Your body is home to about 100 trillion bacteria and other microbes, collectively known as your microbiome. Naturalists first became aware of our invisible lodgers in the 1600s
, but it wasn’t until the past few years that we’ve become really familiar with them. This recent research has given the microbiome a cuddly kind of fame.
We’ve come to appreciate how beneficial our microbes are — breaking down our food, fighting off infections and nurturing our immune system. It’s a lovely, invisible garden we should be tending for our own well-being. But in the journal Bioessays, a team of scientists has raised a creepier possibility.
Perhaps our menagerie of germs is also influencing our behavior in order to advance its own evolutionary success — giving us cravings for certain foods, for example.
Maybe the microbiome is our puppet master. [more inside]
In March 2012, inspectors from the U.S. Department of Agriculture uncovered a problem in Elgin, Texas. Beef sausage from a small family-run meat processor appeared to have been contaminated with a nasty bacterium called Listeria monocytogenes. The bug can make people sick and, in rare cases, be deadly. The processor had to recall more than a ton of sausage. It’s the kind of story that strikes terror in the hearts of other sausage peddlers, including Mike Satzow, so he uses phages to keep his small company's sausages safe to eat.
The Norovirus: A Study in Puked Perfection
, "Each norovirus carries just nine protein-coding genes (you have about 20,000). Even with that skimpy genetic toolkit, noroviruses can break the locks on our cells, slip in, and hack our own DNA to make new noroviruses. The details of this invasion are sketchy, alas, because scientists haven’t figured out a good way to rear noroviruses in human cells in their labs. It’s not even clear exactly which type of cell they invade once they reach the gut. Regardless of the type, they clearly know how to exploit their hosts. Noroviruses come roaring out of the infected cells in vast numbers. And then they come roaring out of the body. Within a day of infection, noroviruses have rewired our digestive system so that stuff comes flying out from both ends." [more inside]
Deciphering the Tools of Nature’s Zombies
: The ability of parasites to alter the behaviour of their hosts fascinates both scientists and non-scientists alike. One reason that this topic resonates with so many is that it touches on core philosophical issues such as the existence of free will. If the mind is merely a machine, then it can be controlled by any entity that understands the code and has access to the machinery. This special issue of The Journal of Experimental Biology highlights some of the best-understood examples of parasite-induced changes in host brain and behaviour, encompassing both invertebrate and vertebrate hosts and micro- and macro-parasites
. Full issue annotated inside: [more inside]
Cosmos: A Personal Voyage
is a thirteen-part television series of one hour shows written by Carl Sagan
, Ann Druyan
, and Steven Soter
, that was aired at the tail end of 1980 and was - at the time - the most widely watched series in the history of American public television. It is best introduced by an audio excerpt of one of his books, The Pale Blue Dot
. Inside is a complete annotated collection of the series. [more inside]
One of the many problems farmers of various kinds of legumes need to deal with is the pea aphid
. They reproduce incredibly fast and live by sucking the sap out of the plants, an electron micrograph of one in action
. However, while they are terrifying parasites of legumes, they have their own yet more horrific parasites, a parasitoid
wasp. Here is a really nice close up picture of one doing its thing
, a video of the act
, and here is a brain meltingly horrific video of a dissection of the mummified aftermath 8 days later
. Essentially, these wasps deposit their eggs in a pea aphid and the growing larva feeds on it, developing there for about a week, and then consuming the host from the inside out
like a Xenomorph
. When it’s done, the wasp larva dries the aphid’s cuticle into a papery brittle shell and an adult wasp emerges from the aphid mummy. Legume farmers love them, and you can even order their mummies online these days
. However, farmers noticed that the wasps didn't work as effectively on all of the aphids, and so researchers went to work figuring out why. It turns out that all aphids have a primary bacterial endosymbiont living inside their cells, in addition to and just like a mitochondria, and that many have some combination of five other secondary endosymbionts
. Interestingly, two of those other five, Hamiltonella defensa
and Serratia symbiotica
have been shown to confer varying levels of resistance to the parasitoid wasp, allowing the aphid to survive infection. However, it turns out that there is yet one more layer to this story, [more inside]
"Why do parasites harm their hosts? Conventional wisdom holds that because parasites depend on their hosts for survival and transmission, they should evolve to become benign, yet many parasites cause harm. Theory predicts that parasites could evolve virulence (i.e., parasite-induced reductions in host fitness) by balancing the transmission benefits of parasite replication with the costs of host death. This idea has led researchers to predict how human interventions—such as vaccines—may alter virulence evolution, yet empirical support is critically lacking." Two papers
demonstrate empirical evidence for related models predicting the origin of virulence: [more inside]
There has been a new discipline developing in molecular biology for some time now, Bioanimation! Projects have ranged in size from WEHI
's colossal compilation
to Harvard Biovision
's magnum opus "Inner Life of the Cell"
to commercially produced masterpieces
to smaller projects by university PIs and enthusiasts. much [more inside]