First person – Carolina Camelo

How would you explain the main findings of your paper in lay terms?

In order to be functional, some organs require the formation of complex interconnected networks of tubes. This is the case with our vascular system for example, in which the vessels are first formed and then connected at specific positions to allow for a functional passage of blood. The same holds true for the fruit fly tracheal system, initially formed by clusters of cells that organize themselves into small tubes that later fuse with each other to allow for efficient air diffusion. In this work, we found that fusion of tracheal tubes requires specialized vesicles, called multivesicular bodies, which also contain small vesicles. When multivesicular bodies fuse with the nascent tracheal connections, they release the internal vesicles, also known as extracellular vesicles, into the tracheal lumen. The formation of multivesicular bodies in these tracheal tip cells depends on a specialized molecular machinery including the small GTPase Arl3, Rab27 and Rab35. In addition, the tracheal cells also release a second type of extracellular vesicles, which carry distinct components, into the tracheal tubes. This work is one of the first descriptions of extracellular vesicles in an organism and will promote a better understanding of the role of these extracellular vesicles in the development of organisms.

Were there any specific challenges associated with this project? If so, how did you overcome them?

After the first screen to identify which Rab GTPases participate in the formation of multivesicular bodies in tracheal tip cells, we were surprised that Rab39 does not directly participate in the formation of these vesicles. Previous work had shown that Rab39 localizes to these multivesicular bodies and that expressing a dominant-negative form of these proteins impairs tube fusion. As we were intrigued by these results, we proceeded to generate double and triple mutants with combinations of Rab27 and Rab35 mutants. The results were even more puzzling as they suggested a more complicated role of Rab39. Although the initial results are discussed in this manuscript, we are currently still trying to understand the role of Rab39 in tracheal tip cells.

When doing the research, did you have a particular result or ‘eureka’ moment that has stuck with you?

I came across the extracellular vesicles by chance when I was double-checking embryos expressing Staccato (Stac; a Munc13-4 protein) tagged with EGFP. This was an exciting moment. Another particular result that I recall was when I could not observe extracellular vesicles in Arl3 mutant embryos, confirming our hypothesis that this protein is essential for the formation of Stac-positive extracellular vesicles and strongly supporting the notion that these extracellular vesicles derive from tracheal fusion events.

Why did you choose Journal of Cell Science for your paper?

The Company of Biologists has a good reputation for scientific integrity, transparency and fairness, characteristics that are appreciated by all team members. JCS published several interesting cell biology papers and we felt our work fitted well in their scope, and we can only recommend the journal as the review process was fair and smooth.

What motivated you to pursue a career in science, and what have been the most interesting moments on the path that led you to where you are now?

I was always fascinated by nature and by how apparently ‘invisible’ entities, such as cells, can function together to form complex tissues and animals. Also, learning new things has always been an addiction to me. As an undergraduate, I did an internship in a laboratory of my university. After a long week of courses and assignments, I still needed to go to the lab to prepare yeast cultures for the next day. After the work was done, I was no longer tired but just excited about the next day's experiment; this was the day I realized that I ‘belong to the lab’.

Who are your role models in science? Why?

I do not like the idea of role models in general. I can mention Jane Goodall, whom I admire for her passion for her work and because it was through watching her documentaries that I first became fascinated with the idea of being a scientist, and Rosalind Franklin for her struggle in a world (still) dominated by men.

What's next for you?

I will start a postdoc position in the group of Carl-Philipp Heisenberg in the IST Vienna early next year to continue studying cellular and development biology.

Tell us something interesting about yourself that wouldn't be on your CV

I love being in nature, going for long backpacking hikes and doing scuba diving. If science does not work out for me, I have a (secret) plan to open a nature/yoga-oriented hostel with friends.