But a study conducted by evolutionary biologists at the University of California, San Diego questions that longstanding paradigm. In a paper published in the November 8 issue of the journal Current Biology, they conclude that not only do bacteria age, but that their ability to age allows bacteria to improve the evolutionary fitness of their population by diversifying their reproductive investment between older and more youthful daughters. An advance copy of the study appears this week in the journal’s early online edition.
“Aging in organisms is often caused by the accumulation of non-genetic damage, such as proteins that become oxidized over time,” said Lin Chao, a professor of biology at UC San Diego who headed the study. “So for a single celled organism that has acquired damage that cannot be repaired, which of the two alternatives is better—to split the cellular damage in equal amounts between the two daughters or to give one daughter all of the damage and the other none?”
The UC San Diego biologists’ answer—that bacteria appear to give more of the cellular damage to one daughter, the one that has “aged,” and less to the other, which the biologists term “rejuvenation”—resulted from a computer analysis Chao and colleagues Camilla Rang and Annie Peng conducted on two experimental studies. Those studies, published in 2005 and 2010, attempted unsuccessfully to resolve the question of whether bacteria aged. While the 2005 study showed evidence of aging in bacteria, the 2010 study, which used a more sophisticated experimental apparatus and acquired more data than the previous one, suggested that they did not age.
“We analyzed the data from both papers with our computer models and discovered that they were really demonstrating the same thing,” said Chao. “In a bacterial population, aging and rejuvenation goes on simultaneously, so depending on how you measure it, you can be misled to believe that there is no aging.”
In a separate study, the UC San Diego biologists filmed populations of E. coli bacteria dividing over hundreds of generations and confirmed that the sausage-shaped bacteria divided each time into daughter cells that grew elongated at different rates—suggesting that one daughter cell was getting all or most of the cellular damage from its mother while the other was getting little or none. Click this link to watch the time-lapse film of one bacterium dividing over 10 generations into 1,000 bacteria in a period of five hours and see if you can see any differences.
“We ran computer models and found that giving one daughter more the damage and the other less always wins from an evolutionary perspective,” said Chao. “It’s analogous to diversifying your portfolio. If you could invest $1 million at 8 percent, would that provide you with more money than splitting the money and investing $500,000 at 6 percent and $500,000 at 10 percent?”
“After one year it makes no difference,” he added. “But after two years, splitting the money into the two accounts earns you more and more money because of the compounding effect of the 10 percent. It turns out that bacteria do the same thing. They give one daughter a fresh start, which is the higher interest-bearing account and the other daughter gets more of the damage.”
Although E. coli bacteria appear to divide precisely down the middle into two daughter cells, the discovery that the two daughters eventually grow to different lengths suggests that bacteria do not divide as symmetrically as most biologists have come to believe, but that their division is really “asymmetrical” within the cell.
“There must be an active transport system within the bacterial cell that puts the non-genetic damage into one of the daughter cells,” said Chao. “We think evolution drove this asymmetry. If bacteria were symmetrical, there would be no aging. But because you have this asymmetry, one daughter by having more damage has aged, while the other daughter gets a rejuvenated start with less damage.”Media Contact: Kim McDonald (858) 534-7572; email@example.com
Kim McDonald | EurekAlert!
If Machines Could Smell ...
19.07.2019 | Fraunhofer-Institut für Produktionstechnik und Automatisierung IPA
Algae-killing viruses spur nutrient recycling in oceans
18.07.2019 | Rutgers University
Adjusting the thermal conductivity of materials is one of the challenges nanoscience is currently facing. Together with colleagues from the Netherlands and Spain, researchers from the University of Basel have shown that the atomic vibrations that determine heat generation in nanowires can be controlled through the arrangement of atoms alone. The scientists will publish the results shortly in the journal Nano Letters.
In the electronics and computer industry, components are becoming ever smaller and more powerful. However, there are problems with the heat generation. It is...
Scientists have visualised the electronic structure in a microelectronic device for the first time, opening up opportunities for finely-tuned high performance electronic devices.
Physicists from the University of Warwick and the University of Washington have developed a technique to measure the energy and momentum of electrons in...
Scientists at the University Würzburg and University Hospital of Würzburg found that megakaryocytes act as “bouncers” and thus modulate bone marrow niche properties and cell migration dynamics. The study was published in July in the Journal “Haematologica”.
Hematopoiesis is the process of forming blood cells, which occurs predominantly in the bone marrow. The bone marrow produces all types of blood cells: red...
For some phenomena in quantum many-body physics several competing theories exist. But which of them describes a quantum phenomenon best? A team of researchers from the Technical University of Munich (TUM) and Harvard University in the United States has now successfully deployed artificial neural networks for image analysis of quantum systems.
Is that a dog or a cat? Such a classification is a prime example of machine learning: artificial neural networks can be trained to analyze images by looking...
An international research group led by scientists from the University of Bayreuth has produced a previously unknown material: Rhenium nitride pernitride. Thanks to combining properties that were previously considered incompatible, it looks set to become highly attractive for technological applications. Indeed, it is a super-hard metallic conductor that can withstand extremely high pressures like a diamond. A process now developed in Bayreuth opens up the possibility of producing rhenium nitride pernitride and other technologically interesting materials in sufficiently large quantity for their properties characterisation. The new findings are presented in "Nature Communications".
The possibility of finding a compound that was metallically conductive, super-hard, and ultra-incompressible was long considered unlikely in science. It was...
24.06.2019 | Event News
29.04.2019 | Event News
17.04.2019 | Event News
19.07.2019 | Physics and Astronomy
19.07.2019 | Physics and Astronomy
19.07.2019 | Earth Sciences