2023-05-09 10:45:48
Cholesterol and phytosterols are sterols, essential fatty compounds for many biological processes, such as the functioning of cell membranes. Until now, it was believed that phytosterols were exclusive to plants, as cholesterol is typical of animals, and that only plants could manufacture phytosterols. A finding has just turned this widespread idea upside down.
Dolma Michellod, Nicole Dubilier and Manuel Liebeke, all three from the Max Planck Institute for Marine Microbiology in Germany, were shocked to discover that a small marine worm called Olavius algarvensis, which lives in the Mediterranean seagrass meadows, has far more phytosterol than cholesterol. .
“We knew that these worms can’t feed on seagrass beds because they don’t have a mouth or gut,” explains Michellod. “We next wondered if the symbiotic bacteria inside the Olavius, which provide them with their nutrition, could make phytosterols, but they don’t,” adds Dubilier. “We were also able to rule out that the worms absorbed phytosterols through the skin. It was then that we realized that the worms must make the phytosterols themselves,” explains Liebeke.
The researchers from the Max Planck Institute for Marine Microbiology, together with colleagues from the Center for Marine Sciences in Bremen, the University of Münster, the University of Hamburg, these three institutions in Germany, as well as North Carolina State University in the United States United States and Imperial College London in the United Kingdom, used a host of analytical techniques including worm DNA and RNA sequencing, protein and metabolite analysis, and sterol imaging to corroborate that the worms are produced by the worm. phytosterols, and that the main phytosterol it produces is sitosterol. This study is the first to show that a metazoan animal can synthesize phytosterols.
The marine worm Olavius algarvensis under a microscope. It is about 2 centimeters long and only 0.5 millimeters wide, and lives among the grains of sand (several of which are also shown in the photo) in the seagrass beds of the Mediterranean Sea. (Photo: Rebekka Jahnke / Max Planck Institute for Marine Microbiology)
Even more surprising to the researchers was the discovery that the gene needed to make sitosterol from cholesterol precursors is widespread in the animal kingdom. “We have discovered a gene that has long been thought to be lost in the evolutionary history of animals,” explains Liebeke. This gene is present in many different groups of animals, from corals and earthworms to clams and mussels. “This means that there is a strong selective advantage for animals to have the gene that allows them to make phytosterols,” adds Dubilier.
The study in which these findings have been made is entitled “De novo phytosterol synthesis in animals”. And it has been published in the academic journal Science. (Fountain: NCYT de Amazings)
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