Sea Slugs, Optogenetics and Blooming Algae

…Elysia chlorotica must possess photosynthesis-supporting genes within its own nuclear genome; most likely acquired through horizontal gene transfer. In simple words, the sea slug stole the genes of its food- Vaucheria litorea, a phenomenon known as kleptoplasty. (photo source Photosynthetic sea slug: A mystery of genes - Save Our Green )

Vaucheria litorea - Wikipedia


Sea slug has taken genes from algae it eats, allowing it to photosynthesize like a plant

…“There is no way on earth that genes from an alga should work inside an animal cell,” Pierce says. "And yet here, they do. They allow the animal to rely on sunshine for its nutrition. So if something happens to their food source, they have a way of not starving to death until they find more algae to eat… the genes to maintain the chloroplasts are already present in the slug genome, Pierce says." Sea slug has taken genes from algae it eats, allowing it to photosynthesize like a plant -- ScienceDaily

A chloroplast /ˈklɔːrəˌplæst, -plɑːst/[1][2] is a type of membrane-bound organelle known as a plastid that conducts photosynthesis mostly in plant and algal cells. The photosynthetic pigment chlorophyll captures the energy from sunlight, converts it, and stores it in the energy-storage molecules ATP and NADPH while freeing oxygen from water in the cells. The ATP and NADPH is then used to make organic molecules from carbon dioxide in a process known as the Calvin cycle. Chloroplasts carry out a number of other functions, including fatty acid synthesis, much amino acid synthesis, and the immune response in plants. The number of chloroplasts per cell varies from one, in unicellular algae, up to 100 in plants like Arabidopsis and wheat… Chloroplasts are highly dynamic—they circulate and are moved around within plant cells, and occasionally pinch in two to reproduce. Their behavior is strongly influenced by environmental factors like light color and intensity. Chloroplasts, like mitochondria, contain their own DNA, which is thought to be inherited from their ancestor—a photosynthetic cyanobacterium that was engulfed by an early eukaryotic cell.[3] Chloroplasts cannot be made by the plant cell and must be inherited by each daughter cell during cell division. Chloroplast - Wikipedia

[2012] “Analysis of the transcriptome of the kleptoplastic sea slug, Elysia chlorotica, has revealed the presence of at least 101 chloroplast-encoded gene sequences and 111 transcripts matching 52 nuclear-encoded genes from the chloroplast donor, Vaucheria litorea… These results show that the symbiotic chloroplasts residing inside the host molluscan cell are maintained by an interaction of both organellar and host biochemistry directed by the presence of transferred genes.” Transcriptomic evidence for the expression of horizontally transferred algal nuclear genes in the photosynthetic sea slug, Elysia chlorotica - PubMed

[2012] ”Chloroplast lineages are likely to be derived from pre-existing transient symbioses, but it is as yet poorly understood what steps are required for the establishment of permanent chloroplasts from photosynthetic symbionts. In the past decade, several species that contain relatively recently acquired chloroplasts, such as the rhizarian Paulinella chromatophora, and non-photosynthetic taxa that maintain photosynthetic symbionts, such as the sacoglossan sea slug Elysia, the ciliate Myrionecta rubra and the dinoflagellate Dinophysis, have emerged as potential model organisms in the study of chloroplast establishment… We conclude by assessing whether chloroplast establishment is facilitated in some lineages by a mosaic of genes, derived from multiple symbiotic associations, encoded in the host nucleus.” What makes a chloroplast? Reconstructing the establishment of photosynthetic symbioses - PubMed

Emiliania huxleyi is a species of coccolithophore found in almost all ocean ecosystems from the equator to sub-polar regions, and from nutrient rich upwelling zones to nutrient poor oligotrophic waters… It is studied for the extensive blooms it forms in nutrient-depleted waters after the reformation of the summer thermocline. Like other coccolithophores, E. huxleyi is a single-celled phytoplankton covered with uniquely ornamented calcite disks called coccolithsEmiliania huxleyi was named after Thomas Huxley and Cesare Emiliani, who were the first to examine sea-bottom sediment and discover the coccoliths within it. It is believed to have evolved approximately 270,000 years ago from the older genus Gephyrocapsa Kampter[5][6] and became dominant in planktonic assemblages, and thus in the fossil record, approximately 70,000 years ago.[5][7] It is the most numerically abundant and widespread coccolithophore species.

…”As with all phytoplankton, primary production of E. huxleyi through photosynthesis is a sink of carbon dioxide. However, the production of coccoliths through calcification is a source of CO2. This means that coccolithophores, including E. huxleyi, have the potential to act as a net source of CO2 out of the ocean. Whether they are a net source or sink and how they will react to ocean acidification is not yet well understood.

“Scattering stimulated by E. huxleyi blooms not only causes more heat and light to be pushed back up into the atmosphere than usual, but also cause more of the remaining heat to be trapped closer to the ocean surface. This is problematic because it is the surface water that exchanges heat with the atmosphere, and E. huxleyi blooms may tend to make the overall temperature of the water column dramatically cooler over longer time periods. However, the importance of this effect, whether positive or negative, is currently being researched and has not yet been established.”

Algae genome could aid medical, climate research

[June 2013] “A ubiquitous phytoplankton found in oceans around the world could hold the key to fields ranging from climatology to dentistry, since a team of scientists led by Cal State San Marcos researchers unlocked the genomes for 14 different strains of the algae. Their findings, published last week in the journal Nature, decoded the DNA of related strains of the algae Emiliania huxleyi. Their study is one of only a handful to unravel the genomes of marine algae and the first ever to document a pan genome - a set of core genes shared by diverse algal varieties. ‘It’s still very rare to have a whole genome sequence for any marine phytoplankton,’ said Sonya Dyhrman, a professor of microbial oceanography at Columbia University and a co-author of the study. “It’s absolutely unprecedented to have multiple strains of the same species sequenced.” While the different strains share 70 to 80 percent of their DNA, about 20 to 30 percent of their genes are unique to each strain. That diversity allows them to inhabit virtually all the world’s oceans except the polar seas, said lead author Betsy Read, a professor of molecular cell biology at CSUSM.

“ ‘They have this tremendous ability to adapt,’ she said. ‘This is why we can pull them from almost every bucket of water in the ocean.’ Read released the findings in the journal Nature last week, in collaboration with CSUSM computer science professor Xiaoyu Zhang, Dyhrman and about two dozen co-authors from a far-flung network of institutions in the United States, Germany, England, France. The findings, Dyhrman said, are as valuable to microbiology as decryption of the human genome has proven to medicine. ‘Any time you unlock that code, it gives you this Rosetta stone to understand how that organism works and how it interacts with its environment,’ she said. The algae are the third most abundant phytoplankton, and are a key component of the ocean food chain, nourishing animals including crustaceans, shellfish and other filter feeders. They’re characterized by their intricate shells, composed of interwoven lattices of calcium carbonate. ‘We kind of think of them as flowers of the ocean,’ Read said.

Those shells reflect light, tinting the ocean surface a milky turquoise shade and leaving chalky remains. The White Cliffs of Dover owe their pale hue to fossilized remains of the algae. Their massive blooms spread across hundreds of thousands of square kilometers of the ocean, rendering them visible in satellite photos. ‘They’re arguably the most important species you can see from outer space, because of the light reflecting properties of its shell,’ Read said. The creatures absorb calcium dioxide to build their shells, playing a crucial role in the global carbon cycle. The family of phytoplankton they belong to can account for 20 percent of total carbon fixation in some systems, the study stated. In addition**, the organic sulfur compounds that E huxleyi release are known to seed clouds and could influence weather**, researchers said. ‘It fixes carbon for energy and its shell, but also releases carbon,’ Read said, noting that scientists are examining the balance between its carbon use and carbon emissions.

‘E. huxleyi represents one of the most cosmopolitan phytoplankton in the world’s oceans,’ said Christopher Gobler, a professor of marine and atmospheric sciences at Stony Brook University in New York, who published the genome for a separate variety of marine algae in 2011. ‘They’re very, very important on the global scale for controlling the earth’s carbon budget.’Their genome could reveal ways to monitor carbon dioxide in the atmosphere and ocean by identifying the genes that trigger processes such as photosynthesis and calcification. And it can help scientists study, through ‘hind-casting,’ the role the algae played in climate during other geologic periods, Dyhrman said.

“The algae’s genetic blueprint could also inspire innovation in medicine and technology. Their natural light-reflecting properties could illuminate development of optoelectronics - devices that produce or control light - Read said. And their shell-forming process could pave the way for calcium-based biomedical devices, such as joint replacements or dental implants. It could also help explain the healthy calcification that happens during bone growth, as well the unhealthy calcium deposits that occur in conditions such as kidney stones and heart disease. ‘Knowing the genes and proteins opens up more waves of research to answer these questions,’ Read said.


[2015] In this study, we present experimental evidence showing that coccoliths have light-scattering anisotropy that contributes to a possible control of solar light exposure in the ocean. Changing the angle between the incident light and an applied magnetic field causes differences in the light-scattering intensities of a suspension of coccoliths isolated from Emiliania huxleyi. The magnetic field effect is induced by the diamagnetic torque force directing the coccolith radial plane perpendicular to the applied magnetic fields at 400 to 500 mT. The developed technique reveals the light-scattering anisotropies in the 3-μm-diameter floating coccoliths by orienting themselves in response to the magnetic fieldsLight intensity modulation by coccoliths of Emiliania huxleyi as a micro-photo-regulator | Scientific Reports

Note this reference @Stephers : PRESTO, Japan Science and Technology Agency (JST), Saitama, 332-0012, Japan

“The purpose of PRESTO is promoting unique and challenging, internationally high-level basic research to… produce creative and innovative technology seeds (new technology seeds) based on new scientific knowledge as a source of scientific and technological innovation that can transform society and the economy…” About The Program | PRESTO

Proton-transporting heliorhodopsins from marine giant viruses

[2022] Abstract

“Rhodopsins convert light into signals and energy in animals and microbes. Heliorhodopsins (HeRs), a recently discovered new rhodopsin family, are widely present in archaea, bacteria, unicellular eukaryotes, and giant viruses, but their function remains unknown. Here, we report that a viral HeR from Emiliania huxleyi virus 202 (V2HeR3) is a light-activated proton transporter. V2HeR3 absorbs blue-green light…” Proton-transporting heliorhodopsins from marine giant viruses - PubMed

Optogenetic Tools Restore Cell Function with Blue Light

August 2022

CINCINNATI, Aug. 22, 2022 — Researchers from the University of Cincinnati (UC), the University of Illinois Urbana-Champaign (UI), and the University at Buffalo (UB) used an optogenetic technique to bring together mitochondria and lysosomes in human stem cells, to revitalize the cells’ fission process.

Mitochondria are dynamic organelles that constantly undergo the processes of fission — separating — and fusion — coming together— in healthy cells. An imbalance in these processes can lead to neurodegenerative diseases such as dementia and certain cancers.

Previous research showed that lysosomes, another type of organelle, can induce mitochondrial fission. Once they are brought in contact with mitochondria, lysosomes act like tiny scissors, cutting and dividing the mitochondria.

The researchers attached two different proteins to the mitochondria and the lysosomes within the stem cells, and stimulated the proteins with blue light. The light-activated proteins bound to each other to form one new protein. In the process, they brought the mitochondria and lysosomes together.

Optogenetics borrows these light-sensitive proteins from plants and uses them in animal cells,” said UI professor Kai Zhang, who developed the optogenetic tools for controlling mitochondria and lysosomes with blue light. “By attaching such proteins to organelles, one can use light to control the interaction between them, such as mitochondria and lysosomes shown in this work.”

… Further research from Zhang’s lab will include developing new optogenetic systems that work with different colors of light, including green, red, and infrared, since a longer wavelength will be needed to penetrate human tissue.

“We would like to further expand the toolbox by introducing multicolor optogenetic systems to give us multiple ways to control how organelles behave and interact,” Zhang said. “For instance, one color makes organelles come together, while the other color forces them apart. This way, we can precisely control their interactions.”

The team hopes to progress from using human stem cells for its research to testing the efficacy of its technique in animal models, as a step toward eventually testing the technique in humans through clinical trials. Diao said that other research groups are studying the use of magnetic fields and acoustic vibrations to accomplish results similar to the team’s light-based technique.

The research was published in Nature Communications (

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This is really fascinating @jenlake. Of course the early radio-isotope work was around photosynthesis. I’ve had at least one person who describes themselves as a TI conjecture that one goal is to make humans photosynthesize. This person also mentioned fungal / spore integration into human biological systems for control purposes.

I can totally see the “adaptability” frame being applied to humans under climate crisis conditions.