Nanotechnology Now

Our NanoNews Digest Sponsors
Heifer International



Home > Press > Slicing mitotic spindle with lasers, nanosurgeons unravel old pole-to-pole theory: Quantitative research shows key organelle of cell division to be more complex than previously thought

The top shows a series of fluorescent images of a spindle taken before the cut and at 5 seconds and 10 seconds after the cut. Scale bar, 10 µm. The bottom shows a graphical representation of the cut microtubules. The cut generates new 'plus' ends (red) and new 'minus' ends (green). The newly generated minus ends remain stable, whereas the new plus ends depolymerize, which creates two depolymerization fronts of opposed polarity.

Credit: Jan Brugués, Harvard School of Engineering and Applied Sciences.
The top shows a series of fluorescent images of a spindle taken before the cut and at 5 seconds and 10 seconds after the cut. Scale bar, 10 µm. The bottom shows a graphical representation of the cut microtubules. The cut generates new 'plus' ends (red) and new 'minus' ends (green). The newly generated minus ends remain stable, whereas the new plus ends depolymerize, which creates two depolymerization fronts of opposed polarity.

Credit: Jan Brugués, Harvard School of Engineering and Applied Sciences.

Abstract:
The mitotic spindle, an apparatus that segregates chromosomes during cell division, may be more complex than the standard textbook picture suggests, according to researchers at the Harvard School of Engineering and Applied Sciences (SEAS).

Slicing mitotic spindle with lasers, nanosurgeons unravel old pole-to-pole theory: Quantitative research shows key organelle of cell division to be more complex than previously thought

Cambridge, MA | Posted on April 26th, 2012

The findings, which result from quantitative measurements of the mitotic spindle, will appear tomorrow in the journal Cell.

The researchers used a femtosecond laser to slice through the strands of the organelle and then performed a mathematical analysis to infer the microscopic structure of the spindle from its response to this damage.

"We've been using this nanosurgery technique to understand the architecture and assembly of the spindle in a way that was never possible before," says Eric Mazur, Balkanski Professor of Physics and Applied Physics at Harvard, who co-authored the study. "It's very exciting."

The spindle, which is made of protein strands called microtubules, forms during cell division and segregates chromosomes into the daughter cells. It was previously unclear how microtubules are organized in the spindles of animal cells, and it was often assumed that the microtubules stretch along the length of the entire structure, pole to pole.

Mazur and his colleagues demonstrated that the microtubules can begin to form throughout the spindle. They also vary in length, with the shortest ones close to the poles.

"We wondered whether this size difference might result from a gradient of microtubule stabilization across the spindle, but it actually results from transport," says lead author Jan Brugués, a postdoctoral fellow at SEAS. "The microtubules generally nucleate and grow from the center of the spindle, from which point they are transported towards the poles. They disassemble over the course of their lifespan, resulting in long, young microtubules close to the midline and older, short microtubules closer to the poles."

"This research provides concrete evidence for something that we've only been able to estimate until now," Brugués adds.

Mazur and Brugués worked with Daniel Needleman, Assistant Professor of Applied Physics and Molecular and Cellular Biology at Harvard, and Valeria Nuzzo, a former postdoctoral fellow in Mazur's lab at SEAS, to bring the tools of applied physics to bear on a biological question.

The team used a femtosecond laser to make two small slices perpendicular to the plane of growth of the spindle apparatus in egg extracts of the frog species Xenopus laevis.

They were then able to collect quantitative data on the reconstruction of the spindle following this disruption and precisely determine the length and polarity of individual microtubules. Observing the speed and extent of depolymerization (unraveling) of the spindle, the team worked backwards to compile a complete picture of the beginning and end points of each microtubule. Finally, additional experiments and a numerical model confirmed the role of transport.

"The laser allowed us to make precise cuts and perform experiments that simply were not possible using previous techniques," says Mazur.

With further inquiries into spindle architecture, the researchers hope that scientists will one day have a complete understanding, and possibly even control over, the formation of the spindle.

"Understanding the spindle means understanding cell division," notes Brugués. "With a better understanding of how the spindle is supposed to operate, we have more hope of tackling the range of conditions—from cancer to birth defects—that result from disruptions to the cell cycle or from improper chromosomal segregation."

The research was supported by the National Science Foundation and by a fellowship from the Human Frontiers Science Program.

####

For more information, please click here

Contacts:
Caroline Perry

617-496-1351

Copyright © Harvard University

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

Virginia Tech physicists propose path to faster, more flexible robots: Virginia Tech physicists revealed a microscopic phenomenon that could greatly improve the performance of soft devices, such as agile flexible robots or microscopic capsules for drug delivery May 17th, 2024

Gene therapy relieves back pain, repairs damaged disc in mice: Study suggests nanocarriers loaded with DNA could replace opioids May 17th, 2024

Shedding light on perovskite hydrides using a new deposition technique: Researchers develop a methodology to grow single-crystal perovskite hydrides, enabling accurate hydride conductivity measurements May 17th, 2024

Oscillating paramagnetic Meissner effect and Berezinskii-Kosterlitz-Thouless transition in cuprate superconductor May 17th, 2024

Govt.-Legislation/Regulation/Funding/Policy

International research team uses wavefunction matching to solve quantum many-body problems: New approach makes calculations with realistic interactions possible May 17th, 2024

Aston University researcher receives £1 million grant to revolutionize miniature optical devices May 17th, 2024

NRL charters Navy’s quantum inertial navigation path to reduce drift April 5th, 2024

Discovery points path to flash-like memory for storing qubits: Rice find could hasten development of nonvolatile quantum memory April 5th, 2024

Nanomedicine

Virginia Tech physicists propose path to faster, more flexible robots: Virginia Tech physicists revealed a microscopic phenomenon that could greatly improve the performance of soft devices, such as agile flexible robots or microscopic capsules for drug delivery May 17th, 2024

Diamond glitter: A play of colors with artificial DNA crystals May 17th, 2024

Advances in priming B cell immunity against HIV pave the way to future HIV vaccines, shows quartet of new studies May 17th, 2024

New micromaterial releases nanoparticles that selectively destroy cancer cells April 5th, 2024

Discoveries

Virginia Tech physicists propose path to faster, more flexible robots: Virginia Tech physicists revealed a microscopic phenomenon that could greatly improve the performance of soft devices, such as agile flexible robots or microscopic capsules for drug delivery May 17th, 2024

Diamond glitter: A play of colors with artificial DNA crystals May 17th, 2024

Finding quantum order in chaos May 17th, 2024

Advances in priming B cell immunity against HIV pave the way to future HIV vaccines, shows quartet of new studies May 17th, 2024

Announcements

Virginia Tech physicists propose path to faster, more flexible robots: Virginia Tech physicists revealed a microscopic phenomenon that could greatly improve the performance of soft devices, such as agile flexible robots or microscopic capsules for drug delivery May 17th, 2024

Diamond glitter: A play of colors with artificial DNA crystals May 17th, 2024

Finding quantum order in chaos May 17th, 2024

Oscillating paramagnetic Meissner effect and Berezinskii-Kosterlitz-Thouless transition in cuprate superconductor May 17th, 2024

Grants/Sponsored Research/Awards/Scholarships/Gifts/Contests/Honors/Records

Aston University researcher receives £1 million grant to revolutionize miniature optical devices May 17th, 2024

Discovery points path to flash-like memory for storing qubits: Rice find could hasten development of nonvolatile quantum memory April 5th, 2024

Chemical reactions can scramble quantum information as well as black holes April 5th, 2024

Discovery of new Li ion conductor unlocks new direction for sustainable batteries: University of Liverpool researchers have discovered a new solid material that rapidly conducts lithium ions February 16th, 2024

Nanobiotechnology

Diamond glitter: A play of colors with artificial DNA crystals May 17th, 2024

Advances in priming B cell immunity against HIV pave the way to future HIV vaccines, shows quartet of new studies May 17th, 2024

New micromaterial releases nanoparticles that selectively destroy cancer cells April 5th, 2024

Good as gold - improving infectious disease testing with gold nanoparticles April 5th, 2024

NanoNews-Digest
The latest news from around the world, FREE




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project