Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Laser micro-scalpel yields biological insights into tissue dynamics

28.03.2003


Using a laser beam scalpel so fine it could inscribe words on the surface of a fly egg, researchers have snipped their way to a new understanding of a key process in a fruit fly’s embryonic development. The process, called dorsal closure, is the complex mechanism by which the embryonic skin of the fruit fly Drosophila knits itself together to protect its innards from the outside world.



Understanding this seemingly arcane process is important because dorsal closure uses molecular and cellular mechanisms very similar to those involved in wound-healing as well as those that can go awry in humans to produce the spinal malformation spina bifida.

The researchers’ achievements were reported in an online article in the February 6, 2003, Sciencexpress -- and will appear in the April 4, 2003, print version of Science -- by an interdisciplinary Duke research team that includes biologists, physicists and a mathematician. It was this broad collaboration, said the scientists, that enabled them to refine the laser scalpel, to perform the microsurgery to dissect the fly tissue and to model the forces involved in key developmental machinery.


“Dorsal closure is a good system for studying these processes because it’s tractable,” said lead author Shane Hutson. “We only have to deal with a few different kinds of cells that are arranged in a planar fashion.”

According to Hutson -- a postdoctoral fellow in Duke’s Free Electron Laser Laboratory (FELL) -- dorsal closure involves the interplay of forces among three kinds of tissues in the fly embryo, which is smaller than a grain of rice. The amnioserosa cells form an inner sheet of tissue involved in knitting the closure; the lateral epidermis is the tissue layer that ultimately forms the fly’s outer covering; and in between these two tissues is a group of “leading edge” cells that form a purse-string structure that somehow tightens to contribute to closure.

“As closure proceeds, the cells of the amnioserosa contract, the purse-string along the boundary contracts, the lateral epidermis cells are stretched, and the two sheets of lateral epidermis along those purse-strings are zipped together into a seam. And so those four processes contribute to how dorsal closure proceeds,” explained Hutson.

The mystery, said Hutson, was precisely how these different tissues, and the forces they exert, work together to effect dorsal closure.

“There are lots of ways you could build a model such that closure would occur,” said Hutson. “It could be the amnioserosa doing all the work. It could be the purse-strings doing all the work. It could be zipping. It could be the lateral epidermis actually growing and pushing itself over the amnioserosa.

“And so, we wanted to systematically investigate the forces in the system to figure out which of these processes were really contributing to closure, and which were simply following along.”

To attack the problem, the team needed to be able to selectively dissect the force-producing tissues, and to simultaneously observe the result through a high-powered microscope. Thus, they designed an optical and steering system for the laser beam scalpel that was implemented and refined by graduate students Yoichiro Tokutake and Ming-Shien Chang at the FELL. The resulting system can produce and guide a laser beam as small as a half-micron in diameter -- roughly a hundredth the diameter of a human hair. Tokutake and Chang went on to become the group’s master laser surgeons.

Said FELL Director Glenn Edwards, one of the paper’s senior authors, “These four forces are working in concert, so in essence we are trying to understand the ‘symphony’ of dorsal closure -- how these forces are coordinated in space and time.” The dissection of the symphony produced surprises, said Hutson. “For example, we found that the system was very resilient,” he said. “When we perturbed only one or another of the tissues, the process kept right on going.

“We were surprised by this finding because we thought we’d find that at least one of these processes was absolutely essential,” he said. “But it does make sense in the end that you’d want a system where, if something’s not quite right in one process, you can compensate and still complete dorsal closure.”

Key to the rigorous understanding of this intricate system was the physical reasoning inherent in creating a quantitative model describing the process -- the result of a team effort led by Edwards, Hutson, Duke biologist Dan Kiehart and Duke mathematician Stephanos Venakides.

As laser surgery produced experimental results, the research team incorporated those results into a model describing the interplay of forces. The next steps, said the scientists, will be to use their approach to further expand their explorations.

Said Dan Kiehart, the other senior author, “One of the next goals of this collaboration will be to use the same kind of modeling to study wound-healing. We may begin with Drosophila, but then progress to studying vertebrate cell cultures, fish or mice, where genetic studies may be of more direct interest to physicians.”

However, emphasized Kiehart -- an expert on the molecular machinery of such contractile processes as dorsal closure -- Drosophila remains an attractive research model because the flies can be genetically manipulated so easily.

Other major questions include how the multiple forces involved in dorsal closure are synchronized, and how the system initially launches the process.

Said Venakides, “One way this system might work is like the unwinding of a clock, with the closure proceeding on its own initial energy. Another analogy might be the driving of a car, where a steady force is being guided.”

More broadly, said Kiehart, such studies “are going to provide a model not only for dorsal closure and wound-healing, but for studying any such developmental process that involve tissue migration and closure.” Essential for these scientific advances, said Edwards, is the value of such interdisciplinary collaboration.

“The FEL Lab is an interdisciplinary think tank, and in this environment my group, Dan’s group and Stephanos came together to work on this problem at the interface of traditional disciplines. And we’ve made a lot of progress towards cracking it,” he said

Dennis Meredith | EurekAlert!
Further information:
http://www.duke.edu/

More articles from Life Sciences:

nachricht Shedding light on the brown color of algae
14.07.2020 | Johannes Gutenberg-Universität Mainz

nachricht New substance library to accelerate the search for active compounds
14.07.2020 | Helmholtz-Zentrum Berlin für Materialien und Energie

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Electron cryo-microscopy: Using inexpensive technology to produce high-resolution images

Biochemists at Martin Luther University Halle-Wittenberg (MLU) have used a standard electron cryo-microscope to achieve surprisingly good images that are on par with those taken by far more sophisticated equipment. They have succeeded in determining the structure of ferritin almost at the atomic level. Their results were published in the journal "PLOS ONE".

Electron cryo-microscopy has become increasingly important in recent years, especially in shedding light on protein structures. The developers of the new...

Im Focus: The spin state story: Observation of the quantum spin liquid state in novel material

New insight into the spin behavior in an exotic state of matter puts us closer to next-generation spintronic devices

Aside from the deep understanding of the natural world that quantum physics theory offers, scientists worldwide are working tirelessly to bring forth a...

Im Focus: Excitation of robust materials

Kiel physics team observed extremely fast electronic changes in real time in a special material class

In physics, they are currently the subject of intensive research; in electronics, they could enable completely new functions. So-called topological materials...

Im Focus: Electrons in the fast lane

Solar cells based on perovskite compounds could soon make electricity generation from sunlight even more efficient and cheaper. The laboratory efficiency of these perovskite solar cells already exceeds that of the well-known silicon solar cells. An international team led by Stefan Weber from the Max Planck Institute for Polymer Research (MPI-P) in Mainz has found microscopic structures in perovskite crystals that can guide the charge transport in the solar cell. Clever alignment of these "electron highways" could make perovskite solar cells even more powerful.

Solar cells convert sunlight into electricity. During this process, the electrons of the material inside the cell absorb the energy of the light....

Im Focus: The lightest electromagnetic shielding material in the world

Empa researchers have succeeded in applying aerogels to microelectronics: Aerogels based on cellulose nanofibers can effectively shield electromagnetic radiation over a wide frequency range – and they are unrivalled in terms of weight.

Electric motors and electronic devices generate electromagnetic fields that sometimes have to be shielded in order not to affect neighboring electronic...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Contact Tracing Apps against COVID-19: German National Academy Leopoldina hosts international virtual panel discussion

07.07.2020 | Event News

International conference QuApps shows status quo of quantum technology

02.07.2020 | Event News

Dresden Nexus Conference 2020: Same Time, Virtual Format, Registration Opened

19.05.2020 | Event News

 
Latest News

Shedding light on the brown color of algae

14.07.2020 | Life Sciences

Color barcode becomes ISO standard

14.07.2020 | Information Technology

New substance library to accelerate the search for active compounds

14.07.2020 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>