EhV on the move

June 8, 2015
Blooms of the alga Emiliania huxleyi can cover thousands of square kilometers in the ocean.....until cells are lysed by the EhV virus. These relatively large double-stranded DNA coccolithoviruses lead to the rapid demise of E. huxleyi blooms. 

It was already known that EhV moves about in oceanic waters through diffusion, advection, and mixing. Now Sharoni et al have recently shown that EhV is distributed through ocean aerosols. Through a series of crafty laboratory experiments, they showed that infective EhV particles can become aerosolized when their host-rich growth medium is actively bubbled. These virions, often moving as aggregates, could sneak through the head space between joined flasks to infect naive hosts nearby. 

Movement in the laboratory is much more comfortable than in the open ocean where temperature, humidity, and light intensities fluctuate to extremes that result in virion decay. Sharoni et al. measured EhV decay in a laboratory setup that mimicked these real-life conditions, and calculated a viral half life of ~20 minutes, which would result in infective virions being present for several hours.  

Moving to the open ocean, they also quantified the number of E. huxleyi cells and EhV virions in aerosol samples collected from a naturally occurring bloom. They found 1,000 algal cells per ml of air, and 50,000 EhV virions per ml of air. Thus, the viruses were present at an abundance that was ~10-fold higher than the abundance of their host, consistent with viral-host ratios in other marine systems.

Putting all of these numbers together for a back-of-the-envelope calculation, Sharoni et al. estimated that 10 million infective EhV virions could travel hundreds of kilometers to find their next meal. It's a long way to go, but the feast is well worth it. 
 

Detailed duel between phage(s) and host

May 15, 2015
It's not every day we get to see an arms race in action. Every gory detail is laid out by Paez-Espino et al in the March/April issue of mBio*. The authors use deep DNA sequencing to track CRISPR acquisition in the bacterium Streptococcus thermophilus when challenged with Streptococcus phage 2972 (a phage featured in Life in Our Phage World). 

As S. thermophilus evolved in the presence of 2972, its CRISPR loci acquired new spacers employed to recognize future invasions of 2972 phage DNA, thereb...

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Catching phages in the act

April 30, 2015
Phages are everywhere but almost none of them can be easily studied. We can scoop up their DNA (and sometimes RNA), sequence it, and try to put the pieces of their biology together. But often we cannot figure out which bacteria they would infect unless we bring them into the lab, coddle their host into culture, and then experimentally mix the two. Now it is becoming feasible to isolate single bacterial cells to see which phage is lurking within, according to a new publication by Labonte et al...
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Life in Our Phage World published!

January 18, 2015
Have you ever wondered about the tiny viruses that are everywhere, on everything, in every organism? What do they look like? Where do they live? Who are they related to? What information is in their genomes? What do they do all day long? 

These questions are answered in Life in Our Phage World, a book I recently co-authored with Forest Rohwer, Merry Youle, Nao Hisakawa, and a brilliant group of phage researchers. Full of short action stories, and beautifully illustrated by Leah Pantea and Ben ...
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Intriguing impurities

May 23, 2013

Many microbiologists begin their workday by opening up the incubator shaker and taking out a culture flask; they then swirl it around to examine the progression of cell growth. They can examine the turbidity of the broth to tell if cells are reproducing as planned. Opening up the lid and sniffing the culture will tell seasoned microbiologists if they’re growing what they think they’re growing, because many bacterial species produce signature aromas. But w...


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Picoplankton post

March 29, 2013
My first contribution to the Small Things Considered blog: 
 

A Day in the Life: Eavesdropping on Marine Picoplankton


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Mite-y resistance

January 16, 2013
When faced with a challenge, animals have the ability to physically move away. Plants are not so lucky. Their interactions with the soil prevent them from up-rooting and finding a better place. But this does not mean that plants don't fight back. Indeed, plants produce an astonishing diversity of chemicals to ward off invaders, such as the ubiquitous arthropod pests. Many of these naturally produced chemicals are analogous to manufactured pesticides, in that they provide a strong selective pr...
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RNA for the bees

December 31, 2012
Becoming a beekeeper can be overwhelming at times. One of the most difficult things for me is figuring out how and when to treat the hives to prevent pathogens and parasites from becoming too numerous. We have attended an Integrated Pest Management course but only walked away with a list of offenders and their chemical treatments, which we had already learned through online research. Why not just treat for all, as often as possible? I'd rather not dump these chemicals (several of which are an...
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Reveling in Ronin

December 21, 2012
The Ronin Institute is a group of scholars that are trying something different.  Recognizing that one need not work at a university to contribute to knowledge, scholars of the Ronin Institute will be conducting research independently, as they find time in between life's activities (e.g., kids, hobbies, other jobs).  This is a timely endeavor as many more PhDs are being obtained than faculty positions are available.  And for many of us, university jobs are becoming less attractive as hours inc...
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Probiotic puzzle

December 4, 2012
Probiotics are live bacteria, formulas of single or multiple species, provided to help establish a healthy gastrointestinal tract.  Probiotics are a hot topic these days, and a potent marketing tool. Despite their popularity, we often don't know if they really work to relieve intestinal problems.  And for those probiotics that do work, we almost never know their mechanism(s) of action.   

Olier and colleagues have taken us a step closer to understanding the mechanism of probiotic action.  They...

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