Recent advancements in biophysics are shedding light on a fascinating aspect of how bilateral animals, humans included, develop asymmetrical internal structures from seemingly symmetrical outward appearances.
Internal Asymmetry in Bilateral Animals
While most animals display bilateral symmetry—which gives them a uniform look—new insights from Vivek Prakash, an assistant professor at the University of Miami’s College of Arts and Sciences, illustrate how this symmetry shifts internally.
Vital organs, such as the heart and liver, are not symmetrically placed, prompting a critical question: How does this internal asymmetry emerge during development?
Current understanding suggests that asymmetric development begins during a crucial stage known as gastrulation.
This early phase of embryonic development involves the division of the embryo into distinct layers, laying the groundwork for the arrangement of internal organs.
Despite its importance, the timing and methods that trigger this asymmetry have long been a mystery—until now.
Cellular Movements and Asymmetry
To shed light on these unanswered questions, Prakash and his colleagues set out to explore chick embryo development using advanced fluorescent microscopy.
Their observations revealed that the physical dynamics of cellular movement carry a built-in asymmetry, contradicting earlier beliefs that this trait was solely the result of genetic influences.
Graduate student Shubham Sinha highlighted the significance of their findings, suggesting that these insights could apply to a range of species, humans included.
Published in the Proceedings of the National Academy of Sciences, this research represents a meaningful step toward understanding the origins of left-right asymmetry in development.
Prakash emphasized a major revelation: the movements of cells in embryos show a distinct left-right asymmetry.
This shift in perspective challenges the long-held view that genetics are the only players in this developmental process.
Implications and Future Research
The research team, consisting of Rieko Asai from Kumamoto University in Japan and Takashi Mikawa from the University of California, San Francisco, utilized fluorescent microscopy and live imaging techniques to gather their data.
By carefully analyzing and distilling extensive video recordings of cellular movements from several chick embryos, they observed that the movements radiated from the center of the embryos in concentric circles.
Notably, these circular motions on the right side were significantly stronger than those on the left, providing direct evidence of left-right asymmetry, a finding supported by quantitative analysis of cell velocities.
This groundbreaking study is poised to enrich our understanding of gastrulation in both humans and mice.
It may also offer crucial insights into how congenital anomalies develop across various animal species.
By identifying key molecular signals during early development, researchers may uncover potential factors that disrupt normal embryogenesis.
For instance, excessive first trimester weight gain has been associated with altered developmental pathways, which could increase the risk of congenital anomalies.
Understanding these mechanisms could pave the way for improved prenatal care and preventive strategies.
Source: ScienceDaily