Archive for the ‘science’ Category

Gereat Idea — Because there’s no way it could go wrong

April 22, 2011

BBC News – GM mosquitoes offer malaria hope

Research groups have already created “malaria-resistant mosquitoes” using techniques such as introducing genes to disrupt the malaria parasite’s development.

The research, however, has a great challenge – getting those genes to spread from the genetically-modified mosquitoes to the vast number of wild insects across the globe.

Unless the gene gives the mosquito an advantage, the gene will likely disappear.

Scientists at Imperial College London and the University of Washington, in Seattle, believe they have found a solution.

They inserted a gene into the mosquito DNA which is very good at looking after its own interests – a homing endonuclease called I-SceI.

The gene makes an enzyme which cuts the DNA in two. The cell’s repair machinery then uses the gene as a template when repairing the cut.

As a result the homing endonuclease gene is copied.

It does this in such a way that all the sperm produced by a male mosquito carry the gene.

The idea is really fairly elegant. And getting mosquitos that disrupted the transmission of malaria would be a pretty wonderful idea (even if the cost of the research would probably buy a year’s worth of bed tents for the entire continent).

And yet a tool that guarantees an inserted gene — any inserted gene — will spread fairly rapidly throughout an entire reproductively connected insect population makes me feel just the tiniest bit nervous. Like the biological equivalent of grey goo.


When even the good news is horrific

July 21, 2010

BBC News – Scientists say vaginal gel cuts HIV-infections by half

They said the gel, containing Aids drug tenofovir, cut infection rates among 889 women by 50% after one year of use, and by 39% after two and a half years.

If you look at the numbers they report, only 8% of women in the treatment group became infected with HIV over the course of 2.5 versus 13% in the placebo group. Which is great. And means that over the course of, say, 12.5 years at the same rate of sexual activity, if the efficacy remains constant, only about a third of the women in the treatment group will become infected, versus a little more than half of untreated women. Only about a third. (And over 25 years, the numbers would be “only” 60% versus 75% in the control group.)

This is what success looks like, and it’s very sad.

The way medical research should be reported

April 14, 2010

Technology Review: RNA-Loaded Nanoparticles Fight Cancer

The researchers developed a nanoparticle carrying a molecular marker that binds to the surface of cancer cells, triggering the cells to absorb it. The siRNA carried within the particle was designed to silence a gene called ribonucleotide reductase M2 (RRM2), which regulates DNA synthesis and repair and is known to be an anticancer target. Because it was the first trial using targeted RNAi delivery for cancer, says Mark Davis, a professor of chemical engineering at Caltech and the study’s lead author, “we wanted to choose a gene that was suspected to be hugely upregulated in a broad spectrum of cancers” in order to increase the likelihood of being able to observe the novel therapy’s effect.

The researchers analyzed biopsy samples from three melanoma patients in the trial who had received different doses of the therapy. They tracked the particles in the different samples, finding that the amounts they could see in the tumor cells correlated with the doses the patients received. “That’s the first time anyone has seen that for any kind of particle delivery system, whether it’s a liposome, a nanoparticle, or anything,” says Davis. They also pulled out samples of mRNA cleaved exactly where the siRNA’s were designed to cut, showing that the RNAi did its job the way it was expected to. The study does not discuss the clinical effects of the treatment on the melanoma patients in the trial; that data, says Davis, will be presented at the meeting of the American Society of Clinical Oncology in early June.

As I was reading this, I kept thinking: yep, that’s all very nice, but does it actually shrink the tumors or help the patients live longer? And lo and behold, the next paragraph would bring up just that question.

OK, everybody in San Francisco drop your laptops.

March 17, 2010

Is a lot of lousy data better than no data at all?

The “Quake Catcher” software is designed to record all vibrations on a computer, but only uploads the info if many computers in the same geographic area record “dramatic shaking.”

Now here’s the thing: serious earthquakes: typically associated with power outages and telecommunications failures. So you’re relying on the notion that in the few seconds before the earthquake brings down your local internet connection, your computer will be able to transmit useful data. Because otherwise no one is going to know there was an earthquake. Uh.

Would this thing be of any use outside the immediate disaster zone? Maybe. A computer accelerometer can do about 1/250 of a g, which corresponds to the bottom of the “weak shaking” category in earthquake effects. If you look at the USGS shakemap for Haiti, for example, all of the island of Hispaniola and parts of nearby islands in the caribbean registered enough shaking to trigger any hypothetical laptop detectors. That could give you a good idea of location and magnitude a few minutes or even an hour before official observatories.

And of course for seismologists reconstructing the disaster in later months or years, the data could lead to any number of publications.

The lunar reconnaissance orbiter is so cool

July 18, 2009

NASA – LRO Sees Apollo Landing Sites

The satellite reached lunar orbit June 23 and captured the Apollo sites between July 11 and 15. Though it had been expected that LRO would be able to resolve the remnants of the Apollo mission, these first images came before the spacecraft reached its final mapping orbit. Future LROC images from these sites will have two to three times greater resolution.

So that means 1-2 foot resolution over much of the surface of the moon. Wow.

Bionics and egalitarianism

March 6, 2009

It sounds like this pretty much works

Bionic eye gives blind man sight

Ron, who has not revealed his surname, told the BBC: “For 30 years I’ve seen absolutely nothing at all, it’s all been black, but now light is coming through. Suddenly to be able to see light again is truly wonderful.

“I can actually sort out white socks, grey socks and black socks.”

“My one ambition at the moment is to be able to go out on a nice, clear evening and be able to pick up the moon.”

Ron’s wife Tracy is also hugely encouraged by the progress he has made.

How the bionic eye works.
She said: “He can do a lot more now than he could before, doing the washing, being able to tell white from a coloured item.

Which is more than an enormous percentage of laundry-doing men in the world seem able to do…

More seriously, it seems that since the nerves are still intact in this guy’s case of retinitis pigmentosa, the implant just replaces the function of the rods and cones.

What’s interesting is the idea that the patients seem to be learning how to “See” again, even though the signals from the implant aren’t very much like the normal signals retinal nerves would get. Which is a crucial point for bionic devices: you don’t have to reproduce the old set of signals exactly, you just have to produce something that the brain can learn to work with.

I don’t speak with an accent, you do

February 22, 2009

speech accent archive: about

The speech accent archive is established to uniformly exhibit a large set of speech accents from a variety of language backgrounds. Native and non-native speakers of English all read the same English paragraph and are carefully recorded.1 The archive is constructed as a teaching tool and as a research tool. It is meant to be used by linguists as well as other people who simply wish to listen to and compare the accents of different English speakers.

penicillin redux?

February 19, 2009

Science News / Sponge’s Secret Weapon Restores Antibiotics’ Power

Researchers led by Moeller, of Hollings Marine Laboratory in Charleston, found a sponge thriving in the midst of dead organisms. This anomalous life amidst death raised an obvious question, says Moeller: “How is this thing surviving when everything else is dead?”

Chemical analyses of the sponge’s chemical defense factory pointed to a compound called algeferin. Biofilms, communities of bacteria notoriously resistant to antibiotics, dissolved when treated with fragments of the algeferin molecule. And new biofilms did not form.

So far, the algeferin offshoot has, in the lab, successfully treated bacteria that cause whooping cough, ear infections, septicemia and food poisoning. The compound also works on Pseudomonas aeruginosa, which causes horrible infections in wounded soldiers, and MSRA infections, which wreak havoc in hospitals. “We have yet to find one that doesn’t work,” says Moeller.

And the results may not just apply to bacteria in communities. The compound is able to reprogram antibiotic-resistant bacteria that don’t form biofilms. When bacteria are treated with the compound, antibiotics that usually have no effect are once again lethal. This substance may be the first one that can restore bacterial resistance, Moeller says. “This resensitization is brand new.”

Of course, as soon as we start using this stuff in tanker-load quantities, we’re bound to turn up the one organism in the world that has a defesne against it, and then, under selection pressure, every other virulent organism will acquire the requisite coding sequence. We should be glad antibiotics still work at all…

This climate goes to 12

February 17, 2009


BBC NEWS | Science & Environment | Global warming ‘underestimated’

“We are basically looking now at a future climate that is beyond anything that we’ve considered seriously in climate policy,” he said.

Prof Field said the 2007 report, which predicted temperature rises between 1.1C and 6.4C over the next century, seriously underestimated the scale of the problem.

He said the increases in carbon dioxide have been caused, principally, by the burning of coal for electric power in India and China.


Prof Field said the impact on temperatures is as yet unknown, but warming is likely to accelerate at a much faster pace and cause more environmental damage than had been predicted.

As malthus once said, self-limiting. Unless we do something really stupid like destabilizing sedimentary methane.

More martian geology

February 9, 2009

Planetary Science Institute

— Lobate flows – Lobe-shaped flow features that have pitted surfaces and raised ridges on their lateral margins are observed on the walls of some craters. These lobes resemble rock glaciers on Earth.

— Channels – Narrow channels often breach crater walls and extend outside the craters, as well as across crater floors, These channels may have been formed by flowing water.

— Crater-wall valleys – Trough-like crater-wall valleys, wider than the above-mentioned channels, typically start at the top of the crater rim and terminate where the wall meets the floor. These valleys are sometimes filled with rough-textured deposits, which may be glacial.

— Gullies and alcoves – Gullies are typically composed of three parts: alcoves at the head of a channel, channels, and debris fans, and are thought to have been formed by flowing water.

— Arcuate ridges – These are small, arc-shaped ridges that enclose depressions at the base of crater walls, often below gullies. Berman interprets these to be glacial moraines, remnants of glacial deposits that have since evaporated.

— Debris aprons – These aprons are pitted and lineated deposits on crater floors. They are similar to debris-covered glaciers or ice-rich landslides seen on Earth.

All of these features suggest a landscape shaped by liquid water and/or ice, Berman said. He found that lobate flows, gullies, and arcuate ridges on the crater walls between latitudes of 30 to 45 degrees face the pole in their hemisphere, whereas equator-facing orientations are more common than pole-facing ones at latitudes between 45 and 60 degrees. In the southern study area, narrow channels generally had pole-facing orientations, whereas wider valleys generally have equator-facing orientations.

It’s a whole effing planet out there waiting to be explored. Probably as much to learn there about planets as on this one. It does kinda boggle the mind.