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Indian-origin scientists find South Asians sharing ancestry with a mysterious population

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Denisovans were probably dark-skinned, unlike the pale Neandertals.n Image source: sci-news.com

New York: Indian-origin scientists among others have found that many bloodlines around the world, particularly of South Asian descent, may actually be a bit more Denisovan- a mysterious population of hominids.

Denisovans lived around the same time as the Neanderthals- researchers including Indian-origin scientists have revealed.

The team from Harvard Medical School and University of California-Los Angeles (UCLA) has created a world map and also used comparative genomics to make predictions about where Denisovan and Neanderthal genes may be impacting modern human biology.

The analysis also proposes that modern humans interbred with Denisovans about 100 generations after their trysts with the Neanderthals.

Denisovan genes can potentially be linked to a more subtle sense of smell in Papua New Guineans and high-altitude adoptions in Tibetans.

Meanwhile, Neanderthal genes found in people around the world most likely contribute to tougher skin and hair.

Most non-Africans possess at least a little bit Neanderthal DNA.

“There are certain classes of genes that modern humans inherited from the archaic humans with whom they interbred, which may have helped the modern humans to adapt to the new environments in which they arrived,” explained senior author David Reich, a geneticist at Harvard Medical School.

On the flip side, there was negative selection to systematically remove ancestry that may have been problematic from modern humans.

“We can document this removal over the 40,000 years since these admixtures occurred,” Reich added.

Reich and lab members, Swapan Mallick and Nick Patterson, teamed up with previous laboratory member Sriram Sankararaman, assistant professor of computer science at the University of California, Los Angeles for the project.

They found evidence that both Denisovan and Neanderthal ancestry has been lost from the X chromosome as well as genes expressed in the male testes.

The team theorises that this has contributed to reduced fertility in males, which is commonly observed in other hybrids between two highly divergent groups of the same species.

The researchers collected their data by comparing known Neanderthal and Denisovan gene sequences across more than 250 genomes from 120 non-African populations publicly available through the Simons Genome Diversity Project.

The analysis was carried out by a machine-learning algorithm that could differentiate between components of both kinds of ancestral DNA, which are more similar to one another than to modern humans.

The study’s limitation is that it relies on the current library of ancient genomes available.

“We can’t use this data to make claims about what the Denisovans or Neanderthals looked like, what they ate, or what kind of diseases they were susceptible to,” said Sankararaman, first author on the paper. “We are still very far from understanding that.”

The new map of archaic ancestry was published in the journal Current Biology. (IANS)

  • Shriya Katoch

    This is really interesting . The idea that South Asians may have a mix of Denisovan with them is fascinating .

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Novel Synthetic DNA Vaccines Safe To Use Against Ebola: Scientists

While there are no licensed treatments available for Ebola virus disease yet, multiple experimental therapies are being developed.

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Ebola, UNICEF. congo, DNA
A Congolese health worker administers Ebola vaccine to a woman who had contact with an Ebola sufferer in the village of Mangina in North Kivu province of the Democratic Republic of Congo

Scientists, including one of Indian-origin, have found that the novel synthetic DNA vaccine is safe against Ebola virus and offers a long-term alternative to traditional vaccines.

The team, from The Wistar Institute in Philadelphia, US, optimised a shorter, dose-sparing, immunisation regimen and simplified vaccine that can be directly administered into the skin. They targeted a virus surface protein called glycoprotein.

This new approach induced rapid and protective immunity from virus challenges.

Importantly, the approach showed strong immune responses one year after the last dose, supporting the long-term immunogenicity of the vaccine — a particularly challenging area for Ebola vaccines.

Ebola, UNICEF. congo, DNA
A boy runs past a dispenser containing water mixed with disinfectant, east of Mbandaka, DRC. VOA

“Synthetic non-viral based DNA technology allows for rapid vaccine development by delivery directly into the skin, resulting in consistent, potent and rapid immunity compared to traditional vaccine approaches,” said lead researcher David B. Weiner, Director of Wistar’s Vaccine and Immunotherapy Center.

“An anti-Ebola virus DNA vaccine like this may provide an important new tool for protection, and we are excited to see what future studies will unveil,” he added.

In the study, published in the Journal of Infectious Diseases, the team detected antibody levels were equal or higher to those reported for other vaccines currently being evaluated in the clinic.

“The success of intradermal delivery of a low-dose regimen is very encouraging,” said Ami Patel, Ph.D., associate staff scientist in the Weiner Lab. “The ultimate goal of our work is to create effective and safe vaccines that are optimised for field use in at-risk areas.”

Ebola, UNICEF. congo, DNA
Photo taken Sept 9, 2018, shows health workers walking with a boy suspected of having the Ebola virus at an Ebola treatment centre in Beni, Eastern Congo. VOA

Ebola virus disease is a serious and often fatal illness that can cause fever, headache, muscle pain, weakness, fatigue, diarrhoea, vomiting, stomach pain and haemorrhage (severe bleeding).

First discovered in humans in 1976 in the Democratic Republic of the Congo, the largest outbreak occurred in West Africa from 2014 to 2016, which claimed more than 11,000 lives, according to the World Health Organization.

Also Read: Ebola Increases The Number of Orphans in DRC: UNICEF

The death rate is about 50 per cent and the virus is spread by contact with contaminated body fluids, including blood and semen.

While there are no licensed treatments available for Ebola virus disease yet, multiple experimental therapies are being developed. (IANS)