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  • The current pandemic has highlighted how important

  • it is for us to know what viruses may be lurking out there.

  • But while we keep one wary eye out for those potentially harmful ones, we're also uncovering

  • just how much viruses have actually shaped humansand the rest of life on Earthin

  • some really surprising ways.

  • 'Virus hunters', as they're known, are

  • scientists who search the hidden corners of the world for viruses that are poised to become

  • human pathogens. In many cases, they're searching for Disease

  • X. That's not the name of an actual illnessit's what we call the hypothetical infection that

  • could cause the next big global disease. The idea is to find it before it finds us.

  • But other researchers are delving into what else viruses are doing on our planet besides

  • making people sick. It's estimated that there are about this many individual viruses

  • on our planet.

  • And we've only made the most miniscule dent

  • in that number: we've found and classified about 9,000 of the viruses on Earth.

  • And of those, only about 200 are known to cause disease in humans.

  • But over the past decade, scientists have been identifying new viruses by the thousands.

  • And the main tool they're using to do that...is metagenomics.

  • This is actually something I'm using in my own research on bacterial communities,

  • so let's break it down together.!

  • In metagenomic sequencing, we take a samplethat

  • can be soil, ocean water, a bodily fluidand we purify it down to the genetic material

  • of just the stuff we're looking for. In this case, let's say it's viruses.

  • So now we have the genomes of all the viruses in our sample. Lets picture each virus's genome

  • as a piece of paper with sentences on it.

  • Because the next stepand this sounds nutsis that we rip each

  • piece of paper up into little strips with just sentences on them.

  • We do this because our sequencing

  • machine has to 'read' all of these genomes.

  • And, if you can picture, it's much faster for lots of people to each read a sentence.

  • And they can each read their sentence at the same time a sentence

  • than it is for one person to read a whole page, one at a time.

  • That's what we're doing

  • when we divide our genome up into little chunks. Now that we've read the sentences in a super

  • efficient way, we can put the sentences back together into the full page, or the full genome.

  • Then we compare that to a library full of known genomes.

  • So we can say, 'this unknown page is the same as this known page that we have on file'.

  • It's a match! We've ID'ed the virus in our sample.

  • And we do this for every virus in our sample.

  • Metagenomic sequencing is an

  • incredibly useful tool that lets us identify huge numbers of microbes really fast.

  • And as scientists have turned that powerful lens on our world to catalogue viruses...they've

  • been astonished at just how many they're finding, everywhere. In the ocean, in our

  • wastewater, inside the spiders in our gardens and of course, inside us. Most of them are

  • totally harmless to humans, and many of them are totally new to science!

  • The viruses in the ocean? They're preying on other marine microorganisms, releasing

  • nutrients. This may be the bottommost foundation of the ocean's food web.

  • The viruses in every ecosystem? They help maintain our planet's biodiversity by keeping

  • other species in check. If viruses suddenly vanished from the planet, it's likely that

  • the balance of other organisms would rapidly get out of whack.

  • And one other major result of all this sequencing is a new understanding of just how thoroughly

  • viruses have shaped life on Earth as we know it.

  • Because they invade living cells to replicate, they're equipped to take over a host's

  • genetic replication machinerysometimes, viral genetic material gets incorporated into

  • the host's. It's estimated that around 8% of human DNA actually came from a virus,

  • including some of our most important skills. Like, the ability of modern humans to give

  • birth probably came from a piece of viral genetic code that jumped over to its mammalian

  • host about 130 million years ago. That gave us our ability to grow a placenta. So, yep.

  • We got hacked, and it's probably the reason we don't lay eggs.

  • Scientists don't know how many more viruses are out there, waiting to be discovered. And

  • of those, we have no idea how many of them may be harmful to us.

  • But sequencing at least some of those nonillion viruses out there is the first step. The next

  • step is to identify what they're living inside...and how exactly these tiny, invisible

  • puppeteers are pulling the strings of our natural world.

  • If you want more on just how many viruses are in our oceans and what they're doing

  • there, you can check out this video, and leave us a comment down below if there's another

  • viral topic you'd like to see us cover. Keep coming back to Seeker for all your microbial

  • updates and as always, thanks for watching. I'll see ya next time.

The current pandemic has highlighted how important

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Viruses Have Shaped Life on Earth as We Know It, Here’s How

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    Summer posted on 2021/09/27
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