To investigate the genetic regulatory mechanisms underlying body color changes of Platax teira in response to stress, we performed an integrated analysis of histological observation and transcriptome sequencing to systematically analyze its adult skin tissue structure, pigment cell distribution, and gene expression profiles under stress conditions, aiming to provide a theoretical reference for the research on body color regulation and stress adaptation mechanisms of this fish. Histological examination reveals that melanocytes, predominantly located in the epidermal layer, are the main type of pigment cells in the skin of P. teira. After stress, the pigment granules in melanocytes rapidly disperse, resulting in a dark black body color. Transcriptome sequencing analysis of the skin tissue of P. teira before and after stress identified 800 significantly differentially expressed genes (DEGs), among which 159 genes were significantly up-regulated and 641 genes were significantly down-regulated. Functional annotation of these DEGs indicated that many DEGs are related to protein synthesis, amide metabolism, cell membrane components, and ion transport. Further pathway analysis of DEGs related to body color synthesis identified four signaling pathways involved in pigmentation: melanogenesis, tyrosine metabolism, Wnt signaling, and MAPK signaling. Quantitative real-time PCR (qPCR) was used to verify the expression trends of eight DEGs in the melanogenesis pathway, and the results were consistent with those of transcriptome analysis, confirming the reliability of the transcriptome data.

High-glucose environments induce cellular stress, particularly endoplasmic reticulum stress (ERS) and oxidative stress, in aquatic animals. Taurine, known for its cell-protective properties, has potential in mitigating such stress. This study investigated taurine's effects on ERS, oxidative stress, apoptosis, and glycogen accumulation in golden pompano (Trachinotus ovatus) muscle cells under high-glucose conditions. Cells were cultured with varying glucose concentrations and taurine supplementation. Techniques including Cell Counting Kit-8 (CCK-8) assay, Nile Red staining, periodic acid–Schiff (PAS) staining, and transmission electron microscopy (TEM) were used to assess cell viability, lipid deposition, glycogen accumulation, and ultrastructural changes, respectively. High glucose increased the ADP/ATP ratio, reactive oxygen species (ROS) levels, and reduced mitochondrial membrane potential (MMP), activating AMP-activated protein kinase (AMPK). This led to glycogen accumulation via increased glycogen synthase (gysm) expression and decreased glycogen phosphorylase (pygm) expression. Taurine supplementation restored glycogen balance, reduced glucose transporter 4 (GLUT4) and peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) protein levels, and alleviated ERS, as evidenced by reduced PKR-like ER kinase (perk) mRNA and glucose-regulated protein 78 (GRP78) protein expression. Also, taurine improved mitochondrial function, inhibiting apoptosis by reducing cytochrome C (CytC) release. In conclusion, taurine alleviated ERS, glycogen accumulation, apoptosis, and mitochondrial oxidative stress, providing new insights into taurine's mechanisms and supporting its potential use as a feed additive in aquaculture.