New insights into the origins of mutations in cancer

Image result for New insights into the origins of mutations in cancer

Researchers at the European Bioinformatics Institute (EMBL-EBI), the University of Dundee and the Wellcome Sanger Institute have used human and worm data to explore the mutational causes of cancer. Their study, published today in Genome Research, also shows that results from controlled experiments on a model organism — the nematode worm C. elegans — are relevant to humans, helping researchers refine what they know about cancer.

Enigmatic DNA mutation and repair

Cancer is caused by DNA mutations which can be triggered by a range of factors, including UV radiation, certain chemicals and smoking, but also errors occurring naturally during cell division. A cell recognises most of these mutations and corrects them through multiple repair mechanisms. However, DNA repair is not perfect, so it can leave certain mutations unrepaired or repair them incorrectly leading to changes in DNA. Understanding the footprints of these mutational processes is an important first step in identifying the causes of cancer and potential avenues for new treatments.

“The DNA mutations we see in cancer cells were caused by a yin and yang of DNA damage and repair,” explains Moritz Gerstung, Research Group Leader at EMBL-EBI. “When we study a patient’s cancer genome, we’re looking at the final outcome of multiple mutational processes that often go on for decades before the disease manifests itself. The reconstruction of these processes and their contributions to cancer development is a bit like the forensic analysis of a plane crash site, trying to piece together what’s happened. Unfortunately, there’s no black box to help us.

Controlled experiments in model organisms can be used to mimic some of the processes thought to operate on cancer genomes and to establish their exact origins.”

What worms can tell us

Previous research has shown that one of the first DNA repair pathways associated with an increased risk of cancer is DNA mismatch repair (MMR). The current study uses C. elegans as a model system for studying MMR in more detail.

“Dr Bettina Meier in my team initiated this project by assessing the kinds of mutations that arise when C. elegans is defective for one specific DNA repair pathway,” says Professor Anton Gartner, Principal Investigator in the Centre for Gene Regulation and Expression at Dundee. “As it only takes three days to propagate these worms from one generation to the next, the process of studying how DNA is passed on is greatly expedited. DNA mismatch repair is propagated for many generations and this allowed us to deduce a distinct mutational pattern. The big question was if the same type of mutagenesis also occurred in human cancer cells.”

To address this question, EMBL-EBI PhD student Nadia Volkova compared the C. elegans results with genetic data from 500 human cancer genomes.

“We found a resemblance between the most common signature associated with mutations in MMR genes in humans and the patterns found in nematode worms,” explains Volkova. “This suggests that the same mutational process operates in nematodes and humans. Our approach allows us to find the exact profile of MMR deficiency and to understand more about what happens when DNA repair goes wrong.”

These findings could lead to a better understanding of the causes of cancer and potentially help to identify the most appropriate treatment.

[“Source-sciencedaily”]

HC seeks Centre, CBI response on reinvestigation of SSC exam leaks

A plea field by several job aspirants alleged that the officials of the SSC, private vendors and others were a part of the syndicate selling seats for Rs 10-20 lakh per candidate.

The Delhi High Court on Thursday asked the Centre and CBI to file their response on a plea by several job aspirants seeking reinvestigation into the cases of Staff Selection Commission (SSC) paper leaks.

Justice S P Garg listed the matter for July 26 on the plea filed by 44 people.

The job aspirants also sought setting up of an enquiry commission headed by a retired judge of the Supreme Court or the High Court in connection with the repeated offences such as cheating in the SSC exam.

The petition said that multiple FIRs are lodged every year over leaks of question papers and several persons are arrested for allegedly aiding the aspirants to cheat for money, but in none of the cases, the probe agencies have been able to bust the racket and arrest the main persons involved in the organised crime.

Advocate Anurag Ahluwali accepted the notice for the Central government and the SSC, while advocate Narender Mann did so on behalf of the CBI.

The plea claimed that the syndicate was still operating as officials from the department of SSC have never been arrested. It alleged that the probe agencies have failed to identify the source of the leaks and the main perpetrators of the crime were still untouched.

“The modus operandi of the syndicate is supported by ultra-modern technologies and the commission of the crime gets detected at very few places as the local police agencies are not well equipped technologically,” it said.

The plea alleged that the officials of the SSC, private vendors and others were a part of the syndicate selling seats for Rs 10-20 lakh per candidate.

The plea said that the exams are conducted for sensitive posts such as inspector, sub-inspector, constables of para-military organisations, National Investigating Agency, Central Bureau of Investigation, Intelligence Bureau, Income Tax, Central Excise, Delhi Police and various coveted post across the government ministries.

“These posts are so sensitive in nature that selection of a tainted candidate can jeopardise the national security of the country,” it said, adding that the future of many deserving candidates has been ruined because of the inaction of authorities to stop the offences since 2013.

The Supreme Court had in March this year dismissed a PIL seeking a CBI probe into the SSC paper leak case after the Centre informed it that the probe agency has already started investigating it.

Amid protests over alleged paper leak, the SSC had recently recommended a CBI probe into it.

 

[“source=hindustantimes”]

With the launch of TESS, NASA will boost its search for exoplanets

illustration of TESS telescpope

NASA is stepping up its search for planets outside our solar system. Its next exoplanet hunting telescope, the Transiting Exoplanet Survey Satellite (TESS), is due to launch from Cape Canaveral on the evening of April 16.

Following the Kepler space telescope’s discovery of more than 5,000 possible exoplanets since 2009, TESS will continue the galactic census — flagging more planetary candidates for further study.

Astronomers expect TESS to find about 20,000 planets in its first two years in operation, focusing on nearby, bright stars that will be easy for other telescopes to investigate later. About 500 of those expected exoplanets would be less than twice the size of Earth — and therefore may be good places to look for life.

NASA’s next exoplanet hunting telescope, TESS

SMALL BUT MIGHTY NASA’s next exoplanet hunting telescope, TESS, is only 1.5 meters tall (shown here with engineers). Its size is partly due to the fact that it was designed to launch on NASA’s small Taurus rocket, but will instead launch on a larger SpaceX Falcon 9 on April 16.

ORBITAL ATK

The TESS mission is “a whole new opening for exoplanet studies,” MIT astronomer Sara Seager, TESS’ deputy science director, said during a news conference describing the upcoming launch.

TESS will be the first NASA science mission launched on the SpaceX Falcon 9 rocket. Once in orbit, the spacecraft will trace an unusual, elliptical path between Earth and the moon that will enable it to observe at least 85 percent of the sky — 350 times as much sky as Kepler saw.

Most of the planets found by Kepler orbit stars 1,000 light-years away or farther. TESS will focus on 200,000 stars that are a few hundred light-years away at most, and shine between 30 to 100 times brighter on average than Kepler’s.

The brighter the star, the easier it is to determine its planet’s characteristics, such as its mass and whether it has an atmosphere, Seager says. “Photons are our currency — the more, the better,” she says.

That follow-up will help TESS avoid some of Kepler’s pitfalls. Because Kepler’s stars were so far and so dim, some of its planet candidates were confirmed as actual planets only by statistics rather than by other telescopes. And not all those confirmations may stick. A recent paper posted at arXiv.org showed that Kepler 452b, an Earth-sized planet that orbits a sunlike star at the same distance Earth orbits the sun, may be a mirage (SN: 8/22/15, p. 16). Many of TESS’ planets won’t face the same uncertainty.

the TESS sattelite

COASTING IN SPACE The TESS satellite’s unusual 13.7-day orbit uses the moon’s gravity to stabilize it, so it needs little fuel. During the part of the orbit colored blue, TESS will observe the sky. During the part marked in orange, it will transmit data back to Earth. The gray ring marks the moon’s orbit.

NASA

But the way TESS will search for exoplanets is the same as Kepler: The satellite will watch stars for signs of dimming, which can indicate that a planet is transiting, or crossing in front of, the star. Measuring how much starlight is blocked can tell astronomers the size of the planet.

Once TESS finds a planet, astronomers will need more information to understand its qualities, such as whether it’s rocky or gassy (SN Online: 6/19/17). For that, other telescopes will follow up. Ground-based telescopes will measure the gravitational tug of a planet on its host star to learn the planet’s density, which is a clue to its composition. Astronomers plan to measure masses for at least 50 TESS planets that are smaller than Neptune in the hopes that many of them will have rocky, and therefore potentially habitable, surfaces.

Undiscovered country

Before TESS, most known planets were more than 1,000 light-years away, with a few closer than 30 light-years (a parsec is 3.26 light-years). TESS (orange circles) will fill in the gap. The size of the circles represents how easy the planets are to find.

graph showing where TESS will be able to detect planets
ZACH BERTA-THOMPSON

NASA’s James Webb Space Telescope, now scheduled to launch in 2020, will then check some of those planets for signs of life (SN: 4/30/16, p. 32).

“This is one of the major questions that TESS is intended to answer: Where will we be pointing Webb?” said the mission’s principal investigator, MIT astronomer George Ricker, at the press conference. Webb will peer at the starlight filtering through planetary atmospheres to try to detect molecules that could be produced by something living on the surface.

It will take a few months for TESS to swing into its regular orbit before it begins collecting data. At that point, it will be able to use the moon’s gravity to stabilize itself for decades in orbit without using extra fuel. The mission is set to last two years, but could continue taking data almost indefinitely.

“TESS is not going to be limited by any expendable or other aspects,” Ricker said. “It will be basically limited by how long NASA has the patience to fund the mission.”

[“Source-sciencenews”]

PM Narendra Modi congratulates ISRO for launch of navigation satellite IRNSS-1I

Image result for PM Narendra Modi congratulates ISRO for launch of navigation satellite IRNSS-1I

NEW DELHI: Prime Minister Narendra Moditoday congratulated ISRO scientists for the successful launch of navigation satellite IRNSS-1I and said it will benefit the common man of the country.

ISRO’s navigation satellite INRSS-1I was today launched by PSLV-C41 from the spaceport at Sriharikota in Andhra Pradesh and was successfully placed in the designated orbit.

“Congratulations to our scientists on the successful launch of navigation satellite IRNSS-1I by PSLV. This success will bring benefits of our space programme to the common man. Proud of team @isro!” the prime minister tweeted.

The PSLV-C41/IRNSS-1I Mission blasted off at 4.04 am from the first launchpad at the Sathish Dhawan Space Centre. It was a normal lift-off, ISRO officials said.

Indian Space Research Organisation (ISRO)Chairman K Sivan described the mission as a success and congratulated the scientists.

He said IRNSS-1I was successfully placed in the designated orbit.

IRNSS-1I is expected to replace IRNSS-1A, the first of the seven navigation satellites, which was rendered ineffective after its three rubidium atomic clocks failed. The seven satellites are part of the NavIC navigation satellite constellation.

The launch is ISRO’s second attempt at sending a replacement satellite.

[“Source-economictimes”]