Hydrothermal vent habitats are characterized by high hydrostatic pressure, darkness, and the continuous release of toxic metal ions into the surrounding environment where sea anemones and other invertebrates thrive. Nevertheless, the understanding of metazoan metal ion tolerances and environmental adaptations remains limited. We assembled a chromosome-level genome for the vent sea anemone,Alvinactis idsseensissp. nov. Comparative genomic analyses revealed gene family expansions and gene innovations inA. idsseensissp. nov. as a response to high concentrations of metal ions. Impressively, the metal tolerance proteinsMTPsis a unique evolutionary response to the high concentrations of Fe²⁺and Mn²⁺present in the environments of these anemones. We also found genes associated with high concentrations of polyunsaturated fatty acids that may respond to high hydrostatic pressure and found sensory and circadian rhythm–regulated genes that were essential for adaptations to darkness. Overall, our results provide insights into metazoan adaptation to metal ions, high pressure, and darkness in hydrothermal vents.

While cell fate determination and maintenance are important in establishing and preserving tissue identity and function during development, aberrant cell fate transition leads to cancer cell heterogeneity and resistance to treatment. Here, we report an unexpected role for the transcription factor p63 (Trp63/TP63) in the fate choice of the squamous versus neuroendocrine lineage in esophageal development and malignancy. Deletion of p63 results in extensive neuroendocrine differentiation in the developing mouse esophagus and esophageal progenitors derived from human embryonic stem cells. In human esophageal neuroendocrine carcinoma (eNEC) cells, p63 is transcriptionally silenced by EZH2-mediated H3K27 trimethylation (H3K27me3). Up-regulation of the major p63 isoform ΔNp63α, through either ectopic expression or EZH2 inhibition, promotes squamous transdifferentiation of eNEC cells. Together, these findings uncover p63 as a rheostat in coordinating the transition between squamous and neuroendocrine cell fates during esophageal development and tumor progression.

The shrimp Anchistus australis was a giant clam commensal species. Here, we explored in detail its mitochondrial (mt) genome, which was 15,396 bp in length, containing 13 protein-coding genes, 2 ribosomal RNA genes, 21 transfer RNA genes, and a non-coding control region 429 bp in length. The overall mt genome organization of A. australis displayed the typical characters for the pancrustacean ground pattern, with exception of translocation of trnW and trnL₁, as well as deletion of trnL₂. Phylogenetic analysis confirmed its evolutionary relatedness to other shrimp of family Palaemonidae within Infraorder Caridea.

Background/Objectives: Chemosymbiotic bivalves play a fundamental role in deep-sea cold seep and hydrothermal vent ecosystems, where essential long-chain polyunsaturated fatty acids (LC-PUFAs) are scarce. Whether these bivalves retain the capacity for endogenous PUFA synthesis remains poorly understood. Here, we investigated the PUFA biosynthetic capacity of two dominant chemosymbiotic bivalves from the Haima cold seep—the mussel Gigantidas haimaensis and the clam Archivesica marissinica. Methods: Genome and transcriptome assembly revealed three fatty acid desaturase (Fad) genes per species, which phylogenetically clustered into Δ5 (GhFads1, GhFads2; AmFads1, AmFads2) and Δ6/8 (GhFads3, AmFads3) clades, with lineage-specific duplications within the Δ5 clade. Functional assays were performed in yeast to characterize the activity of these enzymes. Results:Both Fads3 enzymes (Δ6/8 clade) convert C20:3n-6 and C20:4n-3 into C20:4n-6 and C20:5n-3, respectively, exhibiting Δ8-desaturase activity. Notably, Δ5-clade isoforms showed divergent substrate specificities: GhFads2 and AmFads1 functioned as classical Δ5-desaturases on PUFA substrates, whereas GhFads1 and AmFads2 specifically desaturated the bacterial monounsaturated fatty acid (MUFA) C18:1n-7 to produce C18:2n PUFAs. Conclusions: Together, our results reveal that cold-seep bivalves retain endogenous LC-PUFA biosynthetic capacity and have evolved duplicated Δ5-desaturases with novel regioselectivity toward bacterial MUFAs, likely representing an adaptive membrane modification for survival under extreme deep-sea conditions.