Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

How molecular clocks can help chickens get wings

13.04.2007
A fundamental biological question is on how the body plan is organized during embryonic development. Embryos start as a group of non-differentiated cells that divide and eventually specialise into the different tissues and organs of the body. But how do cells know when to go through their different destinies?

Research to be published on the 27th of April edition of the “Journal of Molecular Biology” by a group of Portuguese scientists provides a piece of the puzzle by showing that formation of the cartilage during chicken wing embryonic development is linked to a gene called hairy2, which seems to act as molecular clock helping cells to know when is time to stop dividing and differentiate.

Their research also suggests that these molecular clocks can be a widespread time measurement mechanism among multicellular organisms. The work has important implications by contributing to a better understanding of embryonic development and consequently also of the diseases resulting from problems in it.

Cyclic or oscillatory genes are genes characterised by going from inactivated (not expressed) to activated (expressed) and back to an inactivated state in continuous cycles. They were discovered almost ten years ago involved in the embryo early segmentation steps although their function in this process is unclear and for a long time they were not found anywhere else. Recent research, however, have report an oscillatory gene in several cells of mouse not connected to segmentation, raising the prospect that their presence could be much more widespread than previously thought.

In order to test this hypothesis Susana Pascoal and Isabel Palmeirim (which was associated with the discovery of the first cyclic genes) at Minho University, Portugal together with colleagues from Gulbenkian Institute of Science and Lisbon University in Portugal and Pierre and Marie Currie University in France decided to study the embryonic development of the chicken wing (one of the most common model of embryonic studies) looking at the expression of the gene hairy2, which is the chicken equivalent of the cyclic gene recently reported in mouse cells.

Limbs in vertebrates develop from small buds on the side of the body and as these buds grow, the undifferentiated cells in them first multiply and then differentiate into the various tissues of the limb, including the cartilage and later the bone that make up the limb skeleton. Pascoal, Palmeirim and colleagues started their study by following, during the different stages of embryonic development, the cells constituting the wing bud to find that hairy2 was expressed in cartilage precursor cells. In fact, it was found that hairy2 oscillated between inactivated and activated states while these cells divided, but, as soon as cells started differentiating hairy2 oscillations stopped and a cartilaginous element of the wing is formed. Furthermore, as cartilage precursor cells divide and the limb bud grows it is even possible to see a wavelike expression of the hairy2 gene through adjacent cells, starting from cells with a low hairy2 expression through to moderate and then onto high hairy2 levels of expression.

Pascoal, Palmeirim and colleagues measured each hairy2 cycle – corresponding to the time necessary for the gene to go from an inactivated state, into activation and back into inactivation – to find that these lasted exactly 6 hours.

The next step was to see if the hairy2 cycle could be related with the formation of cartilage/bone elements in chicken wing since it has been proposed that cyclic genes can work as molecular clocks helping cells decide when to change behaviour. In order to test this supposition the team of researcher followed the formation of the 2nd phalanx of the wing and found that the average time for this process was 12 hours which corresponded to two hairy2 cycles.

This result led Pascoal, Palmeirim and colleagues to propose that the 2nd phalanx precursor cells were able to count hairy2 cycles and use the gene as a molecular clock to measure time and allow an accurate control of the cells growth and differentiation. In the case of the 2nd phalanx the cells “counted” two 6-hours cycles for the formation of one bone element (12 hours). Furthermore, the fact that time control is crucial for development and that cyclic genes seem to present in several embryonic tissues led the researchers to also suggest that oscillators (or cyclic genes) playing the role of molecular clocks are probably quite widespread among the different embryonic tissues of multicellular organisms.

The researchers also suggest that the reason why it has been so difficult to find prove of these cyclic genes comes from the fact that only when adjacent cells are in synchrony (activated-inactivated-activated-etc) is possible to detect a pattern big enough to identify the presence of a molecular clock.

"The discovery of the first cyclic gene by Palmeirim and colleagues was an amazing discovery and our work now supports the idea they are used as molecular clocks by embryonic cells in several tissues” says Susana Pascoal, the first author of the article “we know this is only part of the story, but it is crucial information to understand how embryonic development is regulated”

Pascoal, Palmeirim and colleagues’ work has in fact many and important implications as it contributes to the understanding of how embryos develop, and consequently also the bases of human congenital development defects, but also helps paving the way for one day future technology aiming at biological tissue engineering and repair be developed.

Piece researched and written by: Catarina Amorim (catarina.amorim@linacre.ox.ac.uk)

Catarina Amorim | alfa
Further information:
http://www.smalllinks.com/1EO

More articles from Life Sciences:

nachricht Scientists unlock ability to generate new sensory hair cells
22.02.2017 | Brigham and Women's Hospital

nachricht New insights into the information processing of motor neurons
22.02.2017 | Max Planck Florida Institute for Neuroscience

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Microhotplates for a smart gas sensor

22.02.2017 | Power and Electrical Engineering

Scientists unlock ability to generate new sensory hair cells

22.02.2017 | Life Sciences

Prediction: More gas-giants will be found orbiting Sun-like stars

22.02.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>