Integrated Histological and Transcriptomic Characterization of Prolonged Starvation Responses in the Cavefish Triplophysa rosa

Food scarcity is a major ecological challenge for cavefish; however, their coordinated physiological and molecular responses to prolonged starvation remain poorly understood. Here, we characterized the responses of Triplophysa rosa to 30, 60, and 90 days of food deprivation under controlled laboratory conditions by integrating growth measurements, histology, transcriptomics, quantitative reverse transcription PCR, and transmission electron microscopy. Starvation inhibited growth, reduced the condition factor and hepatosomatic index, and induced hepatocyte shrinkage, consistent with mobilization of hepatic energy reserves. Liver genes with declining temporal expression were enriched mainly in lipid biosynthesis, cholesterol metabolism, ribosomal function, and cell-cycle pathways, consistent with reduced biosynthetic activity. In the spleen, immune-related transcription increased during early starvation and declined at later stages, while the greater prominence of melano-macrophage centers was consistent with greater involvement of cellular clearance and tissue maintenance during prolonged starvation. Prolonged starvation also increased the expression of autophagy-related genes in the liver and spleen, and autophagy-related structures became more prominent in representative transmission electron microscopy images, consistent with increased involvement of intracellular recycling. Together, these findings reveal a coordinated temporal response involving metabolic adjustment, stage-dependent reorganization of splenic immune-related processes, and autophagy-associated cellular maintenance in T. rosa. This integrated approach improves our understanding of physiological maintenance during sustained nutrient limitation in cave-restricted fish.