Month: February 2020

Enlarge / Elon Musk in 2015. (credit: ODD ANDERSEN/AFP/Getty Images)

Tesla will raise $2 billion in a new stock offering, the company announced on Thursday morning.

Tesla's shares are worth about $780 on Thursday morning—up 2 percent over Wednesday's closing price. That's still down from the record high of the more than $940 the stock reached last week.

CNBC notes that as recently as two weeks ago, Musk was saying that Tesla wasn't planning to raise more cash. But the spectacular performance of Tesla's stock over the last two weeks may have made this an opportunity too good to pass up.

Enlarge / Phages on the surface of a bacterial cell. (credit: Dr. Graham Beards )

In many cases, viruses manage to spread so readily because they're so compact, allowing hundreds of thousands of viral particles to explode from a single sneeze. That compact size comes in part from their limited needs. Since viruses use parts of their host cells for much of what they need to do, even the more complicated viruses tend to only need a few dozen specialized genes to do things like evade the immune system or remain dormant in cells. In fact, complexity would seem to go against one of virus' evolutionary advantages: the ability to make lots of copies of itself very quickly.

So it was a bit of a surprise to find that there are giant viruses that carry far more genetic material than they seemingly need. All cells carry the machinery needed to make proteins so, at most, viruses typically carry just a few genes that direct the machinery to focus on the virus' needs. But the giant viruses seemed to carry replacements for much of the basic machinery itself. Those viruses were attacking complicated cells, with a lot of internal structures and many complex biological processes going on in different locations. Maybe carrying all those seemingly superfluous parts was advantageous in that context.

Or possibly not. In a study released today, researchers describe a large collection of giant viruses that target bacteria. While smaller than some of the largest eukaryotic viruses, they're not that much smaller. And given that they infect bacteria, the genomes of the newly described viruses may be a substantial fraction of the size of their host's genome.

Enlarge / This artist's reconstruction shows "Lola" as a young girl, with items that likely would have been part of her daily life, but we have no way of knowing how old she was when she chewed and discarded the lump of birch-bark pitch. (credit: Tom Björklund)

5,700 years ago, a woman in what is now Denmark chewed a lump of birch-bark pitch for a while and then dropped it. Millennia later, the DNA she left behind reveals her entire genome, a census of the bacteria living in her mouth, and a few hints about a recent meal.

Meet “Lola”

If you’re a hunter-gatherer who needs to haft a stone tool, birch-bark pitch makes a handy adhesive, but you might have to chew it to make it pliable enough to work with. Pitch is watertight and contains an antiseptic compound called betulin, so it’s great at preserving DNA. In fact, archaeologists in Scandinavia have found more human DNA in bits of chewed pitch than they have in skeletons (which have been relatively rare at prehistoric Scandinavian sites we've studied thus far).

But this is the first time researchers have managed to sequence an ancient person's whole genome from a lump of chewed pitch. Only about a third of the DNA bioarchaeologist Hannes Schroeder, of the University of Copenhagen, sampled was human; the other 68 percent came from the ancient woman’s microbiome and traces of a prehistoric meal. This single discarded piece of ancient chewing gum tells us that the ancient woman, who Schroeder and his colleagues have nicknamed Lola, was probably lactose intolerant, ate duck and hazelnuts, and may recently have had pneumonia. She also had blue eyes, dark brown hair, and dark skin.

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A widely circulating piece of Android malware primarily targeting US-based phones used a clever trick to reinfect one of its targets in a feat that stumped researchers as to precisely how it was pulled off.

xHelper came to light last May when a researcher from security firm Malwarebytes published this brief profile. Three months later, Malwarebytes provided a deeper analysis after the company’s Android antivirus app detected xHelper on 33,000 devices mostly located in the US, making the malware one of the top Android threats. The encryption and heavy obfuscation made analysis hard, but Malwarebytes researchers ultimately concluded that the main purpose of the malware was to act as a backdoor that could remotely receive commands and install other apps.

On Wednesday, Malwarebytes published a new post that recounted the lengths one Android user took to rid her device of the malicious app. In short, every time she removed two xHelper variants from the device, the malware would reappear on her device within the hour. She reported that even performing a factory reset wasn't enough to make the malware go away.