Sci-Tech

đź“° Where does the variety of colors of the “blue algae” come from, from green to orange?

Nicknamed “blue-green algae”, cyanobacteria can actually take on colors that range from green to orange to pink, depending on the photosynthetic pigment that dominates cells of a particular species. Cyanobacteria therefore do not capture all light (light is the set of electromagnetic waves that are visible to the human eye, that is, contained in wavelengths from 380 nm (purple) to 780 nm (red). That …) in the same way : Prochlorococcus, for example the most abundant cyanobacterium in the ocean (In geography, an ocean is often defined as a huge body of salt water. In fact, it looks more like a volume, the water of which is constantly being renewed by ocean currents. About 71% of .. .) prefer to absorb the violet and blue wavelengths, while its cousin Synechococcus can capture the blue (from the old High German “blao” = brilliant) is one of the three basic colors. Its wavelength is roughly between 446 and 520 nm. It varies in brightness from cyan to one …), green (green is a complementary color, the light with a wavelength between 490 and 490 corresponds to 570 nm. The human eye has a receiver , an M-cone whose bandwidth is focused on this frequency. The …) or both, depending on the pigment type. How can this great variety of cyanobacterial pigments be explained?
Culture flasks with the different pigment types of the marine cyanobacterium Synechococcus.
© L. Garczarek

A research team (Scientific research primarily refers to all measures for the generation and development of scientific knowledge. With metonymic extension denotes scientific research …) international with the participation of scientists from the Biological Station of Roscoff (Roscoff is a town in the Finistère department in Brittany in France. Today it is a dynamic seaside resort. The inhabitants are called …) (CNRS / Sorbonne University) has just demonstrated the relevance of ‘A track already suspected in the past (The past is primarily a concept that connected with time: it consists of all the successive configurations of the world and is opposed to the future on a time scale centered on the present. Intuition of …): the vibrations of water molecules (water is an ubiquitous chemical compound on earth that for all known living organisms it In fact, scientists have shown that there are isons between atoms (an atom (from the Greek ατομος, atomos, “that cannot be divided”) is the smallest part of a body …) in water molecules are subject to vibrations, which absorb certain wavelengths (a wave is the propagation of a disturbance that creates a reversible variation of local physical properties on its way. It transports energy without transporting matter.) Light and thus limits “spectral niches”, ie wavelength ranges that can be used by photosynthetic organisms.

A new mathematical model (a mathematical model is a translation of reality in order to be able to apply mathematical tools, techniques and theories to it, then in general the reverse translation of the mathematical results obtained …) combined with measurements satellite (satellite can focus on :), confirmed that these vibrations divide the light spectra into five niches: purple, blue, green, orange and red (the color red corresponds to different definitions, depending on the chromatic system we use.). The samples from the Tara Ocean Expedition also made it possible to show that the different pigment types of cyanobacteria are well distributed according to these niches: the cyanobacterium Prochlorococcus dominates in large oceanic eddies, while Synechococcus dominates in coastal waters.

Absorption spectra of the various pigment types of cyanobacteria. The absorption peaks are located in different “spectral niches” (purple, blue, green, orange or red) and avoid the “harmonics” (dotted lines) that are generated by the vibrations of the water molecules.
© J. Huisman

These results, published in Nature Ecology and Evolution on November 9, 2020, could improve predictions about the evolution of aquatic ecosystems in context. (The context of an event includes the circumstances and conditions that surround it. The context of a word. A sentence or text including …) global climate change.

Bibliography:
Vibrational modes of water predict spectral niches for photosynthesis in lakes and oceans. Holtrop T., Huisman J., Stomp M., Biersteker L., Aerts J., Grébert T., Partensky F., Garczarek L. and Van der Woerd HJ. Natural Ecology and Evolution, November 9, 2020. DOI: 10.1038 / s41559-020-01330-x.

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