NSF funds hydra research at Rice, UC Davis

Genomic, robotic tools could broaden hydra’s appeal as model organism 

By Greg Watry
Special to Rice News

What comes to mind when you think of the animals scientists use for life sciences research? Worms? Flies? Mice?

While these popular model organisms are staples in research laboratories across the globe, understanding some of life’s mysteries, such as regeneration, require a different kind of creature.

Enter the hydra, a small freshwater invertebrate that’s got a knack for biological immortality and regeneration. Despite its miraculous abilities, the hydra remains understudied. But a new $1.5 million grant from the National Science Foundation could help Rice neuroengineer Jacob Robinson and University of California, Davis molecular biologist Celina Juliano change that.

A $1.5 million grant from the National Science Foundation could help Rice and UC Davis researchers make it easier to research hydrae, a freshwater invertebrate with amazing regenerative abilities.

The grant from NSF’s Enabling Discovery through Genomic Tools (EDGE) program will fund the development of genomic and robotic tools that make it easier to research hydrae, and hopefully increase the number of researchers using the hydra as a model system.

“I’m most excited about creating tools to make it easier to culture and study hydrae in a laboratory setting,” said Robinson, assistant professor of electrical and computer engineering and co-principal investigator on the grant. “One of the reasons fruit flies and C. elegans (worms) have been so successful as model organisms is because it’s easy to raise them in a laboratory. We hope that robotic methods to feed and clean hydra, along with image-tracking algorithms to study their movements, will help hydra achieve similar success as a model.”

The hydra has been referred to as the “eternal embryo.” And the name is fitting. The embryos of any animal, including humans, have the ability to produce all cell types. This ability doesn’t usually continue into adulthood. But hydrae constantly renew all of their cells from stem cell populations throughout their entire lives, meaning these creatures have a bottomless well for replacing every single type of cell in their body.

“If you or I were injured, say our hands were cut off, there’s a specific genetic program that is activated and is required to heal the wound, but the hand wouldn’t grow back,” said Juliano, principal investigator on the new grant and assistant professor of molecular and cellular biology at UC Davis. “That same genetic program is activated after injury throughout the animal kingdom, but in some cases, instead of triggering scarring, it triggers regeneration and thus the missing body part is replaced.”

Juliano and her lab are currently wrapping up a single-cell sequencing project on the hydra. Over the course of the last year and half, they’ve sequenced every cell type in the hydra body, defining the exact genes expressed in each cell type.

With that information, Juliano and her team now know the genes expressed in every cell type, which allows them to understand how all cell types are made in hydrae. This information also gives Juliano and her team greater control over the genes they’d like to study in the cells of their experimental organisms.

Jacob Robinson

“You want to be able to modify gene function and then look at the resulting phenotype, or observable characteristics,” Juliano said. “So you can manipulate gene function and maybe something really drastic would happen. For example, in drosophila (fruit flies), changing the expression of just one gene leads to a leg growing out of the eye. That’s a very extreme example.”

But in order to better control genes, certain tools need to be developed. And that’s where the partnership between Rice and UC Davis comes in. By developing methods that can be used to study gene function in hydrae, the team aims to make it easier to investigate how they regenerate specific cell types, including neurons.

Juliano’s team will construct tools to turn genes on and off at specific times and places in a hydra’s continuous development as an adult. Robinson will contribute tools for studying the hydra’s nervous system, including the first microfluidic technologies designed to probe neural activity and behavior in hydrae. The combination of genetic tools and phenotyping technologies will help the researchers understand how hydrae can regenerate all of their cells, including nerve cells, and potentially, why humans can’t.

For example, Juliano said one tool Robinson is developing will help automate many of the time-consuming tasks required to keep hydrae, including the need to clean them by hand. Robinson’s lab is developing an automated system to handle this chore and others in the daily maintenance of hydrae and their enclosures.

“He’s designing what we’re calling the ‘hydra robot,'” Juliano said.

“With the support from NSF, we can both develop these technologies and disseminate them to researchers who may have never considered using hydrae in their lab,” Robinson said. “I look forward to sharing the tools, and helping other labs begin their own exciting work with hydra.”

–Greg Watry is a science writer at the University of California-Davis College of Biological Sciences