Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Why the heart beats on the left

07.04.2009
In all vertebrates - and thus also in the human - the heart usually beats on the left side of the body. Why this is the case has not been understood in every detail yet. Developmental biologist from Würzburg now made a crucial step towards the solution of this riddle.

When a fertilized ovum is to grow into a viable organism during its embryonic development, one of the things the cells need to know is where left and right are, so that the organs eventually wind up in the right spot in the right shape.

Thus the heart of all vertebrates, for instance, develops from an initially tubular shape that already shows a flexion towards the right side of the body shortly after its formation. This initial asymmetry is the reason why the tip of the heart - after a number of further rotations - in the end points towards the left side of the body.

How the body distinguishes right from left

How does the organism manage distinguish right from left? And which processes are responsible, for example, for the fact that heart usually beats on the left? The Würzburg-based developmental biologist Professor Thomas Brand and his colleague Dr. Jan Schlüter pursued this question. The current online issue of Proceedings of the National Academy of Sciences PNAS reports their result. In chicken embryos, the two researchers were able to characterize a signal pathway that plays a role in the asymmetrical development of the heart.

"So far the leading opinion was that a certain signal pathway is responsible for the left-sided development of organs that needs to be inhibited on the right side so that an asymmetry can develop", says Thomas Brand. As the two developmental biologists have shown now, this concept is not accurate: "With the chicken embryo, we could prove that an autonomous signal pathway also exists on the right side", states Brand.

Asymmetry is the rule, not the exception

Asymmetry in the body: Is it not the exception from the rule that applies to no more than the heart, liver, and spleen, while the majority is virtually built as a mirror-image? "Not at all", says Brand. In principle, the entire body is built asymmetrically; to make it appear symmetrical nevertheless, numerous signal cascades have to become active during the embryonic development.

In their work, Brand and Schlüter intensively examined mechanisms that play a role in the right-left characteristics. One of them is the asymmetrical production of ionic pumps. "This leads to an uneven distribution of electrical charge on the right and left side of the body that seem to show the cells the way", explains Brand. In the developmental biologists' experiments, blocking these ionic pumps led to a random distribution of the cells in the heart that are the preliminary stage of coronary blood vessels: At times they were located, as is usual, on the right side; at times they ended up on the left. In other cases they settled on both sides; occasionally they were missing completely.

Dead cells show the way

"Thus this effect also plays an important role for the lateral orientation of the organs", says Thomas Brand. But to him, this is not sufficient as the sole explanation for the 'left-sided heart'. The same applies to another mechanism: the programmed cell death. "In this case, the organism ensures that cells die along the midline of the embryo to mark the border between the left and the right side of the body", explains Brand. If the scientists prevented this cell death, the cells would settle in the heart, also according to the random principle.

FGF8: This is the name of the signal factor that is responsible for the right-sided development of the chicken heart according to the findings of Brand and Schlüter. Thus, their conclusion is: "The models for the right-left development have to be expanded." The fact that other vertebrates, such as the South African clawed frog or the river lamprey, build hearts in a similar manner speaks for the concept that this aspect of the right-left asymmetry is evolutionarily ancient.

Further research necessary

If this is also relevant for mammals, and thus for humans, is not clear. After all: "FGF8 mutations cause heart deformities in mice. This signal pathway might be significant for the right-directed heart flexion in the very early stage of the development, says Thomas Brand. The focus of his further research will thus be to identify the target genes of this signal pathway to better understand this aspect of the heart development on a molecular level.

Jan Schlueter and Thomas Brand (2009). A right-sided pathway involving FGF8/Snai1 controls asymmetric development of the proepicardium in the chick embryo. Proc Natl Acad Sci U. S. A. Early Edition (EE) the week of April 6, 2009. www.pnas.org/cgi/doi/10.1073/pnas.0811944106

Contact: Prof. Dr. Thomas Brand, phone (0931) 31-84259, e-mail: thomas.brand@uni-wuerzburg.de

Gunnar Bartsch | idw
Further information:
http://www.uni-wuerzburg.de

More articles from Life Sciences:

nachricht What happens in the cell nucleus after fertilization
06.12.2016 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt

nachricht Researchers uncover protein-based “cancer signature”
05.12.2016 | Universität Basel

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

Simple processing technique could cut cost of organic PV and wearable electronics

06.12.2016 | Materials Sciences

3-D printed kidney phantoms aid nuclear medicine dosing calibration

06.12.2016 | Medical Engineering

Robot on demand: Mobile machining of aircraft components with high precision

06.12.2016 | Power and Electrical Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>