Fürkész

A genetically engineered bacterium makes a greener plastic

Fri, 27 Nov 2009 08:10:52 +0200

“One of the most promising alternatives to plastics made from oil is polylactic acid (PLA). It is biodegradable, safe enough to be used as food packaging, can be processed like existing thermoplastics into coloured or transparent material and can be manufactured from renewable resources such as maize and sugarcane.

At the moment PLA is usually made in two stages. First, a source of starch or sugar, which could be an agricultural by-product, is fermented to produce lactic acid—the same substance made by the body during exercise, only in this case it comes from the bacteria exercising themselves in the fermentation process. In the second stage, lactic-acid molecules are linked into long chains, or polymers, in chemical-reaction vessels, to produce PLA. What Dr Lee and his colleagues have succeeded in doing, as they report in Biotechnology and Bioengineering, is to produce PLA directly, in a one-stage process, in bacteria. No chemical “post processing” is required.

Their bacterial platform is E. coli, the workhorse species of microbial genetics. But their version has had genes from several other bacteria spliced into it. One comes from a bug called Clostridium propionicum, another from a species of Pseudomonas, and two more from Cupriavidus necator. Some of these genes, moreover, have been souped up, because the “wild” versions did not work well enough. The result is a set of synthetic metabolic pathways—ones that do not exist in nature—which turn the polymer out in satisfyingly large quantities.”

Source: From The Economist print edition (Nov 26th 2009): Synthetic biology Your plastic pal

An Electronic Clue In The Mystery of DNA Repair

Thu, 19 Nov 2009 05:17:01 +0200

Source: http://www.technologyreview.com/blog/arxiv/24420/

“DNA repair machines may home in on the electrical signals created by mutations.

DNA is regularly damaged by ordinary wear and tear and the constant buffeting of ionising radiation. However, cells possess an extraordinary collection of molecular machines such as repair enzymes that rapidly identify the defects and repair them.

The puzzle is how they do it. One idea is that repair enzymes simply float about for long enough and eventually find damaged regions. But the numbers just don’t stack up. Genes are usually between 1000 and 1,000,000 base pairs long. By contrast, a typical mutation usually involves just a handful of base pairs. That’s just too small to find using a random walk with any reliability. Some other form of active location finding must be going on.

One theory is that mutations change the electrical characteristics of a stretch of DNA and that this creates a signal that repair enzymes can home in on, like electricians locating a break in a circuit. The trouble is that DNA doesn’t conduct electricity like a power cable and so it isn’t clear how this would work.

Now Arkady Krokhin at the University of North Texas and few buddies have worked out how DNA may do it. The key turns out to be that different regions of DNA have different electrical characteristics. The group has calculated from first principles the way in which charge flows in different regions. They say that in exons—the information carrying parts of genes—the energy spectrum of the molecule allows delocalised electrons to exist. In these areas, charge can flow.

However the energy spectrum of the regions that do not carry information—the introns—does not allow for delocalised electrons. So introns are effectively insulators.

That sets up well defined regions within DNA that can be identified electronically.It also means that any change in electronic properties caused by a mutation would be largely confined too. That immediately suggests a way that repair enzymes can home in on damage.

Of course, this work is just one step towards a coherent theory that explains DNA repair (which actually involves many different processes).

But the beauty of this approach is that it could also explain why some damage goes unrepaired, leading to cell death and even cancer.

The thinking is that certain mutations cause less of an electrical change than others. These mutations are “electronically masked” and so go undetected by repair enzymes. There is even experimental evidence for this from resistance measurements done on DNA with cancer-causing mutations.

If this theory is true, one important question is how might it be possible to exploit DNA’s electrical characteristics to detect and even prevent cancer in future?”

Ref: arxiv.org/abs/0911.2953: Inhomogeneous DNA: Conducting Exons And Insulating Introns

Why humans can speak but chimps can't: Evolution of a single gene linked to language

Wed, 18 Nov 2009 07:04:00 +0200

Why humans can speak but chimps can't: Evolution of a single gene linked to language:

“Of the 20,000 genes in the human genome, few are more fascinating than FOXP2, a gene that underlies the faculty of human speech. All animals have an FOXP2 gene, but the human version’s product differs at just 2 of its 740 units from that of chimpanzees, suggesting that this tiny evolutionary fix may hold the key to why people can speak and chimps cannot.

The FOXP2 gene does not do a single thing but rather controls the activity of at least 116 other genes. Several of the genes under FOXP2’s thumb show signs of having faced recent evolutionary pressure, meaning they were favored by natural selection. This suggests that the whole network of genes has evolved together in making language and speech a human faculty. And some of the genes in FOXP2’s network have already been implicated in diseases that include disorders of speech, confirming its importance in these faculties.

The FOXP2 network is certainly not the only set of genes involved in language. For one thing, FOXP2 is equally active on both sides of the human brain, whereas the language faculty is asymmetric.”

Forrás: Speech Gene Shows Its Bossy Nature

Magyarul: Szupergén irányítja az emberi beszédet

Az eredeti Nature cikk

A gene for empathy - Torrice 2009 (1116): 3 - ScienceNOW

Wed, 18 Nov 2009 06:47:00 +0200

A gene for empathy - Torrice 2009 (1116): 3 - ScienceNOW:

“Some people can read your face and know you’ve had a bad day. Others seem oblivious. Now, researchers have pinpointed a genetic explanation for why some people are better empathizers than others.

Empathy is crucial for our everyday social interactions. Scientists have linked a variation, or polymorphism, in the gene that codes for the oxytocin receptor to autism, a disorder defined by impaired social interactions.

The scientists divided the students into two groups based on a single difference in the genetic alphabet of their rs53576 polymorphism. Volunteers whose two copies of the receptor gene had the “G” version of rs53576 made about 23% fewer mistakes—equivalent to two questions on the test—than did those with an “A” version, the type commonly seen in autistic patients. That suggests that the “G” group could read people’s emotions better from facial cues, the team reports online today in the Proceedings of the National Academy of Sciences. The researchers tried to control for environmental factors by ensuring that volunteers in both groups had equally social parents. The results show that some of us have a natural capacity to be more empathic than others and that some people are more naturally closed-off and detached.”

Source: http://sciencenow.sciencemag.org/cgi/content/full/2009/1116/3

Scientists Launch Effort To Sequence The DNA Of 10,000...

Fri, 06 Nov 2009 05:27:00 +0200

Scientists Launch Effort To Sequence The DNA Of 10,000 Vertebrates Scientists have an ambitious new strategy for untangling the evolutionary history of humans and their biological relatives: Create a genetic menagerie made of the DNA of more than 10,000 vertebrate species. The plan, proposed by an international consortium of scientists, is to obtain, preserve, and sequence the DNA of approximately one species for each genus of living mammals, birds, reptiles, amphibians, and fish. Known as the Genome 10K Project, the approximately $50 million initiative is “tremendously exciting science that will have great benefits for human and animal health,” Haussler said. “Within our lifetimes, we could get a glimpse of the genetic changes that have given rise to some of the most diverse life forms on the planet.” By sequencing the DNA of 10,000 vertebrates — roughly one-sixth of the 60,000 species estimated to be living today — biologists will be able to reconstruct the genetic changes that gave rise to this astonishing diversity. Source: Howard Hughes Medical Institute (2009, November 5). Scientists Launch Effort To Sequence The DNA Of 10,000 Vertebrates. ScienceDaily. Retrieved November 6, 2009, from http://www.sciencedaily.com/releases/2009/11/091104132706.htm

The $4400 Genome -- Service 2009 (1105): 3 -- ScienceNOW

Fri, 06 Nov 2009 04:35:25 +0200

The $4400 Genome -- Service 2009 (1105): 3 -- ScienceNOW:

“Complete Genomics, a Mountain View, California-based biotechnology company sequenced three human genomes for about $4400 each, at least in the cost of reagents. The rapid fall in sequencing prices may give genomics an equivalent of Moore’s Law, which describes how the number of transistors on computer chips doubles every 18 months, steadily driving down the cost of computing power. In 2003, the cost of sequencing a human genome was an estimated $300 million. That was down to $1 million in 2007 and $60,000 last year.

Did you know that fruit bats are the only non-primate to engage in oral sex?

Sat, 31 Oct 2009 06:48:00 +0200

Source: PLoS ONE: Fellatio by Fruit Bats Prolongs Copulation Time

Oral sex is widely used in human foreplay, but rarely documented in other animals. Fellatio has been recorded in bonobos Pan paniscus, but even then functions largely as play behaviour among juvenile males. The short-nosed fruit bat Cynopterus sphinx exhibits resource defence polygyny and one sexually active male often roosts with groups of females in tents made from leaves. Female bats often lick their mate’s penis during dorsoventral copulation. The female lowers her head to lick the shaft or the base of the male’s penis but does not lick the glans penis which has already penetrated the vagina. Males never withdrew their penis when it was licked by the mating partner. A positive relationship exists between the length of time that the female licked the male’s penis during copulation and the duration of copulation. Furthermore, mating pairs spent significantly more time in copulation if the female licked her mate’s penis than if fellatio was absent. Males also show postcopulatory genital grooming after intromission. At present, we do not know why genital licking occurs, and we present four non-mutually exclusive hypotheses that may explain the function of fellatio in C. sphinx.

http://sciencenow.sciencemag.org/cgi/content/full/2009/1030/2 :

“Zhang and colleagues have a few theories as to why the females would want to increase the length of intercourse. One idea is that it may facilitate sperm transport. Or it could keep males occupied—and thus away from rival females.

Fellatio may also offer protection against sexually transmitted diseases, based on the antimicrobial properties of saliva. Many male animals, including short-nosed fruit bats, lick their genitals after copulation, and in some species this has been shown to reduce the incidence of such diseases.

“The finding of fellatio in bats is exciting news,” says Frans de Waal, a primatologist at Emory University in Atlanta who has worked extensively with bonobos. He says that although the behavior is likely rare, it may be more common than we think. “Part of the reason fellatio is rarely mentioned is shyness about this issue.” The observation provides a unique opportunity to test some theories about the evolutionary role of fellatio, adds Paul Vasey, a behavioral scientist at the University of Lethbridge in Alberta, Canada. Although it’s possible, he says, that bats are just being sexually playful, like their human and bonobo counterparts.”

Brain Cells Chat, Even Without a Synapse — Willyard 2009...

Sat, 31 Oct 2009 06:06:00 +0200

Brain Cells Chat, Even Without a Synapse — Willyard 2009 (1029): 2 — ScienceNOW :

http://sciencenow.sciencemag.org/cgi/content/full/2009/1029/2

A team of Hungarian researchers at the University of Szeged made the discovery by examining a type of neuron called a neurogliaform cell. These cells are common in the brain’s cortex. Studies have shown that neurogliaform cells can inhibit the firing of other brain cells by releasing a neurotransmitter called GABA (gamma-aminobutyric acid), which typically transmits messages across synapses. But some studies have suggested that GABA can diffuse into the extracellular space as well, where it carries messages between neurons not connected via synapses. To create enough ambient GABA for this to happen, however, scientists speculated that many neurons would have to fire at once.

The Hungarian team used electron and light microscopes to examine brain tissue from rats and humans, they found that neurogliaform cells have bushy axons with many branches. These bushy axons are densely populated with sites where GABA can be released into the extracellular space, the team found. Elsewhere in the brain this occurs mainly at synapses, but only 11 of the 50 release sites examined in neurogliaform cells corresponded to a synapse, the researchers report today in Nature. Additional experiments confirmed that a single neurogliaform cell, when stimulated, releases enough GABA to inhibit the activity of nearby neurons not connected by synapses.

Fall Colors and Autumn Leaves 35 million year puzzle: why fall...

Sat, 24 Oct 2009 06:26:00 +0300

Fall Colors and Autumn Leaves

35 million year puzzle: why fall colors in the US are mainly red and why autumn leaves turn mainly yellow in Europe.

The change in color to reds and yellows in autumn is not caused by the leaves dying, but by a series of controlled biochemical processes. When the green chlorophyll in leaves diminishes, the yellow pigments that already exist become dominant and give their color to the leaves.

Red autumn leaves result from a different process: As the chlorophyll diminishes, a red pigment, anthocyanin, which was not previously present, is produced in the leaf. These facts were only recently discovered and led to a surge of research studies attempting to explain why trees expend resources on creating red pigments just as they are about to shed their leaves.

Lev-Yadun, S., & Holopainen, J. (2009). Why red-dominated autumn leaves in America and yellow-dominated autumn leaves in Northern Europe? New Phytologist, 183 (3), 506-512 DOI: 10.1111/j.1469-8137.2009.02904.x

http://www3.interscience.wiley.com/cgi-bin/fulltext/122453432/HTMLSTART

Was our oldest ancestor a proton-powered rock? - life - 19 October 2009 - New Scientist

Mon, 19 Oct 2009 19:58:00 +0300

Was our oldest ancestor a proton-powered rock? - life - 19 October 2009 - New Scientist:

These vents form when water reacts with the mineral olivine, which is common in the sea floor - and would have been even more common early on, before the Earth’s crust thickened. The process produces a new mineral, serpentine, and releases hydrogen, alkaline fluids and heat. It also makes the rocks expand and crack, allowing more water to percolate down, sustaining the reaction. The warm, hydrogen-rich effluent ultimately breaks through the sea floor as an alkaline hydrothermal vent.

Interest in alkaline vents rose in 2000, when Deborah Kelley and her colleagues from the University of Washington in Seattle stumbled (if one can stumble in a submersible) across an active alkaline vent field just off the mid-Atlantic ridge, exactly where Russell said such vents should be. The team dubbed it the Lost City, partly for its spectacular spires of rock, which form as carbonates precipitate out in the alkaline fluid.

Like ancient vents, the spires of the Lost City are riddled with tiny pores, some with dimensions not dissimilar to modern cells. And the chemistry fits the bill too. A report last year confirmed the presence of methane and other small hydrocarbons, as well as hydrogen itself.

So the idea that ancient alkaline hydrothermal vents were the incubators for life looks very plausible even before you consider their most striking feature: a ready-made proton gradient. Laboratory experiments by a team led by Nobel prizewinner Jack Szostak of Harvard University, published earlier this year, have confirmed that these conditions do indeed concentrate nucleotides and nucleic acids. The team also found that fatty acids become concentrated, leading to the spontaneous formation of cell-like bubbles inside the pores.

The last common ancestor of all life was not a free-living cell at all, but a porous rock riddled with bubbly iron-sulphur membranes that catalysed primordial biochemical reactions. Powered by hydrogen and proton gradients, this natural flow reactor filled up with organic chemicals, giving rise to proto-life that eventually broke out as the first living cells - not once but twice, giving rise to the bacteria and the archaea.

The Past 5,000 Years Mark a New Epoch in Human Evolution

Sun, 18 Oct 2009 06:59:07 +0300

The Past 5,000 Years Mark a New Epoch in Human Evolution:

“A team led by University of Wisconsin-Madison anthropologist John Hawks estimated that positive selection just in the past 5,000 years alone -dating back to the Stone Age - has occurred at a rate roughly 100 times higher than any other period of human evolution. Many of the new genetic adjustments are occurring around changes in the human diet brought on by the advent of agriculture, and resistance to epidemic diseases that became major killers after the growth of human civilizations. In the hunt for recent genetic variation in the genome map the project has cataloged the individual differences in DNA called single nucleotide polymorphisms (SNPs). The project has mapped roughly 4 million of the estimated 10 million SNPs in the human genome. Hawks’ research focuses on a phenomenon called linkage disequilibrium (LD). These are places on the genome where genetic variations are occurring more often than can be accounted for by chance, usually because these changes are affording some kind of selection advantage.

The researchers identify recent genetic change by finding long blocks of DNA base pairs that are connected. Because human DNA is constantly being reshuffled through recombination, a long, uninterrupted segment of LD is usually evidence of positive selection. Linkage disequilibrium decays quickly as recombination occurs across many generations, so finding these uninterrupted segments is strong evidence of recent adaptation, Hawks says.

Employing this test, the researchers found evidence of recent selection on approximately 1,800 genes, or 7 percent of all human genes.”

QuickRoute - simple display of a GPS route on an orienteering map

Thu, 15 Oct 2009 05:17:39 +0300

QuickRoute - simple display of a GPS route on an orienteering map:

QuickRoute is a computer program for Windows that allows you to display a route from a GPS device, such as a GPS-clock, on an orienteering map saved as an image file. The main purpose of QuickRoute is to make it quick and simple to transfer your route from a GPS device onto a map.

World's Smallest Computers Made of DNA and Other Biological Molecules Made to 'Think' Logically

Wed, 14 Oct 2009 06:51:00 +0300

World's Smallest Computers Made of DNA and Other Biological Molecules Made to 'Think' Logically

2009 Chemistry Nobel Laureate Venki Ramakrishnan: by Nature...

Tue, 13 Oct 2009 16:30:00 +0300

2009 Chemistry Nobel Laureate Venki Ramakrishnan: by Nature Video (via NatureVideoChannel)

Creating Garmin Custom Maps in Five Easy Steps

Fri, 09 Oct 2009 18:06:00 +0300

Creating Garmin Custom Maps in Five Easy Steps:

Running the latest beta software releases for Garmin Colorado, Oregon (200, 300, 400 and 550), andDakota devices, using paper maps with Garmin outdoor handhelds is easier than ever with Garmin Custom Maps. This unique feature allows users to combine Garmin map drawing technology with georeferenced map images, effectively putting a paper map inside your Garmin GPS.

In Test of Water on Moon, Craft Hits...

Fri, 09 Oct 2009 17:18:00 +0300

In Test of Water on Moon, Craft Hits Bull’s-Eye

http://www.nytimes.com/2009/10/10/science/space/10moon.html?src=twt&twt=nytimesscience

Fotók, megapixelek és gigabyte-ok

Wed, 07 Oct 2009 12:28:00 +0300

2003-ban készítettem az első digitális fotóimat. A 2003 év “fotótermése” még csak 272 MB-t foglalt az akkor soknak számító 8 GB-os merevlemezzel rendelkező asztali számítógépemen (mostmár az egyik Kingston USB memory stickem-nek van ugyanennyi GB-ja), hiszen a fotóim csak egy mindössze 2.1 megapixeles, kölcsönkért Canon Powershot A200-al készültek, amely flashcard-ra rögzített. Az első saját digitális fényképezőgépem a szintén csak 2.1 MP-s Canon Powershot A60 volt. Egy gólyavédelmi pályázatból 86 euroért vásároltam hozzá 2003 júniusában egy 128 MB-os flashcard-ot.

Azóta cserélődtek a fényképezőgépeim, nőtt a megapixelek száma és már a telefonomba épített kamera is 3.1 MP-es: még nem értünk a 2009-es év végére és az idén készített fotóim máris 17.9 GB-nyi helyet foglalnak pedig általában csak hétvégeken szoktam fotózgatni. Fotóim tárhelyigényének a folyamatos növekedését illusztrálja az alábbi grafikonom.

Mycena luxaeterna From New...

Tue, 06 Oct 2009 18:34:00 +0300

Mycena luxaeterna

From New Scientist: http://www.newscientist.com/gallery/dn15018-pick-of-the-pictures :

“Seven new species of glow-in-the-dark mushroom have been discovered by researchers in Belize, Brazil, the Dominican Republic, Jamaica, Japan, Malaysia and Puerto Rico, bringing the world total of bioluminescent fungi to 71. Four of the species are new to science, while three were not previously known to glow.

Mycena luxaeterna, pictured here, was discovered by Dennis Desjardin of San Francisco State University and colleagues in Sao Paulo, Brazil.

Desjardin says the new discoveries shed light on how luminescence evolved in fungi. “Within Mycena, the luminescent species come from 16 different lineages, which suggests that luminescence evolved at a single point and some species later lost the ability to glow,” he says.

He thinks the bioluminescence attracts nocturnal animals, aiding the dispersal of spores.”

Egy kis statisztika - twitter-rel a madarakért

Tue, 06 Oct 2009 05:43:48 +0300

EuroBirdwatch-os twitterezés statisztikája (24 órára):

507 Mobypicture megtekintés

319 Adevarul de Cluj I. újságcikk megtekintés

http://www.adevarul.ro/rss/articol/cluj-video-foto-cu-ochii-dupa-pasari-la-euro-birdwatch-2009.html

181 Adevarul de Cluj II. újságcikk megtekintés

http://www.adevarul.ro/rss/articol/cluj-eurobirdwatch-2009-in-direct-prin-intermediul-twitter.html

Twitteren eljutott a hír 3827 követőhöz:

840 (Birdfeeders)

2087 (MargaretKinney)

801 (Iggyquiggy)

99 (alulírott)

Impakt összesen: 4837 (összehasonlításképpen: a SOR honlapot egy hónap alatt - szeptemberben - csak 1300 tekintették meg)

Sárgalábú sirály

Tue, 06 Oct 2009 05:11:00 +0300

2009. október 5, ~16.15 két sárgalábú sirály a román opera “jobb oldali” szobrán.

2009 október 6, ~7.20 újra két egyed.