The marine bacterium Marinomonas mediterranea uses a CRISPR system to spot invading RNAs and store a memory of the invasion event in its genome. Research team member Antonio Sanchez-Amat was the first to isolate and characterize this bacterial species. Credit: Antonio Sanchez-Amat, University of Murcia.
A new study has added another twist to the CRISPR story. As we’ve highlighted in several recent posts, CRISPR is an immune system in bacteria that recognizes and destroys viral DNA and other invading DNA elements, such as transposons. Scientists have adapted CRISPR into an indispensable gene-editing tool now widely used in both basic and applied research.
Many previously described CRISPR systems detect and cut viral DNA, insert the DNA pieces into the bacterial genome and then use them as molecular “mug shots” to flag and destroy the virus if it attacks again. But various viruses use RNA, not DNA, as genetic material. Although research has shown that some CRISPR systems also can target RNA, how these systems can archive harmful RNA encounters in the bacterial genome was unknown. Continue reading “CRISPR Serves Up More than DNA”
Researchers created an apparatus to study quorum sensing, a communication system that allows some bacteria to cause dangerous infections. Their findings suggest that blocking bacterial communication might lead to a new way to combat such infections. Credit: Minyoung Kevin Kim and Bonnie Bassler, Princeton University.
If you’ve ever felt a slimy coating on your teeth, scrubbed grime from around a sink drain or noticed something growing between the tiles of a shower, you’ve encountered a biofilm. Made up of communities of bacteria and other microorganisms, biofilms thrive where they can remain moist and relatively undisturbed. As they enlarge, biofilms can block narrow passages like medical stents, airways, pipes or intestines. Continue reading “Cool Video: Watching Bacteria Turn Virulent”
Grew up in: Fort Peck, Montana
Fields: Microbiology, biochemistry, structural biology
Job site: Montana State University
Secret talent: Being a generalist; enjoying many different subjects and activities
When not in the lab, he’s: Running, biking, skiing or playing scrabble with his grandmother
Scientific discoveries are often stories of adventure. This is the realization that set Blake Wiedenheft on a path toward one of the hottest areas in biology.
His story begins in Montana, where he grew up and now lives. Always exploring different interests, Wiedenheft decided in his final semester at Montana State University (MSU) in Bozeman to volunteer for Mark Young, a scientist who studies plant viruses. Even though he majored in biology, Wiedenheft had spent little time in a lab and hadn’t even considered research as a career option. Continue reading “Finding Adventure: Blake Wiedenheft’s Path to Gene Editing”
A Bacillus subtilis biofilm grown in a Petri dish. Credit: Süel Lab, UCSD.
Last summer, we shared findings from Gürol Süel and colleagues at the University of California, San Diego, that bacterial cells in tight-knit microbial communities called biofilms expand in a stop-and-go pattern. The researchers concluded that this pattern helps make food at the nutrient-rich margin available to the cells in the starved center, but they didn’t know how. They’ve now shown that the cells use electrochemical signaling to communicate and cooperate with each other.
Because nutrients and other signals cells use to sense each other and their environment move rather slowly, the researchers looked for a faster, more active communication system in biofilms of the bacterium B. subtilis. They focused on electrical signaling via potassium, a positively charged ion that, for example, our nerve and muscle cells use to send or receive signals. Continue reading “Bacterial Biofilms: A Charged Environment”
As Halloween approaches, we turned up some spectral images from our gallery. The collection below highlights some spooky-sounding—but really important—biological topics that researchers are actively investigating to spur advances in medicine.
The cell skeleton, or cytoskeleton, is the framework that gives a cell its shape, helps it move and keeps its contents organized for proper function. A cell that lacks a cytoskeleton becomes misshapen and immobile. This fibroblast, a cell that normally makes connective tissues and travels to the site of a wound to help it heal, is lacking a cytoskeleton. Researchers have associated faulty cytoskeletons and resulting abnormal cell movement with birth defects and weakened immune system functioning. See fibroblasts with healthy skeletons
Continue reading “Cool Images: A Halloween-Inspired Cell Collection”
Competition encourages bacteria to produce secondary metabolites with therapeutic potential that they would otherwise hold in reserve. Credit: Michael Smeltzer, Vanderbilt University.
Bacteria hold a vast reservoir of compounds with therapeutic potential. They use these compounds, known as secondary metabolites, to protect themselves against their enemies. We use them in many antibiotics, anti-inflammatories and other treatments.
Scientists interested in developing new medicines have no shortage of places to look for secondary metabolites. There are an estimated 120,000 to 150,000 bacterial species on Earth. Each species is capable of producing hundreds of secondary metabolites, but often only under specific ecological conditions. The challenge for researchers is figuring out how to coax the bacteria to produce these compounds.
Now, Brian Bachmann and John McLean of Vanderbilt University and their teams have shown that by creating “fight clubs” where bacteria compete with one another, they can trigger the bacteria to make a wide diversity of molecules, including secondary metabolites. Continue reading “Bacterial ‘Fight Clubs’ and the Search for New Medicines”
Football image credit: Stock image. The colored contoured lines show the periodic stops in the growth of a bacterial colony. Credit: Süel Lab, UCSD.
What do these images of football fans and bacterial cells have in common? By following simple rules, each individual allows the group to accomplish tasks none of them could do alone—a stadium wave that ripples through the crowd or a cell colony that rebounds after antibiotic treatment.
These collective behaviors are just a few examples of what scientists call emergent phenomena. While the reasons for the emergence of such behavior in groups of birds, fish, ants and other creatures is well understood, they’ve been less clear in bacteria. Two independent research teams have now identified some of the rules bacterial cells follow to enable the colony to persist. Continue reading “The Simple Rules Bacteria Follow to Survive”
Credit: New York Academy of Sciences
Sarkis K. Mazmanian, Ph.D.
Born in: The country of Lebanon, moved to Los Angeles when he was 1
Fields: Microbiology, immunology, neuroscience
Works at: California Institute of Technology
Awards won: Many, including the MacArthur Foundation “Genius” grant
Most proud of: The success of his trainees! “There’s nothing that comes close to the gratification and joy I feel when a student or research fellow goes on to be an independent scientist.”
When not in the lab or mentoring students, he’s: Spending time with his family, including his 1-year-old-son or going for an occasional run
As a child, Sarkis Mazmanian frequently took things apart to figure out how they worked. At the age of 12, he dismantled his family’s entire television set—to the dismay of his parents and the unsuccessful TV repairman.
“I wasn’t aware of this at the time, but maybe that was some sort of a foreshadowing that I would enjoy science,” Mazmanian says. “Scientists take biological systems apart to understand how they work.”
Mazmanian never thought he’d become a microbiologist, let alone a leading expert in the field. He began studying microbiology at the University of California, Los Angeles (UCLA), because it was the major that allowed him to do the most hands-on research. But as soon as he entered the field, he fell in love with the complexities of microbial organisms and the efficiency of their functions. Continue reading “Meet Sarkis Mazmanian and the Bacteria That Keep Us Healthy”
Credit: Karen Carlson
Fields: Systems biology, bacterial biofilms
Born and raised in: Alaska
Undergraduate student at: The University of Alaska, Anchorage
When not in the lab, she’s: Out and about with her 3-year-old son, friends and family
Secret talent: “I make some really good cookies.”
Karen Carlson got a surprise in her 10th grade biology class. Not only did she find out that she enjoyed science (thanks to an inspiring teacher), but, as she puts it, “I realized that I was really good at it.”
In particular, she says, “I was good at putting all the pieces [of a scientific question] together. And that’s what I had the most fun with—looking at systems: how things fit together and the flow between them.”
These are perfect interests for a budding systems biologist, which is what Carlson is on her way to becoming. She’s a senior in college on track to graduate this year with a bachelor’s degree in biology from the University of Alaska, Anchorage (UAA). Next, she plans to enroll in a master’s degree program at UAA, and eventually to pursue a Ph.D. in a biomedical field. Continue reading “Meet Karen Carlson”
Modified E. coli bacteria can serve as sensors and data storage devices for environmental and medical monitoring. Credit: Centers for Disease Control and Prevention. View larger image
E. coli bacteria help us digest our food, produce vitamin K and have served as a model organism in research for decades. Now, they might one day be harnessed as environmental or medical sensors and long-term data storage devices .
MIT researchers Timothy Lu and Fahim Farzadfard modified the DNA of E. coli cells so that the cells could be deployed to detect a signal (for example, a small molecule, a drug or the presence of light) in their surroundings. To create the modified E. coli, the scientists inserted into the bacteria a custom-designed genetic tool.
When exposed to the specified signal, the tool triggers a series of biochemical processes that work together to introduce a single mutation at a specific site in the E. coli’s DNA. This genetic change serves to record exposure to the signal, and it’s passed on to subsequent generations of bacteria, providing a continued record of exposure to the signal. In essence, the modified bacteria act like a hard drive, storing biochemical memory for long periods of time. The memory can be retrieved by sequencing the bacteria or through a number of other laboratory techniques. Continue reading “E. Coli Bacteria as Medical Sensors and Hard Drives?”