September 14, 2021 - The first Croatian STED microscope purchased and owned by the Ruđer Bošković Institute (IRB) in Zagreb offers new opportunities for Croatian scientists and researchers.

The super-resolution microscope (STED) worth 4.5 million kuna has become a new edition to the selection of delicate but useful equipment the Ruđer Bošković Institute (IRB) uses to tackle the hottest questions faced by modern science.

As IRB reported in its press release, the microscope made its way to Iva Tolić's lab with thanks to the European Union funds.

"Stimulated Emission Depletion microscopy (STED) is a super-resolution technic of fluorescent microscopy and one of the methods of overcoming the limitations of visible light microscopes in observing matter structures of incredibly small sizes. German physicist Stefan W Hell received the Nobel Prize for developing STED in 2014,'' informed IRB in its press release. It also stated this is the first microscope of its kind in all of Croatia.

''With the help of this STED microscope, we can see three times the amount of small structures in a cell than we could before with the standard microscopes. We'll use them for observing cell division, more precisely for chromosome division. When it comes to division, it's very important that the chromosomes are well-connected microtubules, which are protein pipes that tie chromosomes and pull them onto separate parts of the cell. With this type of microscopy, we'll be able to determine how microtubules are connected to chromosomes in various phases of spindle formation, which is still a mystery,'' explains Iva Tolić.

As TCN previously reported, Iva Tolić's team already made a significant contribution to cell biology and spindle research when their work led them to new information on microtubule-sliding.

In addition, back in 2014, the then-president of Croatia Ivo Josipović awarded her the Order of the Croatian Danica (the medal which boasts an image of a famous scientist, Ruđer Bošković) for her particular contribution to the promotion of science in Croatia and abroad.

''Tolić earned her international reputation due to her research into complex cellular processes. Namely, not so long ago, in cooperation with her colleagues from the Max Planck Institute, Tolić discovered the first potentially immortal organism – a special kind of yeast, which was isolated from African beer. This type of yeast is very special because it rejuvenates every time it reproduces. In the case of most other yeasts, the mother cell creates a young daughter cell while it ages and eventually dies. Contrary to that, the mother cell of this yeast splits into two equal daughter cells, which remain young throughout their divisions,'' wrote IRB on its website at the time of the ceremony.

With Tolić's international reputation and well-established name, as well as scientific findings found by other scientists at IRB, it is understandable that European Union funds supported the further development of IRB's equipment.

''The outstanding power of STED microscopy allows researchers to discover complicated processes in cell structures. These understandings are the basis for further research on how specific medications, chemical compounds or bacteria and viruses affect processes in a live cell,'' concluded IRB's press release.

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June 1, 2021 - Croatian Scientists from one of the most prominent scientific institutse in Croatia, the Ruđer Bošković Insitute (IRB), answered a big question in cell biology regarding the spindle and cell division that has puzzled scientists for decades.

Croatian scientists from the Ruđer Bošković Science Institute (IRB), more precisely, dr. Kruno Vukušić, Ph.D. students Ivana Ponjavić, Patrik Risteski, and Renata Buđa, lead by professor Iva Tolić, researched and have now answered one of the key questions in cell biology.

When it comes to this field of biology specialised in observing and researching cells that make organisms, the spindle is a structure of eukaryotic cells that form during cell division, which is crucial for organisms (including humans, of course) for growth, repair, and reproduction. The spindle is in charge of the distribution of genetic material, but the exact process and molecular mechanisms of that task has baffled scientists for decades.

The aforementioned IRB scientists had their paper published in a prestigious scientific journal, Developmental Cell: Microtubule-sliding modules based on kinesins EG5 and PRC1-dependent KIF4A drive human spindle elongation. The paper described a precise molecular mechanism of molecular microtubule sliding.

''Given that this is one of the key steps in cell division that happens in almost every organism, a molecular mechanism that expands the spindle was the object of interest of many pieces of research. Even though the last 20 years has seen significant progress in understanding these molecular mechanisms, the identity of the protein needed to expand the spindle remained unknown. The importance of the spindle in human cells is apparent, in the fact that besides being the key trigger of moving chromosomes, it encourages the correct segregation of those chromosomes which, if defected, correlate with cancer,'' they said from the IRB in a press release.

This IRB research showed that the proteins KIF11 and KIF4A are the key proteins that stop the expansion of the spindle. This breakthrough was achieved by ''silencing'' several of the many proteins that participate in the process since the previous methods of silencing proteins one by one didn't offer any new knowledge in understanding this process.

Risteski, Ponjavić, Vukušić and Tolić © Ruđer Bošković Institute

''We hope that the results of this paper will encourage more new research on the role of expanding the spindle in the final stages of cell division. The results we presented are the start of explaining the control mechanisms of this protein, the work of which is under the strict control of many other factors within the cell itself. In addition, the principle of common work we described in this paper could help scientists in determining molecular mechanisms in other processes that are important in cells,'' elaborated the research leader, professor Iva Tolić.

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