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/

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: A cavity leads to a strong interaction between light and matter

Researchers have succeeded in creating an efficient quantum-mechanical light-matter interface using a microscopic cavity. Within this cavity, a single photon is emitted and absorbed up to 10 times by an artificial atom. This opens up new prospects for quantum technology, report physicists at the University of Basel and Ruhr-University Bochum in the journal Nature.

Quantum physics describes photons as light particles. Achieving an interaction between a single photon and a single atom is a huge challenge due to the tiny...

Im Focus: Solving the mystery of quantum light in thin layers

A very special kind of light is emitted by tungsten diselenide layers. The reason for this has been unclear. Now an explanation has been found at TU Wien (Vienna)

It is an exotic phenomenon that nobody was able to explain for years: when energy is supplied to a thin layer of the material tungsten diselenide, it begins to...

Im Focus: An ultrafast glimpse of the photochemistry of the atmosphere

Researchers at Ludwig-Maximilians-Universitaet (LMU) in Munich have explored the initial consequences of the interaction of light with molecules on the surface of nanoscopic aerosols.

The nanocosmos is constantly in motion. All natural processes are ultimately determined by the interplay between radiation and matter. Light strikes particles...

Im Focus: Shaping nanoparticles for improved quantum information technology

Particles that are mere nanometers in size are at the forefront of scientific research today. They come in many different shapes: rods, spheres, cubes, vesicles, S-shaped worms and even donut-like rings. What makes them worthy of scientific study is that, being so tiny, they exhibit quantum mechanical properties not possible with larger objects.

Researchers at the Center for Nanoscale Materials (CNM), a U.S. Department of Energy (DOE) Office of Science User Facility located at DOE's Argonne National...

Im Focus: Novel Material for Shipbuilding

A new research project at the TH Mittelhessen focusses on the development of a novel light weight design concept for leisure boats and yachts. Professor Stephan Marzi from the THM Institute of Mechanics and Materials collaborates with Krake Catamarane, which is a shipyard located in Apolda, Thuringia.

The project is set up in an international cooperation with Professor Anders Biel from Karlstad University in Sweden and the Swedish company Lamera from...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

International Symposium on Functional Materials for Electrolysis, Fuel Cells and Metal-Air Batteries

02.10.2019 | Event News

NEXUS 2020: Relationships Between Architecture and Mathematics

02.10.2019 | Event News

Optical Technologies: International Symposium „Future Optics“ in Hannover

19.09.2019 | Event News

 
Latest News

Kirigami inspires new method for wearable sensors

22.10.2019 | Materials Sciences

3D printing, bioinks create implantable blood vessels

22.10.2019 | Medical Engineering

Ionic channels in carbon electrodes for efficient electrochemical energy storage

22.10.2019 | Power and Electrical Engineering

VideoLinks
Science & Research
Overview of more VideoLinks >>>