It’s not Sunday morning, and I’m not looking at editorial pages. Instead, this is intended as a review of articles appearing this week in science journals, including but not limited to Nature, Science, the Proceedings of the National Academy of Sciences, Nature Communications, and a whole stack of open access journals. Occasionally there will also be items lifted from the popular press, such as the dark matter article here which was originally published in Forbes. But the idea, for the most part, it to hang with the peer-reviewed.
The purpose of this article is a little different than that of the Abbreviated Pundit Round-up. Many of the articles included are highly technical. For example, the ant fungus bit at the top of the heap is titled “Three-dimensional visualization and a deep-learning model reveal complex fungal parasite networks in behaviorally manipulated ants” and that’s almost certainly the lowest density headline of the bunch.
Being a Doctor of Nothing, and having collected my last real science degree in 1979 (yes, that sounds as bad to me as it does to you), my intention here isn’t to play “expert” on any topic. Just think of me as a translator — one who went shakily through many of these articles with a dictionary in hand. The goal is to show you real scientists doing real work — both with articles that provide breakthroughs and with those producing results that might lead to breakthroughs down the line.
I also intend to toss in some pieces that show scientists going at each other’s ideas hammer and tongs, like the bit on using genetics to suss out the relationships of fossil mammals. Because that kind of article — a rebuttal to a rebuttal to a proposal — gives a sense of how science works … and also why suggestions that scientists as a whole would engage in some kind of unified conspiracy is so silly.
And … yeah. So, that’s the idea. If it works for you, let me know. If not, let me know. And if it’s somewhere in between … tell me how we can either get it to “I love it” or “I hate it” because the mushy middle sucks.
But let’s start off trying for “I love it.” Come on in.
Zombie ant fungus is even stranger than you thought
There is a fungus that causes ants to climb until they can’t climb any further. Then the ants swell, explode, and spread more of the fungus, starting the process all over again.
Even if you were already aware of this little horror of nature, there’s still news — it’s even worse than it sounds. A large interdisciplinary team including entomologists, infectious disease specialists, and computer scientists has put together a better look at how this “zombie” infection works.
Electron microscopy and 3D reconstructions of host and parasite tissues reveal that this fungus invades muscle fibers throughout the ant’s body but leaves the brain intact, and that the fungal cells connect to form extensive networks.
Rather than invading the ant’s brain and effecting its behavior in that way, the fungus directly connects the muscles into a network, bypassing the brain. Then the fungus itself executes the climbing instructions, coordinating the movement of the ant’s body. The ant’s brain is untouched, leaving the brain as a disconnected ghost in the hijacked shell.
It’s both horrible to contemplate if the ant has any sense of self (which, thankfully, it probably does not) and extraordinary in the sense that a fungus is capable of creating a network that manipulates an animal not by just upsetting some portion of its nervous system, but by essence creating it’s own alternative brain.
Alternatives to dark matter less likely
The Bullet Cluster is composed of a pair of colliding galaxies over three and a half billion light years away. They’re interesting both because they provide a chance to look at the results of two galaxies, each with billions of stars, intersecting. But beyond that they’re also one of the best illustrations of that great astrophysical quandary, Dark Matter.
Dark matter doesn’t have anything to do with color. It’s simply a term to denote that—not just in distant galaxies, but everywhere we look—there appears to be an excess of gravity. The way in which distant objects in the universe move simply suggests that there’s a lot more something there than we can see. And it’s not like that something is merely material that’s dark in the traditional sense. It’s material that seems to only be detectable in the form of that excess gravity — something that’s particularly observable in locations like the Bullet Cluster.
The individual galaxies present within the clusters, like two guns filled with bird shot fired at one another, passed right through one another, as the odds of a collision were exceedingly low. However, the intergalactic gas within each cluster, largely diffuse and making up the majority of the normal matter, collided and heated up, emitting X-rays that we can see today. But when we used our knowledge of General Relativity and the bending of background light to reconstruct where the mass must be, we found it alongside the galaxies, not with the intra-cluster matter. Hence, dark matter must exist.
But the Bullet Cluster has more to tell us than just that there’s some extra gravity out there. There are actually several competing theories about where that gravity comes from (I personally like the idea that gravity may be leaking in from other universes). And that’s where the Bullet Cluster comes in helpful again. Because measurements of the way light is bent by gravity in the area suggest help to make alternatives to dark matter less likely. Darn it.
Fossil mammals refuse to get in line
For more than a century, scientists sorted the relationships of living animals by their physical features and by connecting their relatives in the fossil record. But more recently another tool has been added in the form of comparing genetic sequences.
By looking at differences in genes, evolutionary biologists can not only sort out which creatures are most closely aligned, but get a very good sense of how long ago various branches of plants and animals separated from each other. This kind of examination has led to some surprising realignments of relationships between groups. But it’s also resulted in some frustrating issues among mammals in which three groups in particular — toothed whales, lemurs, and golden moles — fail to fit neatly into the scheme.
The ongoing argument over how these issues should be resolved … is an ongoing argument, and a good example of how scientists take swings at each other’s positions in an process that, usually, brings improved accuracy over time. In fact, there are two articles in these week’s PNAS, arguing opposing points of the discussion.
Mexico ends program to capture rare dolphin
There are probably fewer than thirty vaquitas left on the planet. The short-snouted dolphins are native to the Gulf of California, where they’ve been nearly driven to extinction by fishermen using illegal gillnets.
A joint program between conservationists and the Mexican government has been underway to capture some of the surviving vaquitas. But after after multiple deaths among captured animals, the program to bring the vaquitas into captivity is ending.
Continually plagued by bad weather, the project was halted because the vaquitas reacted poorly to being placed in the sea pen designed to house them. That persuaded researchers that capturing the animals was not worth the risk. “There’s nothing worse than having an animal die in your hands,” says Frances Gulland, the lead VaquitaCPR veterinarian and a scientist at the Marine Mammal Center in Sausalito, California.
The hope had been to move as many as a dozen animals to a temporary sanctuary. Instead Mexico will attempt to step up enforcement of fishing laws in a last ditch effort to save the handful of survivors.
Giving mosquitoes a disease makes them less likely to spread malaria
Wolbachia is a bug disease. More definitively, it’s a gram-negative bacteria which infects arthropods, but doesn’t infect birds or mammals. In many insects, Wolbachia is harmless. Some can’t even reproduce without its help. But mosquitoes aren’t typically infected by this genus of bacteria.
A team from the National Institutes of Health, working with colleagues from Mali, discovered a group of mosquitoes in Burkina Faso that carried a species of Wolbachia. And they made what could be a key discovery about these bug-infected bugs.
Experimental infections indicate that wAnga-Mali infection reduces malaria transmission by a mechanism that affects sporozoites and opens the possibility of exploring the introduction of Wolbachia into natural populations of anophelines as a strategy to reduce disease transmission.
That is, mosquitoes carrying this particular Wolbachia had a harder time passing on malaria to humans. Which opens up a new path to combating a disease that affects millions each year.
Bacteria as the power supply for hybrid nanomotors
The promise of nanotechnology — machines so small they’re microscopic — had often been thwarted by the ability to build and power such tiny devices. Scientists can assemble incredibly small structures atom by atom, but such constructions are often difficult to create and unstable. In particular, they’re hard to power. Batteries aren’t the most efficient means of storing energy at any size, and building them in super-tiny sizes is super difficult.
So … a team from the Institute of Nanotechnology in Rome has bypassed both the difficulty and inefficiency of building a mechanical power source, by harnessing a biological one. You’ve heard of a treadmill for shrimp? They’ve built an engine powered by bacteria.
Swimming bacteria adhere to the surface and act as micropropellers, which can also be switched on and off by using chemical or light signals.
The system they’ve designed actually captures bacteria and locks them into a design that looks like the world’s tiniest water wheel. Go take a look. See the little indicator on the picture that shows 10 micrometers? For comparison, a single red blood cell is about 8 micrometers, while a single human hair is about 100 micrometers in diameter.
Similar engines have been tried before, but have proved difficult both to manufacture and to reliably control. The team from Rome claimed to have solved both these issues — which could prove to be quite a breakthrough.