A Transcriptomic Resource for the Cold‐Water Octocoral Dentomuricea aff. meteor Reveals Shared Stress‐Response Architecture Across Deep‐Sea Invertebrate Lineages

Cold-water octocorals are increasingly exposed to environmental pressures associated with seabed disturbance and metal contamination, resulting from deep-sea mining, yet the molecular systems underlying their stress responses remain to be fully characterized. Previous experimental work on Dentomuricea aff. meteor relied on a small set of targeted molecular markers, providing information on response state but little context for the broader molecular repertoire from which those responses arise. Here, we revisit an archival RNA-seq dataset generated from D. aff. meteor in 2016 and establish a benchmarked transcriptomic resource for gene discovery and comparative analysis. Contemporary reconstruction of the original reads produced 575,058 transcripts and 95,468 predicted coding sequences. Recovery of conserved anthozoan BUSCOs remained low and closely matched that of the original 2016 assembly (3.5% versus 3.4% complete), indicating that the archival dataset should be interpreted as a partial transcriptomic resource rather than a comprehensive gene catalog. Nevertheless, contemporary annotation recovered a substantial functionally interpretable sequence fraction, and targeted curation identified 141 distinct genes supported by Swiss-Prot and/or diagnostic Pfam evidence within a broader stress- and innate-immunity framework. Comparative orthology across five anthozoans assigned 4,172 Dentomuricea genes (8.7%) to orthogroups restricted to the focal species within the sampled panel. The corresponding estimate was 33.1% in a preliminary three-species panel but 8.7% in the separate definitive five-anthozoan panel, illustrating the sensitivity of apparent lineage specificity to comparison-panel composition and taxonomic breadth. Among Pfam-annotated genes remaining in the restricted set, 37.4% contained transposable-element (TE)-associated domains, while sequence-level inspection further showed that several apparent low-copy duplications reflected fragmented transcript reconstruction. A targeted comparison with the independently assembled gill transcriptome of the deep-sea mussel Bathymodiolus azoricus recovered supported candidates for 19 of 22 stress- and innate-immunity targets in both species. Twelve selected protein representatives showed reciprocal sequence similarity within the curated target sets. HSP90, Cu/Zn-superoxide dismutase and ferritin displayed the strongest correspondence, with substantial amino-acid identity and high reciprocal sequence coverage, whereas TLR-, RHD-, JUN- and STAT-associated proteins retained similarity primarily within conserved domains. Together, these analyses transform an incomplete archival dataset into a biologically informative molecular resource, extending earlier biomarker-based ecotoxicology toward a broader view of stress-response capacity in D. aff. meteor. They further show that apparent molecular novelty depends strongly on taxonomic sampling and that core components of protein homeostasis, oxidative defense; iron homeostasis and innate-immune signaling remain recognizable across deeply divergent deep-sea invertebrate lineages.