Without the help of fossils or any other record from the distant past, scientists have identified what they believe represents a common ancestor of all animals on Earth, a microscopic organism with key genetic traits that, until now, have been found only in true animals.
Writing in Tuesday’s Proceedings of the National Academy of Sciences, a team of scientists from the Howard Hughes Medical Institute at the University of Wisconsin-Madison reports the discovery of a key cell communication ge
Sloshing proteins help bacteria find their waists.
Chemical waves may help a bacterium to divide by pinpointing its middle, according to a new model of protein interactions 1 .
Bacteria such as Escherichia coli multiply by dividing. Bacterial division (called binary fission) is simpler than human cell division (mitosis). Human cells erect scaffolding to transport components to the two nascent daughter cells at either end; bacteria just pinch in two.
Using tiny rust-containing spheres to tag cells, scientists from Johns Hopkins and elsewhere have successfully used magnetic resonance imaging to track stem cells implanted into a living animal, believed to be a first.
In the December issue of the journal Nature Biotechnology, the research team report that the neuronal stem cells take up and hold onto the spheres, which contain a compound of iron and oxygen. The iron-laden cells create a magnetic black hole easily spotted by magnetic resonan
Chemists make the world’s smallest building blocks.
US researchers have made the world’s smallest building blocks. The nanocubes are just a millionth of a millimetre (a nanometre) across 1 . Stacked like bricks, they could make up a range of materials with useful properties such as light emission or electrical conduction.
Many chemists are currently trying to develop molecular-scale construction kits in which the individual components are single molecules to
When it comes to locating a meal, insect-eating bats generally employ one of two foraging tactics: capturing prey in the air or snatching it from a substrate. Accordingly, the animals use different kinds of echolocation during these activities. Whereas aerial hunters tend toward longer calls with constant frequency, substrate-gleaning species generate short calls that sweep from low to high frequencies (FM echolocation). Less clear, however, is how effective the latter is at distinguishing the prey i
American Society for Cell Biology Meeting, Washington, December 2001
Microscope captures mitochondria bopping to a beat.
An intricate mesh of tubes wiggle, worm-like across the screen. “They’re speeding,” says Tim Richardson proudly, watching mitochondria, the cell’s energy generators, zoom around the cell. His controversial microscopic method is shooting the cell’s innards as they’ve never been seen before.
Live cell imaging has revolutionised cell biology over th
American Society for Cell Biology Meeting, Washington, December 2001
Stem cells’ fates are a multiple choice.
A single stem cell from adult mouse muscle can form enough blood cells to save another animal’s life – and still switch back to making brawn, researchers announced at the Washington meeting of the American Society for Cell Biology this week.
Stem cells found in mashed up muscle can migrate into the bone marrow and make blood cells 1 . Muscle
Bacteria give skin cells their marching orders.
Bacteria that cause potentially lethal ’flesh-eating’ infections make their entrance by telling skin cells to step aside. The bugs hijack the body’s signal for skin cells to become mobile.
Group A streptococci (GAS) normally infect the surface lining of the throat. But occasionally they penetrate skin or the tissues lining the airways, invading deep into the body and causing life-threatening disease.
Finding out how s
Scientists at the University of Pennsylvania have identified a receptor that plays a key role in restricting embryonic stem cells’ pluripotency, their ability to develop into virtually any of an adult animal’s cell types.
The work is the first demonstration of a mechanism by which pluripotency is lost in mammalian embryos, one that operates with nearly the precision of an on/off switch in mouse embryos.
With further study, the receptor, dubbed GCNF, could open the door to new ways of c
World’s smallest reptile is discovered in the Caribbean forest.
At just 16 mm from nose to tail, the Jaragua lizard is the world’s smallest. In fact, it’s the smallest vertebrate that can reproduce on dry land 1 .
The newly discovered lizard lives on Isla Beata, a small, forest-covered island in the Caribbean off the Dominican Republic. Blair Hedges, an evolutionary biologist at Pennsylvania State University, together with Richard Thomas of the
For more than 150 years, people around the world have made ample use of the explosive trinitrotoluene, otherwise known as TNT. Its use has had unintended consequences, however: the manufacture, storage and disposal of TNT—which ranks among the most toxic explosives employed by the military—have left large areas of land contaminated and polluted. So far, effective and affordable cleanup technologies have remained out of reach. But new research suggests that help may come from what might seem an unlike
In news that will surely fan the flames of the heated debate over genetically modified crops, scientists have found evidence that genes from GM plants can spread far and wide to native ones. According to a report published today in the journal Nature, wild corn from the remote mountains of Oaxaca, Mexico contains transgenic DNA. This, the researchers note, bolsters concerns that such unintentional contamination can threaten the genetic diversity of natural crops.
DNA analyses of the Oaxaca
Rewiring the egg: mechanism remains murky.
From a scientific viewpoint, the cloning of human embryos may be more of a step than a leap, say sceptics. If the signals that turn adult cells into embryonic ones can be found, the creation of cloned embryos for tissue repair may become redundant.
Researchers at Advanced Cell Technology (ACT) in Worcester, Massachusetts, now report that they have created cloned human embryos. They aimed to make blastocysts, hollow balls of cells fr
The size and types of the largest local land animals vary greatly from place to place, prompting scientists to question what controls the success of animals of certain sizes over others. Now a report published in the current issue of the Proceedings of the National Academy of Sciences shows that the size of a landmass limits the maximal body size of its top animal.
Gary Burness and Jared Diamond of the University of California School of Medicine, together with Timothy Flannery of the South
New research is helping to unravel the machinery that allows a mosquito to sniff out its human quarry, which could lead to more and better ways of foiling the disease-spreading insects. A report published today in the online version of the Proceedings of the National Academy of Sciences describes four genes that appear to produce odor-sensing molecules in Africa’s Anopheles gambiae, a carrier of malaria, the number two killer in the developing world. Understanding how such genes operate could en
Talk about multi-tasking. A new study reveals that in the St. John’s Wort plant, Hypericum calycinum, the same chemical not only attracts pollinating insects but also deters herbivores that pose a threat to its survival. The findings appear in the current issue of the Proceedings of the National Academy of Sciences.
To the human eye, the flowers of H. calycinum appear as uniform yellow disks (top image). Insects with ultraviolet-sensitive eyes, however, see a dark, ultraviolet-absorbing ce
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