Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Secrets of the 4 chambers revealed by reptile hearts

04.09.2009
The molecular blueprint for evolution from cold-blooded to warm-blooded has been found

The first genetic link in the evolution of the heart from three-chambered to four-chambered has been found, illuminating part of the puzzle of how birds and mammals became warm-blooded.

Frogs have a three-chambered heart. It consists of two atria and one ventricle. As the right side of a frog's heart receives deoxygenated blood from the body, and the left side receives freshly oxygenated blood from the lungs, the two streams of blood mix together in the ventricle, sending out a concoction that is not fully oxygenated to the rest of the frog's body.

Turtles are a curious transition--they still have three chambers, but a wall, or septum is beginning to form in the single ventricle. This change affords the turtle's body blood that is slightly richer in oxygen than the frog's.

Birds and mammals, however, have a fully septated ventricle--a bona fide four-chambered heart. This configuration ensures the separation of low-pressure circulation to the lungs, and high-pressure pumping into the rest of the body.

As warm-blooded animals, we use a lot of energy and therefore need a great supply of oxygen for our activities. Thanks to our four-chambered heart, we are at an evolutionary advantage: we're able to roam, hunt and hide even in the cold of night, or the chill of winter.

But not all humans are so lucky to have an intact, four-chambered heart. At one or two percent, congenital heart disease is the most common birth defect. And a large portion of that is due to VSD, or ventricular septum defects. The condition is frequently correctable with surgery.

Benoit Bruneau of the Gladstone Institute of Cardiovascular Disease has honed into the molecular forces at work. In particular, he studies the transcription factor, Tbx5, in early stages of embryological development. He calls Tbx5 "a master regulator of the heart."

Scott Gilbert of Swarthmore College and Juli Wade of Michigan State University study evolutionary developmental biology of turtles and anole lizards respectively. When Bruneau teamed up with them, he was able to examine a wide evolutionary spectrum of animals. He found that in the cold-blooded, Tbx5 is expressed uniformly throughout the forming heart's wall. In contrast, warm-blooded embryos show the protein very clearly restricted to the left side of the ventricle. It is this restriction that allows for the separation between right and left ventricle.

Interestingly, in the turtle, a transitional animal anatomically--with a three-chambered, incompletely septated heart, the molecular signature is transitional as well. A higher concentration of Tbx5 is found on the left side of the heart, gradually dissipating towards the right.

Bruneau concludes: "The great thing about looking backwards like we've done with reptilian evolution is that it gives us a really good handle on how we can now look forward and try to understand how a protein like Tbx5 is involved in forming the heart and how in the case of congenital heart disease its function is impaired."

The journal Nature reports the finding in its Sept. 3 issue. The National Science Foundation supports the research.

Lily Whiteman | EurekAlert!
Further information:
http://www.nsf.gov

More articles from Life Sciences:

nachricht How brains surrender to sleep
23.06.2017 | IMP - Forschungsinstitut für Molekulare Pathologie GmbH

nachricht A new technique isolates neuronal activity during memory consolidation
22.06.2017 | Spanish National Research Council (CSIC)

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Quantum thermometer or optical refrigerator?

23.06.2017 | Physics and Astronomy

A 100-year-old physics problem has been solved at EPFL

23.06.2017 | Physics and Astronomy

Equipping form with function

23.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>