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Why is Neanderthal Genetic material Found in only Small amount in Genomes of Modern Humans?

The scientists estimated that these gene variations were able to persist in Neanderthals because Neanderthals had a much smaller population size than humans

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FILE - A model of an adult Neanderthal male head and shoulders by artist John Gurche on display in the Hall of Human Origins in the Smithsonian Museum of Natural History in Washington, D.C. VOA

New York, November 9, 2016: Neanderthal genetic material is found in only small amount in the genomes of modern humans because, after inter-breeding, natural selection removed large numbers of weakly deleterious Neanderthal gene variants, says a study.

Humans and Neanderthals inter-bred tens of thousands of years ago, but today, Neanderthal DNA makes up only one to four per cent of the genomes of modern non-African people.

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Scientists found that natural selection removed many Neanderthal alleles from the genome that might have had mildly negative effects. Click To Tweet

“For a while now we have known that humans and Neanderthals hybridised. Many Europeans and Asians – along with other non-African populations – are the descendants of those hybrids,” said Ivan Juric from the University of California, Davis in the US.

“Previous work has also shown that, following hybridisation, many Neanderthal gene variants were lost from the modern human population due to selection. We wanted to better understand the causes of this loss,” Juric noted.

To understand how modern humans lost their Neanderthal genetic material and how humans and Neanderthals remained distinct, the researchers developed a novel method for estimating the average strength of natural selection against Neanderthal genetic material.

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They found that natural selection removed many Neanderthal alleles from the genome that might have had mildly negative effects.

The scientists estimated that these gene variations were able to persist in Neanderthals because Neanderthals had a much smaller population size than humans.

Once transferred into the human genome, however, these alleles became subject to natural selection, which was more effective in the larger human populations and has removed these gene variants over time.

“Our results are compatible with a scenario where the Neanderthal genome accumulated many weakly deleterious variants, because selection was not effective in the small Neanderthal populations. Those variants entered the human population after hybridisation,” Juric said.

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“Once in the larger human population, those deleterious variants were slowly purged by natural selection,” Juric noted.

These findings, published in the journal PLOS Genetics, shed new light on the role of population size on losing or maintaining Neanderthal ancestry in humans. (IANS)

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Just in! Like Computer Software, Scientists can now Programme Cells in your Body to Fight Diseases!

Scientists found that RNA which is produced abundantly by humans, plants and animals can be genetically engineered to allow scientists to programme cells with specific commands

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Programme cells
Scientists have found that cells can be programmed with pre-defined RNA commands, in the manner of a computer's microprocessor VOA

London, September 19, 2017 : A new technique can help programme cells like a computer to fight cancer, influenza, and other serious conditions, suggests new research.

A common molecule — ribonucleic acid (RNA), which is produced abundantly by humans, plants and animals — can be genetically engineered to allow scientists to programme cells, said the study published in the journal Nucleic Acids Research.

RNAs carry information between protein and DNA in cells, and the research proved that these molecules can be produced and organised into tailor-made sequences of commands — similar to codes for computer software — which feed specific instructions into cells, programming them to do what we want.

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Cells have the capacity to process and respond to instructions and codes inputted into their main system, said lead researcher Alfonso Jaramillo, Professor at University of Warwick in Britain.

Similar to software running on a computer, or apps on a mobile device, many different RNA sequences could be created to empower cells with a ‘Virtual Machine’, able to interpret a universal RNA language, and to perform specific actions to address different diseases or problems, the study said.

This will allow a novel type of personalised and efficient healthcare, allowing us to ‘download’ a sequence of actions into cells, instructing them to execute complex decisions encoded in the RNA.

The researchers made their invention by first modelling all possible RNA sequence interactions on a computer, and then constructing the DNA encoding the optimal RNA designs, to be validated on bacteria cells in the laboratory.

After inducing the bacterial cells to produce the genetically engineered RNA sequences, the researchers observed that they had altered the gene expression of the cells according to the RNA programme — demonstrating that cells can be programmed with pre-defined RNA commands, in the manner of a computer’s microprocessor.

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“The capabilities of RNA molecules to interact in a predictable manner, and with alternative conformations, has allowed us to engineer networks of molecular switches that could be made to process arbitrary orders encoded in RNA,” Jaramillo said.

As well as fighting disease and injury in humans, scientists could harness this technique to control plant cells and reverse environmental and agricultural issues, making plants more resilient to disease and pests.

“Throughout last year, my group has been developing methodologies to enable RNA sensing the environment, perform arithmetic computations and control gene expression without relying on proteins, which makes the system universal across all living kingdoms,” Jaramillo said.

“The cells could read the RNA ‘software’ to perform the encoded tasks, which could make the cells detect abnormal states, infections, or trigger developmental programmes,” he added.  (IANS)

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‘It is Definitely a Woman’ ; DNA tests Reveal First Strong Evidence of a Female Viking Warrior

The researchers say it's the first confirmed remains of a high-ranking female Viking warrior

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Programme cells
Scientists have found that cells can be programmed with pre-defined RNA commands, in the manner of a computer's microprocessor VOA

Berlin, September 12, 2017 : Scientists say DNA tests on a skeleton found in a lavish Viking warrior’s grave in Sweden show the remains are those of a woman in her 30s.

While bone experts had long suspected the remains belong to a woman, the idea had previously been dismissed despite other accounts supporting the existence of female Viking warriors.

Swedish researchers used new methods to analyze genetic material from the 1,000-year-old bones at a Viking-era site known as Birka, near Stockholm.

Charlotte Hedenstierna-Jonson of Uppsala University said Monday the tests show “it is definitely a woman.”

Hedenstierna-Jonson said the grave is particularly well-furnished, with a sword, shields, various other weapons and horses.

Writing in the American Journal of Physical Anthropology, the researchers say it’s the first confirmed remains of a high-ranking female Viking warrior.

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Checkpoint Protein (CHK2) Inhibitor Drug to Protect Women’s Infertility Post Cancer Treatments

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Sep 02, 2017: An existing drug may one day protect premenopausal women from infertility that commonly follows cancer treatments, new research has found.

Women who are treated for cancer with radiation or certain chemotherapy drugs are commonly rendered sterile.

Women are born with a lifetime reserve of oocytes, or immature eggs, but those oocytes are among the most sensitive cells in the body and may be wiped out by such cancer treatments.

The new findings, published in the journal Genetics, raises hope of curbing infertility from cancer treatment.

The study builds on his 2014 research that identified a so-called checkpoint protein (CHK2) that becomes activated when oocytes are damaged by radiation.

Checkpoint protein functions in a pathway that eliminates oocytes with DNA damage, a natural function to protect against giving birth to offspring bearing new mutations.

When the researchers irradiated mice lacking the CHK2 gene, the oocytes survived, eventually repaired the DNA damage, and the mice gave birth to healthy pups.

Also Read: Treatment with Uterine Fibroids helps to restore Fertility in Women

The new study explored whether the checkpoint 2 pathway could be chemically inhibited.

“It turns out there were pre-existing CHK2 inhibitor drugs that were developed, ironically enough, for cancer treatment, but they turned out not to be very useful for treating cancer,” said study senior author John Schimenti, Professor at Cornell University in New York.

“By giving mice the inhibitor drug, a small molecule, it essentially mimicked the knockout of the checkpoint gene,” first author Vera Rinaldi, a graduate student in Schimenti’s lab, said.

By inhibiting the checkpoint pathway, the oocytes were not killed by radiation and remained fertile, enabling birth of normal pups, the study said.

“While humans and mice have different physiologies, and there is much work to be done to determine safe and effective dosages for people, it is clear that we have the proof of principle for this approach,” Schimenti said. (IANS)