Tuesday, March 11, 2008

Morons in Microbiology

No, not the Usual Morons in Microbiology-- These morons have been around for billions of years!!

A moron (in bacteriophage biology) is a DNA element inserted between a pair of genes in one phage genome when the genes of this same pair are adjacent in a related phage genome.
hmmm.. yaaa... Not so helpful, ASM. Luckily, Bossmans lecture on morons in class this week was much clearer.

'Morons' are genes that bacteriophages carry around which are unnecessary for the virus, but helpful for the host bacteria.

This doesnt make sense at first, because when we think of viruses (especially bacteriophages) we think of infection, making lots of baby viruses, and BOOM!!-- cell explodes and all the viruses are released. Why would it care if the bacteria is comfy as its exploding?

Well, thats not really what happens with phages. They infect a cell, insert themselves into the bacterias genome, and chill. They just sorta hang out until some stressor tells the virus its time to jump ship. Think about it-- who is more fit, a virus that blows up its host and produces a thousand progeny who might/might not find another host cell, or a virus that sits silently in a genome, getting passed down through the generations laterally for a million years? The latter! But while hiding in someone elses cell is a good idea, silent phages have the same problem as plasmids-- How do you convince a bacteria to keep you around when you are genetic dead weight?



Morons help the bacteria survive by being novel genes that make the bacteria more competitive with its peers in an old niche, or giving the bacteria the ability to exploit a new niche. Morons are kind of hard for us to appreciate... Like the MORON that encodes Type III secretion effectors that make you poop when youre colonized by Salmonella or the MORON toxins that make you poop when youre infected with Cholera or the MORON toxins that make you poop when you eat spinach sprinkled with E. Coli... but theyre actually a really cool evolutionary story, demonstrating the co-evolution of bacteria and their phages over time! Bacteria even have 'endogenous phages' like we have endogenous retroviruses!

I was rather pouty about getting my PhD in microbiology because of all of the associated 'bacteria based' classes I would have to take (Ive never taken an intro micro class-- cocci-wha?), but this stuff is friggen fun!


HalfMooner said...

The story of how these viruses and host bacterial work together is far more complex than I'd ever imagined. It's like the plot of a soap opera that has been running for fifty years. More characters, twists, turns, and unexpected plot elements than you can shake an RNA strand at.

The Factician said...

Wait until you learn how the cholera phage integrates into its host genome. Way cool...

Cholera is neat...

Moses said...

From the title I was thinking Behe (sp?).

-DG said...

Of course not all phage do this, there are many that don't integrate or sit around and wait and act more like the "classic" viruses everyone thinks about.

There is some really good work out there on Co-evolution with cyanobacteria and their phages. Some of the phages for cyanobacteria actually carry around genes for the photosystem so that the cyanobacteria produces more energy to make phage copies.

One paper from PLoS Biology that may be of interest is:

Prevalence and Evolution of Core Photosystem II Genes in Marine Cyanobacterial Viruses and Their Hosts

Matthew B. Sullivan1, Debbie Lindell1, Jessica A. Lee2, Luke R. Thompson2, Joseph P. Bielawski3,4, Sallie W. Chisholm1,2*

Torbjörn Larsson said...

That is so cool!

Some of the phages for cyanobacteria actually carry around genes for the photosystem so that the cyanobacteria produces more energy to make phage copies.

Like a salesman investing in dinner and drinks to get more out of his customer. Morons!

morons in class

Uh oh, pun bait! Okay, I give - so how do you explain lessons?

monado said...

I wonder who gave them that name? Sounds like something you'd eat when you were feeling more-ish, like peanuts or chips.

Anonymous said...

This is some thing i did not know. Virues are the most smarest organisms, we cannot beat them. Even simple virus which causes cold is a silent killer.Hats off to their Brains.

alison said...

I'm not a microbiologist but this sounds so cool! I love learning new stuff (more nice tidbits for my lectures) & you made this so interesting. Thanks, ERV :-)

Aaron said...

Kind of reminds me of the Black Alien suit in spiderman comics -- helps him out so he wants to wear it even though it's ultimately dangerous. :)

smellybilly said...

OFF topic but need help with daughters project and i read this blog all the time.
I understand if deleted.
Daughter is doing science project on bacteria on grocery carts and toilet seats at stores, (which have more bacteria). We have the culture growing in petri dishes and trying to find out best way to plot results. By different colors of cultures we see, or how many colonies in one dish vs another?
Thanks if you can point us somewhere on this.

-DG said...

Smellybilly: You may actually want to do both. The main problem is whether or not you can identify the bacterial colonies. Lots of different bacteria can exhibit the same colony morphology but be very different in terms of nastiness. But it can be a rough estimate of diversity and since you know the places they were isolated from you may be able to get an estimate of what the colony is likely composed of.

Plotting the total colonies gives you a count of bacterial load, useful information. Plus reporting the types of bacteria found would be interesting and useful as well. Higher bacterial load but mostly harmless versus lower total load but full of nasties for instance.