“Many of these different organisms have these shared core genes, shared biology, so studying one can inform our understanding of the others. One of the questions we have been asking for eons is, what makes us human? By studying a broader diversity of animals, we can learn more about human biology.”

Solving the evolutionary riddle of jellyfish

A fellowship from Rhode Island NSF EPSCoR provides the platform for a doctoral student to ask big questions.

Brown University doctoral student Rebecca Helm, a former Rhode Island NSF EPSCoR graduate fellow, defended her thesis on jellyfish evolution in late May, a moment that capped, from all outward appearances, a linear plan.

Her journey, however, was anything but, muses Helm, 30, of Flagstaff, Arizona, now a postdoctoral researcher at Woods Hole Oceanographic Institution, working with sea anemones.

In retrospect, she credits her 2012-13 EPSCoR fellowship with making her jellyfish research possible, coming at a time when her intended path failed to materialize and she had to regroup and find a new direction.

Helm describes her journey as meandering, starting nowhere near the ocean, a child who struggled with a learning disability and no direct influence in her life to model for her destination.

With a firefighter father and mother who is a nurse, Helm says no one in her immediate or extended family has advanced degrees. She did not know any scientists.

“But, I watched the Discovery channel and my dad read National Geographic to me,” she recalls in a recent interview, days after her defense and staring down revisions. “Being from Arizona, in a very real way, outer space and the ocean seemed equivalently far away.”

Helm took every science class she could, although options were limited at the arts-focused charter school she attended; she volunteered at a museum and observatory.

“That was how I started to meet scientists and talk about what it was like to be a scientist,” Helm says. “I knew I wanted to do marine science. It was so different from anything I had experienced and I loved the vastness of it.”

People didn’t know where blue whales migrated to, she says, and she found that boundless expanse enthralling, a place where something so big as a whale could get lost. At age 10, she saw the ocean for the first time.

Discovering the possibilities

After a childhood of hard-shelled invertebrates in Arizona, Helm was drawn to the strangely aesthetic beauty of jellyfish. Eckerd College in Florida offered a marine science program in a small school setting that would let her immediately jump in with both feet. She graduated with a BS in marine science in 2007.

And yet, beneath the stellar science skills and intrigue in the ocean’s creatures, Helm nursed doubts about her abilities. She says she struggled from an early age with dyslexia and fell behind significantly in elementary school reading, writing and math:

“I was always worried I wouldn’t have the chops to cut it. I didn’t think this would be possible; I didn’t know anybody like me. People really don’t talk about it. Occasionally, you will hear entrepreneurs say they’re dyslexic, but you don’t really hear scientists saying that.”

Despite the inner uncertainty, Helm applied for a Fulbright scholarship to study jellyfish in Capetown, South Africa.

She reflects, “I guess, in some ways, I didn’t think I was competitive enough to get in. I wasn’t so much thinking, ‘Aha, this is what I want to do,’ as much as, ‘Can I make this happen?’ My aha moment came when I was in grad school, when I realized, ‘Oh my gosh, this is actually possible.’”

Brown University materialized from Helm’s search for a school with focus on education, outreach and good science along with a small, tightknit community. She found everything she wanted in the lab of Associate Professor Casey Dunn, biology, through a connection she made at a conference.

Jellyfish life

Helm arrived at Brown in 2009, with the intention of studying gene expression in a group of organisms called siphonophores, a distinctly specialized kind of jellyfish.

“Jellyfish have complex life cycles, like a caterpillar to a butterfly,” she explains. “In the early stage, it’s a polyp — it looks like a coral polyp or sea anemone — and it lives on the sea floor. When the seasons change and food is available, the polyps (go through) metamorphosis and become little jellyfish, and grow into really big jellyfish. It’s really strange.”

But, unlike the complete transformation of the caterpillar, the siphonophore polyps live on and remain connected to the jellyfish. Her initial research goal was to figure out how the colonies of jellyfish bodies and polyps organized themselves.

Helm says developing a greater understanding of the process would inform what we know about humans and our organized growth pattern with specific locations for different body parts set up through patterns of gene expression during development.

“The really hard question in any animal, like the siphonophore, working with the whole body, is what causes what to turn on here and not there?” Helm notes.

However, after years of deep-sea expeditions to collect enough material for her research, Helm came up empty handed and faced the reality of finding a new direction. She says the year and a half period of reconsideration and reflection was a painful time, during which she traveled with Dunn to a little bay in the south coast of France to collect siphonophores.

The search turned up empty, but there was another species, Pelagia noctiluca, she says: “It was the neatest animal I had ever seen. It was beautiful, with a super bright luminescence, like an open ocean jellyfish nightlight.”

They also pack a mean sting, which Helm compares to the feeling of sticking a finger in an electrical outlet. Most importantly, though, the Pelagia are one of the only jellyfish that do not begin life as a polyp — they go straight from embryo to tiny jellyfish, skipping the polyp phase, which begs the question: How does it just drop a portion of development?

With that, Helm found her guiding research mission — how do life cycles evolve? But, she notes, she never would have set off on that track without EPSCoR support.

The EPSCoR difference

Helm says the fellowship saved her at a defining moment, providing funding that allowed her to explore the unknown: “It really provided me with a lot of intellectual freedom. It wasn’t even just that I was allowed to ask more questions, but that I was allowed to take risks and ask questions that no one else was asking.

“Everyone is looking for funding to do the same thing, so we’re advancing this narrow band of knowledge. But, there is so much more that we don’t know.”

Helm’s work also had the critical advantage of access to Brown University’s Center for Computation & Visualization (CCV), which makes its resources available to the entire RI EPSCoR research community across nine institutions of higher education in the state.

As part of her research, Helm induced polyps to make jellyfish in the lab to study development during metamorphosis, which led to three key chapters for her thesis — inducing metamorphosis, polyp vs. embryonic development, and the role of hormone signaling in life cycles.

In inducing metamorphosis, Helm sought to find out whether there were evolutionary preserved signals that led polyps to make jellyfish. She found that there was a set of artificial compounds that induced jellyfish production in almost every tested species; these species may share a common natural mechanism for inducing metamorphosis.

For her second chapter, Helm revisits the question of how a species of jellyfish, like the French Pelagia noctiluca, can bypass a part of the developmental process.

She discovered that certain jellyfish structures develop the same way in species with complex life cycles that include a polyp, and in Pelagia noctiluca that develop jellies directly from embryos. To Helm, this suggests the polyp stage of the life cycle may not be necessary for jellyfish formation.

“The process of natural selection, in many ways, is built on a foundation of random chance,” she says. “For example, perhaps somewhere deep in the ancestry of the Pelagia noctiluca jelly line, the ancestor of this species had polyps. Except maybe a few individuals, for whatever reason, developed jellyfish directly from an embryo. And, these jellyfish floated out into the open ocean and ultimately became a new species.

“Its offspring also lacked polyps, but that was good because in the open ocean there is nothing for a polyp to stick to. Of course it’s probably much, much more complicated than that. But, that is an example of how a random change — a jellyfish that developed from an embryo and not a polyp — could have led to a new jellyfish species.”

In the third chapter, Helm sets out evidence to suggest that perhaps a change in hormone signaling lies behind the French Pelagia’s dispensing with metamorphosis and developing straight from an embryo.

“One of the cool things about metamorphosis is that an organism has to keep track of all these variables,” Helm explains. “Do I have enough fat to grow? When I’m done, will there be food left?”

Scientists already have established that hormone pathways are involved in inducing metamorphosis, she adds: “If they are turning on early, that could completely change the whole direction. Maybe this is one way life cycles evolve.”

Pushing science forward

Helm says the big, seemingly unanswerable questions and the many unknowns about how life works grab her interest.

“I’ve been motivated from an early age by why we look the way we do and why do we do the things we do,” she says. “To me, animals like jellyfish, sea anemones and corals are the most alien looking animals, yet, when you look at the genome of a sea anemone and a genome of a person, there is a scary amount in common.”

As Helms frames the concept, there are a lot of similarities in the genomes, yet they wind up with totally different looking animals. The most obvious occurs in something like jellyfish and polyps — same genome, totally different animal; genetically identical, but doing different things with the tools they have.

These developmental stages provide the perfect place to begin exploring the more complex life cycles.

“Many of these different organisms have these shared core genes, shared biology, so studying one can inform our understanding of the others,” says Helm. “One of the questions we have been asking for eons is, what makes us human? By studying a broader diversity of animals, we can learn more about human biology.”

Story by Amy Dunkle | Jellyfish photos by Stefan Siebert