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Permalink Reply by Dr. Krishna Kumari Challa on April 28, 2020 at 8:41am

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Flashes bright when squeezed tight: How single-celled organisms light up the oceans

Research explains how a unicellular marine organism generates light as a response to mechanical stimulation, lighting up breaking waves at night.

Every few years, a bloom of microscopic organisms called dinoflagellates transforms the coasts around the world by endowing breaking waves with an eerie blue glow.

In a new study published in the journal Physical Review Letters, researchers have identified the underlying physics that results in light production in one species of these organisms.

The international team, led by the University of Cambridge, developed unique experimental tools based on micromanipulation and high-speed imaging to visualize light production on the single-cell level. They showed how a single-celled organism of the species Pyrocystis lunula produces a flash of light when its cell wall is deformed by mechanical forces. Through systematic experimentation, they found that the brightness of the flash depends both on the depth of the deformation and the rate at which it is imposed.

Known as a 'viscoelastic' response, this behavior is found in many complex materials such as fluids with suspended polymers. In the case of organisms like Pyrocystis lunula, known as dinoflagellates, this mechanism is most likely related to ion channels, which are specialized proteins distributed on the cell membrane. When the membrane is stressed, these channels open up, allowing calcium to move between compartments in the cell, triggering a biochemical cascade that produces light.

These findings reveal the physical mechanism by which the fluid flow triggers light production and show how elegant decision-making can be on a single-cell level.

The bioluminescence in the ocean is, however, not 'uneffectual.' In contrast, it is used for defense, offense, and mating. In the case of dinoflagellates, they use light production to scare off predators.

The results of the current study show that when the deformation of the cell wall is small, the light intensity is small no matter how rapidly the indentation is made, and it is also small when the indentation is large but applied slowly. Only when both the amplitude and rate are large is the light intensity maximized. The group developed a mathematical model that was able to explain these observations quantitatively, and they suggest that this behavior can act as a filter to avoid spurious light flashes from being triggered.

Stress-Induced Dinoflagellate Bioluminescence at the Single Cell Level, Physical Review Letters (2020). DOI: 10.1103/PhysRevLett.125.028102

https://phys.org/news/2020-07-bright-tight-single-celled-oceans.htm...

Permalink Reply by Dr. Krishna Kumari Challa on March 9, 2024 at 8:28am

Harnessing the mechanisms of fungal bioluminescence to confer autonomous luminescence in plant and animal cells

In a striking new study published in Science Advances, a team of synthetic biologists  has reported the discovery of multiple plant enzymes—hispidin synthases—that can perform the most complex reaction of the bioluminescence pathway.

This discovery is a significant milestone toward figuring out whether plants can natively produce all the molecules required for light emission. It also means that the glow of bioluminescent plants can now be more closely aligned with their internal biology.
The technology reported in the paper is a hybrid pathway that couples the newly found plant hispidin synthases to other necessary bioluminescence enzymes found in mushrooms. This hybrid pathway allows the subtle inner rhythms and dynamics within plants to be unveiled as an ever-changing display of living light.
This technology is a plug-and-play tool to visualize virtually any molecular physiology at the organismal level, completely non-invasively.
The work also revealed that not only does a single indigenous plant gene effectively substitute for two fungal genes, the plant gene is notably smaller and has simpler biological requirements for luminescence. The gene's reduced size also enhances its usability and flexibility, making it more adaptable for extended applications.
The first product to exploit the hispidin-based pathway is Firefly Petunia, so named because its bright light-emitting flower buds resemble fireflies.
Beyond the advances in aesthetics that luminous vegetation may provide to plant lovers, the foundational science offers profound insights into plant molecular physiology. By enabling continuous monitoring of plant responses to various stresses, such as drought stress or attacks by pests, the technology may lead to significant progress in fields such as crop development and disease resistance.
This bioluminescence pathway has been replicated in other species including yeast and even in human cells.

Kseniia Palkina et al, A hybrid pathway for self-sustained luminescence, Science Advances (2024). DOI: 10.1126/sciadv.adk1992. www.science.org/doi/10.1126/sciadv.adk1992

Permalink Reply by Dr. Krishna Kumari Challa on April 25, 2024 at 11:41am

Bioluminescence first evolved in animals at least 540 million years ago, pushing back previous oldest dated example

Bioluminescence first evolved in animals at least 540 million years ago in a group of marine invertebrates called octocorals, according to the results of a new study from scientists with the Smithsonian's National Museum of Natural History.

The results, published April 23, in the Proceedings of the Royal Society B: Biological Sciences, push back the previous record for the luminous trait's oldest dated emergence in animals by nearly 300 million years, and could one day help scientists decode why the ability to produce light evolved in the first place.

Bioluminescence—the ability of living things to produce light via chemical reactions—has independently evolved at least 94 times in nature and is involved in a huge range of behaviors including camouflage, courtship, communication and hunting. Until now, the earliest dated origin of bioluminescence in animals was thought to be around 267 million years ago in small marine crustaceans called ostracods.
But for a trait that is literally illuminating, bioluminescence's origins have remained shadowy.

Nobody quite knows why it first evolved in animals.
In search of the trait's earliest origins, the researchers decided to peer back into the evolutionary history of the octocorals, an evolutionarily ancient and frequently bioluminescent group of animals that includes soft corals, sea fans and sea pens.

Like hard corals, octocorals are tiny colonial polyps that secrete a framework that becomes their refuge, but unlike their stony relatives, that structure is usually soft. Octocorals that glow typically only do so when bumped or otherwise disturbed, leaving the precise function of their ability to produce light a bit mysterious.

Octocorals are one of the oldest groups of animals on the planet known to bioluminescence. "So, the question 's when did they develop this ability?"
Researchers had completed an extremely detailed, well-supported evolutionary tree of the octocorals in 2022. They created this map of evolutionary relationships, or phylogeny, using genetic data from 185 species of octocorals.

With this evolutionary tree grounded in genetic evidence, DeLeo and Quattrini then situated two octocoral fossils of known ages within the tree according to their physical features. The scientists were able to use the fossils' ages and their respective positions in the octocoral evolutionary tree to date to figure out roughly when octocoral lineages split apart to become two or more branches.

Next, the team mapped out the branches of the phylogeny that featured living bioluminescent species.

With the evolutionary tree dated and the branches that contained luminous species labeled, the team then used a series of statistical techniques to perform an analysis called ancestral state reconstruction.
If we know these species of octocorals living today are bioluminescent, we can use statistics to infer whether their ancestors were highly probable to be bioluminescent or not. The more living species with the shared trait, the higher the probability that as you move back in time that those ancestors likely had that trait as well.
The researchers used numerous different statistical methods for their ancestral state reconstruction, but all arrived at the same result: Some 540 million years ago, the common ancestor of all octocorals were very likely bioluminescent. That is 273 million years earlier than the glowing ostracod crustaceans that previously held the title of earliest evolution of bioluminescence in animals.
The octocorals' thousands of living representatives and relatively high incidence of bioluminescence suggests the trait has played a role in the group's evolutionary success. While this further begs the question of what exactly octocorals are using bioluminescence for, the researchers said the fact that it has been retained for so long highlights how important this form of communication has become for their fitness and survival.

Evolution of bioluminescence in Anthozoa with emphasis on Octocorallia, Proceedings of the Royal Society B: Biological Sciences (2024). DOI: 10.1098/rspb.2023.2626. royalsocietypublishing.org/doi … .1098/rspb.2023.2626