The embryonic nervous system is a hollow tube consisting of elongated neural progenitor cells, which extend from the inner to the outer surface of the tube. In a section inside the tube called the ventricular zone (VZ), these cells divide and produce immature neurons that migrate outwards. This involves well-characterized movements that are coupled to cell division. After a cell divides at the inner-most VZ region, the nuclei migrate to the outer region, where they synthesize new DNA before returning.
Figure 1: Cell nuclei of brain cells accumulate at the outer surface of the ventricular zone when the cell cycle is blocked. Copyright : 2011 Yoichi Kosodo et al.
To determine how the direction of movement is coupled to the cell division cycle, Yoichi Kosodo and colleagues in Matsuzaki's group at RIKEN Center for Developmental Biology labeled nuclei in the embryonic mouse brain with green fluorescent protein. This enabled them to not only track their movements in cultured brain slices using a video-imaging system, but also correlate their positions with phases of the cell cycle. They found that outward nuclear migration involves back and forth ‘ratcheting’ motions and occurs more slowly than inward migration.
Importantly, they discovered that blocking the cell cycle before DNA synthesis caused nuclei to accumulate at the outer VZ surface (Fig.1), and reduced outward migration. Nuclei migrating back inwards normally crowd out those just finished dividing, thus pushing them away from the inner VZ surface.
Examining their results further, the researchers computationally modeled nuclear migration, and incorporated fluorescent magnetic beads into the inner VZ surface. They observed the beads moving away from the inner VZ surface, and remaining at its outer region.
The researchers also showed that inward migration is closely linked to microtubule reorganization orchestrated by a protein called Tpx2, which is initially expressed in the nuclei of progenitors before moving to the mitotic spindle. This separates newly duplicated chromosomes. Translocation of Tpx2 to the cell region nearest the inner VZ surface promotes migration of the nucleus in that direction by microtubule re-organization. Reducing Tpx2 activity lowered the velocity of inward migration, but introducing the human Tpx2 gene into the cells lacking Tpx2 restored normal speed.
The researchers conclude that two mechanisms maintain brain structure during development. One couples cell migration to the cell cycle, and occurs independently of other cells, with Tpx2 providing an active driving force; and the other involves interactions between the nuclei in the VZ.
The corresponding author for this highlight is based at the Laboratory for Cell Asymmetry, RIKEN Center for Developmental Biology
 Kosodo, Y., Suetsugu, T., Suda, M., Mimori-Kiyosue, Y., Toida, K., Baba, S. A., Kimura, A. & Matsuzaki, F. Regulation of interkinetic nuclear migration by cell cycle-coupled active and passive mechanisms in the developing brain. The EMBO Journal 30, 1690–1704 (2011).
Novel mechanisms of action discovered for the skin cancer medication Imiquimod
21.10.2016 | Technische Universität München
Second research flight into zero gravity
21.10.2016 | Universität Zürich
Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.
"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...
In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.
A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...
By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.
"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...
COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.
In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...
'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.
Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...
14.10.2016 | Event News
14.10.2016 | Event News
12.10.2016 | Event News
21.10.2016 | Health and Medicine
21.10.2016 | Information Technology
21.10.2016 | Materials Sciences