Juan José Pierella Karlusich: from plant growth to phytoplankton acclimatization

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Specialized in the study of mechanisms of plant resistance, Juan José Pierella Karlusich is now tackling the issue of phytoplankton adaptation to its environment. Excited by the richness of the dataset collected during the Tara Oceans expedition and attracted by its global approach, the young Argentinian will study the molecular processes enabling micro-algae to develop in variable environmental conditions.
Juan José is currently participating in the “Ocean Plankton, Climate & Development” project initiated by the Tara Expeditions Foundation and financed by the French Facility for Global Environment (FFEM). This cooperative project is a unique opportunity for him to develop new skills and participate in the network of researchers set up by the project.

“My younger brother read an article about Tara in a popular science magazine. That’s how I heard about the schooner for the first time” Juan José admits with a smile. Installed in the École Normale Supérieure (ENS) laboratories, in the Quartier Latin in Paris, the young researcher is already well-established in his office on the 4th floor.

Between land cultivation and exploration of the seas, the 31-year old Argentinian ultimately decided to focus on the least-known environment. “In Argentina, we already know a lot about plants. Our agricultural sector is strong and functions well. In the case of ocean sciences, although there are excellent research groups, there is still a lot to do” he explains.

If we want a viable ocean, we first have to understand how it works.

Phytoplankton adaptation and acclimatization

Juan explains us what is the difference between adaptation and acclimatization: “The first process refers to changes in genetic of the organisms after many generations, for example some genes are lost. The second process refers to the responses of an organism during his life, for example, a group of algae are suddenly in nutrient deficient waters, so they try to incorporate the small amounts of available nutrients by over-expressing those genes involved in nutrient acquisition”.

For his PhD thesis, Juan José studied plant resistance mechanisms in harsh environmental conditions. To survive drought, too much sunlight or the presence of pathogens, plants activate molecular mechanisms acquired throughout their evolution. “When comparing plants with micro-algae, one realizes that the latter have mechanisms which plants haven’t developed. They took different evolutionary paths”.

In the framework of his research project, Juan José will focus on photosynthetic planktonic microorganisms. “I’m going to study phytoplankton’s adaptations and responses to variations in environmental conditions such as light or nutrients”. By analyzing the causes underlying geographic distribution of major phytoplankton groups and cross-referencing these data with genetic sequences, he will investigate how micro-algae adapt and change their gene expression according to conditions they encounter.

After a few months of work, Juan José is now familiar with his dataset, regularly updated with new elements. “We’ve just received data from the Arctic Ocean, but I haven’t had time yet to take a look at these,” he says.



Juan José Pierella Karlusic

“This is really the best way to do science.”

In addition to the quality of the Tara Oceans dataset, described by Juan José as “the most global and exhaustive ever gathered”, he is in total agreement with the research philosophy adopted by the scientific consortium, which makes collaboration and interdisciplinarity the key ingredients to its success. “This is the way I see science, a constant interaction between various laboratories and among scientists,” he says. The more multidisciplinary the collaboration, the more fruitful. “Tara Oceans brought together scientists with various expertise (molecular biology, modeling, bioinformatics, etc.) who rarely have an opportunity to collaborate with each other. This is really innovative and the best way to do science”.

For the scientist who often taught in parallel to his research, knowledge sharing and transfer are also essential. “During my PhD and my last postdoctoral position, I taught students and it made me feel very useful”.

Juan José is excited to work on organisms “collected in their actual living conditions”. It’s important for this Argentinian more used to studying organisms cultured in laboratories or grown in fields, always under precisely controlled conditions.

This is the first step if we want to understand and anticipate the impacts of climate change, and select key areas for protection as a priority.

“In science, we never know where we’re heading.”

Asked about his research future, Juan José serenely answers that “in science, we never know where we’re going. Anyone who pretends otherwise prevents himself from exploring less obvious, innovative paths that might lead to significant discoveries”. Juan José gives himself freedom to orient his research in directions he may not have even seen yet.

Though his path has not yet been clearly traced, he knows very well the overall goal of the project: understand the oceanic ecosystem in all its globality and complexity. “This is the first step if we want to understand and anticipate the impacts of climate change, and select key areas for protection as a priority”.