I don’t need no badges, but I like them anyway

Here are my merit badges from Order of the Science Scouts of Exemplary Repute and Above Average Physique.

Troop badge: Okay, I had to fudge a little on this one, because I kind of am into the business of total world domination. (I’m Dr. Zen, for cryin’ out loud! A name like that, and people have expectations...)

 Talking science badge: I’m an instructor. I’m paid to talk science.

 “I blog about science” badge: You’re reading the evidence that I’ve earned this one. I also have the Marmorkrebs blog. Speaking of which, that qualifies me for...

 “Inordinately fond of invertebrate” badge: I’ve worked with octopus, so I guess I can’t bitch about the symbol being a cephalopod instead of a crustacean.

“I’ve done science with no conceivable practical application” badge: Sometimes, you have to be honest.

 “Cloner” badge: Marmorkrebs again.

 “Experienced with electrical shock” badge (Level I)": Easy one for someone who does electrophysiology. And relax, it's only to small bits of tissue, not entire animals.

“Science has forced me to seek medical attention” badge: It was a loss of footing on some rocks while holding glass.

“Somewhat confused as to what scientific field I actually belong to” badge: Do I study a neuroscience, neurobiology, ethology, neuroethology, evolutionary biology, carcinology, zoology...? It's all biology, I suppose.

“World’s foremost expert on an obscure subject” badge: Nobody knows sand crab digging like this guy.

“I’ve eaten what I study” badge: In my defense, I have not eaten my subjects anywhere near as much as other people would like to eat my subjects. I don’t much care for seafood. And I think I’ve only had the same exact species as I’ve published on once (a small taste of Balmain bugs that I didn’t order).


“I actually grew up and became a marine biologist” badge: I do work with a lot of animals that need salt water.

“Broken heart for science” badge: Some stories are not for telling.

“I somehow convinced someone to part with a lot of money for science” badge (Level I): My REU program.

“I use twitter to spread science” badge: I’m DoctorZen over there.

Update, 22 June 2013:

The “I attended ScienceOnline and connected to a web of science leaders & communicators” badge. 2013!

A fellow traveller removing waste

As I’ve been struggling with the curse of paper in my own office this week (still not done), it’s so good to read that I’m not the only one. I particularly like the disposal highlights list.

How did bats get underfoot?

You think snakes on a plane are crazy? Bats! On the ground!

Before humans arrived on New Zealand, the only mammals living there were bat species. One of only two remaining native Kiwi mammals is Mystacina tuberculata, the lesser short-tailed bat.

This bat’s second claim to fame is that it walks. Only one other bat, the vampire bat, does this, and vampire bats don’t spend anywhere near the same amount of time on the ground as M. tuberculata does. That there are no other land mammals in New Zealand has been suggested as a reason that these bats are such ground huggers. This was suggested by analogy with birds, which are often flightless on islands that don’t have large predators. Indeed, New Zealand provides an example here with the kakapo, which Douglas Adams famously described as the world’s largest and least able to fly parrot.

This is an appealing idea, but tricky to test. You can’t really test an evolutionary hypothesis with only one species, and there are no other species in this bat’s family.

This new paper by Hand and colleagues brings in a second species in this family by way of the fossil record. Importantly, the fossil, Icarops aenae, was not found in New Zealand, but in Australia. Australia famously has an abundant array of marsupials mammals, so bats and birds in this environment would be expected to remain mostly skyborne.

Now, even with the help of an online digital skeleton of this species, I’m way out of my depth with the anatomy described in this paper. (Hey, I’m an invertebrate biologist. This has fur and a backbone. Sue me.) But I appreciate the logic of the analysis.

Based on various molecular and fossil evidence, the fossil predates split that leads to the genus Mystacina in New Zealand. Thus, if walking was due to the predator=free environment provided by New Zealand, then you would expect limb morphology typical of other bats.

The fossil limb shows a lot of ground-dwelling adaptations.

It’s not a smoking gun killing the “lack of predators” hypothesis by any means. There are a raft of assumptions about distribution, timing of divergence, that are important in interpreting the results. Plus, it’s entirely possible that a lack of predators allowed an already ground-dwelling group of bats to go even further towards a land loving lifestyle. Nevertheless, it seems that this line of bats may have already touched down (in the ecological sense of their habitat) before they touched down (in the geographic sense) in New Zealand.

Also, these lesser short-tailed bats are good candidates to evolve into the terrifying predators that will outcompete humanity in the distance future, as seen on the television show Primeval. Primeval's predators are fast on their feet descendents of bats that don’t fly.

Which goes to show that New Zealand could be the source of the things that kill us all. ;)

Reference

Hand SJ, Weisbecker V, Beck RMD, Archer M, Godthelp H, Tennyson ADJ, Worthy TH (2009). Bats that walk: a new evolutionary hypothesis for the terrestrial behaviour of New Zealand's endemic mystacinids BMC Evolutionary Biology, 9 DOI: 10.1186/1471-2148-9-169

DOI not working yet; click here for abstract.

Science is my sword

Previously, I argued that science was never meant to be the reserve of the super intelligent. How did it become viewed as something that was elitist instead of democratic?

Science is like a sword: effective in the hands of the most rank and unskilled amateur, devastating when wielded by a skilled master.

It’s pointless to ask if successful researchers owe more to scientific methods or their intelligence, since those with both will outdo those who have only one.

Science has become practiced by a few by virtue of its own success. As the questions to be tested have become ever more subtle, it has taken more and more time just to establish the working knowledge necessary not to duplicate previous work. Also, the types of equipment needed to answer many of these very subtle questions are often beyond the realm of what most people are able to get their hands on.

Even MythBusters, one of the best examples of DIY science there is right now, often has resources beyond what the average person can cough up. Sure, building a giant ball of Lego is easy in principle... until you realize how many pieces are needed. Just because you know what experiment to do doesn’t mean you can pull it off.

Tuesday Crustie: Briney black

Brine shrimp (Artemia monica).

From user djpmapleferryman on Flickr, used under a Creative Commons license.

Truth for the hard of thinking

Science is hard, according to common expression. After all, when something is easy, what is it compared to? “It ain’t rocket science,” which ends the race in a dead heat with, “It ain’t brain surgery.”

And this feeds into people’s feelings of inferiority where science is concerned. There is this idea that science can only be practiced by the very bright.

This is strange, given that arguably, science was conceived as a way that anyone could find truth about matters. Let’s compare science to the other methods of finding truth that preceded it.

Philosophy was a way of getting at truth that was always seen as an intensely rarefied and intellectual endeavor. In other words, it really was only for smart people. The first Western philosopher, Thales (pictured), was said to have fallen into a well while contemplating the stars. The maiden who rescued him asked how he could know what was in the heavens when he did not know the ground at his feet.

Religion was another way of uncovering truth. But much religion revolves around revelation. Those not blessed with revelation had to hope to be blessed with faith. But those not blessed with faith were kind of out of luck.

Science was a way for both smart and stupid people to get at the truth.

Not very bright or blessed by the divine? Here’s what you do. Look for patterns. Stick to numbers and things that are verifiable. Make predictions. Do tests. Compare the outcomes with predictions. Do that, and you will get answers to your questions. In other words, science spelled out methods that anyone could use. In that sense, science is emphatically not the elitist exercise it’s come to be seen as.

How did science become seen as something that only geniuses could do? That’s some idle speculation for another post.

Quote of the moment, July 2009 edition

After spending most of the weekend chucking paper from my office and still having a long way to go before I hit anything approaching “clean,” this quote from Star Trek: Deep Space Nine felt appropriate:

Humans have a compulsion to keep records and files — so many, in fact, that they have to invent new ways to store them microscopically. Otherwise their records would overrun all known civilization.

(For the sticklers, that’s Constable Odo in the episode “Necessary Evil.”)

Indelible marks

I don’t remember the Apollo 11 mission.

I was rather young at the time, when memories tend not to solidify into more permanent things. But like the astronaut’s footprints on the moon, the mark the Apollo left on me was indelible. The mission that the world is celebrating and remembering spurred my interest in science and shaped my consciousness in ways that I cannot even begin to imagine.

I had the publicity picture of the Apollo 11 astronauts here on my wall. I wrote to NASA and got a big package of stuff from them that I poured over. I visited Cape Canaveral when I was 10 on family vacation. I was fascinated by the thought of space travel, and the possibility of routine flights to the Moon and a mission to Mars. At the time, it seemed it might happen in my late 20s...

Needless to say, I’m not in my late 20s. An opportunity was missed after Apollo. The International Space Station is wonderful, but it seems such a tentative step after the astonishing ones of Apollo. I don’t think there has been an achievement after the moon missions that has had the same impact on kids that NASA’s manned space program had on me.

I’m not alone. A new Nature survey found that half of the respondents said the Apollo missions inspired them to pursue science.

How to deny anything

As someone who has an interest in skepticism’s idiot cousin, denialism, I’ve learned that the topic changes, but the patterns of arguments are amazingly consistent. Over at the Tetrapod Zoology blog, Darren Niash shows that these patterns of arguments aren’t restricted to conspiracy theorists. Sadly, scientists with an axe to grind will pull them out too. The paper in question concerns the relationship between birds and dinosaurs.

Here’s a short list of techniques that you too can use anytime you find the evidence against your position!

• Never assert anything. Your goal is only to find shortcomings in your opponent’s claims. If It doesn’t matter if your criticisms are inconsistent as long as you’re criticizing.


• Ignore relevant information. Just pretend it doesn’t exist. Go back and pull out references from decades ago that could not have taken new information into account.


• Act like you’re being suppressed. Say there are a lot of people with vested interests who don’t want your ideas to get out. Even though we live in a time that makes it almost impossible to silence anyone.

The Scincus that swims through sand like a snake

In old Disney comics, Scrooge McDuck would often be shown swimming in his money bin, diving through the coins like an exuberant dolphin. Leading many young minds to wonder, “How does he do that?” Coins don’t move like water; they’re arguably closer to something like dry sand.

A new paper shows that one lizard may not be able to get through McDuck’s nine cubic acres of money, but it comes a lot closer than anything else we know about so far. Scincus scincus is a cute little lizard a few inches long, whose common name, “sandfish,” tells you a lot about its behaviour.

These lizards dive through sand like Unca Scrooge dives through silver dollars. Previously, people had suspected they paddled though the sand using their legs, much like some fish might use their pectoral fins in addition to their trunk. The problem with testing an hypothesis like this is that sand has this irritating property of being opaque – a problem I had significant personal experience with, I might add. I solved it using wires and recording from muscles.

Maladen and colleagues went to high speed X-ray videography. I suspect that they probably spent a long time trying to find a combination of materials with the right combination of transparencies to X-rays, but they did it. And they found that the sandfish might better be described as a sand eel. The swimming that these lizards did (rather fast, about 10 cm per second) was entirely driven by the trunk. The legs were simply held in position and didn’t play a part after the animal got under the sand. There are some fantastic movies of this in the supplemental material.

From here, the paper looks into the physics of the situation. To be entirely honest, it’s fairly difficult stuff for me. When they write:

It is remarkable that η does not change significantly
for different φ...

I have to take their word for the remarkable nature of those Greek letters. I am rather hoping that some physics blogger out there can walk through the granular materials math in this paper.

Maladen and company end by noting that they have helped to show how organisms can exploit the alternately solid-like and fluid-like properties of sand to move through it. And this is indeed a substantial achievement, but what if you turn that around? If animals can do this, why haven’t more done so? To the best of my knowledge, no animals besides other lizards swim through sand like sandfish do. And I doubt that this is due to visibility problems; I think it is just that digging organisms are relatively rare.

There is so much nice stuff in this paper that I might forgive them for citing a sand crab digging paper from the 1970s instead of more recent and more detailed articles.

Reference

Ryan D. Maladen, Yang Ding, Chen Li, & Daniel I. Goldman (2009). Undulatory Swimming in Sand: Subsurface Locomotion of the Sandfish Lizard Science, 325 (5938), 314-318 DOI: 10.1126/science.1172490

Sandfish photo by user thew...g's on Flickr. Used under Creative Commons license.

No spikes in this worm: Motor neurons without action potentials

If you know a little bit about neurons, even really basic stuff, you probably know that neurons send signals with action potentials (a.k.a. spikes). What fewer people know is that there is great diversity in how neurons signal. There are many sensory neurons and interneurons that work entirely without action potentials.

I once asked my Ph.D. supervisor, Dorothy Paul, “Is there such a thing as a non-spiking motor neuron?” Dorothy did most of her research working on non-spiking sensory neurons in the west coast mole crab, Emerita analoga. She didn’t give me the answer, but told me it was an excellent question and I should think about it. Some time later, I heard another student asking the same question to another researcher at a poster at a Society for Neuroscience poster, and the person said, “No.”

This paper says the answer is, “Yes.” There are non-spiking motor neurons.

Qiang Liu and colleagues did their research on the little nematode worm, Caenorhabditis elegans, and were able to take advantage of the huge knowledge of the genetics of this beast, and our ability to manipulate this animal’s genes. They recorded the output of muscle cells using standard electrical recordings, but instead of using electricity to stimulate the motor neurons controlling those muscles – the classical way of doing things – they genetically engineered the worm.

The authors were able to make the worms express a protein called channelrhodopsin in certain neurons. Rhodopsin is a visual pigment that responds to light. When you flash a light on these worms (did I mention they’re transparent?), the channelrhodopsin opens up a channel that allows electrical current to flow into the neuron. Thus, you can use a flash of light to fire neurons of your choosing.

In neurons with action potentials, activity is like a light switch: flipping the switch harder doesn’t make the light from the bulb any brighter. A key set of data is to increase the light intensity stimulating the motor neurons (shown by different line colours in the figure here), and record the response of the motor neurons. If there was a classic action potential in the motor neuron, you’d expect there to be no response until you hit a threshold, and always the same response in the muscle. But the effect is more like a dimmer than a switch: the greater the light intensity to the motor neurons, the more the muscles responded. This is just what you would as expect for a non-spiking neuron.

There rest of this paper revolves around characterizing the synaptic connections between motor neuron and muscle in much more detail. It mainly looks at how the strength of connections between the cells change with repeated stimulation of the motor neurons.

This is not the first demonstration of non-spiking motor neurons. Another nematode, Ascaris, probably claimed that honor two decades ago (Stretton and Davis 1989). So while I did learn quite a bit from this paper (I didn’t know about the Ascaris work) and am impressed with the techniques in this paper, I am still a bit puzzled as to why it’s in Proceedings of the National Academy of Science (PNAS). PNAS is one of those exclusive high profile journals, sometimes disparagingly called a “glamour mag,” that publishes on what it considers to be “high impact” science. I guess this paper made it in because C. elegans has become such an important model organism, because this paper doesn’t show any previously unknown or unexpected kind of phenomenon.

But considering that the Ascaris work was published before I asked my supervisor about non-spiking motor neurons, I suppose that the phenomenon could stand to be much better known in the neurobiology community.

References

Liu Q, Hollopeter G, Jorgensen E. 2009. Graded synaptic transmission at the Caenorhabditis elegans neuromuscular junction Proceedings of the National Academy of Sciences 106(26): 10823-10828. DOI: 10.1073/pnas.0903570106

Davis RE, Stretton AO. 1989. Signaling properties of Ascaris motorneurons: graded active responses, graded synaptic transmission, and tonic transmitter release. J Neurosci 9(2):415-425. http://www.jneurosci.org/cgi/content/abstract/9/2/415

Interest and inferiority

A short but insightful point about science education from the I Was Lost But Now I Live Here blog:

(T)he reasons people claim to be uninterested in science fall into two categories: problems of interest (”it’s boring”, “it’s irrelevant”, “it’s hard”, etc), and problems of inferiority (“I’m not smart enough”, “it’s not for someone like me”, “it doesn’t match what I believe”, etc). If you can frame the problem correctly, you can form a better solution. For example, if the problem is that it requires too much sustained concentration (i.e. “it’s hard”), then present the science in shorter snippets. If the problem is that the audience feels intellectually inferior, then reassure them that the material isn’t supposed to easy. I think the most important ideas we can convey to non-scientists are that science is about solving mysteries, failure is part of the process, and science is intrinsically a human endeavor. In fact, I started thinking that instead of tricking people into liking science, we should get more people to like the scientists themselves.

Comments for first half of July

Uncertain Principles has a post on science popularization which I threw in my 2 cents.

Over at the Sciencewoman blog, I put on my Grad Program Coordinator hat to comment on, “What should I look for in a grad program?”

And the recurring question of lobster pain comes up again; I provide references.

Deep Sea News asks how conferences should treat bloggers, and I answer.

I add corny geek jokes to a list. Cluelessly added one that was already there...

And finally, I join a post railing against the incorrect use of homology.

Do you know this man?

Recognize this nattily attired fellow? No cheating now!


You don’t?

Even though he was responsible for one of Time magazine’s top 100 novels in 2005? Shouldn’t you know someone who was responsible for a major, critically acclaimed work of art that is credited with revolutionizing the medium?

I mention all this because in discussions about science, science outreach, science education, and all the various permutations thereof, it is often lamented that when asked to name a living scientist, the general public will often retreat to naming someone dead, or naming someone who isn’t a scientist. (Yeah, that’s right, I’m lookin’ at all you people who say, “Al Gore.”)

But maybe we have unrealistic expectations there. There are a lot of creators who have a huge impact on our world who don’t get a second glance as they walk down the street. Can you name a single living chef running a five star restaurant? Or a zillion other occupations? Can you name a single living speech therapist?

For that matter, I was browsing through a blog post and read that E.M. Izhikevich is “one of the most important people in neuroscience right now.” This surprised me just a little, since I do neurobiology, but I’d never heard of this person. Okay, neuroscience is a big field, and I’m in a tiny little patch of that big field, but still, I do try to keep up.

Maybe we should not expect scientists to be more famous than other professions. I’m reminded of Whoopi Goldberg, who at the end of end of Inside the Actor’s Studio, talked about fame: Fame was accidental, she said, and so it was unrealistic to have “Become a famous actor” as a goal. But she noted that fame had nothing to do with being a great actor.

Maybe we should concentrate on people knowing and enjoying the work, and not be trying to create a cult of personality around researchers. We ain’t never going to be rock stars. It’s not our job.

P.S. – For the record, the gentleman pictured is Dave Gibbons, the artist for The Watchmen.

Taking STRIDES

Today, I listened to five K-12 science teachers who had been in our department for the last six weeks doing research internships. They were the first in a new program we have called STRIDES, which I think stands for South Texas Research Internships... something something. We had a real cross section of teachers with different experiences, teaching different grade levels.

It was fun.

It was interesting to hear their reflections on things they learned. For instance, several of them mentioned that they really noticed the high level of vocabulary used in a research setting – the precision that comes with technical terms, and they talked a bit about how they could try to bring some of that to their classrooms.

But more importantly, it was great to see how energized they were by working in a lab, on a bona fide original research project, for a few weeks. I think those teachers are really going to have a chance to light a few fires when their school year starts up again.

Tuesday Crustie: Look up

Sand bubbler crab (Scopimera intermedia).

From budak on Flickr, used under a Creative Commons license. Spotted on The Annotated Budak.

Change in your pocket? Buy a lobster

File under, “Things I never thought I’d see”: a lobster vending machine in Osaka, Japan.

Spotted in 12 Bizarre Vending Machines – which is not for delicate sensibilities. They really will put just about anything in a vending machine in Japan.

Different topic, same problem

As the world prepares to celebrate the 40th anniversary of a human being walking on the Moon, this article looks at those who deny it happened.

Because I am interested in belief, there’s quite a bit to chew on.

Ted Goertzel, a professor of sociology at Rutgers University who has studied conspiracy theorists, said “there’s a similar kind of logic behind all of these groups, I think.” For the most part, he explained, “They don’t undertake to prove that their view is true” so much as to “find flaws in what the other side is saying.”

Mark Fenster, a professor at the University of Florida Levin College of Law who has written extensively on conspiracy theories, said he sees similarities between people who argue that the Moon landings never happened and those who insist that the 9/11 attacks were planned by the government and that President Obama’s birth certificate is fake: at the core, he said, is a polarization so profound that people end up with an unshakable belief that those in power “simply can’t be trusted.”

If you took all the people who denied the moon landing, evolution, climate change, that HIV causes AIDS, that vaccines do not cause autism, the Holocaust, and maybe one or two other ideas that require wild conspiracies... I wonder how large a majority they would form.

And is there any way of reaching such people? Sometimes, I despair...

Bye Anita

It pays to advertise, even on coral reefs

Cleaner fish are undeniably photogenic. They are colourful little fish that much larger fish will sit still for and allow the cleaner to dart all around them, even into the waiting jaws of their “clients,” while the cleaners feast of many small surface parasites. Cleaner fish provide one of the classic examples of mutualism in the animal kingdom, proving that evolution does not always mean bloody competition.

How do “client” fish recognize cleaner fish from a quick snack, particularly given that there are many different species of cleaners? Karen Cheney and colleagues tackle the problem not just from many different angles, but from many different lighting conditions.

First, they found all cleaner fish had either blue or yellow in their colouration, compared to only about 2/3 of a control group of fishes. They also confirmed a previous finding that all cleaner fish had a long stripe on the side.

But why blue and yellow? Is there any particular reason for these particular colours? It is just evolutionary happenstance, where one random colour became established, and later, all the others without it were selected against?

Cheney and colleagues hypothesized that these colours are used because they stand out strongly against the background. Demonstrating this is tricky, because what we see as a colour in a nice, brightly lit aquarium is not necessarily what another fish will see in the natural habitat, for several reasons. First, fish may not see colour like we do. Second, water filters out different wavelengths of light, so the colours change as you descend. Third, the major light source is overhead, whereas aquaria let in light from all sides.

To test this, they did some computer modeling using the known visual properties of several fish species, and seeing how they responded to different colours in front of an average coral reef background. Blue, of almost any shade, came out as the most conspicuous for all species for fairly long distances. Yellow was particularly conspicuous against black – such as the long black stripes that cleaner fish have. It was also highly conspicuous against blue water, the other major visual element in a coral reef habitat.

To top this all off, Cheney and company took some fish models, painted with different colours and patterns, into coral reefs. One was a realistic representation of a local cleaner fish, and the others had some variation of colour pattern. Just knocking out blue from the model significantly dropped the response of client fish (figure shown; click to enlarge).

Blue alone is not enough to attract clients, as several models with blue colours in the wrong places fared no better than the blue-less but otherwise realistic models. The ever more radical departures from the realistic colour scheme showed even more declines in client responses, but none of the “duds” were significantly different from each other.

The authors suggest that cleaner probably evolved before the conspicuous colouration, which is a sensible hypothesis. Just because something is conspicuous does not guarantee a client’s appropriate response. In fact, it is difficult to imagine a scenario where a highly visible colour preceded the evolution of the cleaning behaviour.

This research does a very clean job of examining the signaling end of partnership between cleaner and client. Hopefully, someone will pick up with this on the receiver end, and start examining the sensory capabilities of the client fish that enable them to recognize cleaners and react appropriately to those signals.

References

Cheney, K., Grutter, A., Blomberg, S., & Marshall, N. (2009). Blue and Yellow Signal Cleaning Behavior in Coral Reef Fishes Current Biology DOI: 10.1016/j.cub.2009.06.028

Picture: New Scientist gallery

Meet the new Chair

I’ve had a lot of good science data gathering going on this week, so haven’t been blogging as much as I’d like. But I did feel I should note that we have a new Chair of the Texas State Board of Education, replacing Don McLeroy: Gail Lowe.

EvoSphere blog reports on her record on science education.

Alas.

A quick visual indicator of my current mood

(You’d be grouchy too after getting a manuscript rejected.)

Tuesday Crustie: White and blue edges

Penaeus monodon.

From budak on Flickr, used under a Creative Commons license.

From crusties to people

On Twitter, edenchanges asked:

I'm curious - do you map across your conclusions based on the crustaceans to humans?

I appreciated the question, and thought it deserved a more substantive response than what I can do in 140 characters.

The kind of research questions that interest me are, “How do you get new behaviours over evolutionary time? How do you lose behaviours? How do the nervous systems change as behaviours evolve, and vice versa?”

Those questions have nothing to do with crustaceans. They’re general questions about evolutionary biology and zoology. I could, I suppose, work with those questions in other kinds of organisms. So in that sense, I can connect what I do with crustaceans to humans. Over at my Marmorkrebs blog, I have an occasional series of posts called, “Great moments in crayfish research,” and some of those posts talk about some of the things we’ve learned from crustaceans that have turn out to be widely applicable (e.g., electrical synapses).

That said, it’s really, really hard for me to do.

The way I tackle questions is different than the way a vertebrate neurobiologist tackles questions. The difference between crustacean neurobiology and vertebrate neurobiology is like the difference between a psychologist and a sociologist. A psychologist is more likely to be concerned with individuals. A sociologist is more likely to be concerned with demographics, societal trends, and factors emerging from huge groups of individuals. I get to know neurons one by one and learn their names. A vertebrate neurobiologist looks at entire nations of neurons but is rarely concerned with how the actions of one specific individual neuron, except as one is representative of larger classes of neurons.

Second, it’s fun to generalize, but it’s not always a good idea. People study fighting in crayfish. In crayfish, it’s an innate behaviour that seems to be kicked into overdrive by the neurochemical serotonin. It would be foolish to extrapolate from crayfish immediately to say that humans aggression is innate (which some would read to mean, “inevitable”) and that serotonin would have a special role in regulating human aggression.

Third, I am deeply opposed to the notion that the only reason to do biological research is because it has some implications for humans. (Which, to be clear, I’m not saying edenchanges was implying.) I get pissed when I hear almost every interview on the Science podcast end with some variation of, “Are there any practical applications?” or “Could these findings be applied to humans?” My take is similar to Richard Feynman, though I would replace “physics” with “research” in this quote:

Physics is like sex. Sure, it may give some practical results, but that’s not why we do it.

I don’t do research on crustaceans to learn something about humans. I do research because it is inherently interesting, because it uncovers beauty, and because knowledge is better than ignorance.

You’re not my species, but I’d still totally do you

Some males just don’t know when to quit.

When you think of guppies, you probably think of pretty little fish in the pet store. But male guppies are notorious sexual harassers. They are so bad that they don’t even respect species boundaries, the cads! Male guppies will try to mate not only with a different species of guppy, they will try to mate with fish in an entirely different genus.

Picky they ain’t.

Of course, trying to mate with a female in the wrong genus is unlikely to yield any offspring, so it’s not really worth it for the males to try mating with the wrong genus. So while male guppies have the proverbial “one thing on their brain,” it is to their advantage to use their brain to try to learn which females to stop chasing.

In this experiment, Valero and colleagues tested male guppies’ responses to Skiffia bilineata females (pictured below). They had three conditions.

In one, two male guppies were put in a tank with female guppies for 2 weeks, then repaired in a new testing tank with either the same, familiar female guppies or new, unfamilar female guppies.

In the second, the set up was the same, except the females were Skiffia bilineata.

In the third, critical test, males were paired with females of both species, and then repaired with familiar or new females of both species (guppies and Skiffia bilineata). Half the time, the female guppy was new and the Skiffia bilineata) was familiar to the males; the other half of the time, the female guppy was familiar and the Skiffia bilineata) was new.

In the tests with two species of females, the males increased the proportion of times they tried to mate with the unfamiliar Skiffia bilineata females. Valero and coauthors suggest this means that the males had learned not to try to mate with females that had previously encountered.

When there was only one species, the guppies showed no changes towards females regardless of which species they were and regardless of whether they were familiar or not. The authors suggest that for the males to learn, they have to make a comparison between the different species.

Oddly, though, they did not change how often they displayed to those Skiffia bilineata females. Just the attempted copulations changed. This is surprising, as you might expect that learning would generalize across related sexual behaviours. The authors discuss the costs of sexual displays, but as far as I can see, have nothing to add that might explain why displays are unaffected but attempted copulations are.

Or maybe it’s just more proof that some males don’t know when to quit.

References

Valero, A., Magurran, A., & Garcia, C. (2009). Guppy males distinguish between familiar and unfamiliar females of a distantly related species Animal Behaviour DOI: 10.1016/j.anbehav.2009.05.018

Science communication by clothing

On science blogs that focus on more medical research than here, there is a lot of characters typed about the fear of vaccination. Here’s one and another, just for examples. I generally stay away from the topic, because others are so much better qualified to talk about the science than I am.

In cases like this, fear can really run rampant because success is invisible. You can’t look around in a crowd and know who’s been vaccinated or not, and think, “Wow, there are all those people who have been vaccinated and are fine.”

So I thought the pictured T-shirt was funny, timely, and rather poignant. It’s particularly appropriate that kid’s sizes are available.

In my own field, I am also quite fond of the series of “Teach the controversy” T-shirts. I'm very tempted by the one showing that fossils are the handiwork of the devil.

And I can’t help but think that there are a lot of other topics where people routinely flaunt bad science that could do with some T-shirts.

I declare that I have no financial stake in manufacturers of T-shirts or any other clothing, apparel, jewelry or accessories.

The synapses of Theseus

The Greek hero Theseus had a ship that was used in an annual ceremony. As the ship aged, the planks would slowly rot and were, over the years, replaced. Eventually, after many years, every one of the planks was replaced. Is it the same ship? This philosophical problem plagued the Greeks, and highlights the tension between stability and change.

This problem reappears in neurobiology in many ways. Neurons must have some stability or processing information becomes impossible. Neurons must be able to change or learning becomes impossible.

Neurons could change in many ways during learning, but most of the attention has focused on the synapse, the gap between neurons where chemicals flit from one cell to the next, and cause a change in the target cell. We know synapses can change during learning, but is that the only time they change?

Answering this question is a problem of resolution. You need lots of detail tracked very closely for a long time. Trying to do this in an animal is not going to happen, so Minerbi and colleagues used neurons in culture instead. One of the tricky bits is to keep the cells alive on a microscope slide! This required keeping the slide heated, blowing sterile air through it, and several other things to keep the neurons happy during the days the experiments ran.

The slides also contained a series of electrodes, so that they could record the action potentials of neurons. I am still trying to wrap my head around the “wires” hooking up the electrodes. They’re tiny and transparent. What neurobiologist knew indium tin oxide existed, never mind that it was transparent and conducted electricity?

To see the shape of the synapses, Minerbi and coworkers tagged a protein found mainly in the receiving side of synapses with a fluorescent marker. So now they've got activity, synapse shape, and a system that lets them scan many different areas in their culture every half hour for days.

As expected, when neurons spike a lot, the synapses change. You’d be concerned if they didn’t. interestingly, the small ones tended to get bigger, and the big ones tended to get smaller. They suggest there is perhaps some sort of optimal size the synapses are converging on.

To test what happens when there is no activity, they tossed in a little tetrodotoxin, also known as pufferfish poison. It’s poison because it stops action potentials cold. The authors still saw the synapses changing, although some of the patterns were different. The whole “big get smaller and small get bigger” pattern wasn’t seen. The key point is that the synapses didn’t just stay, as it were, “frozen.”

One issue is that these neurons were cultured from newborn rats, which is obviously a time when brains are still undergoing a lot of developmental changes. It would be very interesting to see if more mature neurons were more stable, or changed in different ways in response to activity, or lack thereof.

There’s more to this paper, but it involves substantial mathematical modeling, and it starts to pull me out of ability to comment coherently. Lots of very interesting data here in a real technical tour de force.

Reference

Amir Minerbi, Roni Kahana, Larissa Goldfeld, Maya Kaufman, Shimon Marom, Noam E. Ziv (2009). Long-Term Relationships between Synaptic Tenacity, Synaptic Remodeling, and Network Activity PLoS Biology, 7 (6)

Why neurotransmitter genes probably aren’t involved in mental disorders

I was listening to this week’s Nature podcast, in particular the first story on the genetics of schizophrenia. The interviewer, Kerri Smith, made a comment about “neurotransmitter genes.”



I had one of those rare moments where I thought, “Wait! I have enough knowledge to know that’s really unlikely!”

Let’s start with what genes do. Very briefly, genes (segments of DNA) interact with a set of molecules to generate shorter pieces of RNA, which in turn interact with other molecules to make proteins.

So, you could expect to find neurotransmitter genes if neurotransmitters were protein molecules. But most neurotransmitters are not proteins, but other kinds of chemicals. Turns out that neurotransmitters are a total ragbag collection of molecules, and it’s difficult to generalize, but to pick a few examples...

Acetycholine, the first chemical discovered to act as a neurotransmitter, is a small molecule with no relationship to proteins at all.

Glutamate, the major neurotransmitter in vertebrate brains, is an animo acid, for example. Amino acids are building blocks for proteins, but you don’t have genes for amino acids, just like an architect doesn’t have a blueprint for a brick. Amino acids are made by other pathways in your body or ingested.

Serotonin and dopamine, to name a couple of other well known neurotransmitters, are monoamines.

That said, there very definitely are small proteins that act as neuroactive chemicals. One I happen to know is proctolin. So it isn’t completely wrong to say that there are genes for neuroactive chemicals – but they are not major players. “Neurotransmitter genes” wouldn’t be the first place I’d look for causes of mental disorders.

Of course, it is entirely possible that what was meant was not “neurotransmitter genes” in the strict sense, but “genes involved in neurotransmitter synthesis” or “genes involved in neurotransmitter release” or some other pathway where proteins have major roles to play.

With that, I will stop showing off and stop nitpicking on interviewer Smith, who generally does a fine job.

Invert science keeps food on table

Simon Leather has a good short article about the problems of working with invertebrates in biology. The problems are not intellectual, but structural. He argues that if you work on invertebrates, you really don’t have much of a chance of getting a job at a major research institution. Some of Leather’s claims are backed by references. But phrases like “it is obvious that” crop up, which are always warning signs for opinions trying to pass themselves off as facts.

It contains this short blast:

Unless something is done soon to remedy the situation, it will be too late and the only animals that the general public will be able to recognize will be polar bears and tigers.

Why we should care, according to Leather, is because of insect pests and their effect on agriculture. Leather misses an opportunity to draw stronger links between invertebrate research and food security. I was surprised not to see honeybee pollination mentioned, for instance. Or the importance of invertebrates as a food source in their own right, either for fish (krill are the base of much of the oceans’ food webs, after all) or for humans (for example, lobster fisheries).

As an invertebrate researcher, I share Leather’s concerns. A couple of things may help. First, as I’ve written before, there is always the possibility that vertebrate researchers are going to price themselves out of the market.

Second, not every academic or research institution is a major research institution. Not every academic job will need publications in Nature or Science. Given that not every institution has the same resources, those that can’t support full blown research on large vertebrates could become centers of excellence for invertebrate research.

Reference

Leather, S. (2009). Institutional vertebratism threatens UK food security Trends in Ecology & Evolution DOI: 10.1016/j.tree.2009.05.002

Dear Canada,

I know we haven’t seen each other but once in the last eight years. And that one time was really because of business, so hardly counts. But I wanted you to know that you’re in my thoughts all the time throughout the year, not just on days like today when “Happy Canada Day” is trending on Twitter. I’d come back in a heartbeat if you had a professional opportunity for me.

Happy birthday.

Here’s to fellow Canadians who, for whatever reason, are living elsewhere in the world.

Predictability is a weakness: Snakes catch stereotyped swimmers

I’ve published a few papers on neurons involved in escape responses in crustaceans. In my recent review on crustacean escape responses, I noted:

Giant neurons and electrical synapses provide for short latency, but stereotyped responses. The non-giant circuit for repetitive tailflipping provides crayfish with flexibility and the potential for sustained escape.

I recall giving a lecture some years ago about crayfish escape responses, I remember trying to emphasize the importance of the non-giant neurons, saying to the students something like, “If you relied on just the giant neurons, which do the same things at every time, don’t you think that at some point, a predator would figure out, ‘If I attack here, the prey is going to end up here’?”

Turns out at least one predator has done just that – it’s just catching fish instead of crayfish.

Fish escape responses, like those of crayfish, are fast and controlled by a well-described set of neurons. The biggest neurons, the Mauthner cells, cause a very stereotyped behaviour when activated alone. If you play a loud sound to the fish’s right side, the Mauthner neuron triggers and sends a signal over to the fish’s left side, contracting muscles and causing the fish to turn away from the sound. (There are also sets of smaller neurons that allow for the fish’s escape to vary somewhat, but don't matter a lot for the purposes of this story, since they usually don’t change the overall right or left direction the fish turns; Foreman and Eaton, 1993).

Somehow, tentacled snakes (Erpeton tentaculatum) have been able to take advantage of this predictable turn away from a loud sound. Somehow, the snake manages to move the trunk of their body just enough to make a vibration big enough to set off the fish’s escape response. This is one of the things I find most fascinating about this: the movement the snake makes is tiny! And it’s very surprising that this subtle little fast bend of the body is enough to set off an escape response. It’s a testament to the highly sensitive sensory systems of the fish.

The snake’s normal hunting position is a sort of J-shaped posture, so the head is roughly in the vicinity that the “escaping” (but actually probably doomed) fish will turn to. The snake isn’t as fast as the fish, so the snake has to start its strike in anticipation of the fish’s response and it aims for where it expects the fish to be after the fish makes its escape.

The fish’s escape behaviour isn’t completely stereotyped, though, and can be modulated by sensory input (Eaton and Emberley 1991). When the fish flips left instead of when it should flip “right,” it usually gets away.

Although Catania ends by saying this could be learned or innate (i.e., evolved), I’m guessing this behaviour is innate. It seems too specific to be learned afresh each generation, and that four snakes tested showed the behaviour would also seem to suggest a species specific evolved behaviour.

The article is open access, and has lot of supplemental video.

Hat tip to this article, which does a great job of summarizing the research and has a video compilation.

References

Catania, K. (2009). Tentacled snakes turn C-starts to their advantage and predict future prey behavior Proceedings of the National Academy of Sciences DOI: 10.1073/pnas.0905183106

Eaton RC, Emberley DS. 1991. How stimulus direction determines the trajectory of the Mauthner-initiated escape response in a teleost fish. J. Exp. Biol. 161(1): 469-487.

Foreman MB, Eaton RC. 1993. The direction change concept for reticulospinal control of goldfish escape. J. Neurosci. 13: 4101-4114.

Number one, baby!

Yeah!