Mono Lake, located in the Eastern Sierras of California, is three times as salty as the ocean and has an alkaline pH of 10. Up until now, only two other species (other than bacteria and algae) were known to live in the lake—brine shrimp and diving flies. However, new research has discovered eight nematode species living in the lake. The worms have interesting characteristics, such as having three different sexes, the ability to survive extremely high levels of arsenic (500 times the lethal human dose), and carrying their young inside their body.
The work is published in Current Biology in a new paper titled “Newly Identified Nematodes from Mono Lake Exhibit Extreme Arsenic Resistance“.
Paul Sternberg, PhD, professor of biology at California Institute of Technology has had a long interest in nematodes, particularly Caenorhabditis elegans. As nematodes are considered the most abundant type of animal on the planet, recently graduated Sternberg lab graduate students Pei-Yin Shih, PhD, and James Siho Lee, PhD, thought they might find them in the harsh environment of Mono Lake.
The eight species they found are diverse, ranging from benign microbe-grazers to parasites and predators. Importantly, all are resilient to the arsenic-laden conditions in the lake and are thus considered extremophiles—organisms that thrive in conditions unsuitable for most life forms.
When comparing the new Auanema species to sister species in the same genus, the researchers found that the similar species also demonstrated high arsenic resistance, even though they do not live in environments with high arsenic levels. In another surprising discovery, Auanema sp. itself was found to be able to thrive in the laboratory under normal, nonextreme conditions. Only a few known extremophiles in the world can be studied in a laboratory setting.
This suggests that nematodes may have a genetic predisposition for resiliency and flexibility in adapting to harsh and benign environments alike.
“Extremophiles can teach us so much about innovative strategies for dealing with stress,” said Shih. “Our study shows we still have much to learn about how these 1000-celled animals have mastered survival in extreme environments.”
The researchers plan to determine if there are particular biochemical and genetic factors that enable nematodes’ success and to sequence the genome of Auanema sp. to look for genes that may enable arsenic resistance. Arsenic-contaminated drinking water is a major global health concern; understanding how eukaryotes like nematodes deal with arsenic will help answer questions about how the toxin moves through and affects cells and bodies.
But beyond human health, studying extreme species like the nematodes of Mono Lake contributes to a bigger, global picture of the planet, said Lee.
“It’s tremendously important that we appreciate and develop a curiosity for biodiversity,” he added, noting that the team had to receive special permits for their fieldwork at the lake. “The next innovation for biotechnology could be out there in the wild. A new biodegradable sunscreen, for example, was discovered from extremophilic bacteria and algae. We have to protect and responsibly utilize wildlife.”
