The Y and X chromosomes are not very similar at all. Even though the Y chromosome imaged in a karyotype does admittedly resemble about half of a chromosome, structurally, it's all there. There is a long and short arm with a centromere dividing them, just like the other chromosomes. The Y chromosome really is much smaller than the X, though. There are about 2000 genes on the X chromosome, and roughly 80 on the Y chromosome. Unlike the non-sex-determining chromosomes, there is almost no recombination between the X and Y (that is to say, the genes on each are not shared between the two).
Chloroplasts, just as with mitochondria, have a small DNA genome of their own. Due to the endosymbiotic relationship that has formed between chloroplasts and their photosynthetic hosts, chloroplasts have found it convenient to offload the majority of their genes to the nucleus. It is estimated that about 90% of the genes necessary for photosynthesis are nuclear, with the rest in chloroplasts, so these sea slugs appear to have acquired the nuclear genes, but not the chloroplast genes.
Chlorophyll itself is made in the cytoplasm, and actually requires relatively few new genes for an animal to be able to produce it, since the complicated steps of its biosynthesis are identical to the heme structures it is already able to make. The real difficulty, and one that this sea slug seems to have been able to surmount according to the Wikipedia page, is the production of the "oxygen-evolving complex," a metalloenzyme with a manganese-calcium core which transfers absorbed energy to a bound water molecule to break it into electrons, protons, and molecular oxygen. Heterotrophic organisms don't produce anything like it.
To be fair, I don't think that list was meant to be comprehensive. In addition to the issues the parent mentions, it's a list of model organisms that includes naked mole rats, but not plain vanilla laboratory rats (they are mentioned in passing, I guess), so contrary to the/. article title, there's no attempt at a ranking here. In terms of a broader list of what sort of organisms are used for biological research, the Wikipedia page for model organism has a lot of examples.
While not on either list, my own work depends on an assist from horseshoe crabs. Horseshoe crabs have a very simple but effective immune system which produces clots upon contact with bacterial endotoxins; blood is extracted from horseshoe crabs (they are caught and released) and a substance called Limulus amebocyte lysate is extracted and is used extensively to test the sterility of drugs and medical devices.
In fact the list makes a conscious effort to avoid some of the most recognizable lab animals- mice and rats in particular- and focus on some lesser-known organisms like voles. The organisms they point out also each have at least one intrinsic characteristic- easily manipulated genes, similar anatomy/physiology to humans, inexpensive, etc. which gives them a particular role in medical research. But laboratory mice stand apart as a jack-of-all-trades.
It's choice number 1- the 8% figure is for all viral insertions in the human genome. The 8% number isn't anything new- it comes from the intial analysis of the sequenced human genome, circa 2001. The focus of this paper is the discovery that some of this material comes from a non-retrovirus, which would not have as obvious a route towards integration into the host genome. It's a virus that specifically infects the cell nucleus, so it's not that surprising that there would have been an accidental event in our history that integrated bornavirus genetic material into our genome, but it is a novelty compared to the purposeful reverse transcription and insertion of retroviruses. The entire bornavirus genome happens to be about 9 kilobases, about 0.0003% the size of the human genome, and smaller than many individual human genes, and according to the paper, we didn't even integrate the whole thing, but rather a few genetic elements from the virus.
Just a minor quibble- Down syndrome is caused by having an extra copy of chromosome 21 (trisomy), not a missing copy (monosomy). In humans, monosomy is fatal for the non-sex determining chromosomes (Turner syndrome is the result of monosomy X), and the only somatic trisomy conditions that are remotely survivable much past birth are those of 13, 19, and 21, and each of those has a set of profound symptoms such that they have an associated syndrome (Patau, Edwards, Down). This does nicely illustrate that issues with genetic insertion, deletion, and translocation are not so much a question of quantity as with placement. Trisomy of chromosome 21 is survivable because there aren't enough vital genes affected to cause inviability (the somatic chromosomes are numbered by size, with 1 the largest).
Your genome can tolerate a significant insertion of genes, as long as they don't cause serious trouble. In terms of viral DNA additions, the most significant risk is for a stretch of viral DNA to insert within an existing gene, breaking it and possibly creating a new gene variant that causes harm. This is believed to be a mechanism of viral infections associated with cancers (e.g. Epstein-Barr and Hodgkin's lymphoma, HPV and cervical cancer).
Thank you, though if I had actually taken the time to read the brief before posting instead of just the decisions of the supporting cases, I would have seen that the arguments I made are handled in pretty similar fashion in section II.B.. The ratio of damages is even calculated to produce the same result on p. 13- "Using a purchase price of 99 cents per song and, assuming contrary to fact, that each download represents a lost sale, the ratio of penalty to actual damage in this case is 22,500 to 1." I suppose that's the entire point of referring to those cases though- show that established criteria for unconstitutional damages exists, and then argue that the damages in the Tenenbaum case meet those criteria.
The argument involved in bringing up the court cases cited in the summary is that the damage award involved in this RIAA case is unconstitutional, as it violates part of the Fourteenth Amendment: "nor shall any State deprive any person of life, liberty, or property, without due process of law;". The decision for BMW of North America, Inc. v. Gore laid out a set of guideposts for whether punitive damage awards are in violation of this clause:
The degree of reprehensibility of the defendant's conduct
the ratio to the compensatory damages awarded (actual or potential harm inflicted on the plaintiff)
Comparison of the punitive damages award and civil or criminal penalties that could be imposed for comparable misconduct.
In my non-lawyer opinion, if awards were overturned in the Gore and Campbell cases under this rationale, there is a far stronger argument to be made here. The behavior of both BMW of NA (was selling slightly repaired cars as "new") and State Farm (had a secret internal scheme to cap payouts) could more reasonably be asserted as reprehensible than that of a music downloader. From a "ratio" standpoint, if you consider the actual damage from illegally downloading a song to be 99 cents as the parent implies, then for the 31 songs involved here, the ratio of punitive to actual is over 20000 to 1, far more than the 1000 to 1 in Gore and 145 to 1 in Campbell. And those were of course awards meant to have punitive effect on gigantic corporations, not to destroy the finances of a single private citizen. From a "comparable misconduct" standard, the $675,000 award is not in the same universe as the penalties for petty larceny if Mr. Tenenbaum had merely shoplifted physical copies of the same music.
It turns out that many clones are genetically identical, but not epigenetically identical. DNA methylation errors are common in nuclear transfer clones, and are thought to be responsible for at least some of the defects that often occur in clones. In particular, some imprinted genes important for normal growth and development may end up with two silenced copies instead of the expected one silent and one active, leading to effects from congenital organ defects to an increased risk of cancer. Curiously, some of the important developmental genes that can experience this situation in most mammals are not imprinted in primates. At least from a technical perspective, it might be easier to clone humans than goats.
The ability to transfer mitochondria is definitely possible, and has been for over a decade- see here for instance, where it was performed between two species of mice. I doubt they bothered with the process though, for several reasons. Mitochondrial transfer has an admittedly low success rate, and of course nuclear transfer has a low success rate, so that to produce a viable clone with both procedures would be extremely difficult. The mtDNA also has a higher mutation rate than nuclear DNA due to the reactive oxygen species the mitochondrion cranks out. It might be that there isn't much meaningful interspecies variation between the mtDNA of extinct ibex and the living egg donor, especially in relation to intraspecies variation.
Also, the mitochondrial DNA in most mammals is about 17,000 base pairs. The average mammalian nuclear genome is a few billion base pairs. The nuclear DNA represents over 99.99% of the total DNA, and given that I'd assume domestic goat mtDNA to have at the very least a 98% concurrence with Pyrenean ibex mtDNA, you'd be looking at a variability consistent with the overall error rate of DNA. The preservation, cloning, and IVF steps likely swamp interspecies mtDNA variation as an overall source of genetic error.
Take my mug, take my hand
Withdrawal I cannot stand
I don't care for caffeine-free,
You can't take my bean from me.
Pour me out a cup of black
Tell Juan to bring another sack.
Burn the land and boil the sea
You can't take my bean from me.
There could be serious immunological issues with a compound like this. While it comes from a beetle, structurally this antifreeze seems to have a lot of similarity with bacterial lipopolysaccharides (LPS), which happen to be the endotoxins in Gram-negative bacteria. We produce the aptly-named lipopolysaccharide-binding protein to seek out LPS and raise the alarm to initiate an inflammatory cascade. In the abstract to the paper, it mentions that a thermal hysteresis effect of 3.7 degrees C was seen at a concentration of 5mg/mL. Making the very rough assumption that the same concentration would be necessary to adequately protect human cells against the deep freeze, the required dose might be hundreds of grams (not unreasonable, considering it would have to integrate into every cell). The toxic response to LPS varies, but bacterial septic shock usually requires about 1/1000th that concentration.
Of course, nothing is known about the human immune response to this just-discovered compound (which hasn't even beeen fully characterized), so it's wild speculation on my part that your immune system might mistake it for a bacterial endotoxin. But if that did turn out to be the case, ironically it wouldn't be the cold that would kill you- it would be a fever.
In addition to the hydrocarbons, there is quite a bit of nitrogen available on Titan that gets fixed into a wide variety of molecules by UV radiation and cosmic rays in the upper atmosphere. It has been suggested that life could make a go of it on Titan with ammonia, nitriles, azides, and amines to provide reactivity. It would have to be a form of biochemistry that treats oxygen as a trace element, but the variety of reactive species you can form with just C,H, and N might be enough to substitute for most of oxygen's roles. It's still doubtful that life ever arose on Titan. A place with the limited chemistry set of Titan would benefit from having a lot of available energy to surmount potential energy barriers of reactions, but instead it's awfully cold there, and the atmosphere is opaque.
It's more like that the Drake equation has gone from an relation where all the variables are unknown to one where about half the variables are unknown. Advances in astronomy have allowed us to refine estimates of the number of stars in the galaxy, the fraction of those stars with planets, and the age of the galaxy. Studies like those the article refers to could potentially pin a value down on the "number of planets that could potentially support life per star with planets." The very meaning of that variable, however, depends on what characteristics you would consider necessary to support life.
From the progress of exoplanet searches so far, it does seem likely that some planets will be found that could support life in an earth-like sense (terrestrial with liquid water, at minimum). So, maybe four variables with potentially supportable estimates (and exoplanet searching is in its infancy, so that estimate will develop over time).
But the other variables in the Drake equation? What fraction of "habitable" planets actually develop life? What fraction of those develop intelligent life? Intelligent life that sends out detectable signals into space? And what is the expected lifetime of such civilizations? Values we might assign to those variables would be pure conjecture, with our only evidence being our own anecdote of existence.
That's comparing apples and oranges though. The value of 30-47 Wh/kg is for a supercapacitor made using the conductive paper, not for a battery. The article itself keeps using the word "battery" (and so does the Stanford release it's based on), but the abstract only offers that "this conductive paper can be used as an excellent lightweight current collector in lithium-ion batteries to replace the existing metallic counterparts."
Well, I thought that they were a system of cracks spreading out from the largest crater on Phobos, Stickney (not visible on the still image in the story, but visible edge-on in the lower right in the movie, or here. It was thought that the impact that created Stickney nearly tore Phobos apart, leaving prominent scars all over the surface, but apparently the system of grooves is far more complex, as was actually determined by the Mars Express mission. One of the sources for the wikipedia page on Stickney is for this paper which maps the striations, and suggests they were formed by ejected material from a series of impacts on Mars.
I'm curious to see how this will turn out in terms of practice of the death penalty in Illinois. There has been a moratorium on executions since 1999- Illinois still has a "death row," as well as the facilities for lethal injections, but hasn't actually executed prisoners in some time.
The denitrifying bacteria (from bacterial genera like Pseudomonas and Bacillus) aren't the mine detectors, but rather just provide a chemical signal for the engineered bacteria (E. coli, workhorse of genetic engineering). They happened to be in the soil already, because denitrifying bacteria happen to live in most soils worldwide. Under a certain depth of soil, atmospheric oxygen is not going to be accessible. Organisms that live there must either be anaerobic, or use a different substance than oxygen in their metabolism. Denitrifying bacteria run their metabolism with the reduction of nitrogen oxides back to nitrogen gas.
That does of course take bioavailable forms of nitrogen out of the soil, and given that it's pretty big business for humans to put bioavailable nitrogen compounds into soil, you might consider denitrifiers to be serious pests. And to some extent they are- one of the effects tilling or aerating soil has is to make atmospheric oxygen more accessible to soil bacteria, making the situation less attractive for denitrification. However, too much nitrogen in soil is also a problem, particularly in the form of nitrates and nitrites. If denitrifiers don't break them down to nitrogen gas, they will eventually enter the water cycle as runoff and feed phytoplankton blooms far downstream, causing hypoxic "dead zones." In other words, the nitrogen will be recycled somewhere on earth- it's really better to have it happen in the soil. Besides, as this landmine project suggests, the denitrifying bacteria can break down organic nitrates that are toxic to most other life.
In most soils, there live denitrifying bacteria, whose metabolism is based on reducing oxidized forms of nitrogen, eventually turning it back into nitrogen gas which reenters the atmosphere. These bacteria are recyclers, generally getting on by "unfixing" the fixed forms of nitrogen most other organisms rely on to survive, and so tend not to be picky about their nitrogen sources. They have enzymes called flavoprotein reductases that let them get nitrogen from organic nitrates, like from decaying organic matter. It turns out, however, that these enzymes also let them use many of our most common nitrated chemical explosives as a nitrogen source as well. In fact, one such enzyme has even been named PETN reductase, like the PETN that's in Semtex. I'm saying that if you spray liquid explosive on soil, the bacteria that already live there will eat it like candy. The mines would far outlast the spraying, which is exactly the problem- landmines around the world have far outlasted the conflicts they were laid for in the first place.
The method proposed by this group from Edinburgh actually takes advantage of that process, though. An old landmine or unexploded ordnance is probably going to be slowly leaching explosive out of the weapon. This means that soil near the device will contain the explosive itself, and also nitrites, which are produced as an intermediate step of breaking down the explosive material.
The group set up a sort of two-factor authorization. They genetically engineered promoters, proteins that bind to DNA and promote transcription of a particular genetic sequence, for two fluorescent proteins. Nitrite ion binds to the promoter for luxAB.GFP, which is a fusion protein of bacterial luciferase and green fluorescent protein. Thus, whenever nitrites are present, this protein gets made, and the bacterium glows a pleasing blue-green color. Not just fluoresces, mind you, but actively puts out light, due to the luciferase part. There is another sequence, for enhanced yellow fluorescent protein (eyfp). That promoter is activated by the presence of trinitrotoluene; the group used computational methods to develop a protein that binds DNA if it is also bound to TNT. Unlike the luxAB.GFP fusion protein, eyfp only fluoresces. It will glow yellow only if higher energy light has been input. So if pure TNT were present, the bacterium would make eyfp, but would only glow under UV light. When only nitrites are present, it actively glows blue. When both are present, the luxAB.GFP dumps light on eyfp, and the bacteria actively glow yellow. And then you call the bomb squad.
It looks like the University of Edinburgh entered this project in the International Genetically Engineered Machine competition, so they have a project page with a lot of information. From what I gather, it would appear that the system is based on a system of enzymes that break down soil nitrites which have been linked to Green Fluorescent Protein. Nitrites are a natural byproduct of the breakdown of nitro-based explosives like TNT and PETN. Of course, soil nitrites from non-leaking landmine sources, like chemical fertilizers would also trigger fluorescence, so the team engineered a non-natural gene promoter protein. The genes to produce the fluorescent complex only get transcribed and translated into protein if the promoter is active. The activator for that promoter is a molecule of TNT, so the bacteria will only glow if TNT is present.
I'd also encourage people to take a look at the other iGEM projects. Lots of interesting reading.
The Monopoly reference doesn't even make sense. I understand that Mayfair is the UK Monopoly equivalent of Boardwalk, but there isn't a Ventura Ave. on either the US or UK boards, at least. The corresponding property to Whitechapel Road in the US game is Baltic Ave.
Slashdot Mirror
There's a Trinity College at both Cambridge and at Oxford: Trinity College, Oxford.
The Y and X chromosomes are not very similar at all. Even though the Y chromosome imaged in a karyotype does admittedly resemble about half of a chromosome, structurally, it's all there. There is a long and short arm with a centromere dividing them, just like the other chromosomes. The Y chromosome really is much smaller than the X, though. There are about 2000 genes on the X chromosome, and roughly 80 on the Y chromosome. Unlike the non-sex-determining chromosomes, there is almost no recombination between the X and Y (that is to say, the genes on each are not shared between the two).
Chloroplasts, just as with mitochondria, have a small DNA genome of their own. Due to the endosymbiotic relationship that has formed between chloroplasts and their photosynthetic hosts, chloroplasts have found it convenient to offload the majority of their genes to the nucleus. It is estimated that about 90% of the genes necessary for photosynthesis are nuclear, with the rest in chloroplasts, so these sea slugs appear to have acquired the nuclear genes, but not the chloroplast genes.
Chlorophyll itself is made in the cytoplasm, and actually requires relatively few new genes for an animal to be able to produce it, since the complicated steps of its biosynthesis are identical to the heme structures it is already able to make. The real difficulty, and one that this sea slug seems to have been able to surmount according to the Wikipedia page, is the production of the "oxygen-evolving complex," a metalloenzyme with a manganese-calcium core which transfers absorbed energy to a bound water molecule to break it into electrons, protons, and molecular oxygen. Heterotrophic organisms don't produce anything like it.
To be fair, I don't think that list was meant to be comprehensive. In addition to the issues the parent mentions, it's a list of model organisms that includes naked mole rats, but not plain vanilla laboratory rats (they are mentioned in passing, I guess), so contrary to the /. article title, there's no attempt at a ranking here. In terms of a broader list of what sort of organisms are used for biological research, the Wikipedia page for model organism has a lot of examples.
While not on either list, my own work depends on an assist from horseshoe crabs. Horseshoe crabs have a very simple but effective immune system which produces clots upon contact with bacterial endotoxins; blood is extracted from horseshoe crabs (they are caught and released) and a substance called Limulus amebocyte lysate is extracted and is used extensively to test the sterility of drugs and medical devices.
In fact the list makes a conscious effort to avoid some of the most recognizable lab animals- mice and rats in particular- and focus on some lesser-known organisms like voles. The organisms they point out also each have at least one intrinsic characteristic- easily manipulated genes, similar anatomy/physiology to humans, inexpensive, etc. which gives them a particular role in medical research. But laboratory mice stand apart as a jack-of-all-trades.
Here is the abstract, but there isn't much mentioned in the abstract beyond what's covered in the press releases.
It's choice number 1- the 8% figure is for all viral insertions in the human genome. The 8% number isn't anything new- it comes from the intial analysis of the sequenced human genome, circa 2001. The focus of this paper is the discovery that some of this material comes from a non-retrovirus, which would not have as obvious a route towards integration into the host genome. It's a virus that specifically infects the cell nucleus, so it's not that surprising that there would have been an accidental event in our history that integrated bornavirus genetic material into our genome, but it is a novelty compared to the purposeful reverse transcription and insertion of retroviruses. The entire bornavirus genome happens to be about 9 kilobases, about 0.0003% the size of the human genome, and smaller than many individual human genes, and according to the paper, we didn't even integrate the whole thing, but rather a few genetic elements from the virus.
Just a minor quibble- Down syndrome is caused by having an extra copy of chromosome 21 (trisomy), not a missing copy (monosomy). In humans, monosomy is fatal for the non-sex determining chromosomes (Turner syndrome is the result of monosomy X), and the only somatic trisomy conditions that are remotely survivable much past birth are those of 13, 19, and 21, and each of those has a set of profound symptoms such that they have an associated syndrome (Patau, Edwards, Down). This does nicely illustrate that issues with genetic insertion, deletion, and translocation are not so much a question of quantity as with placement. Trisomy of chromosome 21 is survivable because there aren't enough vital genes affected to cause inviability (the somatic chromosomes are numbered by size, with 1 the largest).
Your genome can tolerate a significant insertion of genes, as long as they don't cause serious trouble. In terms of viral DNA additions, the most significant risk is for a stretch of viral DNA to insert within an existing gene, breaking it and possibly creating a new gene variant that causes harm. This is believed to be a mechanism of viral infections associated with cancers (e.g. Epstein-Barr and Hodgkin's lymphoma, HPV and cervical cancer).
Thank you, though if I had actually taken the time to read the brief before posting instead of just the decisions of the supporting cases, I would have seen that the arguments I made are handled in pretty similar fashion in section II.B.. The ratio of damages is even calculated to produce the same result on p. 13- "Using a purchase price of 99 cents per song and, assuming contrary to fact, that each download represents a lost sale, the ratio of penalty to actual damage in this case is 22,500 to 1." I suppose that's the entire point of referring to those cases though- show that established criteria for unconstitutional damages exists, and then argue that the damages in the Tenenbaum case meet those criteria.
In my non-lawyer opinion, if awards were overturned in the Gore and Campbell cases under this rationale, there is a far stronger argument to be made here. The behavior of both BMW of NA (was selling slightly repaired cars as "new") and State Farm (had a secret internal scheme to cap payouts) could more reasonably be asserted as reprehensible than that of a music downloader. From a "ratio" standpoint, if you consider the actual damage from illegally downloading a song to be 99 cents as the parent implies, then for the 31 songs involved here, the ratio of punitive to actual is over 20000 to 1, far more than the 1000 to 1 in Gore and 145 to 1 in Campbell. And those were of course awards meant to have punitive effect on gigantic corporations, not to destroy the finances of a single private citizen. From a "comparable misconduct" standard, the $675,000 award is not in the same universe as the penalties for petty larceny if Mr. Tenenbaum had merely shoplifted physical copies of the same music.
It turns out that many clones are genetically identical, but not epigenetically identical. DNA methylation errors are common in nuclear transfer clones, and are thought to be responsible for at least some of the defects that often occur in clones. In particular, some imprinted genes important for normal growth and development may end up with two silenced copies instead of the expected one silent and one active, leading to effects from congenital organ defects to an increased risk of cancer. Curiously, some of the important developmental genes that can experience this situation in most mammals are not imprinted in primates. At least from a technical perspective, it might be easier to clone humans than goats.
The ability to transfer mitochondria is definitely possible, and has been for over a decade- see here for instance, where it was performed between two species of mice. I doubt they bothered with the process though, for several reasons. Mitochondrial transfer has an admittedly low success rate, and of course nuclear transfer has a low success rate, so that to produce a viable clone with both procedures would be extremely difficult. The mtDNA also has a higher mutation rate than nuclear DNA due to the reactive oxygen species the mitochondrion cranks out. It might be that there isn't much meaningful interspecies variation between the mtDNA of extinct ibex and the living egg donor, especially in relation to intraspecies variation.
Also, the mitochondrial DNA in most mammals is about 17,000 base pairs. The average mammalian nuclear genome is a few billion base pairs. The nuclear DNA represents over 99.99% of the total DNA, and given that I'd assume domestic goat mtDNA to have at the very least a 98% concurrence with Pyrenean ibex mtDNA, you'd be looking at a variability consistent with the overall error rate of DNA. The preservation, cloning, and IVF steps likely swamp interspecies mtDNA variation as an overall source of genetic error.
Take my mug, take my hand
Withdrawal I cannot stand
I don't care for caffeine-free,
You can't take my bean from me.
Pour me out a cup of black
Tell Juan to bring another sack.
Burn the land and boil the sea
You can't take my bean from me.
There could be serious immunological issues with a compound like this. While it comes from a beetle, structurally this antifreeze seems to have a lot of similarity with bacterial lipopolysaccharides (LPS), which happen to be the endotoxins in Gram-negative bacteria. We produce the aptly-named lipopolysaccharide-binding protein to seek out LPS and raise the alarm to initiate an inflammatory cascade. In the abstract to the paper, it mentions that a thermal hysteresis effect of 3.7 degrees C was seen at a concentration of 5mg/mL. Making the very rough assumption that the same concentration would be necessary to adequately protect human cells against the deep freeze, the required dose might be hundreds of grams (not unreasonable, considering it would have to integrate into every cell). The toxic response to LPS varies, but bacterial septic shock usually requires about 1/1000th that concentration.
Of course, nothing is known about the human immune response to this just-discovered compound (which hasn't even beeen fully characterized), so it's wild speculation on my part that your immune system might mistake it for a bacterial endotoxin. But if that did turn out to be the case, ironically it wouldn't be the cold that would kill you- it would be a fever.
In addition to the hydrocarbons, there is quite a bit of nitrogen available on Titan that gets fixed into a wide variety of molecules by UV radiation and cosmic rays in the upper atmosphere. It has been suggested that life could make a go of it on Titan with ammonia, nitriles, azides, and amines to provide reactivity. It would have to be a form of biochemistry that treats oxygen as a trace element, but the variety of reactive species you can form with just C,H, and N might be enough to substitute for most of oxygen's roles. It's still doubtful that life ever arose on Titan. A place with the limited chemistry set of Titan would benefit from having a lot of available energy to surmount potential energy barriers of reactions, but instead it's awfully cold there, and the atmosphere is opaque.
It's more like that the Drake equation has gone from an relation where all the variables are unknown to one where about half the variables are unknown. Advances in astronomy have allowed us to refine estimates of the number of stars in the galaxy, the fraction of those stars with planets, and the age of the galaxy. Studies like those the article refers to could potentially pin a value down on the "number of planets that could potentially support life per star with planets." The very meaning of that variable, however, depends on what characteristics you would consider necessary to support life.
From the progress of exoplanet searches so far, it does seem likely that some planets will be found that could support life in an earth-like sense (terrestrial with liquid water, at minimum). So, maybe four variables with potentially supportable estimates (and exoplanet searching is in its infancy, so that estimate will develop over time).
But the other variables in the Drake equation? What fraction of "habitable" planets actually develop life? What fraction of those develop intelligent life? Intelligent life that sends out detectable signals into space? And what is the expected lifetime of such civilizations? Values we might assign to those variables would be pure conjecture, with our only evidence being our own anecdote of existence.
Those are Cyberdemon tracks!
That's comparing apples and oranges though. The value of 30-47 Wh/kg is for a supercapacitor made using the conductive paper, not for a battery. The article itself keeps using the word "battery" (and so does the Stanford release it's based on), but the abstract only offers that "this conductive paper can be used as an excellent lightweight current collector in lithium-ion batteries to replace the existing metallic counterparts."
Well, I thought that they were a system of cracks spreading out from the largest crater on Phobos, Stickney (not visible on the still image in the story, but visible edge-on in the lower right in the movie, or here. It was thought that the impact that created Stickney nearly tore Phobos apart, leaving prominent scars all over the surface, but apparently the system of grooves is far more complex, as was actually determined by the Mars Express mission. One of the sources for the wikipedia page on Stickney is for this paper which maps the striations, and suggests they were formed by ejected material from a series of impacts on Mars.
This is obviously the datacenter that Les Assassins des Fauteuils Roulants will use to disseminate Infinite Jest at the start of the Year of Glad.
I'm curious to see how this will turn out in terms of practice of the death penalty in Illinois. There has been a moratorium on executions since 1999- Illinois still has a "death row," as well as the facilities for lethal injections, but hasn't actually executed prisoners in some time.
The denitrifying bacteria (from bacterial genera like Pseudomonas and Bacillus) aren't the mine detectors, but rather just provide a chemical signal for the engineered bacteria (E. coli, workhorse of genetic engineering). They happened to be in the soil already, because denitrifying bacteria happen to live in most soils worldwide. Under a certain depth of soil, atmospheric oxygen is not going to be accessible. Organisms that live there must either be anaerobic, or use a different substance than oxygen in their metabolism. Denitrifying bacteria run their metabolism with the reduction of nitrogen oxides back to nitrogen gas.
That does of course take bioavailable forms of nitrogen out of the soil, and given that it's pretty big business for humans to put bioavailable nitrogen compounds into soil, you might consider denitrifiers to be serious pests. And to some extent they are- one of the effects tilling or aerating soil has is to make atmospheric oxygen more accessible to soil bacteria, making the situation less attractive for denitrification. However, too much nitrogen in soil is also a problem, particularly in the form of nitrates and nitrites. If denitrifiers don't break them down to nitrogen gas, they will eventually enter the water cycle as runoff and feed phytoplankton blooms far downstream, causing hypoxic "dead zones." In other words, the nitrogen will be recycled somewhere on earth- it's really better to have it happen in the soil. Besides, as this landmine project suggests, the denitrifying bacteria can break down organic nitrates that are toxic to most other life.
In most soils, there live denitrifying bacteria, whose metabolism is based on reducing oxidized forms of nitrogen, eventually turning it back into nitrogen gas which reenters the atmosphere. These bacteria are recyclers, generally getting on by "unfixing" the fixed forms of nitrogen most other organisms rely on to survive, and so tend not to be picky about their nitrogen sources. They have enzymes called flavoprotein reductases that let them get nitrogen from organic nitrates, like from decaying organic matter. It turns out, however, that these enzymes also let them use many of our most common nitrated chemical explosives as a nitrogen source as well. In fact, one such enzyme has even been named PETN reductase, like the PETN that's in Semtex. I'm saying that if you spray liquid explosive on soil, the bacteria that already live there will eat it like candy. The mines would far outlast the spraying, which is exactly the problem- landmines around the world have far outlasted the conflicts they were laid for in the first place.
The method proposed by this group from Edinburgh actually takes advantage of that process, though. An old landmine or unexploded ordnance is probably going to be slowly leaching explosive out of the weapon. This means that soil near the device will contain the explosive itself, and also nitrites, which are produced as an intermediate step of breaking down the explosive material.
The group set up a sort of two-factor authorization. They genetically engineered promoters, proteins that bind to DNA and promote transcription of a particular genetic sequence, for two fluorescent proteins. Nitrite ion binds to the promoter for luxAB.GFP, which is a fusion protein of bacterial luciferase and green fluorescent protein. Thus, whenever nitrites are present, this protein gets made, and the bacterium glows a pleasing blue-green color. Not just fluoresces, mind you, but actively puts out light, due to the luciferase part. There is another sequence, for enhanced yellow fluorescent protein (eyfp). That promoter is activated by the presence of trinitrotoluene; the group used computational methods to develop a protein that binds DNA if it is also bound to TNT. Unlike the luxAB.GFP fusion protein, eyfp only fluoresces. It will glow yellow only if higher energy light has been input. So if pure TNT were present, the bacterium would make eyfp, but would only glow under UV light. When only nitrites are present, it actively glows blue. When both are present, the luxAB.GFP dumps light on eyfp, and the bacteria actively glow yellow. And then you call the bomb squad.
It looks like the University of Edinburgh entered this project in the International Genetically Engineered Machine competition, so they have a project page with a lot of information. From what I gather, it would appear that the system is based on a system of enzymes that break down soil nitrites which have been linked to Green Fluorescent Protein. Nitrites are a natural byproduct of the breakdown of nitro-based explosives like TNT and PETN. Of course, soil nitrites from non-leaking landmine sources, like chemical fertilizers would also trigger fluorescence, so the team engineered a non-natural gene promoter protein. The genes to produce the fluorescent complex only get transcribed and translated into protein if the promoter is active. The activator for that promoter is a molecule of TNT, so the bacteria will only glow if TNT is present.
I'd also encourage people to take a look at the other iGEM projects. Lots of interesting reading.
The Monopoly reference doesn't even make sense. I understand that Mayfair is the UK Monopoly equivalent of Boardwalk, but there isn't a Ventura Ave. on either the US or UK boards, at least. The corresponding property to Whitechapel Road in the US game is Baltic Ave.