#cell division

The Scientific Research Notes of S. Sunkavally. Years: 1986 - 1990.

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When cells prepare to divide, each 'daughter' cell must receive a copy of the blueprints for cellular life – the DNA which allows new cells to develop in the same way. While the job of cleaving a cell in half is challenging enough, here researchers focus on the delicate mechanisms that separate and share out lengths of DNA called chromosomes. During metaphase, structures called kinetochores in the middle of the chromosomes (highlighted in rainbow colours) usually line up in the centre of the cell, pulled there along microtubules (wispy grey lines here) in a process called congression. Removing CENP-E, a protein essential for attaching kinetochores to the ends of microtubules, leaves some chromosomes stranded at the outer 'poles' of the cell (left). Restoring the protein allows more of the chromosomes to begin moving again (right), suggesting a mechanism that might be exploited to disrupt dividing cancer cells.

Written by John Ankers

Image from work by Kruno Vukušić & Iva M. Tolić

Division of Molecular Biology, Ruđer Bošković Institute, Zagreb, Croatia

Image contributed by the authors and originally published with a Creative Commons Attribution 4.0 International (CC BY 4.0)

Published in Nature Communications, October 2025

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Even before fertilisation, there are many careful processes that allow early egg cells or oocytes, to mature. Here we see DNA chromosomes (highlighted in red) inside two starfish oocytes attempting to divide through meiosis. Usually, spindle fibres (blue) pull the cell and DNA apart into two structures of different sizes. While the smaller polar body is recycled, the larger of the two structures becomes the mature egg, keeping most of the cytoplasm and nurturing molecules contained in the original oocyte. In the bottom cell however, larger asters of spindle fibres mean the division is more symmetrical, similar to how a fertilised egg divides. Researchers blocked an important set of linked proteins, the Mos–MAPK pathway, in this oocyte, and they suggest MAPK might serve a switch between asymmetric and symmetrical division, perhaps yielding clues to similar mechanisms in human fertility.

Written by John Ankers

Image from work by Ivan Avilov and colleagues

Research Group Cytoskeletal Dynamics in Oocytes, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany

Image originally published with a Creative Commons Attribution 4.0 International (CC BY 4.0)

Published in Journal of Cell Biology, October 2025

Image request: Abstract, vibrant visualization of DNA strands forming intricate loop structures within a dividing cell – emphasize dynamism and complexity. Style: Sci-fi illustration, neon color palette. Resolution: 4K. Imagine your DNA, stretched out, could reach from Earth to Mars – that’s how much genetic information is packed into every cell. But somehow, this incredibly long molecule isn’t a…