Bio · Science

Bacteria use chat to play the “Prisoner’s Dilemma” game in deciding their fate

Lessons from stressed-out bacteria could help researchers develop cancer therapies. Credit: Eshel Ben-Jacob, Tel Aviv University

SAN DIEGO, March 27, 2012 — When faced with life-or-death situations, bacteria — and maybe even human cells — use an extremely sophisticated version of “game theory” to consider their options and decide upon the best course of action, scientists reported here today. In a presentation at the 243rd National Meeting & Exposition of the American Chemical Society (ACS), the world’s largest scientific society, they said microbes “play” a version of the classic “Prisoner’s Dilemma” game.

José Onuchic, Ph.D., who headed the research team, said these and other new insights into the “chat” sessions that bacteria use to communicate among themselves — information about cell stress, the colony density (quorum-sensing peptides) and the stress status and inclinations of neighboring cells (peptide pheromones) — could have far-reaching medical applications.

“Using this form of cell-to-cell communication, colonies of billions or trillions of bacteria can literally reach a consensus on actions that impact people,” Onuchic explained. “Bacteria that previously existed harmlessly on the on the skin, for instance, may exchange chemical signals and reach a consensus that their numbers are large enough to start an infection. Likewise, bacteria may decide to band together into communities called biofilms that make numerous chronic diseases difficult to treat — urinary tract infections, for instance, cystic fibrosis and endocarditis.”

Excerpt from a press release at ACS. Continue HERE

Bio · Science

New type of extra-chromosomal DNA discovered

A team of scientists from the University of Virginia and University of North Carolina in the US have discovered a previously unidentified type of small circular DNA molecule occurring outside the chromosomes in mouse and human cells. The circular DNA is 200-400 base pairs in length and consists of non-repeating sequences. The new type of extra-chromosomal circular DNA (eccDNA) has been dubbed microDNA. Unlike other forms of eccDNA, in microDNA the sequences of base pairs are non-repetitive and are usually found associated with particular genes. This suggests they may be produced by micro-deletions of small sections of the chromosomal DNA.

This result suggests that the DNA found in tissue cells may exhibit more variation than previously thought, and the implication of this is that sequencing of the DNA in blood cells (which are the cells usually used for sequencing) may give misleading results if micro-deletions have occurred in the DNA of other tissues but not in blood cells. Examples in which this might be important are in genetic sequencing for autism or schizophrenia, which could be caused by incorrect functioning of certain genes in brain tissue. Many cancers are also caused by incorrect functioning of genes; in this case tumor suppressor genes, and sequencing of blood cell DNA could also give misleading results.

Excerpts from an article via PhysOrg