Feast or famine: how sea anemones resize their bodies to survive
In a recent article, researchers from the Steinmetz group characterized the astonishing ability of sea anemones to adapt to food availability by growing and shrinking their body throughout their lives.
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A team of researchers led by from the group of Patrick Steinmetz at the Michael Sars Centre, in collaboration with from the Department of Mathematics at 幸运飞艇计划, focuses on quantifying and characterizing body plasticity in sea anemones. Their results, newly published in the journal , offer new insights into how living organisms adapt to their surroundings and survive without food.
When observing two species of sea anemones in the laboratory, Kathrin and co-author Daria Filimonova noticed that the animals displayed incredible size variations during their lifetime, growing when they have plenty to eat and shrinking when food is scarce. Most interestingly, these drastic changes in body size occurred in a stereotypical fashion. 鈥淚 find the ability of sea anemones to adjust growth to feeding remarkable and it is entirely understudied鈥�, Kathrin explained. 鈥淢ost genetic model organisms don't show this plasticity, so there's nothing we can learn from models like Drosophila about this fantastic trait.鈥�
鈥淚 find the ability of sea anemones to adjust growth to feeding remarkable and it is entirely understudied鈥�
鈥� Kathrin Garschall
This ability to match their size to their environment involves significant changes at the cellular level in the animals. To reveal these mechanisms, the team combined flow cytometry techniques to count and characterize cells, a technique spearheaded in the group by postdoc Eudald Pascual Carreras, with mathematical modelling. Their efforts revealed the most striking discovery of the project: the scale and speed at which this phenomenon occurs. 鈥淎fter feeding, the animal can within two days more than double the number of cells, and it can half the number of cells within a few days of starvation鈥�, Kathrin explained. 鈥淢ost economically you would assume that the animal eats them up again, but the lost cells may just be spat out into the water? Nobody knows yet.鈥�
The multidisciplinary approach adopted by the team was instrumental in understanding their initial biological observations. 鈥淭his is a really exciting example of where modelling and experimental approaches can mutually reinforce鈥�, Iain Johnston explained. 鈥淚t wasn鈥檛 just 鈥渙h let鈥檚 build a model too鈥� or 鈥渙h let鈥檚 do some experiments too鈥� 鈥� the combination of lab work and maths was required to make the scientific progress we did鈥�. Kathrin agreed, adding, 鈥淭he collaboration was extremely enriching for the project and solidified our observations. It allowed us to frame independent experiments into a process that can be quantified and to a large degree predicted.鈥�
Juvenile Nematostella vectensis sea anemones feast on crustacean larvae.
In addition to characterizing the scale of body size variations, the study shows that sea anemones control this plasticity by regulating the cell cycle. When blocking the TOR pathway, a key nutrient sensing pathway, the team observed that the animals were unable to grow even when fed abundantly. 鈥淭he accessibility of nutrients and the relay of this information through the TOR pathway has a major impact on whether sea anemone cells divide or not鈥�, Kathrin explained. By promoting cell growth when food is available and slowing it down when food is scarce, the TOR pathway allows the anemones to survive in fluctuating ecological conditions.
By providing the first rigorous characterization of a phenomenon that had only been observed anecdotally, the study showcases the incredible adaptability of sea anemones. This work lays the foundations for future projects on the nutrient regulation of growth in animals, and opens up new avenues for scientists to explore how organisms might cope with changing environmental conditions.听
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