Weak electric fish provide excellent study systems for analysis. The fish has independently developed electrical organs from the muscle. However, how fish could develop their electrical organs remains unclear.
The new study explains how small genetic changes have allowed electric fish to develop electrical organs. The findings could also help scientists identify genetic mutations behind some human diseases.
Evolution has used the peculiarities of fish genetics to develop electrical organs. All fish have two copies of the same gene that make up sodium channels, which are small muscle engines.
Electric fish have developed electrical organs by turning off one copy of the sodium channel gene in muscle and turning it on in other cells. The tiny bikes that normally tighten the muscles have been transformed into generating electrical signals and bingo! A new body with incredible potential was born.
Harold Zakon, a professor of neuroscience and integrative biology at the University of Texas at Austin and corresponding author of the study, said: “It’s exciting because we see how a small change in a gene can completely change where it manifests.”
The researchers found that a short portion of this sodium channel gene, which is about 20 letters long, checks whether the gene is expressed in a given cell. They confirmed that this control area is either altered or missing for electric fish. Therefore, one of the two sodium channel genes in electrical fish muscle is turned off. However, the consequences are much wider than for the evolution of electrified fish.
Zakon said “This control area is for most vertebrates, including humans.” So the next step in terms of human health would be to examine this area in human gene databases to see how much variability is in normal people and whether some deletions or mutations in this area could lead to decreased expression of sodium channels, which can lead to disease. . “
“The sodium channel gene had to be turned off in the muscle before an electrical organ could develop.”
“If they turned on the gene in both the muscle and the electrical organ, then all the new things that happen with the sodium channels in the electrical organ would also happen in the muscle.” So it was important to isolate the expression of the gene into an electrical organ, where it could develop without damaging the muscles. “
There are two groups of electric fish in the world: South American and African weak electric fish. Electric fish in Africa had mutations in the control area, while electric fish in South America lost them altogether. Both groups came up with the same solution for the development of an electrical organ – the loss of sodium channel gene expression in muscle – although from two different pathways.
Gallant said “If you rewound the tape of life and pressed play, would it play the same way, or would you find new ways forward? Would evolution work the same way over and over again ?. Electric fish, let’s try to answer this question, because they have repeatedly developed these incredible properties. In this paper, we turned to fences and tried to understand how these sodium channel genes were repeatedly lost in electric fish. It was a joint effort. “
- Sarah Lapotin et al. Divergent cis-regulatory development is the basis for the convergent loss of sodium channel expression in electric fish. DOI: 10.1126 / sciadv.abm2970
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