Nilgiris pale tiger an ‘aberrant genetic mutation’

Prelims Related News

Nilgiris pale tiger an ‘aberrant genetic mutation’

Context

• A (White) pale tiger was recently spotted in the Nilgiris Biosphere Reserve, although experts believe it’s just an instance of an aberrant genetic mutation.

Genetic Mutation

• Although no such animal has been recorded in south India so far and the pale tiger of the Nilgiris has managed to won global attention
• The Nilgiri Biosphere Reserve, where the pale tiger was photographed, also includes the Mudumalai-Bandipur-Nagarhole-Waya- nad complex, which is home to the world’s largest wild tiger population.
• Random genetic mutations are a common occurrence in large populations and experts believe that this could just be a random genetic mutation.
• The paler-looking tigers may occur rarely due to reduced levels of the pigment melanin in a phenomenon called leucism
• Leucism is a condition in which there is partial loss of pigmentation in an animal resulting in white, pale, or patchy coloration of the skin, hair, feathers, scales

The ‘white’ gene

• A team of genetic scientists led by Dr Shu-Jin Luo from Peking University in Beijing, using whole-genome sequences of white and normally-colored Bengal tigers, has revealed that a mutation in a single pigment gene, called SLC45A2, is responsible for the unusual coloration of white tigers.
• The white tiger or bleached tiger is a pigmentation variant of the Bengal tiger, which is reported in the wild from time to time in the Indian states of Assam, West Bengal and Bihar in the Sunderbans region and especially in the former State of Rewa
• The gene variant found in the white tiger primarily inhibits the synthesis of red and yellow pigments but has little to no effect on black, which explains why white tigers still show characteristic dark stripes

Nilgiri Biosphere Reserve

• The Nilgiri Biosphere Reserve is an International Biosphere Reserve in the Western Ghats and Nilgiri Hills ranges of South India.
• The Nilgiri Sub-Cluster is a part of the Western Ghats, which was declared a World Heritage Site by UNESCO in 2012. It includes the Mudumalai, Mukurthi, Nagarhole, and Bandipur national parks, as well as the Wayanad and Sathyamangalam wildlife sanctuaries.
• The reserve encompasses 5,520 km² in the states of Tamil Nadu, Karnataka and Kerala. It forms an almost complete ring around the Nilgiri Plateau.
• Fauna includes over 100 species of mammals, 350 species of birds, 80 species of reptiles, about 39 species of fish, 31 amphibians and 316 species of butterflies.
• It has largest population of two endangered species- lion-tailed macaque and nilgiri tahr
• Nilgiris Biosphere Reserve is India’s first and foremost biosphere reserves with a heritage, rich in flora and fauna.

Conclusion

• This genetic mutation is already known to cause light coloration in horses, chicken and fish and has been proved that mutations are natural.
• However, most white tigers may be at a disadvantage in the wild due to lack of camouflage.
• All white tigers in captivity across the world trace their origins to one of the last white tigers in the wild, a male named Mohan with blue eyes and pink nose and paw-pads, which was captured from Rewa in Madhya Pradesh in 1951.

Central labs moot ‘human first’ approach to test malaria vaccine (Ethics meet to conduct human challenge trials in India)

Context

• First-of-its-kind, experts at the Indian Council of Medical Research (ICMR) and labs affiliated to the Department of Biotechnology (DBT), will have a “ethics meeting” to discuss the feasibility of conducting so-called ‘human challenge’ trials in India this November.

The Vaccine candidates

• The meeting will also indulge discussion on two vaccine-candidates.
• One of them causes falciparum malaria.
• The other one is the milder but more prevalent vivax.
• Both were developed at the New Delhi-based International Centre for Genetic Engineering and Biotechnology.

Why it has been a waste of Money?

• Because vaccines involve injecting the body with a mild strain of a parasite, the traditional approach for drugs and vaccines has been to test it in animals and only then, if safe and effective, check them in humans.
• This approach however has meant that several promising candidates, after tons of investment, fail to live up to expectations and consequently wasted money.
• Moreover, there are situations where the dosage requirements in people or, the manner in which disease manifests is different from that in animal models
• However, not all strains are responsive to a human-first, or Controlled Human Infection Model (CHIM) approach.
• The strain of parasite, for instance, must only induce as much infection as can be treated by available medicines.
• Only healthy, human volunteers completely aware of the risks and have given informed consent ought to be recruited for trials.

Immune response

• It has to be a strain that induces an immune response that you are capable of controlling infection.
• If somebody starts getting sick one should be able to abort the infection.
• Challenge trials were being conducted for testing typhoid vaccines at Oxford University, in the United Kingdom as well in other studies in the Netherlands and Africa.
• Though plans to employ such an approach were discussed three years ago, it didn’t materialize.

‘The CHIM’

• Developing and utilizing controlled human models of infection.
• The controlled human infection model (CHIM) helps to assess the efficacy of vaccines against Shigella and enterotoxigenic Escherichia coli (ETEC) that has several unique features that could significantly enhance the ability to test candidate vaccines.