For the past 65 years, the focus of developmental biology has been on DNA as the carrier of biological information. Researchers have typically assumed that genetic expression patterns alone are enough to determine embryonic development.
DNA can make proteins inside cells, but “there is nothing in the genome that directly specifies anatomy.” To develop properly, tissues need spatial cues that must come from other sources in the embryo.
Researchers found how the embryo is molded by bioelectrical signals, particularly ones that emanate from the young brain long before it is even a functional organ.
Even though we know the brain uses electricity for information processing, for a long time science ignored the role of bioelectricity in carrying information about a body’s development.
it’s not just the brain that uses bioelectric signaling — the whole body does. All cell membranes have embedded ion channels, protein pores that act as pathways for charged molecules, or ions. Differences between the number of ions inside and outside a cell result in an electric gradient — the cell’s resting potential. Vary this potential by opening or blocking the ion channels, and you change the signals transmitted to, from and among the cells all around. Neurons do this as well, but even faster.
By changing the voltage of cells in flatworms, over the last few years they produced worms with two heads, or with tails in unexpected places. In tadpoles, they made frogs with extra legs and changing gut tissue into eyes — simply by hacking the local bioelectric activity that provides patterning information.
By changing the resting potential in the cells of tadpoles as far from the head as the gut, they appeared to disrupt the body’s “blueprint” for brain development. The resulting tadpoles’ brains were smaller or even nonexistent, and brain tissue grew where it shouldn’t.
Levin’s work has been cited in more than 300 papers in the scientific literature — more than 10,000 times in almost 8,000 articles — “a great indicator that his work is making a difference.”
Brainless Embryos Suggest Bioelectricity Guides Growth
Long before the nervous system works, the brain sends crucial bioelectric signals to guide the growth of embryonic tissues. In fact, the Spanish neuroscientist and Nobel laureate Santiago Ramón y Cajal once called the brain and neurons, the electrically active cells that process and transmit nerve signals, the “butterflies of the soul.”[3]
References
[3] https://www.wired.com/story/brainless-embryos-suggest-bioelectricity-guides-growth/