For years, the "supply-side" ecology has been a common theme describing mechanisms for benthic species distributions and densities. In general terms, the amount and extent of a particular organism is driven by the supply of larvae to a given area. This larval supply can thus be seen as driving benthic community structure, especially for marine invertebrates - as their life cycles contain a planktonic larval stage which allows for dispersal over relatively long distances. Thus, many of these populations are considered "open" and their continuation is dependent on some large supply of larvae. This makes sense, and it has been demonstrated many times in the literature. However, this has often been demonstrated on hard bottom communities. Soft bottom benthos don't always display similar patterns. A recent paper by Dr. Megan Dethier from the Friday Harbor Laboratory at the University of Washington, details an experiment conducted investigated very small, post set, infaunal recruits. Sampling these habitats is often difficult due to the 3-D nature of soft sediments. She was able to demonstrate that for a number of taxa she was working with, the strongest recruitment was not in areas where the largest adult populations existed. This suggests that for many of the soft bottom benthos she studied, the supply of larvae is not limiting the adult populations, but rather some post-settlement processes, such as predation, competition or abiotic stressors.LEWIN, R. (1986). Supply-Side Ecology: Existing models of population structure and dynamics of ecological communities have tended to ignore the effect of the influx of new members into the communities Science, 234 (4772), 25-27 DOI: 10.1126/science.234.4772.25Dethier, M. (2010). Variation in recruitment does not drive the cline in diversity along an estuarine gradient Marine Ecology Progress Series, 410, 43-54 DOI: 10.3354/meps08636This is a particularly interesting article, because "supply-side" ecology doesn't always hold true in soft bottom benthos. I have observed this first hand with the scallop restoration work on Long Island. Over 6 years, we have monitored larval supply of scallop spat at a number of different locations, and then each winter and spring, we conduct benthic surveys for juvenile densities. There isn't always a match between sites where we had the highest numbers of post-set and the highest juvenile densities. The main causes for this mismatch is likely to be predation or physical factors.On another project, I am investigating scallop settlement on artificial seagrass units. I design collectors to mimic seagrass, each collector has 10 artificial seagrass shoots. Half of the collector (5 shoots) is enclosed in a mesh bag (just under 1mm) and the other half exposed to predation. There is an order of magnitude difference between the number of available settlers (those inside the bags) when compared to those actual "recruits" (those scallops outside the bags). This low pattern of surviving recruits holds up regardless of location within the grass mats (either on small or large mats, at the center or the edge). This indicates to me that predation is a major contributing factor structuring the scallop populations, at least in the estuary in which I work, Hallock Bay, Long Island.... Read more »
LEWIN, R. (1986) Supply-Side Ecology: Existing models of population structure and dynamics of ecological communities have tended to ignore the effect of the influx of new members into the communities. Science, 234(4772), 25-27. DOI: 10.1126/science.234.4772.25
Dethier, M. (2010) Variation in recruitment does not drive the cline in diversity along an estuarine gradient. Marine Ecology Progress Series, 43-54. DOI: 10.3354/meps08636
The primary model for Y-chromosome degeneration is a decrease in X-Y recombination. Because and X and Y chromosomes are not kept the same by swapping DNA segments with each other, but the X can still recombine with itself in females, the Y chromosome is allowed to degenerate. We will discuss how this all works next [...]... Read more »
Kelkar A, Thakur V, Ramaswamy R, & Deobagkar D. (2009) Characterisation of inactivation domains and evolutionary strata in human X chromosome through Markov segmentation. PloS one, 4(11). PMID: 19946363
Lahn BT, & Page DC. (1999) Four evolutionary strata on the human X chromosome. Science (New York, N.Y.), 286(5441), 964-7. PMID: 10542153
Ross, M.T., D.V. Grafham, A.J. Coffey, R.A. Gibbs, S. Beck, J. Rogers, D.R. Bentley, & et al. (2005) The DNA sequence of the human X chromosome. Nature, 325-337. info:/10.1038/nature03440
Skaletsky H, Kuroda-Kawaguchi T, Repping S, Wilson RK, Rozen S, Page DC, & et al. (2003) The male-specific region of the human Y chromosome is a mosaic of discrete sequence classes. Nature, 423(6942), 825-37. PMID: 12815422
Imagine you're about to have to do something horrible or embarrasing, like say, admitting that you read Neuroskeptic. Wouldn't it be nice to be able to switch off your memory for a while, so you at least didn't have to remember it?Well, now you can, as long as you have electrodes implanted in your brain. Lacruz et al, based at London's Institute of Psychiatry, report that Single pulse electrical stimulation of the hippocampus is sufficient to impair human episodic memory.They took 12 people who were undergoing neurosurgery for severe epilepsy, and found that giving a single brief electrical pulse to the hippocampus caused momentary amnesia. Patients were much less likely to remember seeing a word or a picture presented immediately (within 150 milliseconds) after the pulse.It only worked if you zapped the hippocampus on both the left and the right side simultaneously; if you only disrupt one, memory is unaffected, suggesting that one can compensate for the lack of the other.It's been known for 60 years that damage to the hippocampus causes amnesia (e.g.), and previous electrode stimulation studies have shown amnesia after a few minutes of repeated shocks, but this is the first study to show that a single pulse can cause ultra-short memory impairment.Follow up work confirmed that the stimulation only affected memory, rather than the perception of the items. Stimulation immediately before asking people to remember the items had no effect, showing that the hippocampus is only required for encoding, not retrieval.This is a great study which adds to our knowledge of the memory functions of the hippocampus - although we need to avoid the temptation to see the hippocampus as purely a "memory module", since it's also known to be involved in space perception.It's also a good example of why epilepsy patients are the unsung heroes of modern neuroscience - because they're basically the only people in whom it's ethical to do this kind of experiments. Surgeons need to stimulate their brains in order to optimize their treatment. It would be unethical to open someone's skull and poke around their grey matter purely for research purposes, but given that it's going to happen anyway for medical reasons, you might as well do a little research too...Lacruz ME, Valentín A, Seoane JJ, Morris RG, Selway RP, & Alarcón G (2010). Single pulse electrical stimulation of the hippocampus is sufficient to impair human episodic memory. Neuroscience PMID: 20643192... Read more »
Lacruz ME, Valentín A, Seoane JJ, Morris RG, Selway RP, & Alarcón G. (2010) Single pulse electrical stimulation of the hippocampus is sufficient to impair human episodic memory. Neuroscience. PMID: 20643192
Late last year paleontologists Jack Horner and Mark Goodwin made waves by proposing that what had previously been thought to be two distinct genera of “bone-headed” dinosaurs—Stygimoloch and Dracorex—were really just growth stages of Pachycephalosaurus. Together the three body types illustrated how the skull of this peculiar dinosaur was reshaped as it grew—juveniles did not [...]... Read more »
Scannella, J., & Horner, J. (2010) Torosaurus Marsh, 1891, is Triceratops Marsh, 1889 (Ceratopsidae: Chasmosaurinae): synonymy through ontogeny. Journal of Vertebrate Paleontology, 30(4), 1157-1168. DOI: 10.1080/02724634.2010.483632
Wild Muse just perused the latest issue of Conservation Biology and went foraging for substantive research to post about… Hold on tight because we are going to Tasmania. To the Forestier peninsula in southeastern Tasmania, to be exact – where Tasmanian devils are pinned down by a catastrophic disease. Unfortunately, it will not be all fun [...]... Read more »
Lachish S, McCallum H, Mann D, Pukk CE, & Jones ME. (2010) Evaluation of selective culling of infected individuals to control tasmanian devil facial tumor disease. Conservation biology : the journal of the Society for Conservation Biology, 24(3), 841-51. PMID: 20088958
Although bacteria live as isolated cells, they are constantly communicating with surrounding bacteria, particularly those of the same species, which can often band together to form large groups of bacteria surrounded by a sticky mesh. These are known as biofilms (which I cover in more detail here). One of the main ways that bacteria communicate with each other in order to organise structures like this is by quorum sensing.Quorum sensing uses small molecules that bacteria can both excrete and sense. When enough bacteria are in one place then the surrounding concentration of these small molecules reaches a critical level and can activate the genes for a variety of different responses including luminescence, virulence (in pathogenic or disease-causing bacteria) and the formation of biofilms:A recent paper (reference below) looked at a range of different types of biofilm and quorum sensing interactions, in order to explore the different environmental pressures that shaped the differences in these systems. They found that although many species formed biofilms when bany cells joined together some species stopped forming biofilms when they reached a certain cell density. Biofilms are carefully controlled by bacteria, they do not just start growing when a certain number of bacterial cells gather together and then never stop.Using models of mostly infectious biofilm-forming bacteria (such as Vibrio cholerae which causes cholera) they found that as well as helping to bind the cells together and resist man-made antibiotics (which cannot penetrate the biofilm) the biofilm was also a defense against competing bacteria (and may have helped to out-compete them by covering all available living surfaces with slime). The ability to produce biofilms not only helps the V. cholerae against other invading bacteria, it also helps it gain a hold against the body's own internal bacterial defenses that line the internal gut.However once the levels of V. cholerae became too high the bacteria often stopped generating the biofilms. This could be for two reasons, firstly the biofilm takes up valuable resources that could be used in growth and division and secondly it prevents the bacteria within it from travelling very far. V. cholerae infect the body by having periods of growth followed by periods of mad colonisation, which works best if the biofilm actually disperses at high cellular density to allow the cells to spread.This can be contrasted with more sedentary bacteria like P. aeruginosa which likes to settle down once it finds a place to live and occasionally disperse colonies into the body. Rather than loosing its biofilm this bacterial species retains it even at high cell densities. This allows it to out-compete any other bacteria that may be at the site of infection, and hold off both the body's natural defenses and any chemical antibiotic drugs meant to kill it.Comparisons of different V. cholerae strains revealed a wide range of different biofilm formation patterns between strains, all linked to Quorum sensing signalling. This is likely to depend on the internal environment that specific strains occupy, the amount of competition they face and the necessity for quick and frequent bouts of dispersal.As biofilms are traditionally studied in P. aeruginosa I found it fascinating to hear about how other bacteria use them in order to colonize their surroundings. In aeruginosa biofilms are a mark of stability, the bacteria have found a place to stay and invest time and energy in making it as safe and indestructible as possible. In cholerae however, the biofilm is just protection for the growing bacteria, until their numbers get high enough to allow them to break out and invade the body.---Nadell CD, Xavier JB, Levin SA, & Foster KR (2008). The evolution of quorum sensing in bacterial biofilms. PLoS biology, 6 (1) PMID: 18232735... Read more »
Nadell CD, Xavier JB, Levin SA, & Foster KR. (2008) The evolution of quorum sensing in bacterial biofilms. PLoS biology, 6(1). PMID: 18232735
In a good post about puppy mills, Amanda Marcotte made a good point about domesticated versus undomesticated pets (italics mine):
This would probably mean that people couldn't get exotic pets, and that isn't really the sort of thing that would keep me up at night, either. I understand the urge to have something like a pet ferret, but like with smoking, it's an understandable urge that probably is best not indulged. Cats and dogs evolved to be our pets and want nothing more than to be our pets, thus they are the best choices for pets. They may not love every second of being a pet---going to the vet comes to mind as a moment they don't love---but on the whole, what they want is to be a pet. If you've ever adopted a cat that was feral but is well-socialized, you're probably familiar with how true this is. Even though my cat Molly only spent perhaps the first two months of her life as a feral kitten, she is clearly still haunted by the memory. When we had a backyard, I would let them hang out there under supervision, and while Dusty (who was never feral) was simply happy to go out, Molly wouldn't go out unless I left the door open for her so that she could be assured that she could run back into the condo at any second. She was that afraid of ever going back to non-pet status again. If you want a pet, cats and dogs want to be your pet. It's the simplest relationship in the world, and I see no reason to complicate it by insisting that the humble cats and dogs are too boring to be your pet. Read the rest of this post... | Read the comments on this post...... Read more »
UDELL, M., DOREY, N., & WYNNE, C. (2008) Wolves outperform dogs in following human social cues. Animal Behaviour, 76(6), 1767-1773. DOI: 10.1016/j.anbehav.2008.07.028
Gácsi M, Györi B, Virányi Z, Kubinyi E, Range F, Belényi B, & Miklósi A. (2009) Explaining dog wolf differences in utilizing human pointing gestures: selection for synergistic shifts in the development of some social skills. PloS one, 4(8). PMID: 19714197
Okay, this blog is going to get to the core of a topic I find insanely interesting, which is the fact that humans generally live a long, loooong time past their reproductive years. I mean yeah, men can keep churning out the sperm in their old age, but women can sometimes live twice as long [...]... Read more »
Rashidi, A., & Shanley, D. (2009) Evolution of the menopause: life histories and mechanisms. Menopause International, 15(1), 26-30. DOI: 10.1258/mi.2009.009005
You shouldn’t be able to call a species anything you want.
Yes, biologists switched to using Latin names for species because we recognized that common names were too variable and imprecise. Still, that doesn’t mean that common names are infinitely flexible.
A crustacean story has been making the rounds in the news, and alas, the news stories are often botching the basics. I wish I could be surprised. News stories based on journal articles seem to be a never ending well of things to correct.
The first time I saw the article was at New Scientist. Then I spotted it on the front of The Age here. Then I saw it again time here, which was what finally set me off. But before this post went up, it also got featured on National Geographic and Improbable Research.
I had looked at the article abstract, and I thought, “Wait. The headline said this was a shrimp. The abstract says nothing about a shrimp.”
The sometimes interesting but often irritating Science Daily has a picture of the senior author, Alex Ford (right), holding something I would not call a shrimp. It’s an amphipod. I can only find one other picture of this species on the web, on Ford’s home page here. In fact, the title of the Science Daily blurb was exactly that of the journal article – except that the word “amphipod” had been replaced by “shrimp.”
The Age referred to this beast as a “prawn”, and showed a picture of something normally called a prawn, Penaeus monodon, which is an entirely different beast. And it gave it the lurid title referring to crustaceans “getting high.”
The third article showed a picture of another species (Crangon crangon) that is not even close to the one studied in the paper. And this time, the article referred to the animals becoming “suicidal”!
Does calling an amphipod a “shrimp” or a “prawn” matter? Yes! People eat shrimp and prawns, but not amphipods. Bu changing the common name, you introduce a whole new set of worries and fears about the safety of people’s food. It’s made worse considering that the third article is at a website called “Fish2Fork,” which strongly suggests they think it’s a seafood story.
The paper is actually quite interesting, but it shows neither animals “seeing the light” (title and article 1), “getting high” (article 2) or “becoming suicidal” (article 3).
The behaviours that the authors are testing are the tendency of amphipods to swim towards a light (phototaxis) or tendency to swim up or down (geotaxis). I am guessing the former is where “seeing the light” comes from, but “seeing the light” doesn’t capture the actual behaviour well at all. I would expect “seeing the light” to mean that the amphipods gained some ability to see something they couldn’t before.
The authors didn’t just test the effect of Prozac, but two other drugs, and the neuroactive chemical serotonin (which Prozac interacts with and which is often important to crustaceans), and a natural parasitic infection (acanthocephalans).
Amphipods that were infected with parasites, given serotonin, or given Prozac all tended to be more likely to be attracted to light, and more likely to be swimming upwards. Thus, amphipods are more likely to be out in the water in bright light, where they would be more susceptible to being eaten by predators. This, of course, is what parasites “wants” so that they can infect the next host in their life cycle. Still, this is hardly “getting high” or “suicidal” in the way people think of those phrases.
Further reading of the paper reveals a less straightforward interpretation than the headlines say. Guler and Ford didn’t measure the drug concentrations in the water where they collected their animals. They argue that their values are within the ballpark that other researchers have recorded in “STP effluent”. (I don’t know what “STP” means, because the authors don’t define it. A little help here? You know, for those of us who don’t speak acronym.)
Complicating matters further is that the authors tested five concentrations for the drugs they tested, ranging from 0 to 10 µg per liter, but it seems only one concentration of Prozac (0.1 µg per litre) caused a significant difference in the amphipods’ behaviour. So if we’re taking enough anti-depressants, there may not be a problem?
Finally, only used males in this experiment, and there is no explanation why.
This paper is interesting, but it’s yet another case of the researchers and press release writers working too hard.
For more fun with headlines, see the stuff I’ve written with Carin Bondar!
Additional: Deep Sea News also got to this one.
Guler Y., & Ford A. (2010). Anti-depressants make amphipods see the light Aquatic Toxicology. DOI: 10.1016/j.aquatox.2010.05.019... Read more »
How we perceive nature and describe its shape are a matter of values and preferences. Nature does not take notice of our distinctions; they exist only as instruments which aid in our comprehension. I’ve brought this up in relation to issues such as categorization of recessive vs. dominant traits. The offspring of people of [...]... Read more »
Giulio Genovese, David J. Friedman, Michael D. Ross, Laurence Lecordier, Pierrick Uzureau, Barry I. Freedman, Donald W. Bowden, Carl D. Langefeld, Taras K. Oleksyk, Andrea Uscinski Knob.... (2010) Association of Trypanolytic ApoL1 Variants with Kidney Disease in African-Americans. Science. info:/10.1126/science.1193032
Tzur S, Rosset S, Shemer R, Yudkovsky G, Selig S, Tarekegn A, Bekele E, Bradman N, Wasser WG, Behar DM.... (2010) Missense mutations in the APOL1 gene are highly associated with end stage kidney disease risk previously attributed to the MYH9 gene. Human genetics. PMID: 20635188
Until just a few years ago, I never paid that much attention to fossil mammals. Sure, I was impressed by the saber-toothed cat Smilodon and the American mastodon Mammut americanum - badass, extinct versions of living big cats and elephants - but beyond that they never really grabbed my interest. Although clearly different from living [...]... Read more »
Billet, G. (2009) New Observations on the Skull of Pyrotherium (Pyrotheria, Mammalia) and New Phylogenetic Hypotheses on South American Ungulates. Journal of Mammalian Evolution, 17(1), 21-59. DOI: 10.1007/s10914-009-9123-0
Are today’s urban forests another legacy of the Baby Boom generation? A new study of vegetation cover in neighborhoods near Baltimore, Maryland suggests that the wealth and education levels of residents 50 years ago helps explain how many trees we see today. The finding could have implications for current efforts to conserve and restore urban […] Read More »... Read more »
Boone, C., Cadenasso, M., Grove, J., Schwarz, K., & Buckley, G. (2009) Landscape, vegetation characteristics, and group identity in an urban and suburban watershed: why the 60s matter. Urban Ecosystems, 13(3), 255-271. DOI: 10.1007/s11252-009-0118-7
Lasse Jakobsen and Annemarie Surlykke (University of Southern Denmark) show that Vespertilionid bats dynamically increase the width of their echolocation pulses when in the pursuit of prey, without altering their attention. This news feature was written on July 21, 2010.... Read more »
Jakobsen, L., & Surlykke, A. (2010) Vespertilionid bats control the width of their biosonar sound beam dynamically during prey pursuit. Proceedings of the National Academy of Sciences. DOI: 10.1073/pnas.1006630107
Sci couldn’t help but notice all the tweets going around the other day talking about how sex stressed you out but was ultimately good for you. She contemplated saving it for a Friday Weird Science, but it’s not THAT weird (though it is interesting), and anyway Sci has something brewing for teh weird skienz. So [...]... Read more »
Leuner B, Glasper ER, & Gould E. (2010) Sexual experience promotes adult neurogenesis in the hippocampus despite an initial elevation in stress hormones. PloS one, 5(7). PMID: 20644737
by Michele in Promega Connections
We owe a lot to frogs and toads. They help us welcome in spring and summer with their peeps, croaks and snores in the evenings. They serve as bioindicator species that alert us to damaged or toxic environments. And, now, they may even help us kick the fossil fuel habit. Biofuels, based on harvesting and [...]... Read more »
Wendell, D., Todd, J., & Montemagno, C. (2010) Artificial Photosynthesis in Ranaspumin-2 Based Foam. Nano Letters, 2147483647. DOI: 10.1021/nl100550k
To many, “snake eyes” is a bad bet at the craps table. To some, it’s a GI Joe character. To a very small, select group, it’s a minor addition to the oeuvre of Brian De Palma. *
Today, I want to look at the most literal meaning of the term imaginable. But, since this is a biology blog, you could probably guess that I was going to end up talking about the eyes of snakes.
I’m willing to bet that when most people visualize snake eyes, they think of something with a vertical slit for a pupil, like the animal shown here. Such eye look a little scary to humans, because we have circular pupils. Snakes aren’t the only animals to have such pupils; many cats do, too. Why do some animals have vertical pupils, and some have circular pupils?
Brischoux and colleagues set out right away to correct one idea that many people have about vertical eyes that is wrong: it’s not for night vision. They set out to test other hypotheses about the function of pupil shape using snakes as their subjects. One reason for using snakes is that the pupils vary considerably, so compare the animal above to the one below (click to enlarge).
Admit it: it looks friendlier with circular pupils, doesn’t it?
The pupil shape appears to be related to day and night, but in a different way: You can close a slit pupil much tighter than a circular pupil. The yellow snake above has its pupils shut down quite far. This might be advantageous to an animal that normally moves around at night to prevent it from being temporarily blinded by bright light in the day.
The authors also suggest that a vertical pupil may be less recognizable then a round one, making it advantageous for ambush predators who use camouflage. The authors don’t mention that many prey species also use camouflage, and following that logic, might also be expected to have slit pupils.
Brischoux and colleagues coded out about 100 snake species, categorising their pupil shape, type of foraging, and time when the animals were most activity. They found that most snakes fell into a fairly small number of positions in the possible range of values: sit and wait ambush predators that hunted at night tended to have vertical pupils; snakes that actively foraged during the say tended to have circular pupils.
What I don’t get about their figure above, though, is why the data points are scattered. Look at the trio of dots on the lower right corner. Why are they separated? If these are categorical values, all three should be right on top of each other. That implies that they’ve measured something quantitatively, not by category... and if so, where are the value labels for the axes?
Having done all that, the authors admit they still can’t definitively tie pupil shape to any particular adaptive advantage. They suggest some good experiments, such as manipulating pupil shape to see if this affects how readily detectable an potential predator is. They also point out that many other species vary in their pupil shape, and that similar analyses could be done for those groups, too.
Brischoux F, Pizzatto L, & Shine R (2010). Insights into the adaptive significance of vertical pupil shape in snakes Journal of Evolutionary Biology DOI: 10.1111/j.1420-9101.2010.02046.x
Yellow snake photo by MrClean1982 on Flickr. Garter snake photo by C. A. Mullhaupt on Flickr. Both used under a Creative Commons license.
* The film has a special place in my heart, because it was filmed in Montréal when I was living there, and I was able to look in and see the set they had built in the old Montréal Forum when I walked to and from McGill University.... Read more »
Brischoux F, Pizzatto L, & Shine R. (2010) Insights into the adaptive significance of vertical pupil shape in snakes. Journal of Evolutionary Biology. DOI: 10.1111/j.1420-9101.2010.02046.x
The science of superheroes is taking a green and nasty turn this week as we discuss the largest superhero of them all, The Hulk. Join myself and our regular superhero expert Dr Boob as we delve into the science of how we might realise The Hulk in the lab. It was one of the more entertaining interviews I have done for the podcast.
Listen in to this show here (or press play below), and read further for more info:
The Hulk is alter-ego of Dr Bruce Banner, who allegedly bares a striking resemblance to Dr Boob. Banner is a reserved physicist who involuntarily transforms into The Hulk when triggered by a strong emotion such as anger, fear, terror or grief. The Hulk himself is a massive green monster who gets stronger the angrier he gets. He also has bullet-proof skin.
The Hulk’s origin story includes depends on whether we are looking at the comic book Hulk, the Hulk of the two recent movies, or The Incredible Hulk of the TV series (in which it is David Banner, not Bruce Banner, who metamorphoses into The Hulk).
The 2003 movie version "Hulk" includes many of the topics we discuss in the podcast. The movie starts with genetics researcher David Banner – Bruce Banner’s father - working with the military to "improve" human DNA. The opening credit sequence depicts experiments with jellyfish and starfish DNA, and Banner’s notepad mentions bioluminescence. This suggests that the Hulk gets his green colour from jellyfish DNA as some jellyfish bioluminesce at around 450 nm, which is at the blue/green end of the spectrum. In 1961, Osamu Shimomura extracted green fluorescent protein and another bioluminescent protein, called aequorin, from Aequorea victoria while studying bioluminescence. He eventually received the Nobel prize in Chemistry in 2008 for this work. The mention of starfish is also interesting because, as we found with Wolverine, starfish and sea cucumbers have great healing powers and are able to regenerate lost limbs. Evidently, Banner wanted to splice bioluminescence and improved healing into human DNA.
Banner’s experiments then moved to lizards and monkeys, but unfortunately they all died. Naturally, he then decided if his experiments did not work on animals, he would try them on himself – clearly, ethics committees are not part of superhero science. After conducting experiments on his own DNA, he eventually passes on his mutant DNA to his unborn son Bruce. Once David realises this, he changes his approach and works to cure his son of his genetic afflictions, however the research is shut down and an explosion kills David’s wife. David is taken to a lunatic asylum and Bruce is adopted.
Years later, Bruce has followed his father’s line of work and is conducting military research – Bruce’s area of interest is the use of nanomeds in soldiers. This might include such things as targeted drug delivery for rapid recovery from injury. An experimental accident subjects Bruce to an enormous dose of gamma radiation which “activates” his mutant DNA (possibly combining with the nanomeds) and the building rage/stress transforms him into The Hulk for the first time.
Whether or not this is scientifically possible – well, that’s the topic of the podcast so tune in!
Other issues that we discuss include:
Gamma radiation and radiation poisoning;
Genetic transfer and gene therapy – could David Banner change his own DNA in such a way that this change would be copied to his progeny? For more information, check out the Weismann Barrier;
The Hulk’s size – is it possible to rapidly increase your size? Simple conservation of mass equations would suggest no, and bacteria in a Petri dish generally have a 24 hour doubling time. There are also enormous metabolic requirements involved – we need to have resources available to feed these growing cells and Bruce Banner is not excessively fat. Perhaps to do this we need to accelerate Bruce Banner to the near the speed of light, at which point he may relativistically pick up some mass - however, this is not particularly practical!
The Hulk’s strength – is it possible to rapidly increase your strength?
The Hulk's healing properties - could we use some of the science of Wolverine here?
The materials used to create bullet-proof skin. The toughest skins in the animal kingdom are crocodile, elephant, shark and armadillo; however none are bullet (and knife) proof;
What materials could we use to make his "one-size-fits-all" pants? You will notice that no matter what size Bruce Banner or The Hulk are, and no matter what the ripped state of his other clothes, his undies always fit.
And of course, whether The Hulk has irritable bowel syndrome and wears giant green snuggies.
Hope you enjoy this show - we certainly enjoyed recording it, as you will be able to tell by the end! Listen in to this show here (or press play below):
NB: I've now discovered there's a Red Hulk - future show perhaps?
Samples in this podcast are broadcast courtesy of ioda PROMONET. They were:
The Toxic Avenger
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from "Little Baby Souls"
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Shimomura, O., Johnson, F., & Saiga, Y. (1962) Extraction, Purification and Properties of Aequorin, a Bioluminescent Protein from the Luminous Hydromedusan,Aequorea. Journal of Cellular and Comparative Physiology, 59(3), 223-239. DOI: 10.1002/jcp.1030590302
Biologists already know lots of reasons to encourage mathematicians to get hooked on biology. There’s structural biology; population genetics; epidemiology; ecology; bioinformatics; computational neuroscience; and yes, systems biology, to name but a few. But here is a new one. How long have we been studying Darwin’s finches? About 170 years. In all that time, nobody [...]... Read more »
Campas, O., Mallarino, R., Herrel, A., Abzhanov, A., & Brenner, M. (2010) Scaling and shear transformations capture beak shape variation in Darwin's finches. Proceedings of the National Academy of Sciences, 107(8), 3356-3360. DOI: 10.1073/pnas.0911575107
I said in the previous pronghorn article that the modern pronghorn - Antilocapra americana - is but the tip of the phylogenetic iceberg, if you will; the only surviving member of a group that was previously far more diverse [the adjacent photo (from wikipedia) shows Ramoceros osborni. Yes, it really looked like that, read on].
As we'll see here, fossil pronghorns encompassed a reasonable amount of diversity: there were kinds with deer-like pseudo-antlers as well as others that superficially resembled living African antelopes like kudu or nyala, there were tiny dwarf forms, and there were also some real oddballs, unlike anything before or since. All of this is very well known among palaeomammalogists, but as usual the information isn't widely available outside of the technical literature. My aim here is to provide a very brief, introductory review to fossil pronghorns: for in-depth treatments, the reader is directed to Janis & Manning (1997), Heffelfinger et al. (2004) and Davis (2007). Read the rest of this post... | Read the comments on this post...... Read more »
CNS Response are a California-based company who offer a high-tech new approach to the personalized treatment of depression: "referenced EEG" (rEEG). This is not to be confused with qEEG, which I have written about previously. What is rEEG? It involves taking an EEG recording of resting brain activity and sending it - along with a cheque, naturally - to CNS Response, who compare it to their database of over 1,800 psychiatric patients who likewise had EEGs taken before they started on various drugs. They look to see which drugs worked best in people with an EEG profile similar to yours, and give you a fancy report with their recommendations.That's not completely implausible. It could work. Does it? CNS Response and some academic collaborators have just published a paper saying yes: The use of referenced-EEG (rEEG) in assisting medication selection for the treatment of depression. How solid is it? Well, it would be wrong to say that there are many problems with this study. But then if you run off a cliff and plummet into a volcano, you've only made one mistake.Depressed patients were randomized to one of two groups: treatment-as-usual, which generally meant the common antidepressants bupropion, citalopram, or venlafaxine, vs. rEEG-guided personalized drug treatment. The trial was pretty large, with 114 patients randomized, and pretty long, 12 weeks. The patients had failed to respond to at least one antidepressant (mean: 1.5) during the current episode, so they were slightly "treatment-resistant", though not extremely so.What happened? The rEEG-guided group did better on the QIDS16SR self-report scale, and on most other measures. Not enormously: take a look at the graph, notice that the vertical axis doesn't start at zero. But better.Great, they did better. But why? The problem with this study is that the rEEG-guided group got a very different set of drugs to the control group. No less than 55% of them got stimulants, either methylphenidate (Ritalin) and dexamphetamine (speed). These drugs make you feel good. That's why they're illegal, that's why people pay good money for them on the street.It's debatable whether stimulants are clinically useful as antidepressants in the long term, but they've got a good chance of making you feel nice for a few weeks, and make you say you feel better on a rating scale. Plus there's nothing like a pep pill to drive active placebo effects.The authors say that "Almost all of the studies with depression not associated with medical disorders have reported minimal or no antidepressant effect of stimulants", and refer to some 1980s studies - yet their own trial has just shown that they do work in more than 50% of patients, and the latest Cochrane meta-analysis finds stimulants do work in the short term...The other big names in the EEG group were MAOis (selegiline or tranylcypromine). These are often effective in treatment-resistant depression. Not necessarily more so than other drugs, but remember that these patients had already failed at least one SSRI(*). Yet the control group were, it seems, almost all given SSRIs - either citalopram, or venlafaxine, which is effectively an SSRI at low doses, e.g. the average dose used here, 141 mg. (It does other stuff, but only at higher doses of 225 mg or 300 mg.)In summary, there were two groups in this trial and they got entirely different sets of drugs. One group also got rEEG-based treatment personalization. That group did better, but that might have nothing to do with the rEEG: they might have done equally well if they'd just been assigned to stimulants or MAOis etc. by flipping a coin. We cannot tell, from these data, whether rEEG offered any benefits at all.What's curious is that it would have been very simple to avoid this issue. Just give everyone rEEG, but shuffle the assignments in the control group, so that everyone was guided by someone else's EEG. So you'd give control Patient 2 the drugs that Patient 1 should have got, and vice versa; swap 3 and 4, 5 and 6, etc.This would be a genuinely controlled test of the personalized rEEG system, because both groups would get the same kinds of drugs. It would have been a lot easier too. For one thing it wouldn't require the additional step of deciding what drugs to give the control group. The authors decided to follow the STAR*D treatment protocol in this study, which is not unreasonable, but that must have been a bit of a hard decision.Second, it would allow the trial to be double-blind: in this study the investigators knew which group people were in, because it was obvious from the drug choice. Thirdly, it wouldn't have meant they had to exclude people whose rEEG recommended they get the same treatment that they would have got in the control group... and so on.Hmm. Mysterious. Anyway, we may be hearing more about CNS Response soon, so watch this space.(*) - Technically, some of them had failed an SSRI and some had failed "2 or more classes of antidepressants", but one of those classes will almost certainly have been an SSRI, because they're the first-line treatment.DeBattista, C., Kinrys, G., Hoffman, D., Goldstein, C., Zajecka, J., Kocsis, J., Teicher, M., Potkin, S., Pre... Read more »
DeBattista, C., Kinrys, G., Hoffman, D., Goldstein, C., Zajecka, J., Kocsis, J., Teicher, M., Potkin, S., Preda, A., & Multani, G. (2010) The use of referenced-EEG (rEEG) in assisting medication selection for the treatment of depression. Journal of Psychiatric Research. DOI: 10.1016/j.jpsychires.2010.05.009
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