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Iva Tolic-Nørrelykke

2011; Elsevier BV; Volume: 21; Issue: 9 Linguagem: Inglês

10.1016/j.cub.2011.03.018

1879-0445

Iva M. Tolić,

Spaceflight effects on biology

Iva Tolic-Nørrelykke was born in Zagreb, Croatia, where she studied molecular biology at the University of Zagreb and did graduate work at the Rudjer Boskovic Institute. Her thesis work on tensegrity models of the cytoskeleton was carried out at the Harvard School of Public Health in Boston, Massachusetts. For her post-doctoral research she studied the mechanics of the cytoskeleton by displacing organelles using optical tweezers and by cutting the cytoskeleton fibers using laser ablation. This research was performed at the Niels Bohr Institute in Copenhagen, Denmark, and at the European Laboratory for Non-Linear Spectroscopy in Florence, Italy. Iva is presently a group leader at the Max Planck Institute of Molecular Cell Biology and Genetics in Dresden, Germany. Her interdisciplinary group is interested in how microtubules and motor proteins self-organize to create the dynamic interior design of the cell. What turned you on to biology in the first place? With my parents working in humanities, I have absorbed the love for knowledge and books from early childhood onwards. But humanities seemed too fuzzy for me; I wanted to do something more exact. In school I was good at mathematics, went to math competitions, and thought I would study math. Yet, before entering university I decided to study a subject that, in my opinion, posed the most fascinating questions, such as what is life and how it functions. I therefore started studying biology, hoping that I would later be able to use the exact language of math to answer some of biology's questions. How did you get into biophysics? In my undergraduate studies of molecular biology, I loved the problems of biology but I missed the precise and elegant language of math. In the final years I applied to a large number of conferences and summer schools. I wanted to learn about different fields of research in biology, and even more than that I enjoyed travelling the world (which was otherwise financially impossible). So I visited Italy, Hungary, Argentina, Israel, USA, Portugal, Denmark, and Australia. At a meeting in Argentina I learned about possibilities to combine biology and math. I decided to do my PhD in biomathematics, still at the University of Zagreb. I joined the theoretical chemistry group of Nenad Trinajstic at the Rudjer Boskovic Institute in Zagreb. While I worked on theoretical chemistry, my PhD advisor encouraged me to find a place where I could do theoretical biology. I read the Journal of Theoretical Biology, mainly in the library while visiting my parents, who lived in Zurich at the time, because this journal was not available at my home institute. Soon I found an intriguing topic: modeling of the cytoskeleton as tensegrity (tensional integrity) structures, similar to the sculptures of Buckminster Fuller and Kenneth Snelson. The mechanical stability of these sculptures relies on compression-resisting struts and tension-resisting ropes. In the cell, microtubules correspond to struts and actin cables to ropes. I wrote an e-mail to Ning Wang at the Harvard School of Public Health in Boston, saying that I would be interested in working with him for a year or two. He replied that I could come over and see whether it would work out. So I went to Boston, started a theoretical work on testing the tensegrity model, and attended a lot of lunch and dinner seminars that provided free pizza, because I had no salary for the first few months. After my PhD, I realized I did not want to do theory alone and decided to go back to experiments. Because of personal reasons, I got in touch with the optical tweezers group of Kirstine Berg-Sorensen and Lene Oddershede at the Niels Bohr Institute in Copenhagen. This was an excellent opportunity to learn how to manipulate the cells and the cytoskeleton with laser tweezers, as well as how to combine the approaches of physics and math to address problems in biology. Why did you choose fission yeast? I wanted to work on human cells, but we did not have permission to work with human cells at the Niels Bohr Institute. Looking around, I found that our collaborators worked with Escherichia coli and fission yeast. Genevieve Thon gave me some samples of fission yeast cells. When I saw GFP-labeled microtubules in those cute cells, that was love at first sight, which still lasts. Yeast is great for studies of the microtubule cytoskeleton because, unlike in mammalian cells that can have thousands of microtubules, there are only between around three and five microtubules in yeast cells, which means that you can observe the dynamics of each microtubule and manipulate (e.g. cut) a single microtubule and then observe the response of the cell. At the Niels Bohr Institute, I learned about optical tweezers and did microrheology studies of yeast cells. I continued with studies on the cytoskeleton in fission yeast during my second postdoc, in the lab of Francesco Pavone in Florence, where I did laser-cutting experiments of microtubules and of the spindle, as well as displacement of the nucleus with optical tweezers. Which area of biology do you find most exciting? I am fascinated by movement. Life is all about movement, and I would like to understand how this movement comes about inside the “atoms of life” — cells. Movements inside the cells are generated by active processes, such as motor proteins walking along cytoskeleton filaments and growth or shrinkage of these filaments, but some movements are simply thermally driven. One of the most captivating examples of intracellular movement is the division of the nucleus, starting with the formation of the mitotic spindle, continuing with the dance of chromosomes on the spindle, and finishing with their parting. A remarkable feature of chromosome movements, as well as various other intracellular activities, is that they seem random and irregular at first glance — microtubules of the mitotic spindle grow in random directions and chromosomes jitter in the nucleus — and yet, the end result is an accurate and reproducible process: cell division. Today we know the identity of numerous molecular players involved in mitotic spindle formation and chromosome movements, and the challenge is to understand how these molecules interact to create complex and beautiful structures with a vital function, such as the spindle. What is your research focus? My lab focuses on chromosome and nuclear movements that are driven by microtubules and microtubule-based motor proteins: dynein and kinesin. We are trying to understand what drives the nucleus to move in an oscillatory manner in meiotic yeast cells, and how these nuclear movements facilitate chromosome pairing. Whereas the nucleus moves from one end of the cell to the other in meiosis, it makes only small excursions around the cell center in interphase. We want to figure out the physics behind these processes. Finally, because of our interest in the mitotic spindle we study how microtubules of the spindle find chromosomes, and how chromosomes move on the spindle. Do you have a favourite book? I love the cell biology ‘bible’, namely Molecular Biology of the Cell by Alberts et al. If you open this book at a random page, you can easily read a section without having read the preceding sections, and you would always learn something interesting about the cell. This book has pulled out fundamental notions of how the cell works, and explained them in a simple and clear manner, without confusing the reader with the enormous quantity of data that exist in the field. Another book that influenced me is J.D. Murray's Mathematical Biology, in which I found a beautiful fusion of my two favourite subjects. I was reading this book at the end of my undergraduate studies, learning how to build mathematical models for biological systems, and enjoying a variety of examples. One of the fun examples was the explanation of the dynamics of grasshopper outbreaks, which in my mind signified putting into equations the plagues in the Biblical Egypt where locusts “covered the face of the earth”. What is the importance of theoretical approaches in biology? Because biology is incredibly complex, theoretical approaches can help to identify the key elements and mechanisms of the process we study, which are sometimes hard to isolate from large sets of complicated experimental data. The aim of building theoretical models is to provide two things: insights and predictions. The best models describe how a biological process works and predict what may happen if conditions are changed. These predictions are then tested experimentally, and the model is modified or refined based on the results of the experiment. What is your favourite conference? I like both big and small conferences. One of my favourites is the ASCB (American Society for Cell Biology) annual meeting. It has the exciting atmosphere of everyone from the field being there. Because it is such a huge meeting, you have to prepare your itinerary in advance, to be sure to see the most interesting talks and posters. On the other hand, meetings like the Gordon Research Conferences and small topical meetings are more relaxed: there is less running and more time for longer discussions. The atmosphere is friendly and sharing, so you will more likely hear the newest unpublished results at the smaller rather than at the larger meetings. What is the best advice you've been given? Choose your projects carefully! Embarking on a project means that you will spend several years absorbed in it. So it had better be worth the effort. You should find a question that is both interesting to you and important for the field. After defining the question, you decide on how to search for the answer, which includes selecting the model system and the methods. It is better to start an exciting but somewhat risky project for which you will first have to develop new methods, than to pick the low-hanging fruits by solving less interesting problems for which you have the methods ready. What advice would you offer someone wondering whether to start a career in biology? The question is whether you are passionate about science. There should be a topic that entirely occupies your mind, a field that excites you so much that you are willing to work hard even when experiments do not work and you realize you have been on a wrong track for a while. An ideal project is the one that you enjoy working on. When you enjoy doing something, you are likely also good at it. Being good at your work and taking pleasure in the work are tightly connected — it is hard to distinguish which of the two is the cause and which is the consequence. What do you do in your free time? I travel a lot. I love to explore big cities, especially warm and passionate ones, such as Rome and Barcelona, or any place on the Mediterranean. Beach and sailing holidays are my favourite. I am a fervent reader, enjoying modern Croatian, Italian, and German novels. And I go out frequently: I love music, bars, clubs, and various kinds of parties.