I talked yesterday about magnetoreception as a means for navigation, but animals navigating via the stars is old hat. Like, viking helmet level old hat. Anyway, frogs will use just the brightest stars to orient themselves, but there are those that need utilize the entire Milky Way. No, not the candy bar, the galaxy! I am of course referring to this article ( http://www.bbc.co.uk/news/science-environment-21150721 ) on Dr. Dacke’s research of…(wait for it)…DUNG BEETLES. That’s right, those shitty critters follow the most elegant of GPS devices. Full details on the research can be found in Dr. Dacke’s article in Current Biology ( http://www.cell.com/current-biology/retrieve/pii/S0960982212015072 ). Furthermore, you may thank my most esteemed colleague, Marissa, at Medieval Musings ( http://mediaevalmusings.wordpress.com/ ). She’s like me, but with history, better handwriting and better card-making skills. Seriously though, this woman has a rubber stamp collection to rival a craft warehouse and the accompanying skills to make you weep with shame.
Oh and she coerced me into starting this blog, so you can blame/thank her for my nerdy ramblings.
Monthly Archives: January 2013
More Bonus Levels
My body is working on the Rhinovirus boss level of Video Game Moi, I’ve been out all day and go to bed in an hour and a half (I wake up at five). So blogging is not high on my list at the moment. It might not be high on my list tomorrow either (for I do actually have some form of life), but I do have some fun filler to throw around.
So stay tuned!
Magneto is Real and He’s a Shark
If you’re great big nerd like I am and enjoy X-Men comics and/or Sir Ian McKellan, you have probably had some form of the “Mag-neat-o” vs. “Mag-net-o” debate. If you’re not a big nerd and have no idea what I’m talking about, well then get off the internet and go clubbing or something! Skateboard with your hat on backwards, I don’t know, jeez. Whatever it is you cool kids do these days. You could also just smile, nod and keep reading. Anyway, the debate can end! Mag-neat-oreception, the ability to detect the Earth’s magnetic field, is a thing. You’re all so relieved, right? Right.
Although not well studied, magnetoreception is not uncommon. Found in anything from bacteria to bugs to birds to batrachians, this extra sense involves magnetite (an iron oxide mineral) crystals that, when arranged in chains, can align with the Earth’s magnetic fields and allow animals to use those fields in navigation (though there is a receptor involved, the exact mechanism is unknown). Migratory birds and sea turtles are excellent examples of such magnetic navigators. Sadly, they cannot use their magnetoreception to move bridges, but I am sure they’re working on it. Just like we’re working on HOW those suckers use specialized receptors to receive and comprehend the magnetic field data from the magnetite crystals, then use this to solve projected needs (do they need to find breeding grounds? Food?).
Elasmobranchs (sharks, rays and skates) also use magnetoreception, but the sensory organ involved is very different. They use ampullae of Lorenzini (tiiiny holes filled with a salty gel) to sense when prey pass over magnetic fields. But those little ampullae are not only for magnetoreception alone, oh no. Consider the hammerhead shark. Besides being impractical for normal doorways, it is a master of electroreception. That big hammer-shaped head is COVERED with ampullae of Lorenzini for detecting even the electrical signals of a buried fish’s gills. Since the receptors at the bottom of the ampullae respond to voltage variation disturbing the gel, they are also thermosensitive. Nowhere to hide from these badasses. Except land, I’d try land.
Source
Sherwood, Lauralee, Hillar Klandorf and Paul Yancey. 2005. Animal Physiology: From Genes to Organisms. Thomson Brookes/Cole, Belmont, CA.
Bad Bicep Puns and Other Tales
Got your ticket to the gun show right here! Yeah, this right here is banned in seven states, but here in Seattle I am armed and dangerous!
I know, I know, my biceps are impressive to no one except me. But dammit, I worked hard for these and I am proud! Which just tells you how bad they were before…Anyway! That should be a decent segue into more talk about mahscles. Mostly adding detail and fun facts to yesterday’s ramblings. As much as I hate the phrase “fun facts”, I am presenting facts and they are FUN I tell you.
I told you that action potentials trigger muscle contraction, but there’s a little more to it than that. When an action potential reaches the end of an axon attached to a muscle (that end is called a “terminal button”, by the way, the action potential triggers activity in the terminal button. Specifically, the opening of calcium channels. The resultant influx of calcium forces a neurotransmitter, acetylcholine (ACh), out of the button and on over to the target muscle’s ACh receptors. This leads to an action potential (ta da!) across the muscle cell membrane. Yup, muscle cells can get some action (potentials) too. That action potential will result in release of calcium from one organelle (think of it like an organ in a cell) to filaments elsewhere within the muscle fiber cell, which then contract. This, in concert with similar actions in neighboring muscle fiber cells, lead to full muscle flexion and beautiful flexy biceps like mine. Right. But anyway, while it makes sense that certain muscle must relax for others to flex, you may be surprised to hear that relaxing those lovely biceps actually requires energy. Hence rigor mortis (the stiffness of death) in the dead and undead. You see? Zombies only ever wanted to chill out. Also, if you exercise to the extent your muscles just won’t listen anymore (hellooo pointe class), that is because you lack the energy to continue. Sometimes you can even feel the muscles twitch because your nerves are saying, “go” but your body is saying, “HELL NO” (again, hellooo pointe class).
Now, let’s get to know these muscles we’re controlling, hm? There are three major types: slow oxidative, fast-oxidative and fast-glycolytic. The names refer to their primary method of obtaining energy for movement and the speed at which the fiber type itself may do so (fast or slow). Oxidative phosphorylation and anaerobic glycolysis sound scary so I’ll be nice (for now) and just tell you that the first type is slow and fatigue resistant while the second is fast but tires easily. Herd mammals that stand or walk a lot (like cows) have plenty of slow-oxidative muscles for endurance standing. Fast-oxidative muscles come in handy for humans while jogging; these muscles will last longer at higher rates of activity. Small birds, however, use fast-glycolytic muscles for rapid “sprints” of flying. Need a trick for remembering the types? Endurance (slow-oxidative) is for steak, extended jogging (fast-oxidative) is for…cannibal steak…and speed (fast-glycolytic) is for rotisserie chicken! Although, the truth is that most vertebrates possess all of the different muscle types, only the percentage of each varies. Training or differing lifestyles can also vary the percentage of different muscles even between individuals of one species, as with Olympic sprinters (more fast-glycolytic muscle) and marathon runners (most slow-oxidative).
Now remember, if you’re trying to bulk up like me, eat muscle to gain muscle. Eat brains and all you’ll get is kuru.
Source
Sherwood, Lauralee, Hillar Klandorf and Paul Yancey. 2005. Animal Physiology: From Genes to Organisms. Thomson Brookes/Cole, Belmont, CA.
Music of the Neuron: Schwann Lake or I, Robo-Ophid
OK folks, here’s where things get technical and y’all start liking me less. I mean, I don’t blame you; if you’re not at least an aspiring neurobiologist, learning how the movements of ions in and out of neurons control muscle flexion is less Music of the Spheres and more Music of the Drying Paint. But gaining at least a rudimentary understanding of how changes in electrical potential, running down wire-like axons through your body to conduct every movement you make and orchestrate each separate muscle to work in harmony with the others is pretty musical. At the very least you’ll feel like a badass robot. Who doesn’t want that?
Let’s talk about Robo-Ophid’s wires (in third person, apparently?). By wires, I mean the axons, the single, looooong branch of a neuron/nerve cell that is insulated by myelin, a lipid layer produced by Schwann cells on the axon and that increases the conduction speed of signals. The axons only conduct signals away from the main body of the neuron, dendrites (shorter branches) connect to other axons and receive signals. Signals for muscle movement are called action potentials, drastic changes in membrane potential that are propagated from one neuron to another in an un-diminishing fashion until the target muscle is reached. Neuron membrane potential, the difference in electrical charge between the inside and outside of the cell, is about -70mV. For Robo-Ophid to move, the membrane potential is depolarized (given a more positive charge), repolarized (given a more negative charge) and hyperpolarized (given a much more negative charge than it needs). Here’s the quick and dirty explanation of how: sodium channels open, allowing positive ions in; neuron becomes positive, hits peak of action potential/positive charge; sodium channels close; potassium channels open, allowing positive ions to exit; cell goes overboard and gets extra negative (perhaps even buys an emo CD) before returning to normal. Neurons like you, so the action potential itself is easy; the action potential just spreads down the axon to its target. In this case, lets say the spine, and that to another neuron that connects to a muscle. Not so bad, right?
Now, Robo-Ophid needs more than just one action potential to do things. Unlike the autoclave doors at her work, where you have to hold the damn button until the door is all the way shut or it comes open, Robo-Ophid needs multiple action potentials to do anything. Robo-Ophid doesn’t know if this makes her a worse machine than the autoclaves at work, but she doesn’t make inexplicable alarm noise for hours on end so I think we know who wins this round. Me. I win.
Anyway, along with other action potential-dependent signals (like skin temperature), graded contractions depend on the frequency of the action potentials. A higher frequency will lead to a stronger contraction and a lower frequency to a weaker contraction. Take physiology and you’ll get to test this out by poking your lab partners with electrical probes to force their muscles to contract. This is how biologists make friends; by poking people and laughing. Laughing so hard.
Source
Sherwood, Lauralee, Hillar Klandorf and Paul Yancey. 2005. Animal Physiology: From Genes to Organisms. Thomson Brookes/Cole, Belmont, CA.
BREAKING NEWS: WOMBAT!
I am shamelessly stealing a link from someone on my FB to share. It’s a wombat bothering a zookeeper.
Enjoy.
http://www.youtube.com/watch?v=qE82eFD7AjI
Why Marsupials
Since I have heard through the grapevine that wombats make good pets, my interest in marsupials has greatly increased. Now, I own two dogs and little grassy acreage for a wombat to trundle majestically across, BUT A GIRL CAN DREAM. And who wouldn’t want to dream of one of these fuzzy tanks napping ‘neath the rosebushes.
They really are tanks, though. Although they’ll keep your grass short, they have a habit of walking through obstacles, rather than around.
Wombats probably come third on the list of well-known marsupials after kangaroos and koalas, both much less endearing and well-mannered. But if you ask folks what makes these animals marsupials, the answer will inevitably be somewhere along the lines of “they have pouches”. Unless you’re a smartass biologist that likes to talk peoples’ eyes and ears off with a detailed explanation of marsupial reproduction. Lucky for you, I am just such a smartass! I’ll try not to talk off any sensory organs, though.
Marsupials are defined as an order primarily by their unique reproductive tracts. Though they also have more incisors and an opposable toe on the hind feet, the reproductive tract is much more recognizable. While “having a pouch” is a grand simplification of things, it does summarize the situation pretty well. Although if that’s all you know, trying to figure out why the pouch is there gets tricky. I know, I know, “they have a pouch to carry their young in”. But think about it, why do marsupials get a pouch and humans don’t? Wouldn’t our ancestors have enjoyed a built in baby carrier? Ask a few moms if they’d prefer shelling out for a fancy stroller or baby sling to a tummy pouch and see what they say. Actually don’t, that would sound creepy. The answer is in the baby marsupial’s development; they need to chill in a pouch for several months because when born, they still qualify as embryos. Gestation (time spent developing in the womb) is very short, down to 9 days in some, so the newborn eyes, ears and hind limbs will not be fully developed. They can eat, breath and self-maintain, but these naked little suckers will need to remain pouch embryos for a while to finish development. Oh, and did I mention? They are TINY. Since “fractions of an ounce” is vague, imagine pink little kangaroos and wombats the size and shape of jelly beans and bumblebees. TINY. Zoos that own marsupials will often not even know a female is pregnant because they can’t tell until the baby is big enough to peek out of the pouch. Some marsupials, like wallabies, will overlap pregnancies and until big sister is kicked out of the pouch, the fertilized and developing ball of cells that is little brother will actually be put on hold (embryonic diapause). Yep, the mother can hit “pause” and “play” on her pregnancy. Busy human mothers be jealous.
Another particularly interesting trait of marsupial reproduction are the internal organs themselves. While eutherians (non-marsupial mammals, you are a eutherian) have one uterus and vagina connected to a pair of ovaries, marsupials possess paired uteri and vaginas with one ovary leading to each uterus/vagina set. BUT WAIT, there’s more. Young are actually born through a third, middle vagina that (in most marsupials) is temporary. Yet they have only one cloaca from which the embryos exit the mother. It’s a mystery to me, but I will update if I find out more.
Source
-. 2013. Kosciuszko National Park. 27 Jan 2013. NSW National Parks and Wildlife Services.
Cogger, Harold G., Joseph Forshaw, Edwin Gould, George McKay and Richard G. Zweifel. 2002. “Marsupials”. Encyclopedia of Animals. Barnes and Noble Books, New York.
Jackson, Tom. 2010. “Common Wombat”. Illustrated Encyclopedia of Animals of the World. Metro Books, New York.
Marinacci, Peter. 2013. “Wombat Behavior”. Wombania’s Wombat Information Center. 27 Jan 2013
Note: Apologies if the citation for the wombat photo is odd, there wasn’t a lot of info on the photo itself so my citation is mostly on the slideshow it was in on the NSW National Parks and Wildlife Services website.
Another Note: I do not condone keeping wild animals for pets, and considering how wombats like to go all Kool-Aid Man on walls and fences, I see the trouble of owning one. Also, those claws! However, generations of selective breeding can produce animals (dogs, cats, domestic foxes) that live well around humans so I just hope to all that is bright and beautiful that SOMEONE will get on that with wombats.
Late Night with the Ammonites
I’ll be honest, besides contemplating how well their fossils look in various jewelry and home décor, I have not much thought of the ammonite. But now I know I have taken them for granted! If you know your systematics, you may know that cephalopods are mollusks, and c-pods like squid, octopods and cuttlefish evolved a pared down way of living sans the shell typical of their relatives like the clam and delicious-with-butter mussel. However, those shelled mollusks are not in the class cephalopoda, but guess who is? Considering I’ve already told you my blog topic for today, I hope you all guessed ammonite. Ammonites are extinct cephalopods whose shells fossilized very well. Likely because they were swimming mollusks adapted to deep water and therefore more resistant to pressure, so they deteriorated little before other minerals slowly replace the shell’s original components and lead to very solid, jewelry-worthy fossils. That’s a personal inference, but they also lived in large schools, so there were also a LOT of ammonites in the first place and that probably helped more in leaving more, nice fossils.
Speaking of jewelry, I’ve seen ammonite cufflinks and I am now positively tickled to think of those tiiiiny shells scooting around the sea. Because ammonites did scoot, ohhh did they ever. Although they are more closely related to modern octopods, squid and cuttlefish, ammonites are very similar in appearance to nautilids, a modern cephalopod that still possesses a shell (and a spiral one at that!). Nautilids, like their shell-less relatives, scoot about the sea via jet propulsion and so too would the ammonite have done. Perhaps less cute when they got to three feet in diameter, but still fun in the weird, weird way of cephalopods. Well…yeah, OK, at that size and with the (probably poisonous) beak they share with their aforementioned modern relatives, they’d be sort of terrifying. Terrifying scooters of the deep.
Source
-. 2007. Ammonite. Night, Inc. 27 Jan 2013 Photo
-2013. Ammonite. National Geographic. 27 Jan 2013
Laidler, Keith. 2009. Animals: A Visual Guide to the Animal Kingdom. Quercus Publishing Plc, London.
Yancey, Paul. 2011. “Nekton Motility.” Marine Biology. Whitman College. Walla Walla, WA. Lecture.
Is it in the Water?
Hope everyone’s Saturday is going well, I’m going to spend some of mine talking to you about fecal contamination of the water supply. Yeah, that’s right, I live on THE EDGE. Of what, I have no clue. OK, so besides not being a terribly exciting topic, fecal contamination is not exactly a pleasant thing to consider. But some people must do this for a living or you would be gripped with cholera and/or typhoid. The fine people involved in water treatment have some pretty spiffy tricks up their sleeves to save our tap water and environment from raw sewage. Bacteria in raw sewage is the chief concern, specifically coliforms. Coliforms are gram-negative (has an outer membrane covering a thin cell wall, the name refers to a specific test for this feature), facultative anaerobes (can live with or without oxygen) that ferment lactose into acid and gas and that do not form an endospore (protective spore in presence of extreme conditions). They are also rod shaped and are a strong indicator of fecal contamination in water. Dangerous coliforms are many, but you only need to test for one to confirm contamination: E. coli. E. coli is naturally present in the large intestine (which I said in a previous post if y’all were paying attention) and will be much more obvious than say, the bacteria responsible for cholera and typhoid infections. Those bacteria are often outnumbered in water samples so testing only for E. coli saves a lot of time and hassle. Otherwise, those fine people in water treatment would be cranky from testing for every. Single. Effing. Bacteria.
Testing for E. coli is surprisingly simple. I mean, you could mess up the test set-up, but interpreting the results does not require a calculator and star charts. The first test, called the presumptive test, indicates possible contamination. You dip a small sample of water into a lactose broth with a specialized tube, (really it’s a tiny, narrow, upside-down cup) incubate it and see if any gas collects in the tube. If so, whatever bacteria you grew in the broth ferments lactose into acid and gas, so you presume that a coliform is present. Like you presume the one British guy in the middle of Africa and far from anything is Dr. Livingstone. Anyway, next is the confirmed test where you inoculate (treat) a special agar plate (a Levine EMB or endo plate) with your gas-producing sample (cause you would’ve used multiple samples in multiple tubes of lactose broth, you are only using whatever tested positive for this step). Levine EMB agar and Endo agar cause samples with coliforms to grow in colonies of a particular color. Because at this stage you want to separate coliforms from non-coliforms, you streak the plate in such a way that different bacteria will grow separately (this part is tricky, I won’t explain it here cause it’s boring and hard to visualize, but trust me that there is a way). This step is the confirmed step, and if your colonies grow in the coliform positive style, you can move on to the completed test. Finally, the completed test consists of taking a sample of one of the coliform-only colonies and inoculating another lactose broth and a nutrient agar (it’s just got extra stuff in it). The lactose broth should test positive for gas again if it is E. coli and the sample grown on the agar will be stain to confirm that it is gram-negative. Results could still indicate bacteria that did not migrate from your gut, but these three tests narrow the field considerably. OK, so then there’s one more test, but the IMViC just differentiates between E. coli and E. aerogenes, so you cannot skip any earlier test to get the same results. It just don’t work that way.
I hope now fecal contamination has become more interesting. If not, well…I don’t blame you. It’s a shitty topic.
Source
Brown, Alfred E. 2009. Benson’s Microbiological Applications: Laboratory Manual in General Microbiology. McGraw Hill, New York.
Science in Action!
My arms are currently going through a bonus puzzle level in Video Game Me. Which is to say, I burned my arms at work and now I have a couple inflamed spots where Flamethrower Carl has gone to town and made my capillaries leaky. I focused on immune response to pathogens the other day, but white blood cells do react to tissue damage and the immune system will kick in even for a paper cut. It just doesn’t go full hog unless the cut gets infected. Because I have only light burns, there’s no open wound for pathogens to enter so Carl will just calm down when the damaged tissue is taken care of.
Calm down, Carl. Just calm down.
Daily Science (blog) 