Unexpectedly small effects of mutations in bacteria bring new perspectives

Nov 05, 2010

Most mutations in the genes of the Salmonella bacterium have a surprisingly small negative impact on bacterial fitness. And this is the case regardless whether they lead to changes in the bacterial proteins or not. This is shown by Uppsala University scientists in an article being published today in the prestigious journal Science.

The researchers have examined the impact of on the rate of growth of the Salmonella bacterium and show that most mutations have generally very small effects. Moreover the negative effects are of the similar magnitude for changes that lead to substitution of amino acids in proteins (so-called non-synonymous mutations) as for mutations that do not change the protein sequence (so-called synonymous mutations).

"The findings open an entirely new chapter for experimental studies of mutations and show that we need to change our view of how mutations lead to negative effects," says Professor Dan Andersson, lead author of the study.

A central question in , medical genetics, species-conservation biology, and animal breeding is how and why mutations affect an organism's capacity to survive. Usually these questions are studied in DNA sequence analyses from which conclusions have been drawn about what mutations are most common and have become established in the DNA of the organism.

The Uppsala scientists have used another -- experimental -- method whereby they can use various genetic tricks to introduce random individual mutations into any chosen gene, a method that has previously been used primarily in viruses. Two genes that code for proteins that are included in ribosomes were mutated, and using extremely sensitive growth measurements, doctoral candidate Peter Lind showed that most mutations reduced the rate of growth of bacteria by only 0.500 percent. No mutations completely disabled the function of the proteins, and very few had no impact at all.

Even more surprising was the fact that mutations that do not change the sequence had negative effects similar to those of mutations that led to substitution of . A possible explanation is that most mutations may have their negative effect by altering mRNA structure, not proteins, as is commonly assumed.

Explore further: Researchers successfully clone adult human stem cells

Related Stories

New gene linked to muscular dystrophy

Aug 10, 2009

Muscular dystrophy, a group of inherited diseases characterized by progressive skeletal muscle weakness, can be caused by mutations in any one of a number of genes. Another gene can now be added to this list, as Yukiko Hayashi ...

Study questions 'cost of complexity' in evolution

Mar 31, 2008

Higher organisms do not have a “cost of complexity” — or slowdown in the evolution of complex traits — according to a report by researchers at Yale and Washington University in Nature.

Cornell Finds Natural Selection in Humans

Oct 26, 2005

The most detailed analysis to date of how humans differ from one another at the DNA level shows strong evidence that natural selection has shaped the recent evolution of our species, according to researchers from Cornell ...

Recommended for you

Researchers successfully clone adult human stem cells

8 hours ago

(Phys.org) —An international team of researchers, led by Robert Lanza, of Advanced Cell Technology, has announced that they have performed the first successful cloning of adult human skin cells into stem ...

Researchers develop new model of cellular movement

11 hours ago

(Phys.org) —Cell movement plays an important role in a host of biological functions from embryonic development to repairing wounded tissue. It also enables cancer cells to break free from their sites of ...

For resetting circadian rhythms, neural cooperation is key

Apr 17, 2014

Fruit flies are pretty predictable when it comes to scheduling their days, with peaks of activity at dawn and dusk and rest times in between. Now, researchers reporting in the Cell Press journal Cell Reports on April 17th h ...

User comments : 0

More news stories

Researchers successfully clone adult human stem cells

(Phys.org) —An international team of researchers, led by Robert Lanza, of Advanced Cell Technology, has announced that they have performed the first successful cloning of adult human skin cells into stem ...

Plants with dormant seeds give rise to more species

Seeds that sprout as soon as they're planted may be good news for a garden. But wild plants need to be more careful. In the wild, a plant whose seeds sprouted at the first warm spell or rainy day would risk disaster. More ...

Researchers develop new model of cellular movement

(Phys.org) —Cell movement plays an important role in a host of biological functions from embryonic development to repairing wounded tissue. It also enables cancer cells to break free from their sites of ...

Male monkey filmed caring for dying mate (w/ Video)

(Phys.org) —The incident was captured by Dr Bruna Bezerra and colleagues in the Atlantic Forest in the Northeast of Brazil.  Dr Bezerra is a Research Associate at the University of Bristol and a Professor ...

Treating depression in Parkinson's patients

A group of scientists from the University of Kentucky College of Medicine and the Sanders-Brown Center on Aging has found interesting new information in a study on depression and neuropsychological function in Parkinson's ...