With a lot of skillful maneuverings, a team of researchers have finally found a way to image a molecule. The portrait of pentacene, an organic molecule consisting of five benzene rings, shows off the chemical bonds between the carbon and hydrogen atoms.
It may seem a somewhat surprising first, since atoms have been imaged for decades. The earliest pictures of individual atoms were captured in the 1970s by blasting a target – typically a chunk of metal – with a beam of electrons, a technique known as transmission electron microscopy (TEM)…. But strange though it might seem, imaging larger molecules at the same level of detail has not been possible – atoms are robust enough to withstand existing tools, but the structures of molecules are not [New Scientist].
In the new study, published in Science, researchers used an atomic force microscope to image the molecule in unprecedented resolution. The measurement requires extremes of precision. In order to avoid the effects of stray gas molecules bounding around, or the general atomic-scale jiggling that room-temperature objects experience, the whole setup has to be kept under high vacuum and at blisteringly cold temperatures [BBC News]; 5 Kelvin, to be exact. Rather than relying on an optical system to produce pictures, atomic force microscopes use a probe that narrows to an atomic-scale tip, and measures the forces of attraction between the tip and the molecule’s components.
Watermelons could do more than grace the tables at picnics across the land: They could also serve as a source of biofuel. Researchers fermented watermelon juice to produce ethanol, according to a study published in Biotechnology for Biofuels, and while the melons aren’t likely to become a primary biofuel crop, the process could help out farmers.
Nearly one-fifth of the watermelon crop grown in the United States is left in the fields after harvest because of defects on the melons’ rinds. “It’s not that there’s anything wrong with the melon on the inside, but our only method of judgment is the outside,” said [lead author] Wayne Fish [Greenwire]. Although farmers often till the abandoned melons into the soil, the value of the nutrients provided by this practice is much less than the overall cost to farmers of losing so much of their crop.
In a doctor’s office in the near future, part of a smoker’s routine checkup could involve blowing into a tube connected to a small sensor. The doctor will look at the sensor’s display and know immediately whether she has to deliver the grim diagnosis: lung cancer. Researchers in Israel have invented a new “breathalyzer” that can detect chemical compounds produced by lung cancer cells. The finished device should be portable and inexpensive and provide a faster, easier, and more sensitive way to screen for tumours than X-rays or blood tests. Such screening should help doctors detect cancer early, when it’s most treatable [Telegraph].
The new device, described in Nature Nanotechnology, is not the first to find evidence of cancer on a person’s breath. Other attempts to do this have yielded promising results, … but those devices require a higher concentration of the telltale biomarker chemicals than the Israeli device. The chemicals, called volatile organic compounds (VOCs), are metabolic products present in the vapors that we breathe out, but they occur in such small amounts that researchers have had to find ways to increase their concentrations before testing [Technology Review]. But the new sensor has such sensitivity that it can detect traces of the compound in their natural concentrations in human breath, and it can therefore give results immediately, without processing and analyzing the sample in a lab.
India’s first lunar mission has ended not with a bang, but with dead silence. India‘s space agency lost contact with the lunar orbiter, Chandrayaan-I, over the weekend; when efforts to restore communication were futile Indian officials declared that the mission was over.
The launch of Chandrayaan-1 in October 2008 put India in an elite club of countries with moon missions. Other countries with similar satellites are the United States, Russia, the European Space Agency, Japan and China [AP]. Indian officials hope that either NASA or the Russian space agency will agree to track the orbiter, which is currently circling 125 miles from the moon’s surface. The satellite’s orbit will slowly decay over the next several years, and it is expected to crash into the moon in about 1,000 days.
The rodent typically has dark fur (bottom photo), but one Nebraska group of mice evolved to have lighter fur (top photo) after the Sand Hills formed 8,000 to 15,000 years ago. A lighter coat is advantageous because it allows the animal to blend in with its pale surroundings. But what’s more amazing is that before the formation of the Sand Hills, the deer mouse didn’t even possess the gene that controls coat color in the rodents.
The gene, which is known as Agouti, first appeared in deer mice in the Sand Hills about 4,000 years ago; after that, a mutation occurred that gave rise to the mouse’s sandy fur. “The light gene wasn’t in existence, so the mice had to “wait” until a particular mutation occurred and then selection had to act on that new mutation… It’s a two part process. First the mutation has to occur and second, selection has to increase its frequency” [BBC News], said co-author Hopi Hoekstra.
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Image: Emily Kay
Biology Letters, August 23
A fossilized feather has proved that birds had already developed fancy plumage 40 million years ago. Using scanning electron microscopy, researchers examined tiny structures on the feather and determined them to be melanosomes, the organelles inside pigment cells that determine coloration. The organization of the melanosomes resembled patterns seen in the iridescent feathers of birds like starlings and grackles, according to the study. This finding is just the latest progress from a team working to discover the colors of prehistoric birds and even feathered dinosaurs.
Proceedings of the National Academy of Sciences, August 25
In a study that probably provoked fierce debate in text messages, emails, and blogs simultaneously, researchers found that people who frequently multitask are actually bad at multitasking. The researchers expected multitaskers to be better than average at organizing information and switching between tasks quickly, but found just the opposite. Elsewhere in the journal, researchers examined the genome of honeybees and offered a partial explanation of colony collapse disorder. The study suggests that a variety of viruses are damaging the bees’ ability to make proteins that are needed to protect them from all the other slings and arrows of the world, like bacterial infections and food shortages. While this is an incremental step towards understanding what is destroying honeybee hives around the country, every little bit helps.
A week-and-a-half after the first-ever human clinical embryonic stem cell trial was put on hold, Geron Corp. announced why: microscopic cysts that arose in laboratory animals but did not spread to other locations in the animals’ bodies.
In January, the FDA granted the company permission to begin using its stem cell treatment on patients with spinal cord injuries–but then the trial was delayed before the first patient could be enrolled. Although cysts developed occasionally during previous animal trials, they occurred more frequently in the more recent experiment. Geron was quick to point out, however, that the cysts were small and did not appear to be harmful in any way. In fact, the statement pointed out, cysts are not uncommon in victims of spinal cord injury, developing in the spinal cord scar tissue in up to 50% of patients [The Scientist]. In addition, the cysts did not develop into teratomas, a type of tumor that develops from pluripotent stem cells.
Geron said the company is working with the FDA to investigate the issue, and company officials are confident that the trial will soon be back on track. The FDA offered no comment regarding Geron’s announcement, saying they “neither confirm nor comment on clinical holds” [The Scientist].
80beats: FDA Approves the First Clinical Trials Using Embryonic Stem Cells
80beats: GE Plans to Use Human Embryonic Stem Cells as Lab Rats
80beats: Adult Mouse Gets a New Tooth, Grown From Embryonic Cells
Another day, another swine flu story: Amidst all the chatter, it can be hard to find the most reliable sources and relevant info. To keep you informed of the latest intelligence, 80beats will round up the news each week.
On Monday, the President’s Council of Advisors on Science and Technology issued an alarming report spelling out a “plausible scenario” for how the swine flu pandemic will play out during the coming flu season. The report estimated that the H1N1 virus could hospitalize 1.8 million Americans, potentially clogging emergency rooms and intensive care wards, and could kill up to 90,000 people in the United States. In a typical year, the seasonal flu virus kills about 35,000 Americans.
But on Tuesday, some public health officials walked back the report’s conclusions. One expert who helped prepare the report said that the numbers were probably on the high side, given that some weeks had passed since the calculations were finished in early August. “As more data has come out of the Southern Hemisphere, where it seems to be fading, it looks as if it’s going to be somewhat milder,” said the expert, Marc Lipsitch…. “If we were betting on the most likely number, I’d say it’s not 90,000 deaths; it’s lower” [The New York Times].
In an attempt to steer organ donation away from organs purchased on the black market or harvested from executed prisoners, China has announced a system to coordinate voluntary organ donation. The details of the new system are still under development, according to Chinese officials.
Although China is far from the only country facing a shortage of donor organs, the number of people who plan to donate is astoundingly low–since 2003, only 130 people have pledged to give up their organs after they pass away. Chinese officials estimate that 1.5 million Chinese need transplants annually but only 10,000 are performed due to donor shortages [The Wall Street Journal]. Of the transplants performed, officials estimate that at least 65 percent use organs from executed prisoners.
The remarkable diversity among dogs‘ coats–from the shaggy fur of a sheepdog to the sleek coat of a beagle, and everything in between–comes down to a mere three genes, according to a new report published in Science. The broad genetic study determined that one gene controls hair length and softness, another determines whether the hair is straight or curly, and a third controls the pattern in which hair grows, so that dogs with a particular version have wiry hair and moustaches and long facial details known to breeders as “furnishings”…. The combinations in which these genes are inherited then determine a dog’s overall look [The Times].
To reach these conclusions, the researchers first looked at the genetic differences within single breeds that have more than one coat type. Purebred dogs are particularly suited for this kind of study, Dr. Ostrander said, because they have been selectively bred to segregate traits — there are long- and short-haired dachshunds, for example [The New York Times]. By analyzing the genomes of two dachshunds with different types of coats, the researchers were able to determine which gene was linked to the variation in hair length. Similar studies revealed the other two genes.