Ancient Biomarkers: Cyanobacteria, pivotal in Earth’s history for introducing atmospheric oxygen, have long intrigued scientists. Fossil lipids called 2-methylhopanes were once believed to be exclusive markers of Cyanobacteria. However, recent discoveries challenged this notion when it was found that Alphaproteobacteria could also produce these lipids genetically.
An international research team, led by Yosuke Hoshino from the GFZ German Research Centre for Geosciences and Benjamin Nettersheim from the University of Bremen, delved into the phylogenetic evolution of genes responsible for 2-methylhopane lipid synthesis. Their findings indicate that HpnP, a crucial gene for these lipids, likely existed in the last common ancestor of Cyanobacteria over two billion years ago but appeared in Alphaproteobacteria only about 750 million years ago. This data confirms 2-methylhopanes as reliable biomarkers for oxygen-producing Cyanobacteria in periods predating the Alphaproteobacteria’s acquisition of the gene.
Published in the journal Nature Ecology & Evolution, this study showcases how genetics, sedimentology, paleobiology, and geochemistry can enhance the diagnostic utility of biomarkers, refining our understanding of early ecosystems. Cyanobacteria’s role in Earth’s transition from an oxygen-depleted state to a life-sustaining oxygen-rich environment is a critical piece in the puzzle of our planet’s history. Whole Cyanobacteria fossils can serve as indicators of oxygenic photosynthesis, but due to preservation challenges, geochemists have turned to fossilized diagnostic lipids, such as 2-methylhopanes, for insights.
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However, doubts arose regarding the suitability of 2-methylhopanes as biomarkers when the lipid biosynthesis gene was found in Alphaproteobacteria, making it impossible to precisely trace oxygen-producing processes on Earth. Yosuke Hoshino, Christian Hallmann, and Benjamin Nettersheim’s team systematically investigated the presence of genes (SC and HpnP genes) responsible for 2-methylhopanoid production in various organisms, shedding light on when these genes were acquired during evolution. Their findings affirm that 2-methylhopane lipids remain reliable biomarkers for Cyanobacteria dating back over 750 million years.
Moreover, the researchers created a comprehensive record of 2-methylhopane production throughout Earth’s history by combining molecular data with high-purity sediment analyses. This innovative approach offers the potential to trace the evolution of diverse ecosystems with greater temporal and spatial resolution.
In the quest to understand Earth’s past and the role of key species like Cyanobacteria, this research takes us one step closer to unraveling our planet’s complex history.
Our Reader’s Queries
What are the 7 types of biomarkers?
Biomarkers are classified into various types such as diagnostic, monitoring, pharmacodynamic/response, predictive, prognostic, safety, susceptibility/risk, and prognostic versus predictive biomarkers. Each type serves a unique purpose in identifying and predicting diseases, monitoring treatment response, and assessing safety. While predictive biomarkers help in predicting the response to a particular treatment, prognostic biomarkers provide information about the disease outcome. It is essential to understand the differences between these biomarkers to make informed decisions about patient care.
What is biomarkers in history of life?
Biomarkers, also known as “markers of life” or “traces of life,” are biogenic chemical, morphological, sedimentary, or isotopic processes or structures that can be detected to determine the past or present existence of life. These unique indicators provide valuable insights into the presence of life and its evolution over time.
What are biomarkers in fossils?
Biomarkers are like ancient molecular fossils of natural products, such as lipids. When these lipids manage to escape the remineralization process in sedimentary environments, they are often chemically reduced to hydrocarbon skeletons. These skeletons can then be preserved in sedimentary rocks for millions upon millions of years.
What is an example of a biomarker?
Biomarkers can act as a preemptive measure for your health. For instance, elevated levels of lead in the blood may suggest a requirement to examine for cognitive and nervous system disorders, particularly in kids. High cholesterol levels are a prevalent biomarker for the risk of heart disease.