Although, in the majority of cases, the localized presence of Neisseria meningitidis in the throat has no consequence, it can sometimes lead to meningitis or septicaemia. The seriousness of these two infections is driving researchers from arou…
A better understanding of the new “smelling” capabilities of human sperm cells may lead to advances in contraception and fertility treatments. A new study identifies a novel odorant receptor on human sperm and shows how activating this receptor causes the sperm to make a beeline for a target. In a study appearing in the 28 March issue of the journal, Science, German and U.S. researchers report that the binding of certain compounds to the new odorant receptor (hOR17-4) found on the surface of sperm cells, triggers a series of physiological events that may result in the directed movement of human sperm. In this chemosensory response, the sperm cells travel toward elevated concentrations of a sperm-attracting substance called “bourgeonal.”
Global warming and the partial melting of polar ice sheets can dramatically affect not only sea levels but also Earth’s climate, in ways that may be complex, rapid and difficult to adjust to, scientists say in a new study to be published Friday in the journal Science. Sea level and climatic changes in Earth’s distant past, near the end of the last Ice Age about 14,600 years ago, offer significant clues to some phenomena that Earth may experience in the near future, possibly in coming decades or centuries, the study found.
Two-legged dinosaurs may have used their forelimbs as wing-like structures to propel themselves rapidly up steep inclines long before they took to the skies, reports a University of Montana researcher in the January 17 issue of the journal Science. The new theory adds a middle step that may link two current and opposing explanations for how reptiles evolved into flying birds.
A new study has discovered an abundance of microbial life deep beneath the ocean floor in ancient basalt that forms part of the Earth’s crust, in research that once more expands the realm of seemingly hostile or remote environments in which living organisms can apparently thrive. The research was done off the coast of Oregon near a sea-floor spreading center on the Juan de Fuca Ridge, by scientists from Oregon State University and several other institutions. It will be published Friday in the journal Science.
Scientists have long recognized that, despite physical differences, all human populations are genetically similar to one another. But a new study in the journal Science concludes that populations from different parts of the world share even more genetic similarities than had previously been assumed. At the same time, researchers found that tiny differences in DNA can provide enough information to identify the geographic ancestry of individual men and women.
As mammals, our internal (circadian) clock is regulated by the patterns of light and dark we experience. But how that information is transmitted from the eye to the biological clock in the brain has been a matter of scientific debate. Scientists had suspected that a molecule called melanopsin, which is found in the retina, plays an important role. Now researchers have confirmed that melanopsin does indeed transmit light information from the eye to the part of the brain that controls the internal clock. According to the researchers, melanopsin may be one of several photosensitive receptors that work redundantly to regulate the circadian system.
The prevailing view among scientists is that global climate change may prove beneficial to many farmers and foresters — at least in the short term. The logic is straightforward: Plants need atmospheric carbon dioxide to produce food, and by emitting more CO2 into the air, our cars and factories create new sources of plant nutrition that will cause some crops and trees to grow bigger and faster. But an unprecedented three-year experiment conducted at Stanford University is raising questions about that long-held assumption. Writing in the journal Science, researchers concluded that elevated atmospheric CO2 actually reduces plant growth when combined with other likely consequences of climate change — namely, higher temperatures, increased precipitation or increased nitrogen deposits in the soil.
Researchers studying yeast reproductive habits have for the first time observed a rapid method for the creation of new species, shedding light on the way organisms evolve. “Most models of speciation require gradual change over a very long period of time, and geographic or ecological isolation for a new species to arise,” says University of Houston biologist Michael Travisano. “Our study suggests that mating two separate species to produce hybrids can result in a new species readily and relatively quickly, at least in yeast, but possibly in other organisms as well.”
When the human brain is presented with conflicting information about an object from different senses, it finds a remarkably efficient way to sort out the discrepancies, according to new research conducted at the University of California, Berkeley. The researchers found that when sensory cues from the hands and eyes differ from one another, the brain effectively splits the difference to produce a single mental image. The researchers describe the middle ground as a “weighted average” because in any given individual, one sense may have more influence than the other. When the discrepancy is too large, however, the brain reverts to information from a single cue – from the eyes, for instance – to make a judgment about what is true.
By experimentally switching genes off or on at specific stages in an animal’s lifecycle, California scientists have discovered that vigor and lifespan can be significantly extended with no side effects. Many researchers believe that increasing lifespan will dampen reproduction. But the new study of the tiny roundworm commonly known as C. elegans shows that silencing a key gene only in adulthood increases longevity with no effect on reproduction.
Long, dark manes on male lions are more more attractive to females than shorter, lighter manes, researchers reported in today’s issue of the journal Science. Peyton West and Craig Packer of the University of Minnesota set up dummy lions with different mane types at Serengeti National Park in Tanzania. While males were more inclined to approach dummies with lighter, shorter manes, females were drawn to the dummies with big, dark hair. There’s good reason for this: blood tests revealed that males with darker manes tend to have higher levels of testosterone. But the most-wanted males pay a price for their looks: the dark hairs make the lions hotter, literally, and this extra heat results in a good deal of abnormal sperm.