Scientists Discover Vertebrates Acquired Unique Protein from Bacteria Half a Billion Years Ago
The intricate visual system possessed by humans and other vertebrates, resembling a camera, has been traced back 500 million years to an extraordinary protein obtained from foreign bacterial sources. This groundbreaking finding sheds light on the evolution of vertebrate vision.
Charles Darwin, while developing his theory of natural selection, recognized the complexity of the eye as a potential challenge, given its remarkable capabilities that seemed difficult to explain through gradual evolutionary steps.
The distinction in visual prowess between vertebrates and invertebrates can be attributed to a specific protein responsible for the specialization of cells crucial for vision. Known as IRBP (interphotoreceptor retinoid-binding protein), mutations in this protein have been linked to various diseases, including retinitis pigmentosa. However, until now, the origin of IRBP remained a mystery, lacking an apparent genetic precursor.
In a recent study published in the Proceedings of the National Academy of Sciences, scientists from the University of California San Diego School of Biological Sciences employed phylogenetic reconstruction methods to uncover the ancient bacterial origin of vertebrate IRBP. Their investigation, made possible by the wealth of detailed genomic data available today, encompassed the analysis of over 900 genomes spanning the tree of life.
Contrary to expectations, the integration of IRBP into vertebrate eyes did not occur through traditional vertical gene transfer, which involves the modification of existing genetic material. Instead, it was acquired, duplicated, and incorporated through horizontal gene transfer from foreign bacterial genes.
“This discovery represents a significant shift because an entirely novel piece of genetic material has been introduced from bacteria,” explained Professor Matt Daugherty, the senior author of the paper in the Department of Molecular Biology. The study was led by former UC San Diego undergraduate student Chinmay Kalluraya, with computational expertise provided by UC San Diego graduate students Alexander Weitzel and Brian Tsu.
By acquiring the key gene that ultimately became IRBP from bacteria, a new pathway emerged in vertebrates, enabling efficient recycling of retinoids—molecules in the eye responsible for light sensing—between different cell types. This separation of photoreception and retinoid recycling bestowed unique functionality upon vertebrates and their visual capabilities.
The researchers emphasize that as more genomes from diverse organisms become available, it is likely that other essential functions and systems will also be traced back to bacterial origins. This redefines our understanding of evolution and complex structures that appear to have emerged seemingly out of nowhere.
The study received funding from the National Institutes of Health, Pew Biomedical Scholars, the Burroughs Wellcome Fund Investigators in the Pathogenesis of Infectious Disease, UC San Diego’s Halıcıoğlu Data Science Institute, UC San Diego Triton Research, and Experimental Learning Scholars.
Coauthored by Kalluraya, a recipient of the Selma and Robert Silagi Award for Undergraduate Excellence at UC San Diego and now a graduate student at MIT, along with Weitzel, Tsu, and Daugherty, the paper represents a significant contribution to our understanding of the bacterial origins of vertebrate vision.
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Frequently Asked Questions (FAQs) about bacterial origins of vertebrate vision
What is the significance of the discovery regarding the bacterial origins of vertebrate vision?
The discovery sheds light on the evolutionary origins of vertebrate vision, specifically the key role played by a unique protein acquired from bacteria 500 million years ago. It provides insights into the genetic innovation that contributed to the development of vertebrate eyes and their distinct visual capabilities.
What is the protein responsible for the specialization of cells in vision?
The protein responsible for the specialization of cells in vision is called interphotoreceptor retinoid-binding protein (IRBP). It plays a vital role in vertebrate vision by facilitating the efficient recycling of retinoids, the molecules in the eye responsible for light sensing, between different cell types.
How was the integration of IRBP into vertebrate eyes accomplished?
Contrary to traditional vertical gene transfer, the integration of IRBP into vertebrate eyes occurred through horizontal gene transfer. This means that the gene responsible for IRBP was acquired, duplicated, and integrated from foreign bacterial genes rather than being modified from existing genetic material.
What implications does this discovery have for our understanding of evolution?
The discovery challenges the notion of gradual evolutionary steps in the development of complex structures. It highlights the potential for major genetic innovations to arise through horizontal gene transfer, where entirely new genetic material is introduced from bacteria. This suggests that bacterial origins may have played a more significant role in the evolution of various functions and systems than previously thought.
How might this research impact future studies?
With the availability of detailed genomic data and advancements in phylogenetic reconstruction methods, future studies can further explore the bacterial origins of other critical functions and systems. This research opens up new avenues for understanding the genetic innovations underlying complex structures and biological processes in different organisms.
More about bacterial origins of vertebrate vision
- University of California San Diego: Link
- Proceedings of the National Academy of Sciences: Link
- National Institutes of Health: Link
- Pew Biomedical Scholars: Link
- Burroughs Wellcome Fund Investigators in the Pathogenesis of Infectious Disease: Link
- Halıcıoğlu Data Science Institute, UC San Diego: Link
- UC San Diego Triton Research and Experimental Learning Scholars: Link
5 comments
amazing how a tiny protein from bacteria can have such a huge impact on our vision. opens up a whole new understanding of complex structures and the role bacteria play in evolution. fascinating stuff!
wow scientists find bacterial origins of vertebrate vision, who knew?! crazy stuff! bacteria are cool.
this discovery is super important for our understanding of evolution and how our eyes evolved. it’s like a whole new piece of genetic material came from bacteria! mind-blowing!
i love learning about the complexity of the eye. so cool that this protein called IRBP is responsible for our amazing vision. it came from bacteria?? mind = blown!
horizontal gene transfer FTW! this study shows how genetic innovations can come from unexpected sources. bacteria have been influencing our evolution more than we thought. mind-boggling research!