The tiniest things on our planet are often the most captivating. You’ve likely heard about the “last common ancestor” of all living things, known as LUCA, which is essentially a unicellular prokaryotic organism holding the secret of our existence. However, recent discoveries have indicated that the origin of life occurred much earlier, all thanks to sediment found at the bottom of the sea. Now, near the Alaskan border, another minuscule creature has been added to the list.
The discovery. A group of UC Berkeley researchers made a historic breakthrough in the brackish waters of Mono Lake in the eastern Sierra Nevada. In particular, they found an unusual creature among the lake’s well-known tuff formations and abundant artemia.
This intriguing discovery turned out to be a microscopic single-celled life form, known as a choanoflagellate. What made it even more significant was that subsequent studies revealed it to be the closest living relative in the entire animal kingdom.
A unique creature. These tiny organisms have the ability to divide and develop into multicellular colonies, similar to the process by which animal embryos are formed. However, it’s important to clarify that these aren’t animals per se, although choanoflagellates are a key model for understanding the transition from unicellular to multicellular existence.
In any case, researchers found that this particular choanoflagellate, the first of its kind known to science, has its own microbiome, establishing a stable physical relationship with bacteria. “Very little is known about choanoflagellates, and there are interesting biological phonemena that we can only gain insight into if we understand their ecology,” Nicole King, a UC Berkeley professor who studies these creatures, told the university’s news site.
The study. According to the researchers, the study delves more than 650 million years into the past to uncover the origins of animals. Microscopic choanoflagellates, often overlooked by marine biologists, provide important clues about ancient oceans teaming with organisms that existed before animals.
In other words, this finding could help scientists understand the origins of animal-bacteria interactions, which could eventually lead to the development of the human microbiome. “Animals evolved in oceans that were filled with bacteria. If you think about the tree of life, all organisms that are alive now are related to each other through evolutionary time. So if we study organisms that are alive today, then we can reconstruct what happened in the past,” King says.
A surprising discovery. As it turns out, when researchers began analyzing this tiny creature, they unexpectedly found bacterial DNA inside the hollow colony. Upon further examination, they realized that the bacteria weren’t remnants of those consumed by the choanoflagellates, but rather bacteria living and grazing inside the colony. This unique symbiotic relationship, documented within a choanoflagellate, is the first of its kind.
Why this matters. As highlighted in the researchers’ paper, this discovery is important because it could be a critical step in understanding how bacteria influence choanoflagellate behavior, such as mating and colony formation.
The identification of this unusual specimen provides a new perspective for studying the interconnected relationships between microorganisms and their environment. It sheds light on the intricate web of life that shapes our ecosystems and potentially impacts our evolutionary history.
There’s more to it. In their study, the scientists conclude by highlighting their discovery’s potential long-term implications for modern science and medicine. Understanding the interactions between single-celled organisms and bacteria could offer insights into the early stages of multicellularity and its evolutionary benefits.
Furthermore, this research work may provide a better understanding of the intricate interactions within the human microbiome, potentially leading to advancements in the treatment of diseases associated with microbial imbalances.
Image | UC Berkeley
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