Tissue-Specific Gene Expression of Digestive Tract Glands in Paroctopus digueti: Insights for Cephalopod Biology and Aquaculture

Pacific pygmy octopus <i>Paroctopus digueti</i> is a promising model for cephalopod research and aquaculture; its feeding and nutritional biology remain poorly understood. The anterior salivary glands (ASG), posterior salivary glands (PSG), and digestive gland (DG) are central to these processes, but molecular comparisons are lacking. To address this gap, we performed a transcriptomic study to explore the enzymatic repertoire and functional specialization of these tissues. Total RNA was extracted from ASG, PSG, and DG of three pre-adult individuals collected in La Paz Bay, Mexico. RNA-Seq libraries were sequenced, and a non-redundant multi-tissue transcriptome was assembled. The ASG displayed high expression of neuropeptides, playing a role in neuroendocrine regulation. The PSG showed elevated protease expression, supporting its function in extracellular digestion, alongside toxins that reinforce its role as a venom gland. The DG was enriched in proteins linked to biomolecule catabolism and antimicrobial peptides, alluding to metabolic specialization and immune defense. These results were validated by qPCR, and target genes were also amplified in <i>Octopus maya</i> and <i>O. hubbsorum</i>, showing some similarities in expression patterns. Overall, our findings suggest strong glandular specialization in <i>P. digueti</i>, providing insights into cephalopod digestive physiology and supporting its value as a model species.