Enlarge / SEM Micrograph of a tardigrade, more commonly known as a "water bear" or "moss piglet." (credit: Cultura RM Exclusive/Gregory S. Paulson/Getty Images)

Since the 1960s, scientists have known that the tiny tardigrade can withstand very intense radiation blasts 1,000 times stronger than what most other animals could endure. According to a new paper published in the journal Current Biology, it's not that such ionizing radiation doesn't damage tardigrades' DNA; rather, the tardigrades are able to rapidly repair any such damage. The findings complement those of a separate study published in January that also explored tardigrades' response to radiation.

“These animals are mounting an incredible response to radiation, and that seems to be a secret to their extreme survival abilities,” said co-author Courtney Clark-Hachtel , who was a postdoc in Bob Goldstein's lab at the University of North Carolina at Chapel Hill, which has been conducting research into tardigrades for 25 years. “What we are learning about how tardigrades overcome radiation stress can lead to new ideas about how we might try to protect other animals and microorganisms from damaging radiation.”

As reported previously , tardigrades are micro-animals that can survive in the harshest conditions: extreme pressure, extreme temperature, radiation, dehydration, starvation—even exposure to the vacuum of outer space. The creatures were first described by German zoologist Johann Goeze in 1773. They were dubbed tardigrada ("slow steppers" or "slow walkers") four years later by Lazzaro Spallanzani, an Italian biologist. That's because tardigrades tend to lumber along like a bear. Since they can survive almost anywhere, they can be found in lots of places: deep-sea trenches, salt and freshwater sediments, tropical rain forests, the Antarctic, mud volcanoes, sand dunes, beaches, and lichen and moss. (Another name for them is "moss piglets.")

Enlarge / The plague bacteria, Yersina pestis , is a close relative of the toxin-producing species studied here. (credit: Callista Images )

Life-forms with no brain are capable of some astounding things. It might sound like sci-fi nightmare fuel, but some bacteria can wage kamikaze chemical warfare.

Pathogenic bacteria make us sick by secreting toxins. While the release of smaller toxin molecules is well understood, methods of releasing larger toxin molecules have mostly eluded us until now. Researcher Stefan Raunser, director of the Max Planck Institute of Molecular Physiology, and his team finally found out how the insect pathogen Yersinia entomophaga (which attacks beetles) releases its large-molecule toxin.

They found that designated “soldier cells” sacrifice themselves and explode to deploy the poison inside their victim. “YenTc appears to be the first example of an anti-eukaryotic toxin using this newly established type of secretion system,” the researchers said in a study recently published in Nature.

Enlarge (credit: alex-mit )

Human brains (and the brains of other vertebrates) are able to process information faster because of myelin, a fatty substance that forms a protective sheath over the axons of our nerve cells and speeds up their impulses. How did our neurons evolve myelin sheaths? Part of the answer—which was unknown until now—almost sounds like science fiction.

Led by scientists from Altos Labs-Cambridge Institute of Science, a team of researchers has uncovered a bit of the gnarly past of how myelin ended up covering vertebrate neurons: a molecular parasite has been messing with our genes. Sequences derived from an ancient virus help regulate a gene that encodes a component of myelin, helping explain why vertebrates have an edge when it comes to their brains .

Prehistoric infection

Myelin is a fatty material produced by oligodendrocyte cells in the central nervous system and Schwann cells in the peripheral nervous system. Its insulating properties allow neurons to zap impulses to one another at faster speeds and greater lengths. Our brains can be complex in part because myelin enables longer, narrower axons, which means more nerves can be stacked together.

Enlarge (credit: Nathan Devery )

Cellulose is the primary component of the cell walls of plants, making it the most common polymer on Earth. It's responsible for the properties of materials like wood and cotton and is the primary component of dietary fiber, so it's hard to overstate its importance to humanity.

Given its ubiquity and the fact that it's composed of a bunch of sugar molecules linked together, its toughness makes it very difficult to use as a food source. The animals that manage to extract significant calories from cellulose typically do so via specialized digestive tracts that provide a home for symbiotic bacteria—think of the extra stomachs of cows and other ruminants.

Amazingly, humans also play host to bacteria that can break down cellulose—something that wasn't confirmed until 2003 (long after I'd wrapped up my education). Now, a new study indicates that we're host to a mix of cellulose-eating bacteria, some via our primate ancestry, and others through our domestication of herbivores such as cows. But urban living has caused the number of these bacteria to shrink dramatically.

Enlarge (credit: Tanja Ivanova )

In the US, for orange juice to be labeled as such, it must be 90 percent sweet orange, or Citrus sinensis . Thus, citrus producers in the US have long planted 90 percent Citrus sinensis. But this cultivar is extremely susceptible to the bacteria that causes citrus greening disease, which has devastated the near-monocultural Florida crop. There is as yet no way to control the disease; the most effective way to deal with it would be to find citrus cultivars that are resistant to it and breed them with sweet orange to grant them disease resistance.

Sweet oranges are a hybrid of mandarin and pomelo and are not especially genetically diverse. Any disease-resistant citrus we know of, however, does not taste like sweet orange, so breeding with it will produce fruit and juice with off flavors. It has been difficult to define and quantify those off flavors, though, because it has been difficult to define and quantify the components essential for proper orange flavor.

Now, researchers at the USDA Agricultural Research Service performed a comprehensive chemical evaluation of 179 different citrus combinations—oranges, mandarins, and assorted hybrids—and cross-referenced their chemical compositions with evaluations of orange and mandarin flavors in juice samples performed by a “trained panel.”