Navigation Links
Flatworm flouts fundamental rule of biology
Date:1/5/2012

A tiny, freshwater flatworm found in ponds and rivers around the world that has long intrigued scientists for its remarkable ability to regenerate has now added a new wrinkle to biology.

Reporting in the journal Science today, researchers at the University of California, San Francisco (UCSF) and the Stowers Institute for Medical Research in Kansas City, MO, have discovered that the worm lacks a key cellular structure called a "centrosome," which scientists have considered essential for cell division.

Every animal ever examined, from the mightiest mammals to the lowliest insects, has these centrosomes in their cells.

"This is the first time we've found one that didn't," said Wallace Marshall, PhD, an associate professor in the Department of Biochemistry & Biophysics at UCSF, who led the research.

The fact that flatworms lack these centrosomes calls into question their purpose, Marshall added. "Clearly we have to rethink what centrosomes are actually doing," he said.

The Necessity of Even Division

A central component of all multicellular life is the ability of cells to divide and divide evenly. Before a cell divides, it has to assemble two exact copies of its DNA and then make sure that DNA sorts evenly into the two separate halves as they pinch off. Many health problems arise from cells losing this ability.

A hallmark of cancer, for instance, involves abnormalities in this division. Tumor cells often duplicate extra pieces of DNA. Certain forms of childhood mental retardation are also marked by abnormal divisions, which cause the loss of large pieces of DNA, leading to development problems in certain brain structures.

Centrosomes have been seen as animals' ultimate evolutionary fix for this problem. Plants and fungi don't have them, but animals have had centrosomes in their cells, as long as there have been animals. These structures were thought to play a central role in cell division laying down track-like spindles onto which the cells sort their dividing DNA. Centrosomes were seen as so important to cell division that all animals were assumed to have them.

The discovery that at least one animal doesn't came quite unexpectedly.

Interested in the basic mechanics of the centrosome, Marshall and UCSF postdoctoral researcher Juliette Azimzadeh, PhD, teamed up with Alejandro Snchez Alvarado, PhD, a Howard Hughes Medical Institute and Stowers Institute investigator, who has worked with the flatworm Schmidtea mediterranea for several years.

Worm Regenerates Without Centrosomes

With a charming name that masks an otherwise humble appearance, this worm is a puddle wiggler just a few millimeters long at most. But its remarkable regenerative ability has made Schmidtea mediterranea a great scientific curiosity. When cut into tiny pieces, every piece will grow into a perfectly normal worm in a matter of days. Each offspring can then be segmented over and over again as well it's how the worm reproduces.

The original intention of the study Azimzadeh, Marshall and Snchez Alvarado devised was to see what happened to the worm when it lost its centrosome.

Together they manipulated the flatworm to knock out genes needed to assemble these centrosomes. Without centrosomes the worms should have lost their ability to regenerate normally or so they thought.

They were amazed to find that losing these structures didn't affect the worms' ability to regenerate at all. Then they looked more carefully at the worms and discovered that they never had these centrosomes in the first place.

"It came as a surprise to all of us," said Snchez Alvarado. What it means, he said, is that the evolutionary pressure that has maintained these structures in nearly all animals may have very little to do with cell division itself.

"There may be another function for centrosomes that is still obscured," he said.


'/>"/>

Contact: Jason Socrates Bardi
jason.bardi@ucsf.edu
415-502-6397
University of California - San Francisco
Source:Eurekalert  

Related biology news :

1. International research team seeks to unravel flatworm regeneration
2. ORNL fundamental discovery casts enzymes in new light
3. Putting trees on farms fundamental to future agricultural development
4. Ecological scientists assess the fundamentals of animal behavior
5. Lack of access to evidence-based HIV prevention and care is a fundamental violation of human rights
6. Researchers identify a fundamental process in lysosomal function and protein degradation
7. Mouse work: New insights on a fundamental DNA repair mechanism
8. Phytoplankton cell membranes challenge fundamentals of biochemistry
9. The biology of politics: Liberals roll with the good, conservatives confront the bad
10. Tips from the journals of the American Society for Microbiology
11. Scientist-novelist back with second book at cell biology meeting
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
Flatworm flouts fundamental rule of biology
(Date:4/26/2016)... , April 27, 2016 ... "Global Multi-modal Biometrics Market 2016-2020"  report to their ... , The analysts forecast the global ... of 15.49% during the period 2016-2020.  ... of sectors such as the healthcare, BFSI, transportation, ...
(Date:4/15/2016)... 2016  A new partnership announced today will ... decisions in a fraction of the time it ... high-value life insurance policies to consumers without requiring ... Force Diagnostics, rapid testing (A1C, Cotinine and HIV) ... pressure, weight, pulse, BMI, and activity data) available ...
(Date:4/14/2016)... , April 14, 2016 ... and Malware Detection, today announced the appointment of ... the new role. Goldwerger,s leadership appointment comes ... the heels of the deployment of its platform at ... behavioral biometric technology, which discerns unique cognitive and physiological ...
Breaking Biology News(10 mins):
(Date:6/24/2016)... , June 24, 2016  Regular discussions on a range ... place between the two entities said Poloz. Speaking ... Ottawa , he pointed to the country,s inflation ... federal government. "In ... "Both institutions have common economic goals, why not sit down ...
(Date:6/24/2016)... ... June 24, 2016 , ... Researchers at the Universita ... miRNAs in people with peritoneal or pleural mesothelioma. Their findings are the subject of ... now. , Diagnostic biomarkers are signposts in the blood, lung fluid or tissue ...
(Date:6/23/2016)... Mass. , June 23, 2016   ... development of novel compounds designed to target cancer ... napabucasin, has been granted Orphan Drug Designation from ... the treatment of gastric cancer, including gastroesophageal junction ... stemness inhibitor designed to inhibit cancer stemness pathways ...
(Date:6/23/2016)... , June 23, 2016 Houston Methodist ... the Cy-Fair Sports Association to serve as their ... agreement, Houston Methodist Willowbrook will provide sponsorship support, ... connectivity with association coaches, volunteers, athletes and families. ... the Cy-Fair Sports Association and to bring Houston ...
Breaking Biology Technology: