Scientists at the National Institute of Immunology (NII) in Delhi have developed a genetic probe that can detect rhino horn even if it is crushed into powder or mixed with something else to evade recognition by wild life inspectors.

``The probe is so powerful that it can not only find out whether the specimen contained rhino horn but also tell whether it came from rhinoceros in Assam or West Bengal,'' said Sher Ali, head of NII's molecular genetics laboratory.

Ali and his colleagues who analysed the genetic material of India's one horned rhinoceros (rhinoceros unicornis) say they discovered a ``repetitive DNA sequence'' -- a genetic fingerprint which is unique to this species. It was not present in any other animal not even in the double-horned black rhinoceros (dicerosbicornis) of Africa.

``In other words one can use the NII probe to find out if a particular horn came from India or Africa,'' says Ali. It will be a valuable weapon in the hands of conservationists wanting to track down the source of rhino horn in the illegal market.

NII scientists identified the unique genetic fingerprint by analysing the DNA extracted from six wild rhinos from Jaldapara park in West Bengal and one rhino of Assam origin from the Delhi zoo. The DNA fragment was subsequently cloned and sequenced for developing the probe.

The Delhi scientists tried to find out if the DNA fragment was present in any other animal in cattle, buffalo, sheep, goat, rat, mouse, fish, rabbit, pig, camel, kangaroo, and the African species of rhinoceros but the test was negative.

``While the DNA fingerprint is unique to Indian species, the genetic test is sensitive enough to distinguish rhinos of West Bengal from those of Assam,'' Ali said.

The great Indian one-horned rhino which belongs to Schedule-1 animalsof Indian Wildlife Protection Act (1972) is an endangered species. It is confined to a few scattered protected areas of Assam, West Bengal, and Uttar Pradesh.