Parakaryon myojinensis

Parakaryon myojinensis is a unique single-celled organism discovered in the deep sea off the coast of Japan. It was first described in 2012 by a team of Japanese scientists led by Masashi Tsuchiya. The organism is notable for its unusual cellular structure, which appears to be a combination of prokaryotic and eukaryotic features, hence the name "Parakaryon" which means "beside the nucleus" in Greek.

Discovery

Parakaryon myojinensis was discovered in a sample of sediment collected from the Myojin Knoll, a submarine volcano located in the Izu-Bonin-Mariana Arc. The sample was collected at a depth of approximately 1,000 meters. The organism was found within the gut of a marine worm, Capitella teleta, which is known to inhabit deep-sea environments.

Description

The cell of Parakaryon myojinensis measures approximately 10 micrometers in length and 5 micrometers in width. It has a complex internal structure, with a nucleus surrounded by a nuclear envelope, similar to eukaryotes. However, unlike eukaryotes, the nucleus does not contain chromosomes, but instead houses a single circular DNA molecule, similar to prokaryotes.

The cell also contains organelles that resemble mitochondria, but these too are unusual. They have a double membrane, like mitochondria, but they also contain circular DNA and divide by binary fission, like prokaryotic cells.

Classification

The classification of Parakaryon myojinensis is currently uncertain. It does not fit neatly into the established categories of prokaryotes or eukaryotes. Some scientists have suggested that it may represent a new domain of life, while others believe it may be a transitional form between prokaryotes and eukaryotes.

Significance

The discovery of Parakaryon myojinensis has important implications for our understanding of the evolution of life on Earth. It suggests that the boundary between prokaryotes and eukaryotes may not be as clear-cut as previously thought, and that there may be a continuum of cellular complexity in nature.