This article by Samantha Mascuch and Julia Kubanek was originally published on June 13, 2019, in The Conversation. It is republished here under the Creative Common License.

Plants, animals and even microbes that live on coral reefs have evolved a rich variety of defense strategies to protect themselves from predators. Some have physical defenses like spines and camouflage. Others have specialized behaviors – like a squid expelling ink – that allow them to escape. Soft-bodied or immobile organisms, like sponges, algae and sea squirts, often defend themselves with noxious chemicals that taste bad or are toxic.

Some animals that can’t manufacture their own chemical weapons feed on toxic organisms and steal their chemical defenses, having evolved resistance to them. One animal that does this is a sea slug that lives on the reefs surrounding Hawaii and dines on toxic Bryopsis algae. Marine scientists suspected the toxin is made by a bacterium that lives within the alga but have only just discovered the species responsible and teased apart the complex relationship between slug, seaweed and microbe.

Ultimately, noxious chemicals allow predators and prey to coexist on coral reefs, increasing their diversity. This is important because diverse ecosystems are more stable and resilient. A greater understanding of the drivers of diversity will aid in reef management and conservation.

As marine scientists, we too study chemical defenses in the ocean. Our laboratory group at the Georgia Institute of Technology explores how marine organisms use chemical signaling to solve critical problems of competition, disease, predation and reproduction. That’s why we were particularly excited by the discovery of this new bacterial species.

Origins of a chemical defense

In a report published in the journal Science, researchers at Princeton University and the University of Maryland discovered that a group of well-studied toxic defense chemicals, the kahalalides, are actually produced by a bacterium that lives inside the cells of a particular species of seaweed.

The scientific community had long speculated that a bacterium might be responsible for producing the kahalalides. So the discovery of the kahalalide-producing bacteria – belonging to the class Flavobacteria – has solved a long-standing scientific mystery.

Bryopsis provides the bacteria with a safe environment and the chemical building blocks necessary for life and to manufacture the kahalalides. In return, the bacterium produces the toxins for the algae, which protect them from hungry fish scouring the reefs. But the seaweed isn’t the only organism that benefits from this arrangement.

The kahalalides, originally discovered in the early 1990s, also protect a sea slug, Elysia rufescens, that consumes it. The sea slugs accumulate the toxins from the algae, which then protects them from predators.

The discovery of a symbiosis between a bacterium and a seaweed to produce a chemical defense is noteworthy. There are many examples of bacteria living inside the cells of invertebrate animals (like sponges) and manufacturing toxic chemicals, but a partnership involving a bacterium living in the cells of a marine seaweed to produce a toxin is unusual.

The finding adds a new dimension to our understanding of the types of ecological relationships that produce the chemicals shaping coral reef ecosystems.

The medicinal potential of toxins

Our lab is home to an enthusiastic multidisciplinary team of marine chemists, microbiologists and ecologists who strive to understand how chemicals facilitate interactions between species in the marine environment.

We also use ecological insights to guide discovery of novel pharmaceuticals from marine organisms. Chemicals used by marine organisms to interact with their environment, including toxins which protect them from predators, often show promising medical applications. In fact, the most toxic kahalalide, kahalalide F, has been the focus of clinical trials for the treatment of cancer and psoriasis.

Currently, we conduct our fieldwork in Fiji and the Solomon Islands in collaboration with a research group led by Katy Soapi at the University of the South Pacific. There you can find us scuba diving to conduct ecological experiments or to collect algae and coral microbes to bring back for study in the laboratory.

During the course of our field work we have had the opportunity to observe Bryopsis and have been struck by how lovely it is, standing out with its bright green color against the pinks, grays, browns and blues of a coral reef.

The story of the kahalalides is a good reminder that even though seaweed-associated bacteria may be invisible to the human eye and to fish predators, microbes and their chemicals play an important role in shaping coral reef structure and diversity, by allowing organisms to thrive in the face of predation.

Much of the damage from climate change is in front of our eyes: Bleached-out coral reefs, destroyed homes and flooded neighborhoods ravaged by hurricanes, dangerous wildfires scorching Northern California forests. Worst-case scenarios involve remade coastlines, stunted crops, and social unrest caused by scarce resources.

An international group of microbiologists, however, is warning that as science tries to search for solutions to climate change, it’s ignoring the potential consequences for climate change’s tiniest, unseen victims – the world’s microbial communities.

Frank Stewart, associate professor in the School of Biological Sciences, is one of more than 30 microbiologists from nine countries who today issued a statement urging scientists to conduct more research on microbes and how they are affected by climate change.

The statement, “Scientist’s warning to humanity: Micro-organisms and climate change,” was published in the journal Nature Reviews Microbiology. Lead author is Rick Cavicchioli, microbiologist at the School of Biotechnology and Biomolecular Sciences, in the University of New South Wales (Sydney).

“The consensus statement by Cavicchiolli and colleagues is an overdue warning bell,” Stewart says. “Its goal is to alert stakeholders that major consequences of climate change are fundamentally microbial in nature. As a co-author, I'm hopeful this statement finds a wide audience of nonscientists and scientists alike and also serves as a call to action. Microbes must be considered in solving the problem of climate change.”

The impact on microbes

In the statement, Cavicchiolli calls microbes the “unseen majority” of all life on Earth. Their communities serve as the biosphere’s support system, playing key roles in everything from animal and human health, to agriculture and food production.

A cited example: An estimated 90% of the ocean’s biomass consists of microbes. That includes phytoplankton, lifeforms that are not only at the start of the marine food chain, but also do their part to remove carbon dioxide from the atmosphere. But the abundance of some phytoplankton species is tied to sea ice. The continued loss of ice as oceans warm could therefore harm the ocean food web.

“Climate change is literally starving ocean life,” Cavicchioli said in a press release about the consensus statement.

The microbiologists are also worried about microbial environments on land. Microbes release important greenhouse gases like methane and nitrous oxide, but climate change can boost those emissions to unhealthy levels. It can also make it easier for pathogenic microbes to cause diseases in humans, animals, and plants. Climate change affects the range of flying insects that carry some of those pathogens. “The end result is the increased spread of disease, and serious threats to global food supplies,” Cavicchioli said.

“Just as microbes in our bodies critically affect our health, microbes in the environment critically affect the health of ecosystems,” Stewart says. “But microbial processes are changing dramatically under global climate change, including in ways that fundamentally alter food webs and accelerate climate change.”

A call to boost research

Georgia Tech researchers such as Stewart, Mark Hay, Kim Cobb, and Joel Kostka have become experts in researching climate change’s impact on diverse ecosystems, from coral reefs to subarctic peat bogs. Much of their work already focuses on microbes and the roles they play in these stressed environments.

“For example, ocean warming is driving the loss of oxygen from seawater, leading to large swaths of ocean dominated exclusively by microbes,” Stewart says. “Our research at Georgia Tech tries to understand how such changes affect the microbial cycling of essential nutrients.”

According to the consensus paper, that kind of research should play a bigger role when governments and scientists work on policy and management decisions that might mitigate climate change. Also, research that ties biology to worldwide geophysical and climate processes should give greater consideration of microbial processes.

“This goes to the heart of climate change,” Cavicchioli says. “If microorganisms aren’t considered effectively, it means models cannot be generated properly and predictions could be inaccurate.”

Microbiologists can endorse the consensus statement and add their names to it here: https://www.babs.unsw.edu.au/research/microbiologists-warning-humanity

Editor's Note: This story – narrative, photography, and slide show – is by the Georgia Tech students in the 2019 NGS-CR Study-Abroad Program, which is an interdisciplnary program co-taught by School of Public Policy Professor Juan Rogers.

In just five weeks, we interviewed a former vice president of Costa Rica, scrambled up the slopes of a volcano, and came face to face with sloths, vipers, and bullet ants. The Nature, Governance, and Sustainability in Costa Rica (NGS-CR) Study-Abroad Program has been an unbelievable experience. From the remote jungles of Sarapiqui to the stunning peaks of Monteverde, Costa Rica has inspired us to explore and learn at every turn.

Our program started in early May in the capital city of San Jose. We experienced new culture every step of the way, through the museums we visited and atop country’s highest volcano. We made a difference in the community by teaming up with Lead University to reduce plastic pollution by sorting and recycling plastic bottle caps. We also met with Kevin Casas Zamora, a former vice president of Costa Rica, and discussed the nation’s history and current policy concerns.

Next, we went deep into the tropical rainforest to La Selva Biological Station, one of the leading research institutions studying tropical ecology. Hundreds of species of trees towered over us, filled with multicolored bromeliads and orchids and teeming with strange insects and birds. Oh yeah, and sloths! 

Mornings were filled with the warbled calls of birds and the bellows of howler monkeys. Strikingly beautiful yellow and green tree frogs leaped into view when our flashlights found them during our night hikes. Cold rain fell seemingly out of nowhere to dash away the heat of day.

We learned about the history of chocolate, known here as the “drink of the gods.” We heard how locals are educating their communities about climate change and sustainable practices. We left knowing that a single hummingbird can effect change – and with a lot of chocolate.

We then traveled to Monteverde, a mountain town enveloped by clouds, where we welcomed the drop in temperature with open arms. We partnered with the Monteverde Institute, which aims to educate the local community about the importance of sustainability. Visiting small, sustainable farms forced us to confront the unique challenges of sustainable, organic farming.

We trudged through mud and cow manure to visit the farm of a direct descendant of one of the first Quaker families to settle in Monteverde. We were treated to delicious home-cooked meals made from all-natural ingredients, such as fresh, soft tortillas filled with hot gallo pinto, Costa Rica’s national dish, consisting of beans and rice.

Our trip to Monteverde also included delicious tasting of local coffee, and of course, the thrill of zip-lining through the forests.

Our experiences have been part of two interconnected classes, BIOL 4813: Tropical Biology & Sustainability and PHIL 3127: Science, Technology, and Human Values. These classes have integrated biological and social sciences so students can better understand how Costa Rica, the United States, and the world construct political mechanisms to organize societies and sustain natural systems.

Our instructors were Michael Goodisman, an associate professor in the School of Biological Sciences, and Juan Rogers, a professor in the School of Public Policy.

The NGS-CR Study-Abroad Program has been supported by the Office of International Education, the Steve A. Denning Chair for Global Engagement, and the Center for Serve-Learn-Sustain. The program is affiliated with the College of Sciences, and its courses are taught by faculty from the School of Biological Sciences in the College of Sciences and the School of Public Policy in the Ivan Allen College of Liberal Arts.

We are this story’s authors, the participants (and our majors) of the 2019 NGS-CR Study-Abroad Program:

• Biology: Henry Crossley, Sarah Kuechenmeister, Amelia Smith, and Veronica Thompson
• Biochemistry: Rajan Jayasankar
• Environmental engineering: Miriam Campbell, Abigail Crombie, Catherine Mellette, and Isabelle Musmanno
• Industrial engineering: Laura “CC” Gruber
• Psychology: Katherine Chadwick

When I volunteered for a study that will observe and measure movements during walking, I knew only that my participation would help researchers figure out how to make better prostheses for people missing limbs. I didn’t know that the experience would surface strong feelings of empathy for people with ambulatory problems.

On the day of my appointment, I was met by Kinsey Herrin, a prosthetist/orthotist and the clinical liaison for the study, and Samuel Kwak, the graduate student working with Young-Hui Chang on the research study. Chang is a professor in the School of Biological Sciences and the principal investigator of the Comparative Neuromechanics Laboratory, where the study took place.  

The study – “Accelerating Large-Scale Adoption of Robotic Lower-Limb Prostheses through Personalized Prosthesis Controller Adaptation” – compares the motions, forces, and muscle activity during walking of people with amputations versus controls. The goal is to develop better ways of controlling prostheses. I was part of the control group. My counterpart, I learned, is a woman who is amputated below the knee on her left leg.

After the orientation to the study and reminders of confidentiality and safety, Sam and Kinsey put me through several walking sessions: normal, with a knee brace locked in extension, with an ankle brace, and with both braces. Each session started with a measurement of base line, followed by walking on a split-belt treadmill three times, each at a different speed. At each speed, I’d walk for three minutes before data are collected.

Data were collected from the force plates beneath the treadmill and by infrared cameras recording the movements. As I walked, I saw on a monitor the motion of my legs – shown as white dots corresponding to infrared sensors tacked on to various parts of each lower limb.

It was easy-peasy with normal walking; the only mildly tricky part was trying to mind the small gap between the two parts of the split-belt treadmill.

With braces on just one leg, it was a different story. The braces were heavy. My left leg was constrained. I never felt so asymmetrical in my life. Walking without the ability to bend the knee, or flex the ankle, is awkward, at best.

“This is tough,” I heard myself saying over and over. If this is tough for me, I thought, how much more for people without limbs; it must be harrowing for them.

Kinsey has worked with patients who have amputations. While prosthetists are quite adept at creating functional passive prostheses for patients, restoring power naturally during walking is much more challenging.

Prosthetists and patients can spend lots of time in the clinic over multiple visits tuning a powered device to be perfect, Kinsey said. The back and forth can create a burden on the patient and the clinician. The ultimate goal of this study – Kinsey and Sam reminded me several times – is to make prosthesis tuning easier and more automatic for patients and clinicians.

I spent three hours volunteering for the study. I consider those among the most useful three hours of my life, considering that my participation could help ease the life of people with lower limb amputations.

The study needs more volunteers. If you can spare three hours to advance the science of prosthesis control, contact Kinsey at kinsey.herrin@biosci.gatech.edu for more information.

Georgia Tech has selected Troy Hilley as the recipient of the 2019 Process Improvement Excellence Award. Hilley is an academic and research IT support engineer lead in the College of Sciences’ Academic and Research Computing Services (ARCS).

The award celebrates staff who consistently invent or improve tools, processes, or systems and ask: How can we do this better? Why do we do it that way?

For years Hilley was responsible for the day-to-day operations and maintenance of faculty, research group, and administrative computing infrastructure in the School of Biological Sciences. In that capacity he established himself as a leader in thinking creatively and acting proactively to prepare the school for the rapidly changing environment for integrative computing.

“With no budget and limited resources, he used free open-source software to completely overhaul OS X management from installation to end-user software management.”

Hilley’s leadership is evident in the improvements he initiated with the management and support of Apple OS X computers on campus. This problem had been adversely affecting faculty, staff, and students and causing substantial frustration.

Whereas other IT staff merely accepted the status quo, “Troy did a clean sweep of the status quo,” according to a colleague. “With no budget and limited resources he used free open-source software to completely overhaul OS X management from installation to end-user software management.”

Hilley then implemented a system to completely automate most of the software updates. This ensured that systems and end users have the latest security and feature updates immediately.

Still seeing room for improvement, Hilley then put in place a system that enables IT staff to get detailed information on the status of the computers under ARCS management. With this system, IT staff could proactively assist users, saving time and frustration.

The process and tooling improvements Hilley established increased the speed and accuracy of support while simultaneously decreasing the frustration among both IT staff and end users. That they were achieved at no cost is a “rare optimization gem,” a colleague says.

Hilley “continues to innovate and improve tools, processes, and systems that directly help our clients and enhance the organization’s effectiveness,” another colleague says. 

William C. Ratcliff has been named the recipient of the 2018 Sigma Xi Young Faculty Award. The award recognizes outstanding research achievements by a faculty of rank no higher than assistant professor. Ratcliff is an assistant professor in the School of Biological Sciences.

An evolutionary biologist, Ratcliff studies how organisms change over time. In particular, he wants to understand how multicellular organisms can evolve from single cells. This question remains one of the fundamental problems in biology.

His approach is “extremely creative,” a colleague says. “Rather than trying to infer what happened hundreds of millions of years ago, William cut the Gordian knot by evolving novel multicellularity in the laboratory....Few scientists would attempt such an ambitious experiment.”

In a 2016 interview, Ratcliff explained his approach.

“In our lab, we do evolutionary time travel in a test tube, by creating new multicellular organisms, using yeast and algae, in a way that’s simple but which we can examine with huge precision, using all the tools of biology, mathematics, and physics. We’re not trying to explain what happened historically. Rather, we’re trying to show how it can happen in principle.

“We’re interested in how the geometry of cellular clusters influences the outcome of evolution, tipping the balance between cellular cooperation and conflict, and how cells lose their Darwinian autonomy, evolving from individual organisms into parts of a new organism. These are fundamental principles that should be broadly applicable.”

Ratcliff has shown that multicellularity can evolve quickly. The simple multicellular “snowflake” yeasts he has evolved in the lab – by selection for rapid settling through liquid media– possess a multicellular life cycle, reproducing through small propagules, like stem cuttings. Over 1,500 generations, they adapted to the selection pressure by growing faster and evolving a more hydrodynamic shape. They also evolved a simple division of labor, using programmed cell death to sever links between cells and produce more propagules. Experiments with a unicellular algae have yielded broadly similar results.

“[T]his award really reflects the strength of our research community and the benefits of working in an environment so conducive to collaboration.”

From these observations, fundamental insights have emerged about the evolution of multicellular complexity. For example, mutations that are beneficial to the multicellular aggregate but costly to the single cell can accelerate evolution of increased multicellular complexity. In addition, his work has shown how the 3D geometry of yeast clusters allows a rudimentary form of development to arise, guiding the emergence of new multicellular traits from mutations that only directly affect the properties of single cells. Taken together, Ratcliff’s research upends conventional wisdom that the transition to multicellularity must have been slow and difficult and must have required extraordinary conditions.

Ratcliff’s scientific creativity is recognized by generous external support for his research, including the prestigious Packard Fellowship. Even the popular press has noticed: Popular Science named Ratcliff one of the Brilliant 10 in 2016, the magazine’s way of “honoring the brightest young minds reshaping science, engineering, and the world.”

“William has helped define the field of modern multicellularity research,” the same colleague says, “and in so doing, has become one of its leaders.”

“I am of course deeply honored by this recognition” Ratcliff says. “But this award really reflects the strength of our research community and the benefits of working in an environment so conducive to collaboration. Since arriving at Tech in 2014, my research directions have evolved much like snowflake yeast have – in wonderful and unexpected ways. This has been the direct result of having such amazing students, collaborators and colleagues.”