Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Plant genes imported from unrelated species more often than previously thought, IU biologists find

10.07.2003


Scientists have long thought gene exchange between individuals of unrelated species to be an extremely rare event among eukaryotes -- the massive group of organisms that counts among its members humans, oak trees, kelp and mushrooms -- throughout the group’s 2 billion year history.



But a new Indiana University Bloomington study in this week’s Nature suggests that such genetic events, called horizontal gene transfers, have happened more often than previously thought during the evolution of flowering plants. The finding hints other eukaryotes have had significant genetic influence from completely unrelated species.

"It appears horizontal gene transfer occurs for just about any gene in the plant mitochondrial genome," said biologist and Class of 1955 Endowed Professor Jeffrey Palmer, who led the research. "There is no reason to believe that this finding would apply only to plants. We already know from past studies that other eukaryotes experience the same mechanisms of horizontal transfer for certain special pieces of DNA called transposable elements. Our results now extend this phenomenon to the thousands of ordinary genes in a genome."


It has been common knowledge for years that horizontal gene transfer among bacteria is extremely common. Some scientists believe that as much as 25 percent of certain bacterial species’ chromosomal DNA has been acquired by way of horizontal transfer.

In eukaryotes, the rule remains that individuals get their genes from parents intergenerationally through the more familiar process called vertical transmission. But Palmer said scientists have probably underestimated the rate at which non-traditional gene transfer happens in eukaryotes.

"While our data set was small and real rates of eukaryotic horizontal gene transfer were therefore hard to predict, we can infer that even conservatively, horizontal gene transfer must have happened in flowering plants thousands of times," Palmer said.

One of the assumptions scientists make when comparing DNA from different species is that the DNA has followed basic lines of heredity connected in the past by a common ancestor. If DNA used in these gene studies does not descend vertically, from parent to offspring, but horizontally, by jumping from another lineage, analyses might turn up confusing or misleading evolutionary relationships between species. But Palmer isn’t worried about that.

"We don’t believe horizontal gene transfer happens often enough to throw a monkey wrench into molecular genealogical studies," he said.

While the mechanisms of horizontal gene transfer are still unknown, various explanations suggest that viruses, bacteria and fungi pack errant genetic material, or that accidental cross-species mating may play a role. However it happens, Palmer said there is no question it doeshappen. Many scientists have reported unexpectedly finding one species’ gene in another species with no reasonable explanation except horizontal gene transfer.

After encountering unique gene sequences along circular mitochondrial DNA chromosomes in three flowering plant species, Palmer and his team sought to determine the source of the anomalous genetic material. Part of the mystery was that closely related flowering plants did not possess the same gene sequences. Most of the genes the researchers examined encode parts of ribosomes, tiny assembly plants that make proteins by connecting amino acids.

Palmer’s team amassed mitochondrial gene sequence data from about 100 angiosperm species and looked for sequence similarities between them. In creating a tree of relatedness between the sequences, the scientists found that the mitochondrial genes from five flowering species -- kiwi fruit, honeysuckle, birch, bloodroot and Amborella (the most primitive flowering plant in existence) -- appeared far more related to unrelated species than to species more closely related to them, strongly suggesting that the four species had acquired these particular genes by way of horizontal transfer.

In the case of the bloodroot, the researchers were astonished to find a hybrid, "chimeric" mitochondrial gene. Half of this gene was captured by horizontal transfer from an unrelated plant over 100 million years distant in time, while the other half had been transmitted faithfully from parent to offspring in the lineage leading to bloodroot. "This result was so surprising, our first thought was that we’d made a mistake," Palmer said. "Once it was confirmed we had not made an error, we understood that what we’d found was very exciting."


###
Ulfar Bergthorsson (Indiana University Bloomington), Keith Adams (now at Iowa State University) and Brendan Thomason (now at the University of Michigan School of Medicine) also contributed to the study. It was funded by a grant from the National Institutes of Health.

To speak with Palmer or Bergthorsson, contact David Bricker at 812-856-9035 or brickerd@indiana.edu.

David Bricker | EurekAlert!
Further information:
http://newsinfo.iu.edu/

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

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

7th International Conference on Crystalline Silicon Photovoltaics in Freiburg on April 3-5, 2017

03.04.2017 | Event News

 
Latest News

DGIST develops 20 times faster biosensor

24.04.2017 | Physics and Astronomy

Nanoimprinted hyperlens array: Paving the way for practical super-resolution imaging

24.04.2017 | Materials Sciences

Atomic-level motion may drive bacteria's ability to evade immune system defenses

24.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>