Single-cell transcriptome analysis reveals a cellular immune response in freshwater dark sleeper (Odontobutis potamophila) after infection with Aeromonas veronii

Proteomics-Based Investigation of Different Live Prey Administered to Freshwater Dark Sleeper (Odontobutis potamophila): Examining the Effects on Glycolipids and Energy Metabolism

Live prey is characterized by balanced rich nutrients and high palatability and is widely used for the seedling cultivation of freshwater dark sleeper (Odontobutis potamophila) larvae. In this study, we evaluated the effects of four groups of paired feeding regimens (group C (Daphnia magna), group L (Limnodrilus hoffmeisteri), group H (Hypophthalmichthys molitrix fry), and group M (mixed groups C, L, and H)) on glycolipid and energy metabolism in O. potamophila larvae. We observed that fatty acid synthase (FAS) and sterol-regulatory-element-binding protein-1 (SREBP-1) mRNA levels were significantly lower in group H when compared to mRNA levels in the other three groups (p < 0.05) and that carnitine palmitoyltransferase 1α (CPT1-α) mRNA levels were significantly lower in group L when compared to group M (p < 0.05). Relative glucokinase (GK) expression levels were significantly lower in group M when compared to the other three groups (p < 0.05). Using proteomics, we analyzed and compared groups H and L and identified 457 differentially expressed proteins (DEPs), of which 151 were significantly up-regulated and 306 were significantly down-regulated. In the comparison of group M with groups C, L, and H, we found significant enrichment in glycolytic processes, the endoplasmic reticulum lumen, NAD binding, intermediate filaments, and nutrient reservoir activity. Our results provide a theoretical guidance for bait selection during larvae cultivation stages in carnivorous fish.

Fishing Innate Immune System Properties through the Transcriptomic Single-Cell Data of Teleostei

The innate immune system is the first line of defense in multicellular organisms. Danio rerio is widely considered a promising model for IIS-related research, with the most amount of scRNAseq data available among Teleostei. We summarized the scRNAseq and spatial transcriptomics experiments related to the IIS for zebrafish and other Teleostei from the GEO NCBI and the Single-Cell Expression Atlas. We found a considerable number of scRNAseq experiments at different stages of zebrafish development in organs such as the kidney, liver, stomach, heart, and brain. These datasets could be further used to conduct large-scale meta-analyses and to compare the IIS of zebrafish with the mammalian one. However, only a small number of scRNAseq datasets are available for other fish (turbot, salmon, cavefish, and dark sleeper). Since fish biology is very diverse, it would be a major mistake to use zebrafish alone in fish immunology studies. In particular, there is a special need for new scRNAseq experiments involving nonmodel Teleostei, e.g., long-lived species, cancer-resistant fish, and various fish ecotypes.