Comprehensive Genome-Wide Analysis and Habitat-Specific Expression of Aquaporin 3 Genes in Tenualosa ilisha from Bangladesh

Identification, characterization, and functional investigation of the TiAQP3 gene family in Hilsa (Tenualosa ilisha) were the main objectives of the research. Four TiAQP3 genes were identified and confirmed based on the existence of conserved aquaporin domains. Diverse amino acid lengths, weights, and isoelectric points were observed in the identified genes. TiAQP3protein were found in the plasma membrane, highlighting their conserved role in transportation of water. Ten preserved motifs, including critical NPA boxes, were discovered, demonstrating functional conservation. The TiAQP3 genes are closely related to aquaporin genes from other migratory fish, indicating similar methods for maintaining osmotic balance. Structural modelling revealed retained secondary and tertiary characteristics, including six transmembrane helices critical for selective water transport. The expression of the TiAQP3 gene in T. ilisha differs among tissues and habitats, indicating their role in osmoregulation. Higher expression was observed in gill tissue of fish from Chandpur, Bhola, and Haor. Kidney tissue from Cox's Bazar sample showed highest expression, indicating the need for enhanced renal function in response to osmotic stress. Lower level expression in muscle and liver tissues indicates their limited involvement in osmoregulation. This study lays the groundwork for further research into how aquaporins help aquatic organisms adapt to their environment and their evolutionary history.