In the realm of biological research, symbiosis stands as a captivating and complex phenomenon that has long intrigued scientists. Carnegie Science is at the forefront of unraveling the mysteries of symbiotic relationships and their profound implications for human health, agriculture, and ecosystem resilience. Through cutting-edge research and innovative techniques, Carnegie scientists are making groundbreaking discoveries that could transform our understanding of the natural world and pave the way for sustainable solutions to some of the planet's most pressing challenges.
What is symbiosis?
Symbiosis is a biological concept referring to the close and often long-term interaction between two or more different species. The term encompasses a wide range of relationships, which can be mutualistic, commensal, or parasitic:
- Mutualism: Both species benefit from the relationship. For example, the symbiosis between bees and flowers, where bees get nectar as a food source while pollinating the flowers.
- Commensalism: One species benefits without significantly affecting the other. An example is barnacles that attach themselves to the shells of sea turtles. The barnacles get a place to live and feed, while the turtle is typically unaffected.
- Parasitism: One species benefits at the expense of the other. For instance, tapeworms living in the intestines of animals, where they absorb nutrients from the host's food, often harming the host.
Symbiotic relationships are essential for many biological processes, including nutrient cycling, reproduction, and protection, and they play a crucial role in maintaining the balance of ecosystems.
Coral Conservation: Unraveling Symbiotic Secrets
Carnegie Science's Division of Biosphere Sciences and Engineering is leading the charge in studying the intricate relationship between coral and algae. Coral reefs, often referred to as the "rainforests of the sea," are vital to marine biodiversity and human livelihoods. However, they are under severe threat from climate change-induced ocean warming, which leads to coral bleaching.
Carnegie’s Phillip Cleves scuba diving on the Great Barrier Reef in Australia. Cleves uses cutting-edge biology techniques to better understand the risks coral face due to climate change. Credit: Amanda Tinoco/Carnegie Science
The sea anemone Aiptasia pallida. This anemone is hosting the dinoflagellate Breviolium minutum algae, which are responsible for the red fluorescence spots observed in the body of the animal. Carnegie's Arthur Grossman studies the symbiotic relationships that species of the dinoflagellate algae form with coral. Credit: Tingting Xiang/Carnegie Science
Corals are marine invertebrates that build large exoskeletons from which reefs are constructed. But this architecture is only possible because of a mutually beneficial relationship between the coral and various species of single-celled algae called dinoflagellates that live inside individual coral cells. These dinoflagellates are photosynthetic, which means that, like plants, they can convert the Sun’s energy into chemical energy. An alga will share the sugars it synthesizes with its coral host, which in turn provides the alga with the inorganic carbon building blocks it needs, as well as phosphorous, nitrate, and sulfur.
By investigating how corals establish and maintain their symbiotic relationships with algae, Carnegie researchers, including Phil Cleves, Arthur Grossman, and Yixian Zheng, aim to understand the mechanisms behind coral resilience and develop strategies to mitigate the impacts of environmental stressors.
Agricultural Innovation: Harnessing the Power of Symbiosis
Beyond the oceans, Carnegie scientists are exploring the potential of symbiosis in transforming agriculture. Brittany Belin's team is studying the symbiotic exchange between legumes and rhizobia, soil bacteria capable of converting atmospheric nitrogen into plant-fertilizing ammonia. This research holds promise for developing sustainable alternatives to synthetic nitrogen fertilizers, which are critical for reducing the environmental footprint of agriculture. Belin believes that harnessing this powerful interconnection could one day help to naturally and sustainably feed the world’s rapidly growing population.
Brittany Belin studies the relationship between legumes and the nitrogen-fixing bacteria that live in their root nodules. This research holds promise for developing sustainable alternatives to synthetic nitrogen fertilizers, which are critical for reducing the environmental footprint of agriculture. Credit: Navid Marvi/Carnegie Science
“We’re a microbiology lab, but we are interested in which genes make rhizobia better for one host versus another,” explains Belin. “Can you improve the strain to make it more useful for agriculture? What would be the consequences of having this GMO bacterium in the environment—is that long-term a good thing to do? That’s the kind of stuff we think about.”
Nematodes: Unlocking the Secrets of Soil-dwellers
The soil is teeming with microbial life that plays a crucial role in plant health and ecosystem functioning. Carnegie Staff Associate Mengyi Cao is pioneering the use of one such organism, the Steinernema nematode, as a genetic model to study microbial symbiosis. Nematodes are among the most abundant and diverse groups in the soil fauna, and they play a significant role in soil ecology. In partnership with their mutualistic bacteria, these microscopic roundworms offer a unique window into the complex interactions within soil ecosystems due to their multi-faceted antagonistic effects on agricultural pests. Their potential applications in pest control highlight the importance of understanding symbiotic relationships in developing eco-friendly solutions to the devastation caused by invasive species.
Gut Ecology: Exploring the Microbial Universe Within
The human body is a complex ecosystem, home to trillions of microbes that influence our health in myriad ways. Staff Scientist Will Ludington’s lab is delving into the gut microbiota of the fruit fly, Drosophila melanogaster, to uncover the intricate dynamics of microbial community interactions. This research not only sheds light on gut ecology but also provides insights into how these microbial communities impact host health.
William Ludington scans at a vial of fruit flies in the lab. His work teases apart the relationships within the relatively simple gut microbiome of fruit flies so that we can begin to understand more complex microbial ecosystems found in humans and how they impact the health of their hosts. Credit: Navid Marvi / Carnegie Science. Credit: Navid Marvi/Carnegie Science
Despite its importance, researchers have historically lacked a mechanistic understanding of how the gut microbiome as a whole is greater than the sum of its parts. In other words, to what extent do individual microbes influence us, and to what degree are these impacts determined by the interconnected and overlapping interactions between unique species? Studying the underlying biology that governs these relationships is absolutely critical to advancing our understanding of human health. However, the sheer number of different microbes in our gut presents a challenge to cataloging and understanding the effects of their synergy.
Using the natural simplicity of the fruit fly gut microbiome as a model system, the Ludington Lab is starting to untangle this complex web of interactions.
“When people have done other kinds of microbiome experiments, they are asking ’what’s there?’ But we know exactly what’s there,” explains Ludington. “We’re not just being descriptive. We’re saying, ’we have this specific system, and when we put this in or take that away, we can see the effect come and go.’ So, you can really establish causation of the specific bacteria.”
A Symbiotic Future
Carnegie Science’s research into symbiosis and species-species interactions is not just about understanding the natural world; it’s about leveraging this knowledge to address global challenges. From preserving coral reefs and advancing sustainable agriculture to exploring the human microbiome, the insights gained from these studies have the potential to transform our approach to health, food security, and environmental conservation. As we continue to unravel the secrets of symbiosis, we edge closer to a future where humans and nature thrive in harmony.
Inaugural Pew Marine and Biomedical Science Fellowship Awarded to Carnegie Coral Biologist
Carnegie biologist Phillip Cleves was selected by The Pew Charitable Trusts as one of seven recipients of the 2023 Pew Fellowship in Marine Conservation and the first researcher to receive the organization’s Marine and Biomedical Science Fellowship.
The Pew Marine and Biomedical Science Fellowship supports research that applies techniques or technologies more commonly used in biomedical science to enhance marine conservation. Cleves will use genome editing technology to study the genetic basis of bleaching in coral reefs in hopes of informing new conservation strategies, such as the selection and propagation of bleaching-resistant coral populations. Coral reefs around the world have suffered significantly due to warming ocean temperatures associated with climate change.
“Coral reefs are biodiversity hotspots in decline due to stressors associated with climate change. Despite this decline, we still know very little about cellular and genetic mechanisms underlying how corals and their intracellular symbiotic partners cope with a changing climate,” Cleves said. “Just as it has been essential to understand the genetic basis of human disease to develop novel therapeutics, we hope to provide a deeper understanding of the coral stress response to inspire new conservation strategies to preserve the reefs.”
Cleves joins Pew’s global community of 202 marine fellows from 42 countries all working to expand knowledge of the ocean and advance the sustainable use of marine resources. The Pew Fellows Program in Marine Conservation supports mid-career scientists and other experts seeking solutions to challenges affecting the world’s oceans.
Cleves is a leader in applying molecular genetics to study corals and coral bleaching. Among his breakthroughs was the successful CRISPR-mediated gene editing of reef corals. This award perfectly encapsulates his interdisciplinary expertise—deploying techniques that were developed for biomedical research to tackling the greatest environmental challenges facing our planet today.
The Pew Marine and Biomedical Science Fellowship is jointly administered by the Pew Fellows Program in Marine Conservation and the Pew Scholars Program in the Biomedical Sciences with support from the Herbert W. Hoover Foundation. Fellows are selected by an international committee of marine science experts with a range of expertise following a rigorous nomination and review process.
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