Navigation Links
Why a bacterium got its curve -- and why biologists should know
Date:5/8/2014

Drawing from his engineering background, Princeton University researcher Alexandre Persat had a notion as to why the bacteria Caulobacter crescentus are curved a hunch that now could lead to a new way of studying the evolution of bacteria, according to research published in the journal Nature Communications.

Commonly used in labs to study cell division, C. crescentus naturally take on a banana-like curve, but they also can undergo a mutation in which they grow to be perfectly straight. The problem was that in a laboratory there was no apparent functional difference between the two shapes. So a question among biologists was, why would nature bother?

Then Persat, who is a postdoctoral researcher in the group of Associate Professor of Molecular Biology Zemer Gitai, considered that the bacteria dwell in large groups attached to surfaces in lakes, ponds and streams. That means that their curvature could be an adaptation that allows C. crescentus to better develop in the water currents the organisms experience in nature.

In the new paper, first author Persat, corresponding author Gitai and Howard Stone, Princeton's Donald R. Dixon '69 and Elizabeth W. Dixon Professor of Mechanical and Aerospace Engineering, report that curvature does more than just help C. crescentus hold their ground in moving fluid. The researchers monitored C. crescentus growth on surfaces in flow and found that the bacteria's arched anatomy is crucial to flourishing as a group.

"It didn't take a long time to figure out how flow brought out the advantages of curvature," Persat said. "The obvious thing to me as someone with a fluid-dynamics background was that this shape had something to do with fluid flow."

The findings emphasize the need to study bacteria in a naturalistic setting, said Gitai, whose group focuses on how bacterial shapes are genetically determined. While a petri dish generally suffices for this line of study, the functionality of bacterial genes and anatomy can be elusive in most lab settings, he said. For instance, he said, 80 percent of the genes in C. crescentus are seemingly disposable but they might not be in nature.

"We now see there can be benefits to bacterial shapes that are only seen in a growth environment that is close to the bacteria's natural environment," Gitai said.

"For C. crescentus, the ecology was telling us there is an advantage to being curved, but nothing we previously did in the lab could detect what that was," he said. "We need to not only think of the chemical environment of the bacteria we also need to think of the physical environment. I think of this research as opening a whole new axis of studying bacteria."

While most bacteria grow and divide as two identical "daughter" cells, C. crescentus divides asymmetrically. A "stalked" mother cell anchors to a bacterium's home surface while the upper unattached portion forms a new, juvenile version of the stalked cell known as a "swarmer" cell. The swarmer cells later morph into stalked cells then eventually detach before laying down roots nearby. They repeat the life cycle with their own swarmer cell and the bacterial colony grows.

The Princeton researchers found that in moving water, curvature points the swarmer cell toward the surface to which it needs to attach. This ensures that the bacteria's next generation does not stray too far from its progenitors, as well as from the nutrients that prompted cell division in the first place, Gitai said. On the other hand, the upper cells of straight bacteria which are comparatively higher from the ground are more likely to be carried far away as they are to stay near home.

But the advantage of curvature only goes so far. The researchers found that when the water current was too strong, both curved and straight bacteria were pressed flat against the surface, eliminating the curved cells' colonization advantage.

These findings put some interesting boundaries on what is known about C. crescentus, starting with the upper limits of the current in which the organism can thrive, Gitai said. He and Persat also plan to pursue whether the bacteria are able to straighten out and cast offspring downstream when the home colony faces a decline in available nutrients.

At the same time, understanding why C. crescentus got its curve helps in figuring out the evolution of other bacteria, he said. Close relatives of the bacteria, for example, are not curved could it have to do with the severity of their natural environment, such as the powerful turbulence of an ocean? Harmful bacteria such as Vibrio cholerae, strains of which cause cholera, are curved, though the reason is unclear. It's possible this shape could be related to the organism's environment in a way that might help treat those infected by it, Gitai said.

Whatever the reason for a specific bacteria's shape, the Princeton research shows that exploring the influence of its natural habitat could be worthwhile, Gitai said.

"It was clear with C. crescentus that we needed to try something different," Gitai said. "People didn't really think of flow as a major driver of this bacteria's evolution. That really is a new idea."


'/>"/>

Contact: Morgan Kelly
mgnkelly@princeton.edu
609-258-5729
Princeton University
Source:Eurekalert  

Related biology news :

1. Virginia Tech and University of Tuscia lead team to unravel origin of devastating kiwifruit bacterium
2. Bacterium signals plant to open up and let friends in
3. Scientists reveal how natural antibiotic kills tuberculosis bacterium
4. Disappearing bacterium may protect against stroke
5. Scientists confirm that the Justinianic Plague was caused by the bacterium Yersinia pestis
6. Bacterium counteracts coffee ring effect
7. Scientists discover ethnic differences in immune response to TB bacterium
8. Probiotic bacterium lessens severity of Salmonella infections by hoarding iron
9. How quickly can a bacterium grow?
10. Mycobacterium tuberculosis: Our African follower for over 70,000 years!
11. Decades on, bacteriums discovery feted as paragon of basic science
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
Why a bacterium got its curve -- and why biologists should know
(Date:4/28/2016)... , April 28, 2016 Infosys ... (NYSE: INFY ), and Samsung SDS, a global ... that will provide end customers with a more secure, fast ...      (Logo: http://photos.prnewswire.com/prnh/20130122/589162 ) , ... but it also plays a fundamental part in enabling and ...
(Date:4/19/2016)... April 20, 2016 The new ... a compact web-based "all-in-one" system solution for all door ... reader or the door interface with integration authorization management ... control systems. The minimal dimensions of the access control ... the building installations offer considerable freedom of design with ...
(Date:4/13/2016)... 13, 2016  IMPOWER physicians supporting Medicaid patients in ... new clinical standard in telehealth thanks to a new ... higi platform, IMPOWER patients can routinely track key health ... mass index, and, when they opt in, share them ... to a local retail location at no cost. By ...
Breaking Biology News(10 mins):
(Date:6/27/2016)... ... 2016 , ... Cancer experts from Austria, Hungary, Switzerland, and ... new and helpful biomarker for malignant pleural mesothelioma. Surviving Mesothelioma has just published ... , Biomarkers are components in the blood, tissue or body fluids that ...
(Date:6/27/2016)... PHILADELPHIA , June 27, 2016  Liquid ... today announced the funding of a Sponsored Research ... study circulating tumor cells (CTCs) from cancer patients.  ... changes in CTC levels correlate with clinical outcomes ... therapies. These data will then be employed to ...
(Date:6/24/2016)... NY (PRWEB) , ... June 24, 2016 , ... While ... machines such as the Cary 5000 and the 6000i models are higher end machines ... is the height of the spectrophotometer’s light beam from the bottom of the cuvette ...
(Date:6/23/2016)... 2016   Boston Biomedical , an industry ... to target cancer stemness pathways, announced that its ... Drug Designation from the U.S. Food and Drug ... including gastroesophageal junction (GEJ) cancer. Napabucasin is an ... cancer stemness pathways by targeting STAT3, and is ...
Breaking Biology Technology: