Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Key Animal Genes Were Available Before Animals Were

19.12.2001


Without the help of fossils or any other record from the distant past, scientists have identified what they believe represents a common ancestor of all animals on Earth, a microscopic organism with key genetic traits that, until now, have been found only in true animals.


Writing in Tuesday’s Proceedings of the National Academy of Sciences, a team of scientists from the Howard Hughes Medical Institute at the University of Wisconsin-Madison reports the discovery of a key cell communication gene in modern, single-celled microbes known as choanoflagellates.

Long suspected to be close relatives of animals, choanoflagellates have a lineage that dates to more than 600 million years ago, the time when animals -- multicellular organisms with distinct body plans and systems of organs -- are believed to have evolved in the ancient stew of microscopic protozoan life

Ancient microbes eventually gave rise not only to animals, but also plants, fungi, bacteria, and other living things, each going their separate ways to make up the tree of life as we know it today. The evolution of multicellular animals from a unicellular protozoan ancestor has long been recognized as a pivotal transition in the history of life.



"The question is, who were the ancestors of animals and what genetic tools did they pass down to the original animals," says Sean B. Carroll, a UW-Madison professor of genetics and the senior author of the PNAS study. "This is a difficult question to answer because the events are completely invisible in the fossil record."

Choanoflagellates represent an order of transparent, single-celled microbes that propel themselves with whiplike appendages. They exist in many forms today and, like animals, their lineage stretches back hundreds of millions of years to the mix of microscopic life that first evolved on Earth.

"Choanoflagellates thrive today and are the closest non-animal organisms to animals. They are to animals what chimps are to humans, and by studying some of their genetic characteristics, we can begin to make some strong inferences" about how animals evolved, Carroll says.

In recent years, biologists have come to understand that nature, in her use of genes, is thrifty. Instead of inventing new genes to accomplish new tasks, animals tend to redeploy existing genes in new ways. For example, genes used to make the very pedestrian wings of fruit flies are also those that butterflies use in different ways to make their far more colorful and shapely wings.

Understanding this phenomenon has enabled scientists to track evolutionary relationships between animals by looking for common genetic themes.

Undertaking a similar exploration in choanoflagellates, Carroll and his colleague, Nicole King, also of the Howard Hughes Medical Institute at UW-Madison, discovered a signaling gene in a choanoflagellate that, until now, was known only in animals.

"To build a multicellular organism compatible with a multicellular lifestyle is something that is very difficult," explains Carroll. "It takes a lot of genetic machinery to do that, and you have to ask the question, did it all arise when animals came along, or was some of it in place earlier?"

The current study, he says, strongly suggests that the key genes animals use today were indeed already available on the eve of animal evolution.

"We’re starting to get a glimpse of the genetic tool kit we have in common. In choanoflagellates, we’ve found genes that heretofore were believed to exist only in animals. It’s a confirmation of the idea that the genes come first, before their exploitation by organisms."

The gene-based signaling pathway found in extant choanoflagellates, Carroll says, resembles a similar pathway found in organisms as diverse as sponges and humans.

"Choanoflagellates express genes involved in animal development that are not found in other single-celled organisms, and that may be linked to the origin of animals. In other words, it looks like, walks like, and smells like genes that we are familiar with but that, apparently, evolved at the base of the node where animals split off the tree."

The identification of a common ancestor to all animals is important, according to Carroll, because it helps fill in the big picture of the evolution and diversity of life on Earth. It helps us understand, he says, how animals came to be and how nature creatively uses the same molecular tools to sculpt life in different ways

Terry Devitt | International Science News
Further information:
http://unisci.com/

More articles from Life Sciences:

nachricht Symbiotic bacteria: from hitchhiker to beetle bodyguard
28.04.2017 | Johannes Gutenberg-Universität Mainz

nachricht Nose2Brain – Better Therapy for Multiple Sclerosis
28.04.2017 | Fraunhofer-Institut für Grenzflächen- und Bioverfahrenstechnik IGB

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Fighting drug resistant tuberculosis – InfectoGnostics meets MYCO-NET² partners in Peru

28.04.2017 | Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

 
Latest News

Wireless power can drive tiny electronic devices in the GI tract

28.04.2017 | Medical Engineering

Ice cave in Transylvania yields window into region's past

28.04.2017 | Earth Sciences

Nose2Brain – Better Therapy for Multiple Sclerosis

28.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>