identified, such as transferrin gene, β ‐Hemoglobin , Ca2+transporting plasma membrane ATPase , pro‐opiomelanocortin, beta‐actin (Rengmark & Lingaas, ), prolactin (Streelman & Kocher, ). The transcriptome profiles under different salinity challenges detected many osmoregulation related genes (Avarre et al., ; Xu et al., ). These data suggest that the osmoregulation in fish is under control by many genes and is very complicated.…”

Transcriptomic responses to environmental change in fishes: Insights from RNA sequencing

“…A vast array of genes and pathways has been proposed to enable prolonged salinity tolerance, including those involved in ion transport (Lam et al 2014;Wang et al 2014;Gu et al 2015;Nguyen et al 2016), blood pressure regulation and fat metabolism (Xu et al 2015), and both innate and adaptive immunity (Norman et al 2014a(Norman et al , 2014b.…”

“…However, a few experiments dispersed replicates among tanks to eliminate tank variation as a confounding factor (e.g., Narum and Campbell 2015;Prado-Lima and Val 2016). Studies multiple time points are also uncommon because they require multiplying sample sizes, yet they are key to distinguishing between short-term stress and long-term acclimation responses (e.g., Narum and Campbell 2015;Xu et al 2015;Place 2016a, 2016b). The number of individual and tank replicates required is highly dependent on the amount of biological variation within and between groups, which can be difficult to anticipate as it will likely be extremely case specific.…”