Sometime in the late Pleistocene period, humans and Neanderthals are believed to have lived together. Only one species still exists, and people who study human pre-history have battled for decades over the reasons why. One of the more popular theories is that modern humans migrating out of Africa killed off the Neanderthal, because the humans were...
Like shiny gemstones embedded in a rocky matrix, star-forming clouds of dust and gas glimmer within the swirling structures of our galaxy in an infrared image from ESA's Herschel Space Observatory.
The image was acquired as a part of Hi-GAL, a survey mapping the entire plane of the Milky Way in a wide range of infrared light that Herschel was specially designed to detect. The image above is just a small section of a larger version, which in itself is just 1/30th of the entire Hi-GAL survey.
Normally invisible to our eyes, vast filaments of gas and dust fill the plane of the galaxy where stars like our Sun reside. As these cold clouds of interstellar material collapse, they get denser and denser until they eventually form stars, which then blaze with heat and light.
The energy from these newborn stars blasts out into nearby space, illuminating the shrouds of material they were born in as well as ionizing them with shockwaves of radiation.
These ionized 'shock fronts' also release light in wavelengths corresponding to the elements within the clouds, and can also eventually lead to the formation of yet more stars — a continuous cycle of star birth on a galactic time scale."
A rebellion has broken out against the traditional way of naming species in the peculiar, shape-shifting world of fungi.
Many fungi are shape-shifters seemingly designed to defy human efforts at categorization. The same species, sometimes the same individual, can reproduce two ways: sexually, by mixing genes with a partner of the same species, or asexually, by cloning to produce genetically identical offspring.
The problem is that reproductive modes can take entirely different anatomical forms. A species that looks like a miniature corn dog when it is reproducing sexually might look like fuzzy white twigs when it is in cloning mode. A gray smudge on a sunflower seed head might just be the asexually reproducing counterpart of a tiny satellite dish–shaped thing. Just by looking at them, you’d never know.
When many of these pairs were discovered, sometimes decades apart, sometimes growing right next to each other, it was difficult or impossible to demonstrate that they were the same thing. So one species would get two names. Careful observation later suggested that officially different species are actually one, but the pairs of names remained. In fact, it soon became standard mycological practice to name many species twice — once for the sexual form, once for the asexual one.
Now, mycologists have a chance to set the record straight. A group of upstart scientists has rebelled against the dual-naming system, arguing that DNA analysis can endow fungi with a one-species, one-name system. Having won a major victory at a recent international scientific congress, they are poised to bring their field into a new era of genetic nomenclature. But however justified genetically, their project is not without perils.
"Researchers at the Universiti Teknologi MARA in Malaysia have conducted a study on the mangrove ecosystem to search for actinomycetes bacteria. The mangrove ecosystem is known as a highly productive habitat for isolating actinomycetes, which has the potential of producing biologically active secondary metabolites."
Carbon — the basis for life — is present in the earth, seas, sky, and every living creature. Geologists have long known that significant amounts of carbon are stored as calcium carbonate in certain rocks, such as marble, and returned to the atmosphere through volcanic eruptions. But how calcium carbonate from rocks transforms into carbon dioxide gas has been unclear.
Researchers have begun teasing apart the genes behind regeneration.
Planarian flatworms are one of nature's little wonders. Although their 'cross-eyed' appearance is endearing, their real claim to fame comes from their regenerative ability. Split a planarian down the middle and you'll soon have two cross-eyed critters staring back at you; cut one up and each piece will regenerate an entire flatworm. How do they pull of such an incredible feat? In 2011, researchers discovered that planarian regeneration depends on the activity of stem cells ('neoblasts') distributed throughout the flatworm's body, but important questions about the process have remained unanswered. Are certain stem cells responsible for each organ? What activates the stem cells when regeneration is needed? An enterprising team of scientists at the Stowers Institute for Medical Research has brought us closer to answering these questions by developing a new technique to study planarian regeneration and using it to discover some of they genes involved.
Regeneration isn't a uniquely planarian trait; starfish are well-known for growing back lost body parts, and even humans can regenerate to some extent (think of a wound healing). Planarians certainly excel at it, though; a flatworm can recover from being cut up into a staggering 279 tiny pieces, each of which regenerates into a new worm! Here's a fun conundrum for those inclined to such things: which worm, if any, can claim to be the 'original worm'? What if it were only two pieces instead of over 200? Would it make a difference if the two pieces were different sizes?
Using this technique, which they termed 'chemical amputation', the team induced lesions in planaria and investigated which genes were activated over the course of the regeneration process. The pharynx lacks neoblasts, but cells near the wound quickly start dividing and regenerate the amputated organ. To identify genes which were interesting, the team combined two screening approaches. First, a microarray picked out genes which were active during regeneration, providing a list of 356 candidates. Next, the team used RNAi to block the activity of each gene in amputated flatworms and checked whether the pharynx still regenerated. This narrowed the list down to twenty genes, which the team divided into different sets. Some genes affected stem cells in general, other affected feeding behaviour, and a handful directly affected the development of the pharynx. Of these, the transcription factor FoxA seemed to play the greatest role in regenerating the pharynx.
The team next looked at how regeneration went wrong in planaria with FoxA knocked down. They found that stem cells still migrated to the wound site and multiplied there, but the resulting outgrowth failed to become a pharynx. They also tried amputating the tails or heads of FoxA knock-downs, which then successfully regenerated. "Targeting FoxA completely blocked pharynx regeneration but had no effect on the regeneration of other organs," said Adler in a press release. “Currently, we think that FoxA triggers a cascade of gene expression that drives stem cells to produce all of the different cells of the pharynx, including muscle, neurons, and epithelial cells.” FoxA is known to play a role in specifying the pharynx in the sea anemone and in the nematode Caenorhabditis elegans, as well regulating the development of the intestine in vertebrates, so it makes sense that it's a central player in pharynx regeneration in planaria. More importantly, its identification can serve as a wedge to pry apart the details of regeneration; coupled with the other genes picked up in this study, it offers an exciting opportunity to expand our understanding of this important process.
Adler C, et al. Selective amputation of the pharynx identifies a FoxA-dependent regeneration program in planaria. eLife 3:e02238. (2014) doi:10.7554/eLife.02238
Rossant J. Genes for Regeneration. eLife 3:e02517. (2014) doi:10.7554/eLife.02517
Physicists from the FOM Foundation and the University of Amsterdam have discovered that the ancient Egyptians used a clever trick to make it easier to transport heavy pyramid stones by sledge. The Egyptians moistened the sand over which the sledge moved. By using the right quantity of water they could ...
What if spacetime were a kind of fluid? This is the question tackled by theoretical physicists working on quantum gravity by creating models attempting to reconcile gravity and quantum mechanics. Some of these models predict that spacetime at the Planck scale (10-33cm) is no longer continuous – as held by classical physics – but discrete in nature. Just like the solids or fluids we come into contact with every day, which can be seen as made up of atoms and molecules when observed at sufficient resolution. A structure of this kind generally implies, at very high energies, violations of Einstein's special relativity (a integral part of general relativity).
"Located in south central Bulgaria, the city of Plovdiv, known to many as the "Eternal City of Bulgaria", is among the oldest cities in Europe, with evidence of human settlement going back 6,000 years. Established first as the Thracian settlement of Eumolpia, today its ancient remains near the city center are most often identified with the name Philippopolis by archaeologists. That was the name given to the city after it was Hellenized within the Macedonian Empire under Philip II during the 4th century, B.C.E. But its most visible ancient remains took shape when the city was absorbed into the orbit of ancient Rome during the 1st century B.C.E. - 1st century C.E., the time period of Augustus. It was during this time when the great monumental structures, such as the Theater, Stadium, Treasury, Thermae, Odeon, and other associated structures of its central Forum, were built.
A team of archaeologists under the auspices of the RSF Archaeological Trust and the Plovdiv archaeological museum are now exploring an unexcavated area of the Forum, hoping to shed additional light on the character and uses of the complex, its phases of construction, and what may have stood there before its construction."