These strange structures are called membrane nanotubes, and the most relevant thing is that, according to the study, these small tubes make it possible for these living beings to transfer material by generating an exchange bridge, a kind of hose that connects with nearby cells, allowing them to transfer substances from some cyanobacteria to others. Since the discovery of these organisms, this is the first time that physical and direct contact between them has been demonstrated.

“This finding has enormous implications, and strengthens the idea that we need to change the way we think about cyanobacteria,” said researcher José Manuel García. Challenging the idea that these organisms operate in isolation, the study suggests that they could act as a kind of network in which they interact, a premise of great relevance considering that these living beings are the most abundant photosynthetic organisms on the planet, representing a veritable “lung” for the oceans, and being indispensable for the sustenance of life as we know it.

In recent years the study, led by principal investigator María del Carmen Muñoz, has mobilized a multidisciplinary group composed of, among others, the UCO’s Departments of Biochemistry, Molecular Biology, and Cell Biology; the Maimonides Institute for Biomedical Research (Cordoba), the University of Cádiz’s University Institute of Marine Research, the Institute of Plant Biochemistry and Photosynthesis (Seville), and oceanographer Sallie W. Chisholm, a member of the Massachusetts Institute of Technology and discoverer of the Prochlorococcus genus of cyanobacteria.

Key details

Since the study began, and after reviewing the literature available on these nanotubes in other bacteria, the team has launched different experiments in the laboratory, such as the use of fluorescent proteins and their monitoring by fluorescence microscopy; and the use of electron microscopy for the characterization of these structures. Through these tests they have been able to confirm that there is an exchange of material from the interior of one cell to the other. In addition, as doctoral student and the study’s first author Elisa Angulo explained, the work has shown that this transfer of substances not only occurs in cyanobacteria of the same lineage, but also between those of different genders, something that has been verified not only at the laboratory level, but also in natural ocean samples.

New questions

As is often the case in science, these findings now open the door to new questions: is this transfer of molecules a support mechanism or a weapon to compete for survival? What other substances could be exchanged, beyond proteins? Is there any relationship between this mechanism and the amount of food available in the environment? Elisa Angulo, a researcher at the University of Cordoba, is already trying to answer this last question, and has just concluded a voyage on the high seas in which she has been researching the behavior of these living beings in oligotrophic areas of the Pacific poor in nutrients. We will have to wait for the next few months to continue acquiring knowledge about these marine bacteria, the living beings that invented photosynthesis and that, more than 3.5 billion years old, represent one of the oldest known forms of life. Their study, therefore, is not only of vital importance for ecosystems, but also to understand fundamental processes in the vast field of Biology.

Nanoparticles are contained in a large number of products, but they are also produced during wear and tear as well as through combustion processes (see box). “We absorb these substances from the environment via our food, cosmetics or the air we breathe,” explains Bürki. Some of these nanoparticles are suspected of harming babies in the womb. Low birth weight, autism and respiratory diseases are among the possible consequences for the child.

Mysterious remote effect

It is still unclear how the nanoparticles affect the unborn child. “We already know that the placental barrier retains many nanoparticles or at least delays their transport to the embryo,” says Bürki. However, damage to the fetal tissue occurs, even if no particles have been detected in the fetus. The Empa team is now getting to the bottom of this long-range effect of nanoparticles. Together with clinical partners from the Cantonal Hospital of St. Gallen and research partners from the University of Geneva, the Amsterdam University Medical Center and the Leibniz Institute for Environmental Medical Research in Düsseldorf, the team is investigating the consequences of common nanoparticles such as titanium dioxide or diesel soot on the function of the placenta and their indirect damage to embryonic development.

For this purpose, the team used fully functional human placentas that were made available after planned caesarean sections. “Human placental tissue is the only way to obtain meaningful results on the transport and effect of nanoparticles,” says the Empa researcher. “The structure, metabolism and interaction of maternal and fetal tissue are unique and species-specific.”

The experiments showed that nanoparticles in placental tissue disrupt the production of a large number of messenger substances. And it is these messengers that can trigger serious changes in embryonic development, such as disturbed blood vessel formation.

These effects can be visualized in laboratory models using chicken eggs. The blood vessels in the egg actually grow at an enormous speed and density to enable embryonic development. A dense network of fine blood vessels covers the inside of the eggshell. The situation is strikingly different in eggs treated with the altered messenger substances from the nanoparticle-treated placenta: In the experiments, the blood vessel system was not as dense but rather coarse-meshed. “Nanoparticles apparently have an indirect effect on the child in the womb by inhibiting the formation of blood vessels via messenger substances,” says Tina Bürki.

Health consequences

The researchers are currently investigating the entirety of the messenger substances released by a nanoparticle-treated placenta, the so-called secretome. Uncontaminated, the interplay of hormones, inflammatory mediators and signaling substances for the formation of organ systems resembles a perfectly tuned orchestra. It is already clear that the communication between the placenta and the unborn child is disrupted by the presence of nanoparticles and damages the formation of blood vessels. However, initial results show that the development of the nervous system does not appear to be affected. Future analyses will show what other disorders the nanoparticles can trigger indirectly. “As the effects can have an impact on the health of the pregnant woman and the development of her child, these findings should be taken into account in the risk assessment of nanomaterials,” says the researcher.

The clinical partner, the Cantonal Hospital of St. Gallen, is also interested. As Thomas Rduch from the Women’s Clinic and also a Clinical Research Fellow at Empa puts it: “A healthy placenta is of utmost importance for the development of the child. Correct risk assessments of environmental pollution are therefore crucial for pregnant women.”

The placenta

The placenta is an organ that forms exclusively during pregnancy. It supplies the child in the womb with nutrients and also serves as a filter for environmental influences. This so-called placental barrier offers the unborn child a certain degree of protection against pathogens or harmful substances. However, some substances, such as environmental estrogens can pass through the placental barrier and are suspected of being associated with various diseases.

Nanoparticles

Nanoparticles are only a few millionths of a millimeter in size. They include titanium dioxide, for example, which can be found in many foods, cosmetics and medicines. Silicon dioxide is found in paints and printing paper, for example, and is also used as a food additive. Other nanoparticles come from environmental pollution processes such as plastic abrasion (nanoplastics) or industrial soot. They can enter the human body via the respiratory tract, the digestive tract or the skin.

Siegelman first made the connection between our planet and the gas giant in 2018 when she noticed a striking similarity between images of Jupiter’s huge cyclones and the ocean turbulence she was studying. To a physicist, air and water are both considered fluids so applying ocean physics to Jupiter isn’t as far-fetched as it sounds, said Siegelman. “Jupiter is basically an ocean of gas.”

This initial observation led Siegelman to co-author a 2022 study published in Nature Physics that analyzed high-resolution infrared images of Jupiter’s cyclones taken by NASA’s Juno spacecraft. The analysis revealed that a type of convection similar to what is seen on Earth helps maintain Jupiter’s storms, which can be thousands of miles wide and last for years.

The 2022 study focused directly on Jupiter’s cyclones, but Siegelman also saw wispy tendrils, known to researchers as filaments, in the spaces between the gassy vortices. These filaments also had earthly analogs, and Siegelman used Juno’s detailed imagery to study whether this similarity to our planet’s oceanic and atmospheric processes was merely skin deep.

Published on June 6 in Nature Physics (LINK TK) and funded by Scripps and the National Science Foundation, Siegelman’s follow-up study finds additional similarities between the processes fueling Jupiter’s cyclones and those acting on Earth. The study shows that the filaments between Jupiter’s cyclones act in concert with convection to promote and sustain the planet’s giant storms. Specifically, Jupiter’s filaments act in ways that resemble what oceanographers and meteorologists call fronts on Earth.

Fronts are often discussed in weather forecasts — cold fronts or storm fronts, for example — but they apply to both gases and liquids. A front is the boundary between gas or liquid masses with different densities due to differences in properties like temperature. In the ocean, fronts can also be due to differences in salinity, which influences the density of seawater along with temperature. A key feature of fronts is that their leading edges feature strong vertical velocities that can create winds or currents.

To try to understand the role of the filaments she could clearly see in between the cyclones on Jupiter in Juno’s images, Siegelman looked at a series of infrared images from Juno. The batch of images were of Jupiter’s north polar region and were taken in 30-second increments.

The fact that the images were in infrared allowed Siegelman and her co-author Patrice Klein of NASA’s Jet Propulsion Laboratory, California Institute of Technology, and the Ecole Normale Superieure to calculate temperature — bright areas were warmer and dark areas were cooler. On Jupiter, the hotter parts of the atmosphere correspond to thin clouds and the colder parts represent thick cloud cover, blocking more of the heat emanating from Jupiter’s super-heated core. The researchers then tracked the movement of clouds and filaments across the 30 second intervals separating the photographs to calculate horizontal wind speeds.

These two pieces of information allowed Siegelman and Klein to apply methods from ocean and atmospheric science to Jupiter, allowing them to calculate the vertical wind speeds that would correspond to the temperatures and horizontal wind speeds the researchers derived from the images. Once the team calculated the vertical wind speeds, they were able to see that Jupiter’s filaments were indeed behaving like fronts on Earth.

Those vertical wind speeds at the edges of fronts on Jupiter also meant that the fronts were involved in transporting energy in the form of heat from the planet’s hot interior to its upper atmosphere — fueling the giant cyclones. Though convection is the main driver, the fronts account for a quarter of the total kinetic energy powering Jupiter’s cyclones and forty percent of the vertical heat transport.

“These cyclones on Jupiter’s poles have persisted since they were first observed in 2016,” said Siegelman. “These filaments in between the large vortices are relatively small but they are an important mechanism for sustaining the cyclones. It’s fascinating that fronts and convection are present and influential on Earth and Jupiter — it suggests that these processes may also be present on other turbulent fluid bodies in the universe.”

Siegelman also said that Jupiter’s massive scale and Juno’s high-resolution imagery can allow for a clearer visualization of the ways in which smaller-scale phenomena like fronts connect to larger ones like cyclones and the atmosphere at large — connections that are often hard to observe on Earth where they are much smaller and more ephemeral. However, she added, a long-awaited new satellite known to researchers as SWOT, is poised to make these kinds of ocean phenomena vastly easier to observe.

“There is some cosmic beauty in finding out that these physical mechanisms on Earth exist on other far-away planets,” said Siegelman.