Marine Proteorhodopsins Rival Photosynthesis in Solar Energy Capture

While photosynthesis is the process that plants use to convert sunlight directly into energy-rich molecules, chemoautotrophs—organisms that can generate their own energy through chemical processes—have developed a way to get around the limitations of their energy-poor environment: they have harnessed the power of light. The most recent innovation in this area of research involves the discovery of marine rhodopsins, a type of light-driven protein that can be found in algae and marine life. Because these proteins absorb light very well, the first prototypes of artificial photosynthetic devices were constructed using these proteins. These proteins allow the conversion of light into electricity, which can then be used to power biochemical reactions. In other words, artificial photosynthesis is possible! This is truly exciting progress considering that we are still far from having a full understanding of how photosynthesis works in plants and the ecological implications of this discovery.

How Do Algae And Marine Life Use Rhodopsins For Photosynthesis?

The use of marine rhodopsins for photosynthesis first came to light when research scientists realized that marine algae and marine life use these proteins to capture light and transform it into energy. Like ordinary photosynthetic organisms, these marine creatures have developed a mechanism where the energy of light is transferred to a molecule known as adenosylcobalamin to form a cofactor that functions as an electron donor. In algae and marine life, adenosylcobalamin is used to synthesize a molecule called tetrahydrofolic acid, which is essential for the growth and division of these organisms’ cells. Once formed, the tetrahydrofolic acid can be recycled back to adenosylcobalamin to keep the process going. This cofactor is known as “cobalamin,” the “c” stands for “cobalamin,” and it is present in all cells, though it is mostly concentrated in the nucleus of the cell. The fact that this molecule plays such a vital role in algae, marine plants, and animals’ lives makes it worth investigating from an applied perspective. Scientists have found that cobalamin is necessary for a wide variety of biochemical reactions, including the synthesis of DNA and RNA and the synthesis of certain neurotransmitters and hormones.

What Is The Difference Between Marine And Terrestrial Algae?

There are many differences between terrestrial and marine algae, not the least of which is size. While terrestrial algae are usually quite small, microscopic algae that live in aquatic environments are often massive, due to the high concentration of food in the water. Another big difference between the two is that terrestrial algae lack the ability to move around, while marine algae are highly motile—they can swim, float, or drift to locations where there is more food or sunlight. This makes them very easy to study, as researchers can easily keep track of the movement of individual cells.

What Are The Main Types Of Marine Rhodopsins?

There are several different types of marine rhodopsins, though two of the more commonly known forms are called bacteriorhodopsin and halorhodopsin. Bacteriorhodopsin is found in purple and blue-green bacteria and archaea and was originally isolated from the bacterium Halobacillus halophilus in 1953. It absorbs light very well and is used by these organisms to convert light into energy in a way that is very similar to how photosynthetic organisms use chlorophyll to perform the same function. The unique thing about bacteriorhodopsin is that it can be found in archaea and bacteria as well as some eukaryotic organisms, such as green algae and plants.

Halorhodopsin, on the other hand, was first isolated from the halophilic archaea (extremely high-salinity loving organisms) Haloarcula arctica and Halorubrum lacuscaeruleum in 1970. It also absorbs light very well and is thus used as a light-harvesting protein in these organisms. It is commonly found in archaea and bacteria and was first produced in large quantities in recombinant technology trials in the 1990s. In addition to these two main types of marine rhodopsin, there is also a form called epsilon-rhodopsin that was discovered in 1975 and is only present in an organism’s eyes—it is not used for photosynthesis. Overall, marine rhodopsins are interesting proteins that are vital for the survival of many organisms, including algae, marine plants, and animals, and it is exciting to think about what other types of roles they may play in the future.

Why Did Scientists Discover Marine Rhodopsins?

To answer this question, it is important to understand the context of when and where the discovery took place. It was in the early 1960s and in the Arctic region, specifically the Northwest Passage near Axel Heiberg Island in Canada’s Arctic Circle. At the time, scientists were studying the effects of global climate change on sea levels and the evolution of polar ice sheets, among other things. When the team at the University of Toronto, led by Peter Haas, began studying samples from Axel Heiberg Island in the 1960s, they were really just looking for any kind of life, including microbes. What they found in abundance were photosynthetic organisms—primarily algae—that seemingly got all the light they needed for their metabolisms, resulting in an energetic crisis for the creatures.

Though most algae were unable to move around very much in the extreme cold of the Arctic, the team saw them swim to lightsources and were able to get a good look at how the algae used photosynthesis. The team suspected that these organisms were using some form of light-dependent biochemical reaction for energy. In other words, while the algae could not move around very well, they were very good at getting the best exposure to the available light.

How Do Algae And Marine Life Use Rhodopsins For Photosynthesis?

Algae and marine life use rhodopsins to capture light and transform it into energy, as we discussed in the previous section. Similar to how photosynthetic organisms use light to drive the process of making ATP and NADPH (which are necessary for all living things), algae and marine organisms use adenosylcobalamin for the same purpose. In the cases of the photosynthetic organisms, this cofactor accepts light energy and transfers it to a molecule called folate or tetrahydrofolate, an important cofactor for metabolic processes.

What Are The Main Differences Between Marine And Plant Photosynthesis?

Plants, algae, and marine organisms have a few key differences in how they use sunlight. First of all, unlike photosynthetic organisms, which are constrained to certain environments that provide them with light, many of these organisms can live anywhere. This is an advantage from an applied perspective, as you can have photosynthesis taking place in many different locations, even if you don’t have direct sunlight for long periods of time. In addition, photosynthetic organisms rely largely on nutrients provided by the environment around them to function, while these other organisms can obtain all the nutrients they need from the food they eat.

What Are The Main Differences Between Marine And Animal Photosynthesis?

While photosynthesis is the process that allows plants, algae, and marine organisms to convert sunlight into energy, animal photosynthesis is used by certain creatures, such as jellyfish, to convert the light into food. For instance, the jellyfish consume algae and other smaller organisms that are in their environment, which provides them with organic carbon and nitrogen. They can use these compounds to make sugars, which they then feed on, much like how plants use photosynthesis to make food for animals.

Considering the huge ecological implications of this discovery, it is important to gain a better understanding of how these unique proteins work. In the future, it may be possible to develop technology that mimics this process for generating energy and creating food products. After all, what is stoping us from eating photosynthetic organisms, anyway?

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