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Genome of the Asian elephant sequenced for the first time in India

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While over 95 per cent of the genes were found to be similar to the African elephant, there are 1,500 bases that are unique to the Asian elephant including those responsible for the heightened sense of smell.

Why is there an increase in tuskless males among Asian elephants? Why do only males have tusks in Asia, while in Africa, both the sexes have tusks? Why does the elephant in the sub-continent have a keener sense of smell – sharper than that of a dog – than its African counterparts?

The answers to these questions are there in the genome of the Asian elephant, which has been sequenced perhaps for the first time in India.

A team of scientists from the city-based Centre for Ecological Science at the Indian Institute of Science (IISc) and the Indian Institute of Science Education and Research (IISER), Pune, have not only sequenced the entire genome of the animal, but have also for the first time mapped the ‘transcriptome’ — that is, a section of genes active in a particular cell — for the blood cells of the species.

Jayaprakash, a captive male elephant in Bandipur National Park, provided ear vein blood as well as venous blood sample that were sequenced in the Pune lab to identify nearly 3.1 billion genetic bases.

While over 95 per cent of the genes were found to be similar to the African elephant, there are 1,500 bases that are unique to the Asian elephant including those responsible for the heightened sense of smell.

“There are over 4,000 olfactory receptors in the Asian elephant, double that of a dog which is considered to have the sharpest sense of smell. What this means is that pheromones of the Asian elephant (which migrated around 7 million years ago from Africa) will not be smelled by the African species,” says Sanjeev Galande, from IISER who co-authored the paper published in Journal of Biosciences along with P. Chandramouli Reddy, Ashwin Kelkar, F. Habib and S.J. Pradhan from the institute.

Similarly, sequencing the transcriptome of the blood cell led to the realisation that like the African elephant, the Asian elephant, too, has a particular gene — known to inhibit cancer — that has been copied 20 times, rather than a single copy present in most mammals.

Having the genome sequence eventually builds a foundation (or, as the researchers say, “guidebook”) for further investigation into the genetic make-up of an elephant, its evolutionary path, as well as the possible conservation measures.

“For instance, the elephant’s susceptibility to certain diseases can be studied — leading to devising methods to shield the endangered species from climate and habitat changes,” says Ishani Sinha, research associate, who along with ecologist R. Sukumar at IISc participated in the project.

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Printable version | Jun 19, 2018 6:52:04 PM | http://www.thehindu.com/news/national/karnataka/genome-of-the-asian-elephant-sequenced-for-the-first-time-in-india/article8006026.ece