New biophysics research enhances our understanding of how left-right asymmetry develops in living organisms.
Most living beings, including humans, exhibit bilateral symmetry, meaning our external appearance is generally symmetrical.
However, internally, the situation is quite different.
“Internally, we are not symmetrical — our organ placements like the heart, liver, and stomach differ from one side to the other,” explained Vivek Prakash, an assistant professor of physics at the University of Miami College of Arts and Sciences, an expert in biophysics. “We sought to determine when this asymmetry first appears.”
This internal left-right asymmetry is thought to commence very early during development, specifically when a tiny embryo undergoes gastrulation, a process that ultimately helps position our internal organs.
Nevertheless, the precise timing and mechanics behind the start of this asymmetry remained uncertain.
To explore this, Prakash and three researchers examined chick embryonic development with fluorescent microscopes to track cell movements. They found that these movements demonstrated asymmetrical behavior, contrasting with previous studies that suggested genetics was the primary cause for such asymmetry.
“Our research unveils crucial insights into a significant phase of early animal development, aiding in the understanding of left-right asymmetry’s origins,” remarked Shubham Sinha, a graduate student in Prakash’s lab.
Their results provide new perspectives on early developmental processes and are likely relevant to various species, including humans. Consequently, this study was published in the Proceedings of the National Academy of Sciences this week, potentially aiding scientists in unraveling the foundations of left-right asymmetry.
“Cell movement plays a vital role, and our observations show that left-right asymmetry in chick embryos arises from these movements,” Prakash noted. “This represents a significant shift, as it was long believed that genetic factors were solely responsible for this asymmetry.”
This study involved Prakash, Sinha, Rieko Asai, a researcher at Kumamoto University in Japan, and Professor Takashi Mikawa of the University of California, San Francisco.
Using fluorescent microscopy and live imaging techniques, the team examined and quantified cellular motion in numerous chick embryos. By compressing 10 hours of cell activity into just 10 seconds of video, they noted that cells moved in outwardly spiraling patterns from the embryo’s center, with these movements being more pronounced on the right side than the left. This provided visual evidence of left-right asymmetry, further confirmed by precise measurements of cell speeds. This cellular motion is crucial for embryonic development.
“This finding is significant for enhancing our understanding of gastrulation in humans and mice, and the potential emergence of birth defects in various animals,” Prakash added.
