Saturday , April 17 2021

What the axolot genome can teach to human medicine



Axolot is a lively amphibian with four legs, a corona of curvature of plumosa texture and one long flaky tummy fin. It can have a pale pink color or be golden, gray or black, plump or smooth, and Your facial expression is similar to that of the slightly smiley emoji. This creature is unusual among amphibians because it does not go through a metamorphosis: She reaches sexual maturity and spends her entire life as a giant ugly baby.

According to an Aztec legend, The first of these smiling salamanders was a god who took this form to prevent him from sacrificing him, Here's your name in Nahuatl, axolotl. Currently, ajolotes face an uncertain future. They can only be found in the canals of the lake of XochimilcoOn the southern tip of Mexico City, where you have been affected by the degradation of your habitat and the introduction to the fish channel that eat the plants where axolots leave their eggs.

However, The axes in captivity now prosper in laboratories around the world. In an article published on January 24 in Genome Research, a team of researchers reported on the most comprehensive amphibian DNA mapping so far. This work opens the way for future advances in regenerative human medicine.

Many animals are capable of carrying out some kind of regenerationBut it seems that Axolots have virtually no limits in their ability to do so. As long as they do not cut their heads, they can "create an almost perfect replica" of almost any part of their body, Including up to half of his brain, explained Jeramiah Smith, assistant professor of Biology at the University of Kentucky and author of the new article. To understand the way in which these healing superpowers developed, Smith and his colleagues checked the DNA of the amphibian.

The size of your genome is ten times greater than that of the human being, So it was not a simple gesture to analyze the axolot genetic map. "It's huge"Melissa Keinath, a postdoctoral fellow at the Carnegie Institute for Science in Baltimore and co-author of the article, said.

From a previous study, Keinath and his colleagues made a map of more than 100,000 parts of the DNA and grouped them according to their chromosomes, the structures that contain the genetic material in the nucleus of each cell. The genome that came together with axolot is the largest that you have compiled with this level of detail.

Scientists used a so-called approach genetic mapping by linkage, It takes advantage of the fact that DNA sequences that are physically close on a chromosome usually inherit together.

To identify the specific axolot DNA, the researchers contrasted axolots with tiger salamanders, Close relatives. They crossed the axolots with the tiger salamanders and then compared these first-generation hybrids with pure axolots.

After monitoring the patterns of genetic inheritance in 48 of these second-generation hybrids, the researchers were able to infer what DNA sequences belonged to axolots and where they were physically next to the fourteen amphibian chromosomes (Humans have a greater number of chromosomes, but those of axolot are much larger).

It was like "joining fourteen linear puzzles"Randal Voss, professor of Neuroscience at the University of Kentucky, and co-author of the study, said.

In the process of validating their results, To identify a genetic mutation that causes a heart defect commonly studied in aerosol, so its research will accelerate the future process to scan the axolot genome in search of mutations.

Learn how to position DNA throughout amphibian chromosomes fundamentally "Let me start thinking about the functions and how genes are regulated"Voss said. Much of the genome, for example, consists of sequences of non-coding DNA that activate and deactivate specific genes. Often, These non-coding sequences are presented on the same chromosomes as those with genes with which they interact.

"When these relationships are known, we can ask questions about whether the same type of controls appear in other animals, such as humans"Jessica WHITED, professor and expert in limb regeneration, told Harvard Medical School, who did not participate in the study.

He explained that this will help scientists understand if there are predictable ways of "Make humans more like ajolotes", the fantastic regenerators of the animal kingdom.

Copyright: c.2019 New York Times News Service


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