phytosterols
Study describes marine worms that can synthesize phytosterols de novo,
and shows that many other animals have the genes to make these plant sterols


Date:
May 4, 2023
Source:
Max Planck Institute for Marine Microbiology
Summary:
Phytosterols are good for your health, but humans and other animals
are not able to make them themselves, only plants can. To acquire
phytosterols, humans are increasingly turning to supplements, green
smoothies, or a Mediterranean diet with plenty of plant-based foods.

Researchers have now discovered that tiny gutless worms from the
Mediterranean can synthesize phytosterols on their own. Their
study provides evidence that many other animals also have the
genes needed to make their own phytosterols.


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==========================================================================
FULL STORY ========================================================================== Cholesterol and phytosterol are sterols, fatty compounds essential for
many biological processes such as the functioning of cell membranes. Up to
now, it has been assumed that phytosterols are characteristic for plants,
and cholesterol for animals, and that only plants can make phytosterols,
while animals typically make cholesterol. Dolma Michellod, Nicole Dubilier
and Manuel Liebeke from the Max Planck Institute for Marine Microbiology
in Bremen, Germany, were therefore surprised when they discovered that
a small marine worm called Olavius algarvensis, which lives in seagrass
beds in the Mediterranean, has much more phytosterol than cholesterol.

"We knew the worms couldn't be eating the seagrass because they do
not have a mouth or gut," explains first author Michellod. "We next
wondered if the symbiotic bacteria inside Olavius, which provide them
with their nutrition, might make phytosterols, but this wasn't the case"
adds Dubilier. "We were also able to exclude that the worms were taking
up phytosterols through their skin.

It was only then that we realized that the worms must be making the phytosterols themselves" explains Liebeke.

The Max Planck researchers, together with colleagues from the MARUM --
Center for Marine Environmental Sciences in Bremen, the University of
Mu"nster, the University of Hamburg, North Carolina State University and Imperial College London, used a wealth of methods that included sequencing
of the worm's DNA and RNA, protein and metabolite analyses and imaging
of sterols to reveal that it is the worm that makes the phytosterols,
and that the main phytosterol they make is sitosterol. Their study is
the first to show that a metazoan animal can synthesize phytosterols
and was published in the journal Science on May 5th.

From worms to corals -- five animal phyla have the genes for making phytosterols Even more surprising for the researchers was their
discovery that the gene needed to make sitosterol from precursors of cholesterol is widespread in the animal kingdom. "We discovered a gene
that was thought to have been lost long ago in the evolution of animals," explains Liebeke. Michellod adds: "It was exhilarating to discover this
gene in so many different groups of animals, from corals and earthworms
to clams and mussels." "This means there is a strong selective advantage
for animals in having the gene that allows them to make phytosterols. We
think phytosterols might make animal membranes more permeable, but so far, that's just wild speculation," adds Dubilier.

The Good, the Bad, and the Ugly: Understanding the role of cholesterol
and phytosterols So far, sterol research in animals has focused
on cholesterol. Known for being "The Good, the Bad, and the Ugly,"
some forms of cholesterol are essential for building cell membranes and producing hormones, while others are harmful and can block blood vessels,
and increase the risk for cardiovascular diseases. A wealth of recent
findings on the benefits of phytosterols for humans indicate that they
may improve blood cholesterol levels, thereby reducing the risk of heart attacks or strokes. But the precise manner in which phytosterols provide benefits is far from understood. The researchers from the Max Planck
Institute for Marine Microbiology are convinced that the tiny marine worm Olavius algarvensis is a valuable model organism for better understanding
the beneficial role of plant sterols for animal health and well-being.

* RELATED_TOPICS
o Health_&_Medicine
# Cholesterol # Heart_Disease # Diseases_and_Conditions
o Plants_&_Animals
# Life_Sciences # Marine_Biology # Wild_Animals
o Earth_&_Climate
# Oceanography # Rainforests # Environmental_Awareness
* RELATED_TERMS
o Mediterranean_diet o Herbivore o Dog_health o Nutrition o
Health_science o Healthy_diet o Micronutrient o Jane_Goodall

========================================================================== Story Source: Materials provided by Max_Planck_Institute_for_Marine_Microbiology. Note: Content may be edited
for style and length.


========================================================================== Journal Reference:
1. Dolma Michellod, Tanja Bien, Daniel Birgel, Marlene Violette, Manuel
Kleiner, Sarah Fearn, Caroline Zeidler, Harald R. Gruber-Vodicka,
Nicole Dubilier, Manuel Liebeke. De novo phytosterol synthesis
in animals.

Science, 2023; 380 (6644): 520 DOI: 10.1126/science.add7830 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2023/05/230504155632.htm

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