Seasonal transcriptome profile across three different tissues of the Andean Killifish Orestias ascotanensis

• Maldonado-Agurto, Rodrigo

• Pez Killi Andino

The Andean killifish Orestias ascotanensis inhabits the high-altitude Ascotán Salt Pan, an environment with variable salinity, high UV exposure, low oxygen, and extreme daily temperature fluctuations. These conditions make it an excellent model for studying high-altitude fish biology. However, the transcriptomic responses of O. ascotanensis to seasonal acclimation remain unexplored. To investigate seasonal and tissue-specific transcriptomic profiles, RNA-seq was performed on 42 libraries from gills, skin, and muscle tissues of 14 individuals collected in summer (n = 7) and winter (n = 7). Each library had a median of 105 million reads. Principal component analysis revealed strong tissue-specific expression, and seasonal differential expression analyses identified significant transcriptomic changes within each tissue. Additionally, a bioinformatics pipeline identified 10,365 high-confidence long non-coding RNAs (lncRNAs), predicted by at least three computational tools. Compared to protein-coding genes, lncRNAs exhibited higher tissue specificity, with a predominance of monoexonic structures and shorter exon lengths. This dataset provides the first comprehensive view of seasonal mRNA and lncRNA expression in O. ascotanensis tissues.