Intronides

Intronides are a newly described class of microscopic eukaryotic organisms first reported in 2007 from marine sediment samples near the Mid-Atlantic Ridge. They belong to the phylum Alveolata and are classified within the subclass Peruseria. Intronides are distinguished by their small, translucent bodies measuring 4–7 micrometres in diameter, a single-celled nucleus, and a unique arrangement of alveoli beneath the cell membrane that resembles a dorsal armor. Their name derives from the characteristic pattern of intronic regions in their ribosomal RNA genes, which show unusually long internal segments compared to closely related taxa.

The life cycle of intronides appears to be primarily asexual, consisting of a trophozoite stage that engulfs bacterial prey and a cyst stage that forms in response to environmental stress. Observations under electron microscopy reveal a complex feeding apparatus comprised of a pseudopodial extension and a specialized secretory organelle that secretes matrix proteins to capture prey. Genetic analyses show that intronides possess a small mitochondrial genome, lacking conventional genes for oxidative phosphorylation, suggesting a highly reduced metabolic capability.

Ecologically, intronides are thought to play a role in the benthic microbial loop by contributing to the degradation of bacterial biomass in deep-sea environments. Their relatively high abundance in certain hydrothermal vent communities indicates a potential niche specialization. Current research focuses on sequencing additional intronide genomes to clarify their phylogenetic relationships within Alveolata and to explore the evolutionary origins of their unique intronic structures.