Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

What do a shark fin and a human leg have in common?

01.08.2006
One of the most important milestones in the evolution of life occurred when paired fins (and later limbs) appeared, leading to new types of locomotion.

Now, in the advanced online issue of Nature1, scientists show that, although originating from different cell types, human limbs and median fins share a common developmental mechanism. These results support the idea that it was from median fins that all fins and limbs evolved, a hypothesis that has been around since the 19 century, but, until now, has never been proved.

The earliest vertebrate fossils show only well-developed dorsal and ventral (median) fins what has led researchers to suspect that these were the basis for which all paired fins and limbs evolved. However, their different location (median versus side of the body) seemed to indicate that they appeared from different cells in the embryo, which challenged the common-origin idea.

In order to investigate the issue, Renata Freitas, a Portuguese scientist, together with Guang Jun Zhang and Martin J. Cohn, all working at the department of Zoology, University of Florida, studied the embryonic development of Catshark’s fins. Catsharks are sharks found in the Atlantic and owe their name to their flat heads and long, catlike eyes.

The researchers started by marking the different cells from the embryo and following their development, in order to understand which cells originated the different parts of the shark’s body. Next, they investigated the activity of different genes during fin development. From these two experiments, Freitas and colleagues discovered that the median fin of Catsharks, although originating from different embryonic cells, uses the same genes (Hox and Tbx18) during development as limbs and paired fins.

“Given that paired fins made their evolutionary debut at a particular location on the sides of the body, intuitively one would think the genetic tools for fin development would be brought together in that place,” said developmental biologist Martin Cohn, an associate professor with the University of Florida (UF) departments of zoology and anatomy and cell biology and a member of the UF Genetics Institute. “We’ve discovered that the genetic circuitry for building limbs first appeared in an entirely different place — the midline of the animal.”

To further confirm this hypothesis, Freitas, G Zhang and Cohn decided to study lampreys, which developed into an independent lineage before the appearance of the first modern fish (and so before the appearance of paired fins). Again, they found that lamprey’s median fin used the same developmental program as catshark’s median fins or human limbs.

“That we see these same mechanisms operating in lamprey fins tells us they must have been assembled in the median fins first, and later in evolution this entire genetic program was simply reutilized in a new position to build the first paired fins,” Cohn said. “It tells us our own arms and legs have their evolutionary roots in the dorsal, caudal and anal fins of our fishy ancestors.”

Furthermore, the fact that lampreys – one of the most primitive of living vertebrates- already use this fin’s developmental mechanism raises the possibility that this genetic program might have developed even before vertebrates. To investigate that, the researchers now plan to see if cephalocordates, which have appeared before the vertebrates, share a similar genetic mechanism behind the development of their fins.

Catarina Amorim | alfa
Further information:
http://www.oct.mct.pt

More articles from Life Sciences:

nachricht Fingerprint' technique spots frog populations at risk from pollution
27.03.2017 | Lancaster University

nachricht Parallel computation provides deeper insight into brain function
27.03.2017 | Okinawa Institute of Science and Technology (OIST) Graduate University

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Northern oceans pumped CO2 into the atmosphere

27.03.2017 | Earth Sciences

Fingerprint' technique spots frog populations at risk from pollution

27.03.2017 | Life Sciences

Big data approach to predict protein structure

27.03.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>