Nav: Home

The smallest skeletons in the marine world observed in 3D by synchrotron techniques

February 14, 2019

Coccolithophores are microscopic marine algae that use carbon dioxide to grow and release carbon dioxide when they create their miniature calcite shells. These tiny but very abundant planktonic microorganisms could therefore be seriously impacted by current increasing carbon dioxide emissions. Scientists from the CNRS, Le Mans Université, Sorbonne Université, Aix-Marseille Université and the ESRF, the European Synchrotron, have revealed the nano-level 3D structure of their calcite shells, providing new perspectives for assessment of the role of these tiny microorganisms in the global carbon cycle. A study, published in Nature Communications, shows new correlations between their mass and the size of the organic template around which the calcite nucleation and growth take place.

You have probably never heard of them, but you may have inadvertently noticed coccolithophores in satellite images of the sea when a magnificent milky-turquoise coloured patch shows up in surface waters indicating that trillions of these single-celled calcified phytoplankton are present.

About one-third of the carbon dioxide released into the atmosphere as a result of human activity is absorbed by the oceans, where it reacts chemically and makes the water more acid. This, in turn, makes it difficult for certain calcifying marine organisms, such as sea stars, sea urchins, corals, and coccolithophores to build their shells or skeletons.

When tiny organisms impact the global carbon cycle

Coccolithophores, single-celled organisms much smaller than the pixels on your computer screen, are active players in the carbon cycle. They live in surface layers of the sea, where they use light to photosynthesize, fixing CO2 into organic matter leading to a decrease in dissolved CO2 in the ocean. Unlike other photosynthetic phytoplankton, coccolithophores produce calcite (i.e. CaCO3) in the form of minute platelets called "coccoliths". Coccolithophore calcification uses bicarbonate (HCO3) from seawater and releases CO2. When coccolithophore cells die, coccoliths and associated organic matter slowly sink to the seabed, thus contributing to the storage of carbon in the deep ocean reservoir. Although they are tiny organisms, the coccolithophores play a key role in the global carbon cycle because of the fact that they are very abundant in the oceans.

Several recent laboratory and field studies indicate that ocean acidification is likely to hamper coccolithophore calcification. However, some studies have reported an increase of coccolithophore calcification in more acidic conditions.

Unveiling the mass of coccoliths

Understanding how environmental factors influence the degree of calcification of coccoliths is therefore of significant interest. The crucial issue is to be able to accurately estimate the mass of the calcite shell of these microorganisms. "We have developed a method to estimate the mass of individual coccoliths using automated optical microscopy", says CNRS scientist Luc Beaufort. "Although this technique is very useful for measuring the mass of a large quantity of coccoliths in a short period of time, it was crucial to assess the accuracy of these measurements by comparing with another very precise method."

Scientists Alain Gibaud and Thomas Beuvier, regular users of the ESRF, put Yuriy Chushkin and Federico Zontone, scientists at the ESRF, in touch with the palaeontologists Luc Beaufort and Baptiste Suchéras-Marx and the marine biologist Ian Probert. The coherent X-ray diffraction imaging technique on ESRF beamline ID10 was used to generate incredibly detailed information on the 3D structure (and therefore mass) of shells and individual coccoliths of several species of coccolithophore.

The team were able to calibrate the optical microscopy method and found that each coccolith in the shell has different characteristics, despite all being created in the same environmental conditions. To explain the variations in coccolith size and mass within single coccolithophores, they found that the mass of coccoliths is proportionate to the size of the organic scale around which calcite nucleation occurs every 110-120 nm.

"The experiment at the ESRF was challenging because the samples, at 5 to 7microns, were almost too big for us to study. With coherent diffraction imaging, we managed to get information in 3D and reconstruct the individual calcite crystals of the coccoliths", says Yuriy Chushkin, scientist at the ESRF. "In fact, the largest samples scattered the beam so well that in one hour we had the full 3D data set that we needed", he concludes.

The next step for the team is to use the 3D computed images of these coccoliths to get a deeper understanding of how calcification is controlled by these extraordinary phytoplanktons and of the mechanical properties of these tiny but very intricate calcite structures.
-end-
Reference

X-ray nanotomography of coccolithophores reveals that coccolith mass and segment number correlate with grid sizeg, T.Beuvier, I.Probert, L.Beaufort, B.Suchéras-Marx, Y. Chushkin, F.Zontone and A.Gibaud. Nature Communications, 14 février 2019. DOI : 10.1038/s41467-019-08635-x

Contacts

Scientist contacts: Thomas Beuvier (tbeuvier@yahoo.fr, +33 (0)6 37 81 82 62), Alain Gibaud (alain.gibaud@univ-lemans.fr, +33 (0)6 41 67 15 00)

Press contact: Delphine CHENEVIER,

Head of communications, ESRF, delphine.chenevier@esrf.fr, +33 (0)6 07 16 18 79

Link to download the picture: https://we.tl/t-8NIHL4dQzo

European Synchrotron Radiation Facility

Related Microorganisms Articles:

Lost in translation: Organic matter cuts plant-microbe links
Soil scientists from Cornell and Rice Universities have dug around and found that although adding carbon organic matter to agricultural fields is usually advantageous, it may muddle the beneficial underground communication between legume plants and microorganisms.
Montana State researcher harnesses microorganisms to make living building materials
Chelsea Heveran, assistant professor in the Department of Mechanical and Industrial Engineering, is the lead author of a new study showing that certain bacteria can be used to create an easily recyclable, concrete-like substance.
Crop residues are a potential source of beneficial microorganisms and biocontrol agents
While studies of the microbiomes (which comprises all the microorganisms, mainly bacteria and fungi) of the phyllosphere and the rhizosphere of plants are important, scientists at INRA believe more attention should be given to the microbiomes of crop residues.
Soil scientist researches nature versus nurture in microorganisms
Ember Morrissey, assistant professor of environmental microbiology at West Virginia University, uncovered that nature significantly affects how the tiny organisms under our feet respond to their current surroundings.
Microorganisms reduce methane release from the ocean
Bacteria in the Pacific Ocean remove large amounts of the greenhouse gas methane.
Microorganisms build the best fuel efficient hydrogen cells
With billions of years of practice, nature has created the most energy efficient machines.
How microorganisms protect themselves against free radicals
There are numerous different scenarios in which microorganisms are exposed to highly reactive molecules known as free radicals.
Scientists' warning to humanity: Microbiology and climate change
When it comes to climate change, ignoring the role of microorganisms could have dire consequences, according to a new statement issued by an international team of microbiologists.
Climate change could affect symbiotic relationships between microorganisms and trees
An international research consortium mapped the global distribution of tree-root symbioses with fungi and bacteria that are vital to forest ecosystems.
Microorganisms on microplastics
A recent study shows that that the potentially toxin-producing plankton species Pfiesteria piscicida prefers to colonize plastic particles, where they are found in 50 times higher densities than in the surrounding water of the Baltic Sea and densities about two to three times higher than on comparable wood particles floating in the water.
More Microorganisms News and Microorganisms Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: Reinvention
Change is hard, but it's also an opportunity to discover and reimagine what you thought you knew. From our economy, to music, to even ourselves–this hour TED speakers explore the power of reinvention. Guests include OK Go lead singer Damian Kulash Jr., former college gymnastics coach Valorie Kondos Field, Stockton Mayor Michael Tubbs, and entrepreneur Nick Hanauer.
Now Playing: Science for the People

#562 Superbug to Bedside
By now we're all good and scared about antibiotic resistance, one of the many things coming to get us all. But there's good news, sort of. News antibiotics are coming out! How do they get tested? What does that kind of a trial look like and how does it happen? Host Bethany Brookeshire talks with Matt McCarthy, author of "Superbugs: The Race to Stop an Epidemic", about the ins and outs of testing a new antibiotic in the hospital.
Now Playing: Radiolab

Dispatch 6: Strange Times
Covid has disrupted the most basic routines of our days and nights. But in the middle of a conversation about how to fight the virus, we find a place impervious to the stalled plans and frenetic demands of the outside world. It's a very different kind of front line, where urgent work means moving slow, and time is marked out in tiny pre-planned steps. Then, on a walk through the woods, we consider how the tempo of our lives affects our minds and discover how the beats of biology shape our bodies. This episode was produced with help from Molly Webster and Tracie Hunte. Support Radiolab today at Radiolab.org/donate.