Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Time to rewrite the species rulebook

09.02.2005


From person to piranha to petunia, it’s pretty easy to spot different species in the human-scale part of the plant and animal kingdoms. But a new study shows that species differences aren’t so clear, at least as currently measured, when it comes to microscopic bacteria.



MSU researchers have spotted significant differences in genetic libraries among thought-to-be similar bacteria strains. The results, published this week in the journal the Proceedings of the National Academy of Sciences, suggest that new definitions are needed to catalogue bacteria – single-celled organisms with at least a 3.5 billion-year history. "It’s important to point out the importance of these small microbes on Earth; even though they are small, their mass in soil and water is equal to that of all plants," said MSU microbiologist James Tiedje, one of the study’s authors. "Furthermore, they are responsible for recycling the key elements of life so life on Earth can continue."

DNA, used by all life including bacteria to store genetic information, is a double-stranded molecule. When a given DNA molecule is split in two, for instance by heating it up, its two strands will spontaneously find each other, or reassociate, when the temperature drops. Scientists have long exploited this fact in their rough rule-of-thumb approach for saying just what makes up a species of bacteria. Single strands of DNA from two bacteria are mixed together. If most of these strands reassociate – specifically, if 70 percent of strands from bacteria A come together with strands from bacteria B – then the two bacteria strains are said to members of the same species.


Tiedje and his MSU colleague, microbiologist Konstantinos Konstantinidis, set out to put this mix and match approach to the test. The two scientists selected 70 related bacteria whose genomes, or complete genetic libraries, had been fully sequenced. A sequenced genome gives scientists what amounts to a card catalogue guide to an organism’s genetic information.

The MSU scientists downloaded the already-sequenced bacteria genomes from a variety of sites on the Internet. Then they did some cross-card catalogue comparisons. To their surprise, many bacteria that are considered members of the same species by the current mix and match approach, often share as few as 65 percent of their genes. Humans, in comparison, share 75 percent of their genes with fish. No one’s calling for the species rules to be rewritten so that humans are lumped with their distant underwater relatives. And when it comes to bacteria, the authors say, the current species definition appears to be too liberal.

Much of the differences between genetically-similar bacteria appear to be the result of environmental pressures. E. coli bacteria, for instance, exists everywhere from the intestines of warm blooded animals to paper mills. Any new way of tallying up bacteria species should "accommodate the ecological distinctiveness of the organisms," the authors write. "The point is about the value of a correct understanding of species – people expect a species to have certain traits and live in certain habitats," said Tiedje, whose work is also supported by the Michigan Agricultural Experiment Station. "If the species definition is not reasonably predictive of this, then it loses its value. This can be important for pathogen identification, quarantine or biotechnology, for example."

Konstantinidis and Tiedje also noted that even bacteria with genetic card catalogues that were as much as 99 percent similar had enough outward differences to be separate species. This shouldn’t come as a shock. Humans and chimpanzees, in comparison, share 98.7 percent of their DNA. But that small difference at the genetic level results in a big difference when it comes to outward appearance and Konstantinidis and Tiedje’s work is supported by the Bouyoukos Fellowship Program, the U.S. Department of Energy’s Microbial Genome Program, the Ribosomal Database Project and the MSU Center for Microbial Ecology.

Jim Tiedje | EurekAlert!
Further information:
http://www.msu.edu

More articles from Life Sciences:

nachricht Could this protein protect people against coronary artery disease?
17.11.2017 | University of North Carolina Health Care

nachricht Microbial resident enables beetles to feed on a leafy diet
17.11.2017 | Max-Planck-Institut für chemische Ökologie

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 “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

Im Focus: Researchers Develop Data Bus for Quantum Computer

The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.

Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...

Im Focus: Wrinkles give heat a jolt in pillared graphene

Rice University researchers test 3-D carbon nanostructures' thermal transport abilities

Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

NASA detects solar flare pulses at Sun and Earth

17.11.2017 | Physics and Astronomy

NIST scientists discover how to switch liver cancer cell growth from 2-D to 3-D structures

17.11.2017 | Health and Medicine

The importance of biodiversity in forests could increase due to climate change

17.11.2017 | Studies and Analyses

VideoLinks
B2B-VideoLinks
More VideoLinks >>>