KNOW A SCIENTIST

Dr. Venkataraman Ramakrishnan, an Indian-born American & British citizen, carried out his post doctoral research on ribosomes after obtaining Ph.D. degree in Physics, as a staff scientist at Brookhaven National Laboratory from 1983-95. Ramakrishnan and   colleagues published a 5.5 Angstrom   resolution and complete molecular   structure of the 30S subunit of   ribosome and its complexes with   several antibiotics and determined the   atomic structure of the whole ribosome   in complex with its tRNA and mRNA ligands. Dr. Venki Ramakrishnan is also known for his past work on histone and chromatin structure.

He was honored with Nobel Prize in Chemistryin the year 2009 for his contribution on structure and functions on the ribosome, along with Thomas A. Steitz and Ada E. Yonath, at the MRC Laboratory of Molecular Biology in Cambridge, England.

Release of State of the Art (Series - 8)

Publication of Our ENVIS Centre by the Hon'ble Chief Guest, Shri. A. K. Srivastava, Chief Secretary, Government of Sikkim

National Interaction cum Evaluation Workshop for ENVIS held at Gangtok, Sikkim | 28-30 March, 2014.

A Few Drug-Resistant Bacteria May Keep the Whole Colony Alive

Drug-resistant mutant bacteria produce large amount of compounds called indoles that can protect large numbers of nonresistant colony mates. In a bacterial population exposed to a killer drug, a few lucky individuals might have a genetic mutation that kept them alive. They survived to reproduce, while the rest of the population perished. In short order, the entire colony consisted only of the offspring of the drug-resistant founders.

But a new study finds that just a few resistant mutants can protect large numbers of normal bacteria that would have been thought to be susceptible to the drug therapy. The research appears in the journal Nature.

The key seems to be indoles, which help bacteria tough out tough times. And the indoles from the mutants buck up the regular, nonresistant bacteria. The mutants themselves seem to be acting altruistically—their own growth is slowed by their indole production.

Source: www.scientificamerican.com

Bacterial Resistance to Antibiotics

History of antibiotics and emergence of antibiotic resistance

The first antibiotic, penicillin, was discovered in 1929 by Sir Alexander Fleming, who observed inhibition of staphylococci on an agar plate contaminated by a Penicillium mold. and he named the active substance penicillin but was unable to isolate it.

Several years later, in 1939, Ernst Chain and Howard Florey isolated penicillin and used it to treat bacterial infections during the Second World War. The new drug came into clinical usage in 1946 and made a huge impact on public health. For these discoveries Fleming, Chain and Florey were awarded the Nobel prize in 1945. Their discovery and development revolutionized modern medicine and paved the way for the development of many more natural antibiotics.

While Fleming was working on penicillin, Gerhard Domagk, a German doctor, discovered a synthetic molecule with antibacterial properties, called Prontosil, and it became the first of a long series of synthetic antibiotics called sulfonamides or sulfa drugs. Prontosil was introduced to clinical use in the 1930s and was used to combat urinary tract infections, pneumonia and other conditions. While sulfa drugs in many cases are not as effective as natural antibiotics, they are now in widespread use for the treatment of many conditions. Gerhard Domagk was awarded the  Nobel prize in 1939 for his discovery of Prontosil.

Initially, the antibiotic was effective against all sorts of infections caused by staphylococci and streptococci. Penicillin had unbelievable ability to kill these bacterial pathogens without harming the host.

In the late 1940s and early 1950s, new antibiotics were introduced, including streptomycin, chloramphenicol and tetracycline, and the age of antibiotic chemotherapy came into full being. These antibiotics were effective against the full array of bacterial pathogens including Gram-positive and Gram-negative bacteria, intracellular parasites, and the tuberculosis bacillus. Synthetic antimicrobial agents such as the "sulfa drugs" (sulfonamides) and anti-tuberculosis drugs, such as para aminosalicylic acid (PAS) and isoniazid (INH), were also brought into wider usage.

In the center of the plate is a colony of Penicillium notatum, a mold that produces penicillin. After appearance of the mold colony, the plate was overlaid with a bacterial culture of Micrococcus luteus which forms a yellow "lawn" of growth. A zone of inhibition of bacterial growth surrounds the fungal colony where penicillin has diffused into the medium.

Source: www.textbookofbacteriology.net