Hidden Genetic Mechanisms Reveal Features That Make Us Unique

Cynthia McKanzie – MessageToEagle.com – Our individuality is encrypted in our DNA, but it is deeper than expected. There is a remarkable difference well-hidden in the genome and it explains why we are all unique individuals.

Providing a glimpse of the hidden workings of evolution, a group of researchers at UC Santa Barbara have discovered that embryos that appear the same can start out with surprisingly different instructions.

The difference was uncovered when one of the switches was removed and the discovery helps researchers to understand undercover evolution and why patients can show very different responses to particular drugs.

Hidden Genetic Mechanisms Reveal Features That Make Us Unique

Photo credit: Genetic Engineering & Biotechnology News

“Many of the distinctive features that make us unique, including our color, height and susceptibility to diseases, are determined by our genomes,” Professor Joel Rothman in the Department of Molecular, Cellular, and Developmental Biology at UCSB said.

“But since everyone looks pretty similar as embryos, the genetic assembly instructions that get us started at conception were thought to be nearly identical between us.”

Indeed, although members of the same species are identical across the vast majority of their genomes, including all the genetic instructions used in development, Rothman and his colleagues found that key parts of the assembly instructions used when embryos first start developing can differ dramatically between individuals of the same species.

“It’s stunning that such an important event at the earliest stages of embryo formation can occur by such different means within one species and yet produce essentially the same outcome,” said Rothman. “Prior to these findings, we were unaware that the blueprints for an early embryo change so rapidly within a species.”

This discovery would be equivalent to finding that the manufacturing of two iPhones, which look and function identically, started out with different assembly instructions, the researchers said.

While humans are a far cry from C. elegans, once the initial events in embryo development begin, the later genetic instructions that create the endoderm appear to be similar to those likely used in all animals with a digestive tract, including humans.

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This result is particularly striking given that the endoderm is both the first layer formed in embryos and was probably the first to evolve over half a billion years ago. “It reveals an extreme version of the first part of the ‘hourglass’ view of embryo development, in which very similar instructions across widely different animals during the middle stages of development are preceded and followed by very different starting and ending points,” Rothman said.

Large variation in the genetic switches for key events in the early embryo in a single species is consistent with the "hourglass" view of embryo evolution

Large variation in the genetic switches for key events in the early embryo in a single species is consistent with the “hourglass” view of embryo evolution. Credit: Pradeep Joshi

Thus, just as two people who might look very similar can respond very differently to a drug therapy, so these little worms of the same species respond dramatically differently to an administered substance as a result of their subtle but all-important genetic individuality, the researchers said.

The discovery of such hidden genetic mechanisms could help guide how pharmaceuticals are developed in this era of precision medicine, in which drugs are ideally tailored to an individual’s genome.

This discovery also underscores the importance of natural variation in allowing evolution to occur. “Genetic variation fuels the machine of evolution,” Rothman said. “Without it, life would be stuck in a dead end. There is much more of this variation than we had realized when evolution sculpts the remarkable entities known as embryos.”

The scientists’ research is published in the journal eLife.

Written by Cynthia McKanzie – MessageToEagle.com Staff Writer