Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Study backs theory that accumulating mutations of ’quiet’ genes foster aging

15.10.2002


A theory that suggests the aging process might be safely slowed by targeting genes that are quiet early but threaten damage later in life has gotten a boost from new findings from the University of Illinois at Urbana-Champaign.



The researchers don’t promote such tinkering in their paper, which appears online this week in advance of publication by the Proceedings of the National Academy of Sciences. Rather they detail their tests, based on models of mathematical prediction, of the two leading evolutionary theories of aging on the reproductive success of 100 different genotypes of fruit flies (Drosophila melanogaster) across various age groups.

The results suggest that more needs to be learned about which genes do what and when in the aging process so that artificial manipulation does not cause evolutionary damage in future generations, said Kimberly A. Hughes, an animal biologist in the Program in Ecology and Evolutionary Biology at Illinois.


The study provides the strongest support yet for the theory of mutation accumulation (MA), Hughes said. The theory, which has been difficult for scientists to test, proposes that aging is the result of an accumulation of mutations of genes that are kept in check by reproductive-oriented selection processes early in life and only are active later on.

Examples are genes associated with Huntington’s disease and forms of cancer that strike late in life. Such mutations exist in prime reproductive years but only have noticeable effects late in life. In old age, when reproduction is not an organism’s primary function, accumulating mutations are no longer checked by selection, increasing the risk of disease.

The other, more widely accepted theory of antagonistic pleiotrophy (AP) says that aging occurs when genes that offer help during the reproductive years -- those that produce estrogen, for example -- take on harmful roles later in life. Selection under AP theory favors the early life effects because these lead to the production of offspring but does not oppose the deleterious effects in late life, Hughes said.

Building on her theoretical study of age-related inbreeding depression and genetic variability (PNAS, June 1996) while a doctoral student at the University of Chicago, Hughes and colleagues raised fruit flies to test the effect of delayed mutations.

The new study found that the deleterious effects of mutations on reproduction rose dramatically with age during the reproductive years in both genotypes -- homozygous (those with many identical genes, or inbreeding) and heterozygous (those having a variety of genes present). Reproductive success declined more rapidly, however, in the homozygous lines, as predicted by the MA theory.

"This study allowed us to detect certain kinds of genetic effects called dominance variance that are predicted to increase with age only under the MA theory," Hughes said. "The power to detect these effects is critical to tests of evolutionary aging theories, because an age-related increase appears to be a unique prediction of the MA theory, while other kinds of genetic effects can increase under either model."

While the study shows support for the MA theory, the scenario under the antagonistic pleiotrophy theory is not discounted. "They are not mutually exclusive,Ó Hughes said. "They can both be happening. Both kinds of genes can be accumulating.Ó

If geneticists try to remove bad late-in-life effects of a gene that has a positive role early in life, then its overall function could be negatively altered in future generations, Hughes said. Manipulating genes with no early life benefits to negate their deleterious late life effects, she said, might not cause negative evolutionary changes in the future.


The authors of the paper are Hughes, postdoctoral researcher Jenny M. Drnevich and doctoral student Rose M. Reynolds, all of Illinois, and former postdoctoral associate Julie A. Alipaz, who now is at Harvard University.

The National Science Foundation, National Institutes of Health and the School of Integrative Biology at Illinois funded the research.

Jim Barlow | EurekAlert!

More articles from Life Sciences:

nachricht Desert ants cannot be fooled
23.11.2017 | Max-Planck-Institut für chemische Ökologie

nachricht Bacteria as pacemaker for the intestine
22.11.2017 | Christian-Albrechts-Universität zu Kiel

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Frictional Heat Powers Hydrothermal Activity on Enceladus

Computer simulation shows how the icy moon heats water in a porous rock core

Heat from the friction of rocks caused by tidal forces could be the “engine” for the hydrothermal activity on Saturn's moon Enceladus. This presupposes that...

Im Focus: Nanoparticles help with malaria diagnosis – new rapid test in development

The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.

Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....

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....

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

Water cooling for the Earth's crust

23.11.2017 | Earth Sciences

Nano-watch has steady hands

23.11.2017 | Physics and Astronomy

Batteries with better performance and improved safety

23.11.2017 | Power and Electrical Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>