UT Austin researchers confirmed that the genetic control region they discovered only controls the expression of a sodium channel gene in muscle and no other tissues. In this image, a green fluorescent protein lights up only in trunk muscle in a developing zebrafish embryo.
Image credit: Mary Swartz/Johann Eberhart/University of Texas at Austin.
Creationists might want to avoid reading this because it contains information, not only about evolution and how it forms the basis of scientific understanding of the facts, but also because it is about how new genetic information arose by gene duplication and subsequent repurposing of a duplicate gene to create a new organ - something that creationist frauds say can't happen because this is 'macroevolution' which requires a magic designer. The information comes from a research team from the University of Texas Austin and Michigan State University, led by Professor Harold Zakon of UT Austin, who have worked out how electric fish evolved their electric organs.
This is exciting because we can see how a small change in the gene can completely change where it’s expressed.
Professor Harold Zakon, corresponding authorDepartment of Neuroscience
And Department of Integrative Biology
The University of Texas, Austin, TX, USA.
If they turned on the gene in both muscle and the electric organ, then all the new stuff that was happening to the sodium channels in the electric organ would also be occurring in the muscle, so, it was important to isolate the expression of the gene to the electric organ, where it could evolve without harming muscle.
Professor Harold ZakonThis research could have an application in human health by helping to understand how the variants of this gene work in conditions in which reduced sodium pump efficiency plays a part.
If you rewound the tape of life and hit play, would it play back the same way or would it find new ways forward? Would evolution work the same way over and over again? Electric fish let us try to answer that question because they have repeatedly evolved these incredible traits. We swung for the fences in this paper, trying to understand how these sodium channel genes have been repeatedly lost in electric fish. It really was a collaborative effort.
Jason R. Gallant, co-author
Department of Integrative Biology
And Ecology, Evolution, and Behavior Program
Michigan State University, East Lansing, MI, USA.
Department of Integrative Biology
And Ecology, Evolution, and Behavior Program
Michigan State University, East Lansing, MI, USA.
There are two groups of electric fish in the world—one in Africa and the other in South America. The researchers discovered that the electric fish in Africa had mutations in the control region, while electric fish in South America lost it entirely. Both groups arrived at the same solution for developing an electric organ—losing expression of a sodium channel gene in muscle—though from two different paths.
One of the next questions the researchers hope to answer is how the control region evolved to turn on sodium channels in the electric organ.
The team have published their results, open access, in the journal Science Advances:
Copyright: © 2022 The authors. Published by the American Association for the Advancement of Science.
Open access. (CC BY-NC 4.0)
AbstractJust to recap for any creationists who managed to stay the course and get through to the end: what this paper shows is not only that the authors regard the TOE as the foundation of their science, but also that new information can arise by gene doubling followed by mutation and environment-driven repurposing of redundant copies, but also that information can give rise to new structures with new functions, and all driven by natural selection from what is available to it, and with relatively few changes to the DNA. The advantages of this new organ can be seen from the fact that it evolved twice from the same starting point and converged on the same solution. And all without the assistance of magic.
South American and African weakly electric fish independently evolved electric organs from muscle. In both groups, a voltage-gated sodium channel gene independently lost expression from muscle and gained it in the electric organ, allowing the channel to become specialized for generating electric signals. It is unknown how this voltage-gated sodium channel gene is targeted to muscle in any vertebrate. We describe an enhancer that selectively targets sodium channel expression to muscle. Next, we demonstrate how the loss of this enhancer, but not trans-activating factors, drove the loss of sodium channel gene expression from muscle in South American electric fish. While this enhancer is also altered in African electric fish, key transcription factor binding sites and enhancer activity are retained, suggesting that the convergent loss of sodium channel expression from muscle in these two electric fish lineages occurred via different processes.
LaPotin, Sarah; Swartz, Mary E.; Luecke, David M.; Constantinou, Savvas J.; Gallant, Jason R.; Eberhart, Johann K.; Zakon, Harold H.(2022)
Divergent cis-regulatory evolution underlies the convergent loss of sodium channel expression in electric fish
Science Advances 8(22); DOI: 10.1126/sciadv.abm2970
Published by the American Association for the Advancement of Science, Open access
Reprinted under a Creative Commons Attribution-NonCommercial 4.0 International license (CC BY-NC 4.0)
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