Friday, April 30, 2010

Monsoons went erratic 18,000 years ago

Syed Akbar
Hyderabad, April 30: Erratic rainfall during present day monsoons is not a new phenomenon, but a result of climatic changes that occurred in the Arabian sea some 18,000 years ago.

The Arabian sea, from which emerge the monsoons bringing in rainfall to the Indian sub-continent, turned warmer by 4 degrees Celsius about 18 millennia ago, leading to reduced rainfall in the region. The phenomenon continues till day causing erratic monsoons.

Researchers at the National Institute of Oceanography and the National Centre for Antarctic and Ocean Research have reconstructed the rainfall viability over thousands of years to study what went wrong with the monsoon system, since the Indian sub-continent largely depends on the monsoon for rainfall.

The joint research team of NIO-NCAOR has found that the Arabian sea was 4 degrees C cooler during 18,000 years ago, while the general belief is that the sea was cooler by just 2 degrees C. "In our study we have demonstrated that Arabian sea was 4 degrees C cooler during 18 kilo annum (18,000 years), which had a strong bearing in the initiation of monsoon rainfall in the Asian sub-continent," Dr Pothuri Divakar Naidu of NIO, Goa.

He told this reporter that the reconstruction of rainfall viability over thousands of years reveal that from 10.5 to 3.5 ka (10,500 years to 3,500 years ago) there was good amount of rainfall in the subcontinent. "But from about 3,500 years onwards descending phase of monsoon rainfall started due to arid climatic conditions in the Indian  subcontinent," Dr Divakar pointed out.

The team studied variations in sea surface temperature, sea water and salinity in the Arabian sea. They reconstructed the atmospheric model for the past 68,000 years using a sediment core from the Eastern Arabian Sea to understand the changes in evaporation and precipitation associated with the monsoon system.

The southwest monsoon emanates from the temperature and pressure gradients that occur between the Indian Ocean and Tibet Plateau during summer. The upper ocean heat supplies the necessary evaporation and atmospheric moisture transport during this phenomenon. Thus, a strong link exists between ocean dynamics and the atmospheric heat and moisture transfer behind the monsoon

"The socio-economic and agriculture development of southeast Asia depend on the monsoon precipitation from June through September,
which contributes about 70 to 90 per cent of the annual precipitation in the region. Therefore, an understanding of the monsoon system beyond historical records is desired," he said.

Friday, April 23, 2010

Tiny nanotubes to deliver biomaterials like DNA and RNA for effective gene therapy

Syed Akbar
Hyderabad, April 23: A group of city scientists has developed tiny nanotubes that could serve as next generation micro pills to deliver biomaterials like DNA and RNA for effective gene therapy.

Researchers at the Indian Institute of Chemical Technology and the Centre for Cellular and Molecular Biology have already patented this unique technology. The nanotubes developed from organic material, for the first time in the world, could be useful not only to deliver small regulatory RNA and DNA as therapeutic materials but also to optimise pill-like properties for orally ingested materials.

"This beautiful technology may help in making the next-generation micro pills to deliver biomaterials for effective gene therapy and novel cargoes for molecular diagnostics. It can also be used for mass delivery of therapeutic biomolecules via food in various animal populations for the improvement of animal husbandry," Dr Utpal Bhadra of CCMB told this correspondent.

The IICT-CCMB team comprising JS Yadav, MP Lavanya, PP Das,
Manika Pal Bhadra and Utpal Bhadra zeroed in on a special material for construction of nano tubes. They selected p-aminobenzoic acid
or PABA in short. This is a natural material that forms part of folic acid and the vitamin B complex present in the human liver. Since it is a natural non-protein amino acid, it has little side effects on animals or human beings. Moreover, PABA is also known to support folic acid production by intestinal bacteria.

The PABA nano tubes will also help in increase of PABA concentration in the intestine during oral ingestion, which might help intestinal bacteria to convert it into folic acids, and protect against strokes, cardiovascular diseases and even certain cancers. Therefore, ingestion of PABA nano tubes plays a dual role, directly as a delivery vehicle of therapeutic agents and indirectly by preventing different diseases as a therapeutic agent itself.

"These nano structures minimise many obstacles including absorption in body fluids, systemic spreading and the reduction of immunogenetic symptoms. The tubes also maintain their fluorescent activity for a long period of time and do not suffer from dissociation or decay of fluorescence," Dr Bhadra said.

The advantage of nano tubes is that they spontaneously adsorb onto the membrane and later accumulate within intracellular compartments.

Referring to the safety of the new technology, the team points out that in drosophila studies no difference in size or any abnormalities in their sexual behaviour were observed. The egg laying capacity of adult females for six consecutive days after hatching and the sex of hatched flies were counted. No significant difference was detected in egg laying capacity and male/female ratios in nano tube-fed females as compared to the wild type.