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Posts Tagged ‘discovery

Genetically engineered mosquitoes pass lethal gene to offspring

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  • Scientists carry out ‘positive’ trial on Cayman Islands
  • New breed of insect could be used to tackle malaria and dengue fever
  • But critics say it could lead to public health problems

Breakthrough or danger? A UK-based research team has found a way of genetically modifying the Aedes aegypti mosquito so they pass on a deadly gene to their offspring

Breakthrough or danger? A UK-based research team has found a way of genetically modifying the Aedes aegypti mosquito so they pass on a deadly gene to their offspring

Serious concerns have been raised over the release of a new breed of disease-fighting mosquito which has been genetically engineered to kill their own offspring.

There are hopes the project could be used to control agricultural pests and tackle deadly insect-borne illnesses such as dengue fever and malaria.

But the research has raised concerns about the possible side-effects on public health and the environment because, once released, the mosquitos cannot be recalled.

A UK-based scientific team revealed there had been positive signs from the first release into the environment of the mosquitoes, which are engineered to pass a lethal gene onto their offspring, killing them before adulthood.

The study team – which includes experts from Imperial College London and the Liverpool School of Tropical Medicine – released batches of modified mosquitoes in an area of the Cayman Islands where the dengue virus-carrying Aedes aegypti mosquito is common.

The study, published in Nature Biotechnology journal, looked at how successfully the lab-reared, genetically modified insects could mate.

About 19,000 mosquitoes engineered in a lab were released over four weeks in 2009 in a 25-acre area on Grand Cayman island.

Based on data from traps, the genetically engineered males accounted for 16per cent of the overall male population in the test zone, and the lethal gene was found in almost 10 percent of larvae.

Those figures suggest the genetically engineered males were about half as successful in mating as wild ones, a rate sufficient to suppress the population.

Disease fighter? The new breed of mosquitoes could be used to tackle killer illnesses like dengue fever and malaria which affect the world's poorest populations

Disease fighter?  The new breed of mosquitoes could be used to tackle killer illnesses like dengue fever and malaria which affect the world’s poorest populations

Luke Alphey, chief scientific officer at Oxitec, the firm which devised the technique, told the BBC: ‘We were really surprised how well they did.

‘For this method, you just need to get a reasonable proportion of the females to mate with GM males – you’ll never get the males as competitive as the wild ones, but they don’t have to be, they just have to be reasonably good.’

HOW MOSQUITOES KILL THEIR OWN CHILDREN

  • The genetic approach used to create the mosquitoes is a system known as tetracycline-controlled transcriptional activation (tTA).
  • The technique is an extension of one successfully used for decades to control or eradicate pests which involves sterilising millions of insects with radiation.
  • But the process has not worked with mosquitoes, partly because the radiation also injures them, making it difficult for them to compete with healthy counterparts for mates.
  • So Oxitec has now created the Aedes aegypti mosquitoes with a gene that will kill them unless they are given the common antibiotic tetracycline.
  • With tetracycline provided in the lab, the mosquitoes can be bred for generations and multiplied.
  • Males are then released into the wild, where tetracycline is not available.
  • They live long enough to mate but their progeny will die before adulthood.

 

Authorities in the Florida Keys hope to carry out an open-air test on the modified insects as early as December after experiencing the region’s first cases of dengue fever in decades.

Dr Alphey said the technique was safe because only males were released as it was only the females that bite people and spread the disease.

But critics say the process is by no means foolproof.

Alfred Handler, a geneticist at the Agriculture Department in Gainesville, Florida, said the mosquitoes can evolve resistance to the lethal gene while being bred for generations in a lab.

Todd Shelly, an entomologist for the Agriculture Department in Hawaii, also said in a commentary published on Sunday by Nature Biotechnology that 3.5per cent of the insects in a lab test survived to adulthood despite presumably carrying the lethal gene.

Also, the sorting of male and female mosquitoes, which is done by hand, can result in up to 0.5per cent of the released insects being female, the commentary said.

If millions of mosquitoes were released, even that small percentage of females could lead to a temporary increase in disease spread, it was reported by the New York Times.

Oxitec and a molecular biologist, Anthony A. James of the University of California, Irvine, say they have developed a solution — a genetic modification that makes female mosquitoes, but not males, unable to fly.

The grounded females cannot mate or bite people, and separating males from females before release would be easier.

The World Health Organisation expects to release guidance on how GM insects should be deployed in developing countries by the end of the year.

 

Via DailyMail

12 new species of frogs discovered in India

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Scientists have found 12 new species of night frogs living in the lush mountains of southwest India, and rediscovered three that had been thought extinct.

Evolution biologist Sathyabhama Das Biju from the University of Delhi says he hopes the discoveries draw attention to amphibians as important indicators of environmental health.

He said Saturday that there are now 336 known frog species in India, and that many are threatened by habitat loss.

Night frogs are hard to find as they come out only after dark and during the monsoon season. Biju and student researchers had to sit in dark tropical forests listening for frog sounds and shining flashlights under rocks and across riverbeds.

The research is published in the latest issue of international taxonomy journal Zootaxa.

 

Via DiscoveryOn

Written by Nokgiir

September 26, 2011 at 2:19 am

The mystery creature that nobody can identify

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If this cute little chap looks a wee bit confused, it’s no wonder.

His big wide eyes stare out at the world around him – which in turn is staring back at him.

Because nobody has seen a creature quite like this one before.

Who am I? The unidentifed animal sitting in his cage after being handed in to Wenling Zoo, in China

Who am I? The unidentifed animal sitting in his cage after being handed in to Wenling Zoo, in China.

With a nose that looks more like a rodent’s but long, pointy paws and white fur dappled with brown and orange, he is quite unique.

And zookeepers at Wenling, in eastern China, who were handed the animal by an anonymous man, have been unable to work out exactly what species he belongs to.

They think they are looking at some strange type of monkey – but other students of nature might recognise the characteristics of a bush baby.

As he sits in his cage, the creature therefore awaits an uncertain fate.

And the zookeepers sit and monitor his development and hopes he grows up into something slightly more recognisable.

Where did I come from? The rodent-like creature was handed in anonymously

Where did I come from? The rodent-like creature was handed in anonymously.

Via DailyMail

Written by Nokgiir

September 26, 2011 at 1:47 am

Gene that lights up under green light could help find cure for HIV

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Glowing kittens with resistance to disease have been created by scientists searching for a cure for Aids.

The domestic cats had their DNA modified with a gene that fights off an HIV-like virus and a second one – from a fluorescent jellyfish – that makes their bodies shine green under ultraviolet light.

The purpose of the study was to show how a natural protein that prevents macaque monkeys developing Aids can do the same in cats.

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Way to glow: The eerie looking feline that has been genetically modified with DNA from a fluorescent jellyfish protein

Way to glow: The eerie looking feline that has been genetically modified with DNA from a fluorescent jellyfish protein

Hard to hide: The kitten's fur, claws and whiskers emit an eerie green glow

Hard to hide: The kitten’s fur, claws and whiskers emit an eerie green glow

The two genes are linked and the jellyfish gene is used to track the other one for the protein.

Shining a UV light on the cats produced an eerie green glow, confirming that the protein was being made in their tissues and that the technique had worked.

The genetically modified cats’ creators say the research will speed up the search for vaccines and treatments against HIV, the Aids virus that has claimed more than 30million lives around the world.

With HIV-like viruses also wreaking havoc among felines, from domestic moggies to big cats, the research could improve animal health.

In future, people could buy pets that are resistant to numerous diseases, removing the need for frequent and expensive trips to the vet for vaccination.

Novelty glow-in-the-dark breeds are also a possibility.

Test subject: Under normal lighting the cat's ability to glow remains a secret

Test subject: Under normal lighting the cat’s ability to glow remains a secret

But critics say the technique takes a high toll on animal welfare and that scientists should be reducing the number of animals they experiment on.

The researchers, from the respected Mayo Clinic in the U.S., used harmless viruses to transfer genes into eggs removed from pet cats during routine spaying.

One gene makes a fluorescent protein, the other produces a protein that fights off feline immunodeficiency virus, or FIV, the cat version of HIV. The eggs were then fertilised through IVF and implanted in surrogate mothers.

Sharp thinking: The cat's paws glow too. Scientists say that cats are the best subjects for this kind of research

Sharp thinking: The cat’s paws glow too. Scientists say that cats are the best subjects for this kind of research

Twenty-two attempts led to the birth of five kittens – three of which survived, the journal Nature Methods reports.

Two were healthy but one suffered medical problems, although the researchers do not believe they were linked to the genetic manipulation.

The anti-viral gene was also present and cells taken from the kittens were able to resist infection with FIV better than those from normal cats.

Two of the cats went on to have kittens of their own, all of which carried the new genes.

Via DailyMail

Written by Nokgiir

September 19, 2011 at 3:12 am

Immune System Trained to Kill Cancer

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A year ago, when chemotherapy stopped working against his leukemia, William Ludwig signed up to be the first patient treated in a bold experiment at the University of Pennsylvania. Mr. Ludwig, then 65, a retired corrections officer from Bridgeton, N.J., felt his life draining away and thought he had nothing to lose.

Doctors removed a billion of his T-cells — a type of white blood cell that fights viruses andtumors — and gave them new genes that would program the cells to attack his cancer. Then the altered cells were dripped back into Mr. Ludwig’s veins.

At first, nothing happened. But after 10 days, hell broke loose in his hospital room. He began shaking with chills. His temperature shot up. Hisblood pressure shot down. He became so ill that doctors moved him into intensive care and warned that he might die. His family gathered at the hospital, fearing the worst.

A few weeks later, the fevers were gone. And so was the leukemia.

There was no trace of it anywhere — no leukemic cells in his blood or bone marrow, no more bulging lymph nodes on his CT scan. His doctors calculated that the treatment had killed off two pounds of cancer cells.

A year later, Mr. Ludwig is still in complete remission. Before, there were days when he could barely get out of bed; now, he plays golf and does yard work.

“I have my life back,” he said.

Mr. Ludwig’s doctors have not claimed that he is cured — it is too soon to tell — nor have they declared victory over leukemia on the basis of this experiment, which involved only three patients. The research, they say, has far to go; the treatment is still experimental, not available outside of studies.

But scientists say the treatment that helped Mr. Ludwig, described recently in The New England Journal of Medicine and Science Translational Medicine, may signify a turning point in the long struggle to develop effective gene therapies against cancer. And not just for leukemia patients: other cancers may also be vulnerable to this novel approach — which employs a disabled form of H.I.V.-1, the virus that causes AIDS, to carry cancer-fighting genes into the patients’ T-cells. In essence, the team is using gene therapy to accomplish something that researchers have hoped to do for decades: train a person’s own immune system to kill cancer cells.

Two other patients have undergone the experimental treatment. One had a partial remission: his disease lessened but did not go away completely. Another had a complete remission. All three had had advanced chronic lymphocytic leukemia and had run out of chemotherapy options. Usually, the only hope for a remission in such cases is a bone-marrow transplant, but these patients were not candidates for it.

Dr. Carl June, who led the research and directs translational medicine in the Abramson Cancer Center at the University of Pennsylvania, said that the results stunned even him and his colleagues, Dr. David L. Porter, Bruce Levine and Michael Kalos. They had hoped to see some benefit but had not dared dream of complete, prolonged remissions. Indeed, when Mr. Ludwig began running fevers, the doctors did not realize at first that it was a sign that his T-cells were engaged in a furious battle with his cancer.

Other experts in the field said the results were a major advance.

“It’s great work,” said Dr. Walter J. Urba of the Providence Cancer Center and Earle A. Chiles Research Institute in Portland, Ore. He called the patients’ recoveries remarkable, exciting and significant. “I feel very positive about this new technology. Conceptually, it’s very, very big.”

Dr. Urba said he thought the approach would ultimately be used against other types of cancer as well as leukemia and lymphoma. But he cautioned, “For patients today, we’re not there yet.” And he added the usual scientific caveat: To be considered valid, the results must be repeated in more patients, and by other research teams.

Dr. June called the techniques “a harvest of the information from the molecular biology revolution over the past two decades.”

Hitting a Genetic Jackpot

To make T-cells search out and destroy cancer, researchers must equip them to do several tasks: recognize the cancer, attack it, multiply, and live on inside the patient. A number of research groups have been trying to do this, but the T-cells they engineered could not accomplish all the tasks. As a result, the cells’ ability to fight tumors has generally been temporary.

The University of Pennsylvania team seems to have hit all the targets at once. Inside the patients, the T-cells modified by the researchers multiplied to 1,000 to 10,000 times the number infused, wiped out the cancer and then gradually diminished, leaving a population of “memory” cells that can quickly proliferate again if needed.

The researchers said they were not sure which parts of their strategy made it work — special cell-culturing techniques, the use of H.I.V.-1 to carry new genes into the T-cells, or the particular pieces of DNA that they selected to reprogram the T-cells.

The concept of doctoring T-cells genetically was first developed in the 1980s by Dr. Zelig Eshhar at the Weizmann Institute of Science in Rehovot, Israel. It involves adding gene sequences from different sources to enable the T-cells to produce what researchers call chimeric antigen receptors, or CARs — protein complexes that transform the cells into, in Dr. June’s words, “serial killers.”

 

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‘Super-Earth’ Found in Habitable Zone

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The Milky Way abounds with low-mass planets, including small, rocky ones such as Earth. That’s the main conclusion of a team of European astronomers, based on their latest haul of extrasolar planets. The new discoveries—55 new planets, including 19 “super-Earths”—were presented here today at the Extreme Solar Systems II conference by team leader Michel Mayor of the University of Geneva in Switzerland. “We find that 40% of all Sun-like stars are accompanied by at least one planet smaller than Saturn,” he says. The number of Earth-like planets is expected to be even higher.

The new planets were found with HARPS (High Accuracy Radial velocity Planet Searcher), an extremely sensitive instrument used to analyze starlight, mounted on the 3.6-meter telescope of the European Southern Observatory (ESO) at Cerro La Silla in northern Chile. HARPS detects the minute periodic wobbles of stars, caused by the gravity of orbiting planets. So far, HARPS has discovered 155 exoplanets, including two-thirds of all planets less massive than Neptune.

Of the 19 newly found super-Earths (exoplanets between a few and 10 times the mass of Earth), the most intriguing is HD 85512b, which weighs in at only 3.6 Earth masses. Its orbit lies in the habitable zone of its parent star, which means temperatures are just right for liquid water to exist on its surface, says Lisa Kaltenegger of the Max Planck Institute for Astronomy in Heidelberg, Germany. “We’re entering an incredibly exciting period in history.”

Meanwhile, scientists disagree about which technique offers the best chances of finding the first true “Earth analog”—an Earth-like planet orbiting in the habitable zone of its Sun-like star. (H85512b is too massive, and it’s star is too cool.) Mayor says HARPS might find this Holy Grail of exoplanet research within 5 years or so, after new upgrades to increase the instrument’s sensitivity. But planet hunter Geoffrey Marcy of the University of California, Berkeley, disagrees. NASA’s Kepler space telescope is “by far the best,” he says. “We will find them if they’re there, probably within the next 2 or 3 years.”

At the meeting, Kepler co-investigator Natalie Batalha of NASA’s Ames Research Center announced that the number of exoplanet candidates from the Kepler mission has increased by some 50% since last February, to 1781. Most are less than three times the size of the Earth. Kepler, launched in March 2009, finds planets by measuring the slight periodic dimming of their parent stars, when they happen to pass between the star and Earth.

No matter who finds the first Earth analog, the HARPS planets offer better prospects for detailed follow-up observations, Mayor says, because HARPS focuses on relatively nearby stars, while almost all Kepler stars are much farther away. For instance, ESO astronomer Markus Kissler-Patig predicts that the future 39.2-meter European Extremely Large Telescope (E-ELT) should be able to directly image HD 85512b. Analyzing the starlight it reflects will provide important information about the planet’s atmospheric composition. “The E-ELT will be able to probe for biomarkers,” Kissler-Patig says, referring to chemicals thought to indicate the presence of life.

While ESO is planning more-sensitive planet-hunting instruments for its existing Very Large Telescope and for the future E-ELT, Kepler is facing an uncertain future. “Kepler’s goal of finding true Earth analogs can only be reached by extending the mission duration” past its planned operational lifetime of 3.5 years, Batalha says. In February 2012, NASA will decide on a possible mission extension. Marcy is optimistic. Kepler is so incredibly successful, he says, that it seems unlikely NASA will terminate the mission next year. “I’m sure NASA is wiser than that.”

 

Via ScienceNow

Southern lights are sweeter in space

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NASA

The greenish glow of an auroral display sweeps around Earth’s south polar region in this photo, captured from a vantage point on the International Space Station. The shuttle Atlantis and its robotic arm, as well as one of the station’s solar arrays, loom up in the foreground.

The pilot for NASA’s last space shuttle flight, Doug Hurley, says one of the highlights of Atlantis’ trip to the International Space Station was seeing an “incredible” display of southern lights — and after seeing these pictures, I’d have to agree with him.

This photo from the space station shows the greenish auroral glow sweeping around the south pole, following the edge of the atmosphere. Atlantis is in the foreground with its robotic arm extended into the center of the frame, and one of the station’s gold-colored solar arrays juts in the right edge. You can even see the stars hanging in the night sky.

Another picture provides a more detailed view of the shimmering lights, with Atlantis’ inspection boom poking through the frame.

NASA

Thursday night’s southern lights shimmer in a picture taken from the International Space Station, with Atlantis’ inspection boom angling through the picture.

The southern lights, like the northern lights, are sparked when electrically charged particles from the sun interact with Earth’s magnetic field. For more amazing views of Atlantis’ auroras, check out NASA’s photo gallery for the shuttle mission, as well as Space.com’s report about the pictures.

 

– Alan Boyle.