Researchers at Harvard Medical School and Harvard University have made a remarkable discovery about the development of the zebrafish embryo heart. Using advanced optical electrophysiology tools, they observed the moment when cells in the zebrafish embryo heart start beating in unison for the first time. The team found that the heart cells begin beating suddenly and all at once as calcium levels and electrical signals increase. It was also observed that each heart cell is capable of beating on its own, without the need for a pacemaker, and that the heartbeat can start from different locations.
By studying the basic biology of the heartbeat, scientists hope to gain a better understanding of cardiac rhythm disorders in humans. The researchers believe that this study, which provides an in-depth examination of the heartbeat, will contribute significantly to existing knowledge. This research, titled “A bioelectrical phase transition patterns the first vertebrate heartbeats,” was published in the journal Nature.
The development of a complete organism from just a few cells requires precise cellular organization and cooperation. In the case of the heart, cells that are initially static must begin beating in perfect unison. The researchers highlight that the first heartbeat is a unique event and studying this process can lead to a better understanding of the mechanisms underlying the heartbeat.
While the researchers did not initially set out to study how the heart starts beating, they realized that there were still gaps in knowledge about this process. Their study aimed to investigate how heart cells go from being silent to beating. Using fluorescent proteins and high-speed microscope imaging, the team observed changes in calcium levels and electrical activity in heart cells of developing zebrafish embryos.
To their surprise, the researchers discovered that all the heart cells transitioned abruptly from not beating to beating, characterized by simultaneous spikes in calcium and electrical signals. This synchronized beating starts from one region of the heart and rapidly spreads to the rest of the cells. Interestingly, the heartbeats can start from different spots in different zebrafish embryos.
Unlike adult hearts, where pacemaker cells drive the heartbeat, most cells in the embryonic heart have the ability to beat on their own. This finding challenges the prediction of the location of the first beats. The researchers explain that gradual and asynchronous development of single-cell bioelectrical properties leads to the transition from quiescence to coordinated beating.
In conclusion, this study provides a groundbreaking insight into the development and synchronization of the zebrafish embryo heart. Understanding the fundamental mechanisms of the heartbeat could shed light on cardiac rhythm disorders in humans. The researchers’ findings pave the way for further research in this field.
– “A bioelectrical phase transition patterns the first vertebrate heartbeats,” Nature
– Harvard Medical School and Harvard University