It was a lofty experience listening for the first time a carnatic musician and that of a calibre of Sudha Raghunathan, a padma sri receipient. Upon suggestion of a friend who is into carnatic music for years, we all went to attend the concert in Hindu temple of Atlanta. Quite genuinely, even though I didn't understand the language of the compositions, it was simply majestic. The clear, melodious voice in lower octaves or higher was so fresh,undulating and bewitching! The joy of music knows no language :)

Bacterial conversations

Oct 23rd issue has an interesting article on how bacteria coordinate when in close proximity (quorum), everything, from infection to luminiscence by turning on genes that work better in group. Luminescence, virulence and exchanging DNA (for new antibiotic resistance or catabolizing an energy source) - all work better if group carries out .

The chemicals released are called autoinducers, mostly AHLs-acyl homoserine lactone (with a conserved homoserine lactone ring and having 4-18 carbon acyl chains with different variations in chain length giving distinct quorum sensing words) which are continuously released at low levels in near by surroundings. Bacteria also have receptors that can detect when other bacteria are sending signals (either externally by membrane proteins which dimerizes and initiates phosphorylation cascade or diffusing through membrane and detected intracellularly by LuxR protein which on binding to it dimerizes and binds to DNA activating target gene). Activated gene can code for proteins that are involved in producing toxicity or virulence.

As a result of this quorum sensing, another feature formed is biofilm. After reaching quorum, many bateria secrete a complex mix of proteins, carbohydrates creating a sticky matrix that keeps nutrients from diffusing away and antibiotics from diffusing in. Many scientists across are developing strategies to prevent bacteria from communicating- developing phenylacetic acyl chain inhibitors which can bind to AHL receptor in bacteria preventing their binding to AHL.
One firm in Australia, Biosignal, is building furanone inhibitors based on pentanediones which cyclize into several quorum sensing mimics inhibiting conversations. They are testing whether furanone coated contact lenses can prevent biofilm formation in lenses that causes red-eye and inflammation or using them in toothpaste to reduce plaque.

The search for quorum sensing inhibitors and molecules continues. Meanwhile, It gives us the lesson to brush our teeth often enough!