Harmful algal blooms (HABs) are a growing threat to marine ecosystems and human health. These blooms are caused by a variety of microscopic algae that can produce toxins that are harmful to fish, shellfish, and humans. One of the most common HABs is caused by the alga Karenia brevis, which produces a neurotoxin called brevetoxin. Brevetoxin can cause a variety of respiratory and neurological problems in humans, including coughing, wheezing, shortness of breath, nausea, vomiting, and diarrhea.

In a new study, researchers from the University of California, Santa Cruz, have discovered that K. brevis uses nitric oxide (NO) to help it grow and produce brevetoxin. NO is a small, gaseous molecule that is produced by a variety of organisms, including plants, animals, and bacteria. NO has been shown to have a variety of biological effects, including promoting cell growth, inhibiting cell death, and regulating immune responses.

The researchers found that K. brevis produces NO by using an enzyme called nitric oxide synthase (NOS). NOS catalyzes the conversion of L-arginine to NO and citrulline. The researchers also found that NO levels are higher in K. brevis cells that are growing rapidly and producing brevetoxin.

These findings suggest that NO plays an important role in the growth and toxicity of K. brevis. By understanding how NO is involved in these processes, researchers may be able to develop new ways to control HABs and protect marine ecosystems and human health.

The study was published in the journal Proceedings of the National Academy of Sciences.