About 1,500 years ago a fortress that is now called “Sandby borg” came under a surprise attack. Archaeologists found that the inhabitants were slaughtered, many of them didn’t even have the chance to face their attackers. This picture shows the skeleton of a teenager who fell backward over a dead or dying adult. The house where these two were found has at least nine dead individuals. [Read more about the ancient massacre site]
Credit: Kalmar County Museum
This teenager was found at Sandby borg in the house where at least nine people were killed suddenly. The skeleton of half a herring suggests that the people in this house were eating when they were attacked.
Credit: Daniel Lindskog
Some fantastic jewelry has also been discovered at Sandby borg. This photograph shows jewelry found in the house where at least nine people were killed. A brooch along with glass beads, rings and other forms of jewelry were discovered. Four deposits of jewelry were found in other locations at Sandby borg.
Credit: Daniel Lindskog
Five gilded brooches that were found in five different hidden deposits at Sandby borg. Made of silver and gilded with gold archaeologists believe that they belonged to aristocratic women.
Evidence of time
Credit: Daniel Lindskog
More of the jewelry discovered at Sandby borg. At left is a glass sword bead. At center is a gold coin showing Roman Emperor Valentinian III (reign 425-455) and at right is a gilded sword pendant.
Desecrated and deserted
Credit: Kalmar County Museum
A plan of Sandby borg. 53 structures are surrounded by a wall that is four to five meters (13 feet to 16 feet) high and has three gates. The site was abandoned after the attack, the dead were not even buried.
Credit: Sebastian Jakobsson
This photograph shows “house 4” being excavated. It is located beside the walls of the fortress.
Biofilms are a collective of one or more types of microorganisms that can grow on many different surfaces. Microorganisms that form biofilms include bacteria, fungi and protists.
One common example of a biofilm dental plaque, a slimy buildup of bacteria that forms on the surfaces of teeth. Pond scum is another example. Biofilms have been found growing on minerals and metals. They have been found underwater, underground and above the ground. They can grow on plant tissues and animal tissues, and on implanted medical devices such as catheters and pacemakers.
Each of these distinct surfaces has a common defining feature: they are wet. These environments are “periodically or continuously suffused with water,” according to a 2007 article published in Microbe Magazine. Biofilms thrive upon moist or wet surfaces.
Biofilms have established themselves in such environments for a very long time. Fossil evidence of biofilms dates to about 3.25 billion years ago, according to a 2004 article published in the journal Nature Reviews Microbiology. For example, biofilms have been found in the 3.2 billion-year-old deep-sea hydrothermal rocks of the Pilbara Craton in Australia. Similar biofilms are found in hydrothermal environments such as hot springs and deep-sea vents.
Biofilm formation begins when free-floating microorganisms such as bacteria come in contact with an appropriate surface and begin to put down roots, so to speak. This first step of attachment occurs when the microorganisms produce a gooey substance known as an extracellular polymeric substance (EPS), according to the Center for Biofilm Engineering at Montana State University. An EPS is a network of sugars, proteins and nucleic acids (such as DNA). It enables the microorganisms in a biofilm to stick together.
Attachment is followed by a period of growth. Further layers of microorganisms and EPS build upon the first layers. Ultimately, they create a bulbous and complex 3D structure, according to the Center for Biofilm Engineering. Water channels crisscross biofilms and allow for the exchange of nutrients and waste products, according to the article in Microbe.
Multiple environmental conditions help determine the extent to which a biofilm grows. These factors also determine whether it is made of only a few layers of cells or significantly more. “It really depends on the biofilm,” said Robin Gerlach, a professor in the department of chemical and biological engineering at Montana State University-Bozeman. For instance, microorganisms that produce a large amount of EPS can grow into fairly thick biofilms even if they do not have access to a lot of nutrients, he said. On the other hand, for microorganisms that depend on oxygen, the amount available can limit how much they can grow. Another environmental factor is the concept of “shear stress.” “If you have a very high flow [of water] across a biofilm, like in a creek, the biofilm is usually fairly thin. If you have a biofilm in slow flowing water, like in a pond, it can become very thick,” Gerlach explained.
Finally, the cells within a biofilm can leave the fold and establish themselves on a new surface. Either a clump of cells breaks away, or individual cells burst out of the biofilm and seek out a new home. This latter process is known as “seeding dispersal,” according to the Center for Biofilm Engineering.
Why form a biofilm?
For microorganisms, living as a part of a biofilm comes with certain advantages. “Communities of microbes are usually more resilient to stress,” Gerlach told Live Science. Potential stressors include the lack of water, high or low pH, or the presence of substances toxic to microorganisms such as antibiotics, antimicrobials or heavy metals.
There are many possible explanations for the hardiness of biofilms. For example, the slimy EPS covering can act as a protective barrier. It can help prevent dehydration or act as a shield against ultraviolet (UV) light. Also, harmful substances such as antimicrobials, bleach or metals are either bound or neutralized when they come into contact with the EPS. Thus, they are diluted to concentrations that aren’t lethal well before they can reach various cells deep in the biofilm, according to a 2004 article in Nature Reviews Microbiology.
Still, it is possible for certain antibiotics to penetrate the EPS and make their way through a biofilm’s layers. Here, another protective mechanism can come into play: the presence of bacteria that are physiologically dormant. In order to work well, all antibiotics require some level of cellular activity. So, if bacteria are physiologically dormant to begin with, there is not much for an antibiotic to disrupt.
Another mode of protection against antibiotics is the presence of special bacterial cells known as “persisters.” Such bacteria do not divide and are resistant to many antibiotics. According to a 2010 article published in the journal Cold Spring Harbor Perspectives in Biology, “persisters” function by producing substances that block the targets of the antibiotics.
In general, microorganisms living together as a biofilm benefit from the presence of their various community members. Gerlach cited the example of autotrophic and heterotrophic microorganisms that live together in biofilms. Autotrophs, such as photosynthetic bacteria or algae, are able to produce their own food in the form of organic (carbon containing) material, while heterotrophs cannot produce their own food and require outside sources of carbon. “In these multi-organismal communities, they often cross feed,” he said.
Biofilms and us
Given the vast range of environments in which we encounter biofilms, it is no surprise that they affect many aspects of human life. Below are a few examples.
Health and disease
As research has progressed over the years, biofilms — bacterial and fungal — have been implicated in a variety of health conditions. In a 2002 call forgrant applications, the National Institutes of Health (NIH) noted that biofilms accounted “for over 80 percent of microbial infections in the body.”
Biofilms can grow on implanted medical devices such as prosthetic heart valves, joint prosthetics, catheters and pacemakers. This in turn leads to infections. The phenomenon was first noted in the 1980s when bacterial biofilms were found on intravenous catheters and pacemakers. Bacterial biofilms have also been known to cause infective endocarditis andpneumonia in those with cystic fibrosis, according to the 2004 article in Nature Reviews Microbiology, among other infections.
“The reason that biofilm formation is a great cause of concern is that, within a biofilm, bacteria are more resistant to antibiotics and other major disinfectants that you could use to control them,” said A.C. Matin, a professor of microbiology and immunology at Stanford University. In fact, when compared to free-floating bacteria, those growing as a biofilm can be up to 1,500 times more resistant to antibiotics and other biological and chemical agents, according to the article in Microbe. Matin described biofilm resistance combined with the general increase in antibiotic resistance among bacteria as a “double whammy” and a major challenge to treating infections.
Fungal biofilms can also cause infections by growing on implanted devices.Yeast species such as the members of the genus Candida grow on breast implants, pacemakers and prosthetic cardiac valves according to a 2014 article published in the journal Cold Spring Harbor Perspectives in Medicine. Candida species also grow on human body tissues, leading to diseases such as vaginitis (inflammation of the vagina) and oropharyngeal candidiasis (a yeast infection that develops in the mouth or throat). However, the authors note that drug resistance was not shown in these instances.
Sometimes, biofilms are useful. “Bioremediation, in general, is the use of living organisms, or their products — for example, enzymes — to treat or degrade harmful compounds,” Gerlach said. He noted that biofilms are used in treating wastewater, heavy metal contaminants such as chromate, explosives such as TNT and radioactive substances such as uranium. “Microbes can either degrade them, or change their mobility or their toxic state and therefore make them less harmful to the environment and to humans,” he said.
Nitrification using biofilms is one form of wastewater treatment. During nitrification, ammonia is converted to nitrites and nitrates throughoxidation. This can be done by autotrophic bacteria, which grow as biofilms on plastic surfaces, according to a 2013 article published in the journal Water Research. These plastic surfaces are just a few centimeters in size and distributed all through the water.
The explosive TNT (2,4,6-Trinitrotoluene) is considered a soil, surface water and groundwater pollutant. The chemical structure of TNT consists of benzene (a hexagonal aromatic ring made of six carbon atoms) attached to three nitro groups (NO2) and one methyl group (CH3). Microorganisms degrade TNT by reduction, according to a 2007 article published in the journal Applied and Environmental Microbiology. Most microorganisms reduce the three nitro groups, while some attack the aromatic ring. The researchers — Ayrat Ziganshin, Robin Gerlach and colleagues — found that the yeast strain Yarrowia lipolytica was able to degrade TNT by both methods, though primarily by attacking the aromatic ring.
Microbial fuel cells
Microbial fuel cells use bacteria to convert organic waste into electricity. The microbes live on the surface of an electrode and transfer electrons onto it, ultimately creating a current, Gerlach said. A 2011 article published in Illumin, an online magazine of the University of Southern California, notes that bacteria powering microbial fuel cells break down food and bodily wastes. This provides a low-cost source of power and clean sustainable energy.
Our world is teeming with biofilms. In fact, by the mid-20th century, more bacteria were found on the inside surfaces of containers holding bacterial cultures, than floating freely in the liquid culture itself, according to the 2004 article in Nature Reviews Microbiology. Understanding these complex microbial structures is an active area of research.
“Biofilms are amazing communities. Some people have compared them to multicellular organisms because there is a lot of interaction between single cells,” Gerlach said. “We are continuing to learn about them, and we are continuing to learn about how to control them better; both for reduced detriment, as in the field of medicine, or for increased benefit as in bioremediation. We are not going to run out of interesting questions in that area.”
At Live Science, we delve into science news from around the world every day — and some of those stories can get a little weird. Here are some of the strangest science news articles from this week.
Uranus smells terrible
In case you were wondering, Uranus smells like farts. A new study found that the seventh planet from the sun has an upper atmosphere filled with hydrogen sulfide. This makes Uranus different from the gas giants Jupiter and Saturn, which have more ammonia in their upper atmospheres. [Read more about Uranus’ smell]
Giant ground sloth
About 11,000 years ago, ancient humans followed a giant ground sloth, stepping in the tracks of its clawed paws. These track marks are now fossilized and indicate that the humans once interacted with — and possibly hunted — these now-extinct towering sloths in what is now New Mexico. [Read more about the fossilized footprints]
In a new internet trend, videos show crumpled aluminum foil balls transforming into beautifully smooth and highly polished spheres. But how do the people convert these ugly balls into stunning globes? Live Science looked into it and found that the technique has similarities with Japanese samurai sword making. [Read more about the aluminum foil spheres]
A sneaky, parasitic ant uses chemical warfare to get a free meal and home. This Central American ant has a potent venom that can scare off invaders. And even though this ant eats baby ants, it’s still accepted into the homes of certain ants that use it as a guard dog. [Read more about the sneaky ants]
Human bone daggers
The warriors of New Guinea used to carve daggers out of two unusual thighbones — those from humans and others from flightless, dinosaur-like birds called cassowaries. But which dagger was better? A new analysis shows that the human-bone daggers were stronger, largely because of the way they were carved. [Read more about the bone daggers]
A 19-year-old man in India got into a brawl and ended up with a key embedded 1.5 inches (3.8 centimeters) into his skull. So, how did he survive? Luckily, the key didn’t cause internal bleeding or any damage to his brain, doctors said. [Read more about the key injury]
Want more weird science news and discoveries? Check out these and other “Strange News” stories on Live Science!
Deadly Fungus Cells Talk Amongst Themselves to Infect You Better
By Rachael Rettner, Senior Writer |
The idea of microbes joining forces inside your body to wreak havoc and cause disease sounds frightening — and it should. Now, scientists have found that a particular type of fungus does just that, and the fungal cells use a surprising method to team up and communicate with each other.
What’s more, the findings may explain why this fungus can infect healthy people, a characteristic that’s unusual for fungal infections, which more typically strike people with weakened immune systems.
The study focused on a fungus called Cryptococcus gattii, which lives in soil and is found mostly in tropical and subtropical regions. However, in 1999, a strain of this fungus popped up in British Columbia, Canada, and later, in Oregon and Washington state, mostly causing infections in otherwise-healthy people.
The infection, which people catch by inhaling fungal spores, can be life-threatening, causing a pneumonia-like illness in the lungs, as well as serious infections of the brain and tissues surrounding the brain and spinal cord. From 2004 to 2010, there were 60 reported causes ofCryptococcus gattii in the U.S., and among the 45 cases with known outcomes, nine (20 percent) died from their infections, according to a 2010 study from researchers at the Centers for Disease Control and Prevention.
Previously, researchers found that Cryptococcus gattii was so virulent because it had the “remarkable ability to grow rapidly within human white blood cells,” study author Ewa Bielska, a postdoctoral research fellow at the University of Birmingham in the United Kingdom, said in a statement. In 2014, Bielska’s colleagues found that this rapid growth resulted from a “division of labor,” meaning that the fungal cells worked together to coordinate their behavior and drive rapid growth. [10 Bizarre Diseases You Can Get Outdoors]
In the new study, Bielska and colleagues figured out exactly how the fungal cells are joining forces: The microbes use microscopic, fluid-filled sacs called extracellular vesicles to communicate.
“These vesicles act like ‘carrier pigeons,’ transferring messages between the fungi and helping them to coordinate their attack on the host cell,” said study senior author Robin May, director of the University of Birmingham’s Institute of Microbiology and Infection.
This is the first time that scientists have found a connection between extracellular vesicles and fungal virulence, the researchers said.
The scientists also found that, surprisingly, the fungal cells could use extracellular vesicles to communicate across relatively long distances between cells.
“Our initial expectation was that the fungus would only be able to communicate within a single host cell, but in fact we discovered that it can communicate over very large — in microbiology terms — distances and across multiple host cell barriers,” May said.
The findings “provides us with a potential opportunity to develop new drugs that work by interrupting this communication route during an infection,” he said.
The study was published April 19 in the journal Nature Communications.
The ‘End of the World’ Is Today. Here’s Why We’re Still Here.
By Jeanna Bryner, Live Science Managing Editor |
Today is the day.
It’s the beginning of the end, according to practiced doomsday diviner David Meade. On April 23, 2018, Meade says, the sun, the moon and Jupiter will line up in the constellation Virgo (in actuality, they will not be in that constellation) — an alignment that has biblical disaster written all over it.
In the Bible, Revelation 12:1-2 speaks of a “woman clothed with the sun, with the moon under her feet and a crown of twelve stars on her head,” who labors to give birth to a dictator who will ultimately bring about the world’s end.
Meade did a lot of numerical and cosmic gymnastics to come up with today’s apocalypse — one that, of course, will not come to be.
The same passage used for today’s prediction was also the basis for Meade’s end-of-the-world prediction last year, when he said the sky would essentially fall on Sept. 23. It did not. [End of the World? Top 10 Doomsday Threats]
And, in fact, his current forecast seems to have long roots: Baptist preacher William Miller made multiple failed doomsday predictions, and one of them was for April 23, 1843.
Sadly, perhaps for Meade, the planet Jupiter will appear not in Virgo but in the constellation Libra from Earth’s perspective; the sun will appear to align with Aries, while the moon will lurk in the constellation Gemini today,according to The Sky Live.
This celestial alignment is, according to Meade, just the beginning of the cosmic catastrophe. From there, a rogue planet called Planet X will supposedly pass by Earth in October and cause a planetwide mess (worldwide volcanic eruptions) that will culminate in the return of Jesus Christ — also based on the Book of Revelation.
There are a few problems with this part of the prediction. For one, Planet X, also called Nibiru, is fictional. And whereas scientists are looking for an Earth-size planet that they sometimes refer to as “Planet X” or “Planet Nine,” this is a different world altogether from the one described by Meade and others.
Nibiru, in fact, is the baby of conspiracy theorist Nancy Lieder, who floated the idea in the 1990s. This rogue planet — a body that astronomers who stare at the skies, looking for actual alien worlds, would not miss — was the basis for the failed 2012 Maya apocalypse, among others.
Besides Nibiru being a made-up world that has been debunked repeatedly, the Revelation passage also has some issues.
“The author of Revelation was wrong in his predictions, so neither this book nor any other ancient book is of much relevance for predicting the future,” Allen Kerkeslager, a professor of ancient and comparative religion at St. Joseph’s University in Philadelphia, told Live Science earlier this month.
All this is to say, the doomsday prediction is bogus. Happy Monday.