Browsing by Author "Valdes, Juan Antonio"

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    Gills de novo assembly reveals oxidative stress, unfolded protein, and immune response on red cusk-eel ( Genypterus chilensis ) under thermal stress
    (2024) Dettleff, Phillip; Toloza, Carla; Fuentes, Marcia; Aedo, Jorge; Zuloaga, Rodrigo; Estrada, Juan Manuel; Molina, Alfredo; Valdes, Juan Antonio
    The heat waves on the South Pacific coast could lead to thermal stress in native fish. The red cusk-eel ( Genypterus chilensis ) is relevant for Chilean artisanal fisheries and aquaculture diversification. This study examined the effect of high-temperature stress in the gills of G. chilensis in control (14 degrees C) and high-temperature stress (19 degrees C) conditions. High-temperature stress induces a significant increase in gills cortisol levels. Additionally, oxidative damage was observed in gills (protein carbonylation and lipoperoxidation). RNA-seq data was used to build the first transcriptome assembly of gills in this species (23,656 annotated transcripts). A total of 1138 downregulated and 1531 up-regulated transcripts were observed in response to high-temperature stress in gills. The enrichment analysis showed immune response and replication enriched processes (on down-regulated transcripts), and processes related to the folding of proteins, endoplasmic reticulum, and transporter activity (on upregulated transcripts). The present study showed how gills could be affected by high-temperature stress.
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    High-Temperature Stress Induces Autophagy in Rainbow Trout Skeletal Muscle
    (2023) Molina, Alfredo; Dettleff, Phillip; Valenzuela-Munoz, Valentina; Gallardo-Escarate, Cristian; Valdes, Juan Antonio
    Ectothermic animals, such as teleosts, have increasingly been exposed to stressful high-temperature events due to global warming. Currently, the effects of thermal stress on skeletal muscle, a key tissue for fish growth, are unknown. This study examined the impact of high-temperature stress on the skeletal muscle transcriptome of rainbow trout (Oncorhynchus mykiss) in control (15 & DEG;C) and high-temperature (20 & DEG;C) conditions. Additionally, we examined the plasmatic levels of cortisol, glucose, and creatine kinase activity, and examined oxidative damage and autophagy activation in skeletal muscle. High-temperature stress induced significant increases in cortisol and glucose plasmatic levels. Nevertheless, no changes were observed in creatine kinase activity in plasma and skeletal muscle oxidation. Skeletal muscle RNA was isolated and sequenced using the HiSeq Illumina platform. A total of 383,796,290 reads were mapped onto the reference rainbow trout genome. The transcriptomic analysis showed that 293 genes were upregulated in the high-temperature group, mainly associated with autophagosome assembly, amino acid transport, and the glutamine metabolic process. On the other hand, 119 genes were downregulated in the high-temperature group, mainly associated with digestion, proteolysis, and the muscle contraction process. In addition, RT-qPCR of differentially expressed representative genes and Western blot analysis of LC3-II/LC3-I levels confirmed skeletal muscle autophagy induced by high temperature. This study sheds light on intriguing facets of the adaptive response of rainbow trout skeletal muscle to high-temperature stress and provides significant insights into the physiology of autophagy in teleosts.