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 A novel socio-ecological approach helps identifying suitable wolf habitats
17.02.2017 | Universität Zürich

nachricht New, ultra-flexible probes form reliable, scar-free integration with the brain
16.02.2017 | University of Texas at Austin

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

Biocompatible 3-D tracking system has potential to improve robot-assisted surgery

17.02.2017 | Medical Engineering

Real-time MRI analysis powered by supercomputers

17.02.2017 | Medical Engineering

Antibiotic effective against drug-resistant bacteria in pediatric skin infections

17.02.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>