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For the first time scientists have seen bacteria "fishing" for DNA from dead friends



Bacteria are slippery little suckers. They develop rapidly, develop resistance to antibiotics and are therefore becoming increasingly difficult.

For the first time in 2018, researchers have captured one of the mechanisms microbes use for rapid evolution.

Two Vibrio cholerae bacteria – the pathogen responsible for cholera – sit under a microscope and glow in a glowing green. As we watch, a tendril snakes out of a bacterium that harps a piece of DNA and returns it to the body.

This appendage is called Pili, and the process by which bacteria incorporate the new genetic material of a different organism into its own DNA to accelerate its development is called horizontal gene transfer.

And in June 201

8, scientists first observed a bacterium directly with a pilus to effect this gene transfer; It is a mechanism that has been suspected for decades.

"Horizontal gene transfer is an important way to shift antibiotic resistance between bacterial species, but this process has never been observed because the structures involved are so small," said biologist Ankur Dalia of Indiana University Bloomington.

"It's important to understand this process because the more we understand how bacteria share DNA, the greater our chances of thwarting it."

Exactly how bacteria used their pili to trap DNA was elusive, in part because of the extremely small scales. A pilus is more than 10,000 times thinner than a human hair and is therefore very difficult to observe.

What the team did – and why these bacteria glow with an eerie green light – is the development of a new method of coating both pili and DNA with fluorescent dye. When they put the entire kit and the kaboodle under a microscope, they saw the process for the first time with their own eyes.

In the video at the top of this page you can see this on the right side. The picture on the left side looks like the scene without the dye looks like.

 Bacteria Harpoon Still (Ankur Dalia / Indiana University)

The Pili occupation a line through the pores in the cell wall to add a piece of DNA snap, which is then rewound with fine precision.

"It's like threading a needle," said biologist Courtney Ellison.

"The size of the hole in the outer membrane has almost the exact width of a DNA helix bent in two halves, which is probably the case. If there were no pilus leading the DNA, there would be a chance that the DNA hits the pore at exactly the right angle The cell is virtually nil.

Antibiotic resistance can be transferred between bacteria in various ways – and there are several mechanisms for horizontal gene transfer Environment is referred to as transformation.

When bacteria die, they split and release their DNA, whereupon other bacteria can capture them, and when the dead bacterium has antibiotic resistance, the bacterium that loots the DNA of the dead develops Also, this resistance – and spreads it to its own offspring.

In this way, the resistance can be like wildfire in a population au And it's a big problem. According to the CDC, at least 23,000 deaths from antibiotic resistance have occurred in the US.

Finding out the exact mechanisms that bacteria use to spread antibiotic resistance, researchers hope to find ways to prevent it.

The next step is to find out how the pili lock into the exact right place in the DNA – especially since the protein involved in the process seems to interact with the DNA in a way that did not exist before ,

I hope to be able to apply their method of applying fluorescent dye to observe the other functions of the pili.

"These are really versatile attachments," said Dalia. "This method, invented at the IU, opens up our basic understanding of a whole range of bacterial functions."

The research was published in the journal Nature Microbiology .

A version published this article was first published in June 2018.


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