Researchers testing a new way to read DNA from very small samples have found a pond organism that does not follow a rule biologists long treated as nearly universal. The organism is a microscopic protist, and it was not the target of the study.
According to a summary from the Earlham Institute, the team was trying out a sequencing method that can work with tiny amounts of genetic material, potentially from a single cell. They examined a previously unknown protist collected from a freshwater pond in Oxford University Parks in England. The organism is called Oligohymenophorea sp. PL0344.
What the microbe does differently
Cells build proteins by reading genes in three-letter units called codons. Most codons specify an amino acid. A few act as punctuation and tell the cell to stop building the protein.
In this protist, two codons that normally mark the end of a gene instead encode two different amino acids. The Earlham Institute reports that these two stop signals were thought to evolve together, which is why the finding stands out. A PLOS Genetics study, as described by ScienceDaily, reports that this combination of reassignments had not been seen before.
The organism belongs to the ciliates. These are swimming single-celled organisms that live in many watery environments. According to ScienceDaily’s account, ciliates have long interested geneticists, and the group is known for variations in how the genetic code is read.
An accident, not a hunt
The discovery was made by Dr. Jamie McGowan, then a postdoctoral scientist at the Earlham Institute. He worked with colleagues there and with a group led by Professor Thomas Richards at the University of Oxford.
The project was not about how the genetic code evolves. Its aim, as the institute describes it, was to improve tools for studying organisms that are hard to grow and analyze in a laboratory. The unusual code showed up as a side result of testing that method.
That detail matters beyond the anecdote. Many microbes cannot be cultured, so most of what scientists know about them comes from sequencing. A method that works on one cell could bring more of these organisms into view. It could also reveal more cases like this one.
Not the first rule-bender
Departures from the standard code are known, though they are uncommon. A separate report from the University of California, Berkeley, published in February, described a methane-producing archaeon, Methanosarcina acetivorans. It sometimes treats a stop codon as a signal to add an unusual amino acid and keep going. The same instruction can therefore yield two different proteins. According to that report, the microbe functions normally despite this flexibility.
The two cases are different. The archaeon reads one codon two ways, while the Oxford protist has permanently reassigned two stop codons to specific amino acids. Both challenge the idea that the code is fixed.
What is still open
The summaries available do not say how the protist tells a real gene ending from an amino-acid codon. They also do not say how widespread the trait is among related ciliates. Those questions would need the full paper in PLOS Genetics.
The Earlham Institute’s framing is that the finding shows the genetic code may be more flexible than scientists assumed. That is a reasonable reading of one organism, but it rests on a single new species so far.
The work was first reported in May 2026 and was highlighted again this week by ScienceDaily.