Thursday, May 6, 2010

Survivor bacteria linked to diabetes, say experts | Deccan Chronicle | 2010-05-06

Hyderabad, May 5: Researches in the city have found a link between a notorious bacterium that lives in milk and the type 1 diabetes which mostly affects children.
Though the exact cause of type 1 diabetes is yet to be ascertained, doctors generally blame genetics and environmental factors.
For the first time, a group of researchers from Hyderabad have gathered concrete proof of a link between the bacterium and type 1 diabetes. The bacterium infects people through milk and contaminated water.
The study was carried out by Dr P. Sandhya Rani and Dr Niyaz Ahmed of the University of Hyderabad, in collaboration with Dr L.A. Sechi, from the University of Sassari, Italy. The bacterium, mycobacterium avium sub-species paratuberculosis, or simply MAP, is very dangerous as it survives in milk even after pasteurisation.
MAP causes chronic infection in the intestines of cattle (Johne’s Disease) and causes enteritis in human beings (Crohn’s Disease).
“With increasing recognition of the link between MAP and Crohn’s Disease, it has been postulated that MAP is an occult antigen which, like Crohn’s, could trigger type 1 diabetes.
Studies implicate MAP as one of the triggers of diabetes. Also laboratory analyses in diabetic patients from Sardinia (Italy) point a finger at the bacterium,” Dr Sechi said.The study is significant as the type 1 diabetes is the second most common chronic disease during childhood and the most common form of diabetes affecting three out of every 2,000 children world-wide.
In the South Indian urban population, the type 1 diabetes occurs in 26 out of every 10,000 children under 15 years of age. The MAP bacterium enters the human body through the faecal-oral route. Infected animals release MAP in their milk and faeces.
The bacterium is found to be present in untreated water and in water-bodies contaminated by agricultural runoff. The treatment of water to make it potable by the processes of sedimentation, filtration and chlorination has little or no effect on the bacteria.
Though the team has identified MAP as a trigger for the type 1 diabetes, it will take further research to unravel the puzzle of how the bacterium damages the production of insulin.

Tuesday, May 4, 2010

New article added to PLoS ONE Prokaryotic Genome Collection

'While the bulk of the finished microbial genomes sequenced to date are derived from cultured bacterial and archaeal representatives, the vast majority of microorganisms elude current culturing attempts, severely limiting the ability to recover complete or even partial genomes from these environmental species. Single cell genomics is a novel culture-independent approach, which enables access to the genetic material of an individual cell. No single cell genome has to our knowledge been closed and finished to date. Here we report the completed genome from an uncultured single cell of Candidatus Sulcia muelleri DMIN. Digital PCR on single symbiont cells isolated from the bacteriome of the green sharpshooter Draeculacephala minerva bacteriome allowed us to assess that this bacteria is polyploid with genome copies ranging from approximately 200–900 per cell, making it a most suitable target for single cell finishing efforts. For single cell shotgun sequencing, an individual Sulcia cell was isolated and whole genome amplified by multiple displacement amplification (MDA). Sanger-based finishing methods allowed us to close the genome. To verify the correctness of our single cell genome and exclude MDA-derived artifacts, we independently shotgun sequenced and assembled the Sulcia genome from pooled bacteriomes using a metagenomic approach, yielding a nearly identical genome. Four variations we detected appear to be genuine biological differences between the two samples. Comparison of the single cell genome with bacteriome metagenomic sequence data detected two single nucleotide polymorphisms (SNPs), indicating extremely low genetic diversity within a Sulcia population. This study demonstrates the power of single cell genomics to generate a complete, high quality, non-composite reference genome within an environmental sample, which can be used for population genetic analyzes'.
Woyke T, Tighe D, Mavromatis K, Clum A, Copeland A, et al. (2010) One Bacterial Cell, One Complete Genome. PLoS ONE 5(4): e10314. doi:10.1371/journal.pone.0010314