HMN 2025: How Some sea slugs eat algae, incorporate photosynthetic components into their very own our bodies to maintain producing vitamins

It could possibly be the plot of a summer time sci-fi blockbuster: A creature feeds on its prey and inherits its “superpower.” Only that is actual.

A brand new study led by Harvard biologists describes how some sea slugs eat algae and incorporate their photosynthetic organelles into their very own our bodies. The organelles proceed to carry out photosynthesis, offering vitamins and vitality to their hosts and serving as emergency rations in occasions of hunger.

“This is an organism that may steal components of different organisms, put them in their very own cells, and use them,” mentioned Corey Allard, lead writer of the brand new study and a former postdoc within the Department of Molecular and Cellular Biology. “And I assumed that was a number of the craziest biology I’d ever heard of.”

The study, published within the journal Cell, describes how so-called “solar-powered” sea slugs maintain the organelles alive inside “kleptosomes”—specialised membranes that operate like organic loot baggage. This analysis could yield insights into the evolution of eukaryotic cells and result in potential biomedical purposes.

“I feel the wow issue is that sea slugs can primarily steal ‘superpowers’—right here the power to make vitality from mild by algae,” mentioned Amy Si-Ying Lee, an assistant professor of cell biology at Harvard Medical School, researcher on the Dana-Farber Cancer Institute, and a review co-author. “Others steal the power to assault by stinging or the power to glow in the dead of night. And what’s very cool is we found out how they keep these stolen superpowers to make use of for their very own survival advantages.”

The study started a number of years in the past when Allard, now an assistant professor on the Medical School, labored within the Bellono Lab, which had been learning endosymbiosis, the method by which one species lives contained in the physique of one other. Unlike corals, which combine complete algae cells, sea slugs used solely components—tiny organelles inside the cells of their prey.

In the brand new paper, the workforce stories how the ocean slug Elysia crispata, a species native to the tropical waters of the western Atlantic and Caribbean, eat algae however don’t totally digest the chloroplasts.

Instead, the slugs divert these organelles into intestinal sacs and encase them inside a particular membrane that the scientists termed a “kleptosome.” Within this distinctive slug construction, the stolen organelles are stored alive to proceed photosynthesis.

Apparently, the slugs have developed a capability to downregulate the lysosomes, the “trash disposal” organelles of the cells that usually degrade such materials.

Chemical evaluation revealed that the stolen chloroplasts contained slug proteins. This suggests the hosts had been maintaining the stolen organelles alive. Meanwhile, the organelles continued to supply their very own algae proteins, proving they had been nonetheless functioning contained in the slugs.

The slugs stored the stolen organelles in leaf-like buildings atop their backs, (“Basically, it’s a photo voltaic panel,” says Allard) and well-fed slugs took on a greenish shade.

Then the researchers observed one other peculiarity: When slugs had been starved, their our bodies turned orange like leaves in autumn. Apparently, the chlorophyll (the inexperienced materials inside chloroplasts) was degraded when the stolen organelles had been digested as a “final resort” type of vitality.

Some of the prevailing scientific literature claimed the slugs totally lived off photo voltaic vitality, however Allard believes photosynthesis alone shouldn’t be ample to maintain them alive.

“The precise operate of this stuff could possibly be much more difficult than easy photo voltaic panels,” he mentioned. “They could possibly be meals reserves, camouflage, or make them style unhealthy to predators. It’s most likely all of these issues.”

The lowly slugs may present hints about some grand occasions within the historical past of life.

Endosymbiosis has been a serious driver of evolutionary novelty. For instance, each chloroplasts (which carry out photosynthesis in vegetation and algae) and mitochondria (the energy-producing components of cells) had been initially free-living cells that had been included as organelles inside host cells.

“In many methods of endosymbiosis, like our mitochondria or plant chloroplasts, that is the way it began: An historical prokaryotic cell was taken in and included into the host,” mentioned Nick Bellono, professor of molecular and mobile biology and senior writer of the brand new paper. “In the case of the slug, it is doing this in a single lifetime. Could this transition to a extra long-lasting relationship over some loopy period of time? Maybe.”

The historical occasions of endosymbiosis occurred billions of years in the past, so the proof has been misplaced to time. In the case of sea slugs, the biologists caught the organelle thieves within the act—enabling them to research endosymbiosis in actual time.

Elysia should not the one sea slugs identified to steal organelles. In his Med School lab, Allard is researching one other group of sea slugs from the genus Berghia that eat sea anemones, go the fabric by their digestive tracts, and mount the venom-coated barbs on their very own backs to defend in opposition to predators.

Even extra extremely, the slug hosts can join these stolen organelles to their very own nervous methods to fireplace what Allard described as a “bag filled with spear weapons.”

Allard believes the findings could prolong far past slugs. Insights in regards to the organelle regulation is likely to be relevant to neurodegenerative situations or to lysosomal storage issues, a category of metabolic ailments by which the physique can’t correctly break down waste merchandise.

“Often in these instances, the lysosomes both do not type correctly or do not work correctly,” defined Allard, “and it nearly mimics what the slugs have tailored to do in some methods.”

This story is revealed courtesy of the Harvard Gazette, Harvard University’s official newspaper. For extra college information, go to Harvard.edu.