Tiny wonders of the aquarium world, zebrafish can regenerate organs and tissues, including hearts, eye parts and fins. When a fin is lost, the fish regenerates a perfect copy in two weeks by orchestrating the growth of many tissue types, including bone, nerves, blood vessels, connective tissue and skin.
Scientists hope that understanding how zebrafish repair themselves will lead to new treatments for human conditions caused by damaged tissue, such as heart failure, diabetes and spinal cord injuries.
The regeneration regulator is one of a group of recently discovered molecules called microRNAs: small pieces of ribonucleic acid (RNA) that each can potentially control the activity of dozens of different genes. In humans, microRNAs play important roles in cell growth and death, among other functions. There are hundreds of kinds of microRNAs, and scientists are constantly discovering new roles they play.
In zebrafish, one or more microRNAs appear to be important to keep regeneration on hold until the fish needs new tissue, the Duke researchers say. In response to an injury, the fish then damp down levels of these microRNAs to aid regrowth. The team discovered that the ability of zebrafish to replace amputated fins is particularly sensitive to levels of a particular microRNA called miR-133.
The discovery makes sense because any animal that can rapidly grow new tissue needs to keep the system in check, said senior author Kenneth Poss, Ph.D., assistant professor of cell biology. "They probably need to have mechanisms to reduce the potential for unwelcome growth. The implication is that in order to make human tissue regenerate more effectively, we might want to look at some of these microRNAs as potential targets."
The results appear in the March 15, 2008 issue of the journal Genes & Development. Postdoctoral scholar Viravuth Yin, Ph.D., a member of Poss' lab, is first author on the study. Funding was provided by the National Institutes of Health, the American Heart Association, the Whitehead Foundation and Pew Charitable Trusts.
Poss and many other cell biologists believe that mammals may have the same tissue regeneration capability as zebrafish, salamanders and newts, but that it is locked away somewhere in our genome, silenced in the course of evolution. "The key is finding a way to turn on this regenerative ability in humans," Poss said.
The Duke researchers began their study by ferreting out any microRNAs present in fins at different stages of regrowth, then measuring whether there was a lot or a little of each molecule.
Dr. Poss' team eventually zeroed in on some of the most important microRNAs for regrowth by studying genetically modified zebrafish. The modification allows a critical signaling pathway to be shut down during regeneration. The pathway sends biochemical cues called growth factors that stimulate cell division and organ growth.
Levels of one microRNA in particular, miR-133, dropped during normal regeneration. But when the scientists blocked the signaling pathway briefly during regeneration, the amount of miR-133 jumped back up to the level found in uninjured fins. Further experiments showed that tweaking the concentration of miR-133 affected fin growth. When levels were raised, fin regrowth slowed; when they were dropped, regeneration sped up.
"Our work shows microRNAs appear to have an important role in regenerating complex tissues. Further studies could help us discover potential ways to stimulate this ability in mammals," Poss said.
Debbe Geiger | EurekAlert!
New technique to determine protein structures may solve biomedical puzzles
11.12.2019 | Dana-Farber Cancer Institute
NTU Singapore scientists convert plastics into useful chemicals using su
11.12.2019 | Nanyang Technological University
In a joint experimental and theoretical work performed at the Heidelberg Max Planck Institute for Nuclear Physics, an international team of physicists detected for the first time an orbital crossing in the highly charged ion Pr⁹⁺. Optical spectra were recorded employing an electron beam ion trap and analysed with the aid of atomic structure calculations. A proposed nHz-wide transition has been identified and its energy was determined with high precision. Theory predicts a very high sensitivity to new physics and extremely low susceptibility to external perturbations for this “clock line” making it a unique candidate for proposed precision studies.
Laser spectroscopy of neutral atoms and singly charged ions has reached astonishing precision by merit of a chain of technological advances during the past...
The ability to investigate the dynamics of single particle at the nano-scale and femtosecond level remained an unfathomed dream for years. It was not until the dawn of the 21st century that nanotechnology and femtoscience gradually merged together and the first ultrafast microscopy of individual quantum dots (QDs) and molecules was accomplished.
Ultrafast microscopy studies entirely rely on detecting nanoparticles or single molecules with luminescence techniques, which require efficient emitters to...
Graphene, a two-dimensional structure made of carbon, is a material with excellent mechanical, electronic and optical properties. However, it did not seem suitable for magnetic applications. Together with international partners, Empa researchers have now succeeded in synthesizing a unique nanographene predicted in the 1970s, which conclusively demonstrates that carbon in very specific forms has magnetic properties that could permit future spintronic applications. The results have just been published in the renowned journal Nature Nanotechnology.
Depending on the shape and orientation of their edges, graphene nanostructures (also known as nanographenes) can have very different properties – for example,...
Using a clever technique that causes unruly crystals of iron selenide to snap into alignment, Rice University physicists have drawn a detailed map that reveals...
University of Texas and MIT researchers create virtual UAVs that can predict vehicle health, enable autonomous decision-making
In the not too distant future, we can expect to see our skies filled with unmanned aerial vehicles (UAVs) delivering packages, maybe even people, from location...
03.12.2019 | Event News
15.11.2019 | Event News
15.11.2019 | Event News
11.12.2019 | Materials Sciences
11.12.2019 | Information Technology
11.12.2019 | Life Sciences