Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

How an ancient vertebrate uses familiar tools to build a strange-looking head

15.09.2014

Sea lamprey studies show remarkably conserved gene expression patterns in jawless vs. jawed vertebrates

If you never understood what "ontogeny recapitulates phylogeny" meant in high school, don't worry: biologists no longer think that an animal's "ontogeny", that is, its embryonic development, replays its entire evolutionary history.


This shows the morphology of an adult sea lamprey (top); the ventral view of the unique oral disc, adapted for a parasitic lifestyle (bottom left); and a transient transgenic lamprey embryo (bottom right).

Credit: Image courtesy of Krumlauf Lab, Stowers Institute for Medical Research and Bronner Lab, California Institute of Technology

Instead, the new way to figure out how animals evolved is to compare regulatory networks that control gene expression patterns, particularly embryonic ones, across species. An elegant study published in the September 14, 2014 advance online issue of Nature from the Stowers Institute for Medical Research shows just how humbling and exhilarating that pursuit can be.

In the study, Investigator and Scientific Director Robb Krumlauf, Ph.D. and colleagues show that the sea lamprey Petromyzon marinus, a survivor of ancient jawless vertebrates, exhibits a pattern of gene expression that is reminiscent of its jawed cousins, who evolved much, much later. Those genes, called Hox genes, function like a molecular ruler, determining where along the anterior-posterior (AP) axis an animal will place a particular feature or appendage. The new study means that that the genetic program used by jawed vertebrates, including fish, mice, and us, was up and running ages before a vertebrate ever possessed a recognizable face.

"Hox genes regulate a tissue's character or shape, as in head or facial features. Our work in the past has addressed how factors make unique structures, for example, what makes an arm different from a leg," says Krumlauf. "Now, we are excited by the common role that similar sets of genes play in creating a basic structural plan."

The team at Stowers, collaborating with Marianne Bronner, Ph.D., professor of biology at Caltech, focused on the sea lamprey because the fossil record shows that its ancestors emerged from Cambrian silt approximately 500 million years ago, 100 million years before jawed fish ever swam onto the scene. The question was, could the hindbrain gene regulatory network that constructs the "modern" vertebrate head have originated in animals that lack those structures?

To answer it, the researchers created so-called "reporter" genes from stretches of regulatory DNA flanking a specific Hox gene in zebrafish or mice and linked them to fluorescent tags. When inserted into an experimental animal these types of reporters glow in tissues where the gene is activated, or "expressed". The researchers chose this particular battery of Hox reporters because when inserted in embryos of a jawed fish they fluoresce in adjacent rainbow stripes up and down the embryonic hindbrain.

The paper's startling finding came when they inserted the very same reporters into lamprey embryos using a technique developed by Hugo Parker, Ph.D., a postdoctoral fellow in the Krumlauf lab and the study's first author: the lamprey embryos displayed the same rainbow pattern of Hox reporters as did jawed fish, in exactly the same order along the AP axis of the hindbrain.

"We were surprised to see any reporter expression in lamprey, much less a pattern that resembles the pattern in a mouse or fish," says Parker, who pioneered the lamprey reporter approach as a graduate student at London's Queen Mary University. "That means that the gene regulatory network that governs segmental patterning of the hindbrain likely evolved prior to divergence of jawed vertebrates."

Researchers knew that in mouse and zebrafish short stretches of DNA in one Hox reporter (Hoxb3) formed a landing pad recognized by a DNA-binding protein that flips on the gene. As you would expect, when inserted into zebrafish embryos, reporters mutant in those sequences were inactive (they didn't glow) in the hindbrain. Remarkably, the mutant reporter was inactive in lamprey embryos also, meaning that this control switch has been around for a very long time.

"These results suggest that regulatory circuits controlling hindbrain patterning were likely 'fixed in place' in ancient vertebrates," says Bronner. Some may find this surprising, as adult mammals (like us!) bear absolutely no resemblance to lampreys. "However, embryos of lamprey and other vertebrates show many striking similarities, so it makes sense that there are features common to all."

###

This study was funded by the Stowers Institute and by grants from the National Institutes of Health (R01NS086907 and R01DE017911). The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH.

About the Stowers Institute for Medical Research

The Stowers Institute for Medical Research is a non-profit, basic biomedical research organization dedicated to improving human health by studying the fundamental processes of life. Jim Stowers, founder of American Century Investments, and his wife, Virginia, opened the Institute in 2000. Since then, the Institute has spent over one billion dollars in pursuit of its mission.

Currently, the Institute is home to nearly 550 researchers and support personnel; over 20 independent research programs; and more than a dozen technology-development and core facilities.

Kim Bland | Eurek Alert!
Further information:
http://www.stowers.org/

More articles from Studies and Analyses:

nachricht New study first to predict which oil and gas wells are leaking methane
21.12.2018 | University of Vermont

nachricht Droughts boost emissions as hydropower dries up
21.12.2018 | Stanford's School of Earth, Energy & Environmental Sciences

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Ten-year anniversary of the Neumayer Station III

The scientific and political community alike stress the importance of German Antarctic research

Joint Press Release from the BMBF and AWI

The Antarctic is a frigid continent south of the Antarctic Circle, where researchers are the only inhabitants. Despite the hostile conditions, here the Alfred...

Im Focus: Ultra ultrasound to transform new tech

World first experiments on sensor that may revolutionise everything from medical devices to unmanned vehicles

The new sensor - capable of detecting vibrations of living cells - may revolutionise everything from medical devices to unmanned vehicles.

Im Focus: Flying Optical Cats for Quantum Communication

Dead and alive at the same time? Researchers at the Max Planck Institute of Quantum Optics have implemented Erwin Schrödinger’s paradoxical gedanken experiment employing an entangled atom-light state.

In 1935 Erwin Schrödinger formulated a thought experiment designed to capture the paradoxical nature of quantum physics. The crucial element of this gedanken...

Im Focus: Nanocellulose for novel implants: Ears from the 3D-printer

Cellulose obtained from wood has amazing material properties. Empa researchers are now equipping the biodegradable material with additional functionalities to produce implants for cartilage diseases using 3D printing.

It all starts with an ear. Empa researcher Michael Hausmann removes the object shaped like a human ear from the 3D printer and explains:

Im Focus: Elucidating the Atomic Mechanism of Superlubricity

The phenomenon of so-called superlubricity is known, but so far the explanation at the atomic level has been missing: for example, how does extremely low friction occur in bearings? Researchers from the Fraunhofer Institutes IWM and IWS jointly deciphered a universal mechanism of superlubricity for certain diamond-like carbon layers in combination with organic lubricants. Based on this knowledge, it is now possible to formulate design rules for supra lubricating layer-lubricant combinations. The results are presented in an article in Nature Communications, volume 10.

One of the most important prerequisites for sustainable and environmentally friendly mobility is minimizing friction. Research and industry have been dedicated...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Our digital society in 2040

16.01.2019 | Event News

11th International Symposium: “Advanced Battery Power – Kraftwerk Batterie” Aachen, 3-4 April 2019

14.01.2019 | Event News

ICTM Conference 2019: Digitization emerges as an engineering trend for turbomachinery construction

12.12.2018 | Event News

 
Latest News

Additive manufacturing reflects fundamental metallurgical principles to create materials

18.01.2019 | Materials Sciences

How molecules teeter in a laser field

18.01.2019 | Life Sciences

The cytoskeleton of neurons has been found to be involved in Alzheimer's disease

18.01.2019 | Health and Medicine

VideoLinks
Science & Research
Overview of more VideoLinks >>>