Electricity-breathing bacteria! (Microbial fuel cells)

I made a 90-second “pod”cast of why microbial fuel cells work. I don’t yet know if This Week in Science is or was interested in playing it. [Update: this was featured in the November 6, 2007 broadcast! Hooray!] Either way, once I find a way to make it available without killing my bandwidth I shall. I’ll probably do more of them – if nothing else I obviously need the practice.

It was oddly difficult getting myself to actually talk to the microphone – more so than actually publically speaking to real people. I’m not sure why. It strikes me as something I’ll get over quickly once I’ve done it a few times, and my voice won’t sound quite so bland in the future.

In any case, microbial fuel cells are possibly the topic that got me really interested in a college education in applied biotechnology. I’ve been meaning to do a post on why they work for a while, so here’s one, in somewhat more detail than the 90-second audio version.

First, some quick review: We all remember that atoms are made of positively-charged protons, uncharged neutrons, and negatively-charged electrons, right? Protons and usually neutrons in the middle, and electrons hovering around. When atoms chemically react with each other, they’re really just having a fight over who gets to keep the electrons. When the reaction is over, some kinds of atoms or groups of atoms will have gained at least partial custody of electrons that used to belong to some of the other atoms or groups of atoms. The ability of a kind of atom to take electrons away from other atoms is called “electronegativity”. The second most electronegative element in the universe just happens to be a major part of our atmosphere – Oxygen.

As bacteria break down food molecules to get biological energy, there are electrons left over along the way. The bacterial cells have specific carrier molecules that take these extra electrons away, where they can be later dumped elsewhere into any of a variety of other useful biological reactions that need them. The one we’re concerned with today is called the Electron Transport Chain.

In many bacteria, and in the mitochondria of plants, fungi, and animals, the Electron Transport Chain regenerates a huge amount of a cell’s biochemical energy. The extra electrons get sucked into the beginning of this chemical chain, and as they are pulled along, the force of this pull drives a process which regenerates the cells’ main energy-carrying molecule, called ATP. This process is “respiration”, and it’s also exactly the reason you need to breathe oxygen. Humans need so much energy just to remain alive that we couldn’t survive without the huge amount of extra energy that respiration provides.

What drives this whole chain is some chemical at the other end pulling the electrons out. In aerobic organisms, this is oxygen. Some bacteria can use other chemicals, like nitrates, sulfates, and ferric iron (yes, there are bacteria that can breathe rust…) None of these chemicals provide quite as much energy as oxygen does, but it’s better than nothing and gives bacteria that could be damaged by oxygen something to breathe.

Normally, this last step happens inside the cell, but some bacteria have ways of extending this last step so that the final hand-off of the electrons happens outside itself. Some bacteria even make electrically-conducting biological “nano-wires” that this can happen through. Others make “shuttle” molecules that can pick up electrons, dissolve out of the cell, hand off the electrons somewhere outside, and then dissolve back into the cell to pick up more.

Now, we can make a microbial fuel cell. An electrode is put where the bacteria are growing – without oxygen – and a wire runs from this, out of the area where the bacteria are and to another electrode which is exposed to oxygen. It’s like an electric snorkel for bacteria. From the electrode and through the wire, the oxygen sucks electrons away from the bacteria. An electrical device stuck between the ends of the wire can use this energy exactly the same way that it could use the energy from electrons being sucked from one end of a battery to another.

Interestingly, the common “simple stain” Methylene Blue can also act as an artificial “shuttle” molecule. When reduced (carrying extra electrons) methylene blue is actually colorless, and I would swear I’ve seen protocols somewhere that use this to measure just how active a yeast culture is, and one of the demonstration microbial fuel cell setups actually uses a culture of yeast in methylene blue rather than a microbe that can naturally breath through electrodes.

By the way, if you thought you could tell a human from a realistic humanoid robot bent on world domination by the fact that only humans eat, I’ve got bad news for you. One interesting application of microbial fuel cells is Gastrobots. Literally, robots with digestive systems, where bacteria breaking down the contents of the “stomach” act as a microbial fuel cell to power the robot.

I hope you find this explanation useful and interesting. If you have (or even if you haven’t) please let me know. I can’t necessarily tell if I’m doing anybody any good without feedback!

Stir-fried random…

Just a few brief random comments for the moment:

  • Am I the only one who is already completely sick and tired of the word “spooky”?
  • I think I’ve figured out what Descartes’ problem is. He’s gone on this meditation where he’s convinced himself that as far as he knows, nothing exists…except for himself. I think what happens next is that he gets horribly lonely, so when he realizes that his thoughts also exist with him, that’s when he developed that unwholesome passion for them and inability to bear leaving them that I’d previously mentioned. “But what kind of thing am I? I’m a thing that thinks. A thinking thing is what I am. But what kind of thing is that? Oh, yeah, I already said, it’s a thinking thing. Did I mention I was a thinking thing that thinks thoughts?….”. Okay, Descartes, we got it the first time…
  • One of my fellow “college science bloggers whose obscurity currently keeps them low in the vote totals” actually has a pretty neat blog. The Biourbanist focusses on features and attributes of urban areas. Well worth adding to your RSS feeds, I think. After you’ve already voted for me, of course…
  • I am currently attempting to put together my first netcast, in which I shall attempt to crunch an explanation of why microbial fuel cells work, in a form hopefully comprehensible to anyone with a good junior-high-school science education (or a mediocre high-school education, which is probably sadly more common), that fits into 90 seconds. Wish me luck.

More to follow…
UPDATE: Got the “pod”/netcast done – a real blog post on the subject of Microbial Fuel Cells to go with it may be found here tomorrow (Tuesday, October 16th) sometime, so long as nothing unexpected happens…

Saturday Night Meta-Blogging

I’d like to thank (profusely and repeatedly) everyone who has been coming to check out my blog via the College Blogging Scholarship site. Whether you’re deciding to vote for me or not, I hope you’ll keep coming back.

First, the bad news. We all know how this goes: the finalists are announced, and they all go ask all their friends and associates to vote for them, and to pass on the message to go vote for them. When someone, given the “Go vote for Sean” (or whoever) message, lands on the voting page, they’re confronted by a list of 19 other blogs besides the one they went there to vote for. How many of them REALLY think “Gosh, I should probably check out all of the other blogs to see which one really deserves my vote!”. The vast majority, I’m sure we all realize, just click on whoever they came to vote for and leave. Obviously whoever has the largest network of affiliated bloggers to send out repeated “vote for my buddy” posts every day has a huge advantage. Checking my server logs, I see that this is definitely true. (I’m lookin’ at YOU, scienceblogs.com! Unfair? No, actually, not at all. Jealous? You bet your sweet bippy I’m jealous!)

Since the start of the competition, I’ve gotten a total of 465 unique visits referred from the scholarship finalists announcement page. At present, there are 19,740 votes that have been cast – so less than 2.5% of the voters have bothered to check out the other blogs.

Now, the good news: This is actually much higher than I would have guessed. Given the comparative obscurity of my blog (at the moment), the fact that more than one in fifty voters have at least looked over the first page of my blog makes me very happy. So, again, thanks, and I hope you’ll keep coming back.

In other news, Josh Charles of “[website]$sudo life” suggests that my post suggesting a “War on Science” could be a good thing for science would make a good basis for an entertaining spoof documentary. I’m kind of liking that idea…

Enough of that for now, though. I’ll be getting back to my science communication, amateur science, and microbiology roots in the next few posts. Stay tuned…

“Dog Philosophy”

But first, a quick request for information for anyone who happens by: where you live, what is the job market like for Ph.D. Geologists (with a background in stratigraphy, mining, and petroleum, among other things) and what kind of opportunities for non-medical biotechnology graduate programs are in your local colleges?

(And a quick side-question: is it obvious to most people that you get extra information if you hover over or click on things that look like this? I’ve never formally checked the usability of this trick for normal people…)

No login required to answer – they’ll appear as soon as I’ve filtered out any spam. Okay, on with the meat of this post.

In case anyone’s wondering what the “Epicanis” handle is all about: it’s a pun on the concept of “Dog Philosophy”, based on the name of the famous Greek philosopher “Epicurus” and the word “Canis”. Yes, I know, “Canis” is Latin, not Greek, but I figured “Epicanis” would be more a more recognizeable pun to most people than “Epicynus”.

Properly defining “Dog Philosophy” involves a joke which necessarily incorporates mild profanity and adult situations. In case any of the readers are of more delicate sensibilities, I present instead a more matter-of-fact (but sadly less funny) version.

Plato once famously wrote that dogs were philosophers. Like all philosophers that I know of, dogs consider the nature of what is real (metaphysics). To the dog, everything that exists external to the dog can be assigned to one of four categories:

  • Food
  • Toys
  • Companions

    • and

  • Everything Else, which is generally useless except as a surface for territory marking

You may wonder what that has to do with “Applied Empirical Naturalism” or science blogging.

The explanation is simple: science is fundamentally a method for examining the natural world to determine how and why it works. That’s what I like about science. One can find novel or unexpected applications of any system or thing by learning how and why they work, or in other words, it’s a method for, among other things, taking things from the “useless” category to one of the “useful” categories. Finding ways to make otherwise-useless things beneficially useful for people strikes me as a particularly rewarding purpose in life.

In addition to wanting to make the world a better place, I’m also kind to puppies and kittens and I think people should be nicer to one another.

(This shameless display of sympathy-solicitation has been brought to you by my participation in the following competition:)

Going to have to re-examine Socrates…

Figuratively speaking, of course, since he’s dead and all…

Man, Descartes so far is a serious disappointment. He seems to have an almost Dickensian tendency to verbal puffery (though thankfully the Descartes “Meditations” are much smaller than the big sack of tedium that was “David Copperfield”). It’s like he’s developed an unwholesome lust for his own thoughts and can’t keep his metaphysical hands off of them.

You’d think a guy clever enough to come up with “The Cogito™” could do better.

When I heard Descartes described years ago, I’d heard he started with “I think, therefore I am” and then from there proved the existence of The Supreme Being somehow. While I didn’t expect an unquestionable Proof, I did at least expect to see some spectacular theological philosophy taking place.

Instead, I (metaphorically, of course) show up at Descartes’ intellectual feast expecting some unique and exotic fare, only to see Descartes rummage around in his kitchen to come up with an old, freezer-burnt old package of leftover AquinasAnselm (oops), which he spottily defrosts in the consumer-grade-microwave of his argument. Bah. Not even worthy of dirtying my mental spork on. (There, do I sound arrogant enough to be an old-school philosopher myself yet?)

In other news: Celebration time! I’ve advanced all the way from 1st loser to 3rd loser! WOOHOO! It’s a bit of a jump to get up to the next tier (blogs getting an average of around 50-100 votes/day) but I can make it…

Calling on the entire internet to study for a Philosophy exam…

I’ll probably do two posts today, but only because this one is a preview and an attempt to gather opinions…

I find writing helps me think, and we’ve got a Philosophy exam day after tomorrow. We’ve got a “study sheet” with eight concepts and fourteen potential essay questions that might come up on the exam. Is anyone reading this particularly interested in any of these (some of these have been addressed in earlier posts, but here’s the whole list)?

Concepts: “valid argument”, “sound argument”, “a priori knowledge”, “a posteriori knowledge”, “epistemology”, “metaphysics”, “doctrine of recollection”, “Objective reality/formal reality”

Essay topics (in short):

  • Describing the “Socratic Method” and contrasting it with the sophist method.
  • Discuss some of the Socratic philosophical positions that might call into question the view that what is right for a person is whatever that person believes is right.
  • Discuss Socrates’ claims that evil harms the evildoer and that “the unexamined life is not worth living”, and whether or not he’s justified in these claims
  • Critically discuss Socrates’ claim (at his trial) that he could not have been knowingly and willingly corrupting the youth
  • Discuss Socrates’ arguments in the “Apology” that death is not something to be feared
  • Discuss the “Learner’s Paradox” in the “Meno” (roughly – is it possible to “learn” something without being “taught”, and if so, how can this be?)
  • What was the point of the “slave boy” portion of the “Meno” (Socrates’ attempts to demonstrate that someone who doesn’t understand Geometry can come to have knowledge of geometry without being taught.)
  • Discuss Meno’s definition of “virtue” and Socrates’ objection to it
  • Discuss the distinction (in the “Meno”) between “true knowledge” and “opinion”, and how it relates to the question of whether virtue can be taught
  • From “Euthyphro”, discuss the issues around whether or not whether something is “pious” because The Gods love it, or if The Gods love it because it is “pious”.
  • State clearly and describe Descartes’ three levels of doubt
  • Discuss Descartes’ contention in the first Meditation that he cannot know if he is not dreaming
  • Discuss The Cogito (“I think, therefore I am” and why Descrates couldn’t instead say (for example) “I walk, therefore I am”
  • Discuss: “I hear a noise, I feel heat. These things are false since I am asleep. Yet I certainly do seem to see, hear, and feel warmth. This cannot be false.” (A quote from our translation of Descartes’…)

That’s what we’ve been given to work with. What are the odds that any of that is interesting to any of you? If so, please comment (no login required, and go ahead and put a fake email address in the comment form if it bothers you – as long as it doesn’t appear to be spam I’ll post it.). Come on, you’ll be doing me a favor, and you’ll automatically sound like a genius because we’re discussing philosophy.

Followup post later today…

I’m an interdisciplinary nerd…

Oh woe! Oh woe! Last time I checked, I was dead last on the College Scholarship Blogging Competition! Now, as I’ve mentioned elsewhere, I may be a cynic but I’m an optimistic cynic, and therefore think that surely if I apply my full mighty nerd powers, I can figure out what’s wrong and fix it.

First, what is going wrong? I thought for a while, and came up with a few possibilities:

  • God Hates Me
  • God Loves Me And Wants Me To Win, But Doesn’t Exist And Therefore This Does Me No Good
  • The divine is not involved, but there is a conspiracy against me involving the CIA, the NSA, the BATF, The Teamsters, the Freemasons, and the World Aquaculture Society.
  • Blatant Age Discrimination by a bunch of dang whippersnappers (Git offa my lawn!)
  • Dang Yankees
  • Perhaps my young and under-promoted blog is simply still too obscure and not well enough established to have the large number of connections that older and better-promoted blogs have, and this is just a natural result of more popular blogs being able to get their “vote for me” message out to more people, who in normal human fashion will vote for the blog with which they are most familiar.

    • (Hey, I was brainstorming, so even crazy ideas like this were considered…)
    Then, finally, the problem became obvious to me:

  • It’s too much work to vote for me

It’s so obvious now! Hordes of adoring fans are coming out of the metaphorical woodwork and going to vote for me, but are becoming exhausted and collapsing before they manage to find my name, buried near the bottom of the list of 20 different blogs!

You may not realize this, but I’m back in college because I’m trying to start my life over. I may be microbial biotechnology nerd now, but in my former life, I was a professional “computer nerd for 15 years. My amazing nerd powers are therefore being applied to solve this problem (see also the update at the end of this post):

There – one click on the image (aw, look, Cornelia wants you to vote for me!), click the confirm button that pops up, and you’ve voted for me. Problem solved. When clicked and confirmed, a new window should open and you should see the current standings. If you are presented instead with an unselected voting form, it didn’t work – let me know. Now go! Go, my fellow conspirators! Click us to victory!

But seriously – I may yet come up with a way to gain enough fame quickly enough to have a shot at the prize, but right now I’m in last friggin’ place…which means I’m free! I don’t have to worry at all about “oh, gosh, if I do that will I lose the crucial vote that loses me first place?!?!?” and I can pretty much do whatever I want, within the bounds of ethics and legality, and it’ll make no difference. Therefore, I want to point something out:

Down at the bottom of this post, you’ll see that this material is made available under a Creative Commons license. Basically, as long as you’re not a commercial venture and you give me credit, you’re allowed to take and use anything you like from here, including taking and remixing the one-click-vote thing there. And, yes, this explicitly applies to my competition (Money or no money, I really can’t imagine how a scholarship competition counts as “commercial”.)

I’ll even go one step further: if any of you other finalists happen to see this and would like to use this on your own blog, let me know and I’ll send you a version tweaked to vote for you blog instead of mine. I’ll even try to help you get it inserted into your blog if you’d like. All I ask is that you mention and link to my blog somewhere in one of your posts. Obviously I’d prefer something complimentary, but if you feel the urge to write “I hear that Sean at The Big Room rapes puppies, eats babies, and has an unnatural attraction for maple trees”, what the heck, as long as there’s a link…

What do you think? Good idea? Bad idea?
UPDATE: Dangit, I swear it looked like it was working yesterday, but the ‘one-click’ (plus confirmation) thing is unexplainably just not getting the vote in, though everything else was working correctly. For the moment, I’ve reverted to having the link bring up the official vote form in a separate window…

The offer to make it available to others still stands, however, if anyone’s interested. I’ll re-revise this post if I figure out how to get it working.

Do Not Taunt Happy Fun Park

Here’s a brief interlude for my new readers. Members of my immediate family have seen this before elsewhere, but what the heck, I may as well share with you all.

Related to my recent posts about this year’s field-trip to Yellowstone National Park, I am reminded of a trip my wife and I took last year to Norris Geyser Basin in the same park.

I’ve heard of “communing with nature”, when the natural world seems to speak to you and put you at ease. Well, on this occasion it didn’t just seem to be speaking to me, and it hardly put me at ease. The conversation between me and the park went something like as follows that day. (Forgive all the scrolling, it WAS a several-hour conversation after all. If it bugs you, feel free to say so in the comments…)

Sign:No Restroom in Geyser Basin

Well, okay, I don’t smoke, I didn’t bring a bicycle, we left the dog at home. And I guess we can hold it until later. It’s a small price to pay to go out to nice, happy, peaceful trails, away from, for example, all the annoying road construction.Traffic cone, in the middle of the trailWow! Look at that! Do I spy the Fruiting Body of the rare Yellowstone Giant Orange Holewarning Mushroom?!?!?No, wait…that’s just a traffic cone over a hole in the trail! What the heck? I thought I was getting away from road construction!

Well. Maybe things will get more natural-looking once we get a chance to walk off into the wilderness. Maybe the map’ll show where we can go.

Map of Norris Geyser Basin, with Warning to Stay On Designated Trails
Ah, look at all the lovely trails. Plenty of space to roam around in.
What? I can’t leave the trails?
sign:Stay On Designated Trails

Can’t I take a mere step or two off? Just a little bit???

Sign:Stay on TrailSign:Stay On WalkYeah, yeah, whatever. What are you going to do if I don’t – have me arrested?

 

Sign:Unlawful to Leave Walkway
What kind of criminal act could possibly be involved with just leaving the silly walkway? Littering? Vandalism?
Sign:It is UNLAWFUL and UNSAFE to: Leave the walkway in thermal areas or throw objects into or deface thermal features

Oh, come on! Look, there’s a beautiful green pool over there, full of no doubt fascinating little animalcules. Can’t I just go over and take a little look?

Sign:Keep Off - Thermal Area
“Thermal Area”? What the heck is that supposed to mean? It’s a little windy and chilly today, maybe I want to be warmed up a little. So, why not? What’s so bad about a “Thermal” area?

Sign:Hazardous Ground - Thin Crust - Boiling Water

What’s that supposed to mean?

 

Sign:Dangerous Ground -with illustration of kid falling into ground and getting broiled-
Children are prone to explode out of the ground unexpectedly?Walkway shown crossing the top of the steaming opening of Green Dragon SpringWhat the heck? Is Green Dragon Spring actually devouring the ground under that walkway?!?! Oh! I get it – you’re saying the park itself can swallow you up and and cook you?
So everything here is flaming hot death, then, right?

Sign:Warning: Trail My Be Icy

Is there no end to the dangers this place threatens innocent visitors with? Can there possibly be anything else this park can do to us?!?!?

 

Solfatara: Very Dangerous Landscape spewing Sulfuric Acid Gas!
“Thin Crust”? “Boiling Water”? Broiled flesh cooked in acid? Ice?
Is this a park, or the kitchen at a Chinese restaurant? Is this how “Hot and Sour Soup” is made?!?!? Is there nothing that can stand in this realm of violent burning chemical death without fear!?!?!?
Fearless Geyser

But what of us poor, fragile fleshy people? We aren’t safe here!That does it! I’m getting out of here! No more of these horrible Killer Thermal Death Areas of Doom for me! I think maybe I’ll just go look at the nice cuddly animals that Yellowstone is also famous for.
Sign: Caution - Wild Animals are Unpredictable and Dangerous!
This whole friggin’ place wants to gore, dismember, maul, cook, devour, and digest me! That does it. No more of this dangerous stuff for me – I think I’ll just go read a nice book for a while…
Bookstore:Closed
NOOOOOOOOOOOOOOOOOOOOOoooo!!!!!!

Yatta! I Fail to Reject the Null-Scholarship!

(Oops, got so excited I got carried away with the title. Fixed now.)

I am thrilled to notice this morning that I am in the running for the College Blogging Scholarship, honestly, if this even attracts a larger population of active readers, I’ll consider that alone an excellent “Runner-Up” prize.

Not that the scholarship money wouldn’t be much appreciated…but more about that later.

For the moment though: Hello, current and new readers, to the internet’s self-proclaimed foremost authority on Expired JellO, among other things. I suppose that since I’m asking people to vote for me, I should probably give a quick description of myself and this blog. I’ll keep it short for the moment:

My actual name is Sean Clark; the explanation for the “Epicanis” handle deserves a post of its own. I am a “non-traditional” student at Idaho State University, working on finishing my long-overdue B.S. in Microbiology. This is actually the 5th college institution I’ve attended. It’s not that I’ve been kicked out of the others or anything, just that I keep having to move and start over. I’m finally in one place here long enough to actually finish the degree. Where I end up doing my graduate work depends on where (and if) we end up moving next year – I’ll post about this if anybody’s interested.

My primary interest is in “applied” microbiology, particularly non-medical biotechnology. I’ve been convinced for many years that non-medical applications of microbial biotechnology are underappreciated and somewhat neglected, and I’d rather people not have to get sick before they can benefit from whatever I might come up with…

Incidentally, Hillary Clinton agrees with me (“we should increase investments in non-health applications of bio-technology” – see paragraph 23). Whether that helps or harms my position no doubt depends on your political opinions, but still, I appreciate that someone with some kind of official authority agrees with me. And, hey, maybe this means I’ll be able to find a decent job during or after graduate school. Anybody think the Office of Technology Assessment will be hiring again soon?…

This blog itself is primarily concerned with sharing some of my education, and science in particular, as an exercise in communicating science. I, for one, think I’ve gotten better as the blog has progressed.

A couple of important points: This is a blog, not a magazine: participation is encouraged. If nothing else, the voting for the scholarship looks like it goes on for a couple of weeks, so if you are thinking to yourself “Gosh, I’d vote for you, but you don’t talk enough about X” or “you talk too much about Y” or “I hate the background color of the webpage” or whatever, now’s your chance to speak up. You do not need to be logged in to comment (but I do screen comments, so spammers: you’re wasting both your time and mine), so please do. Also consider subscribing to the RSS feed, found in the upper-right area of the page.

I try to update at least a couple of times each week, though lately I’ve managed to maintain a nearly daily pace. Participation helps here, as comments from readers helps me come up with additional topics to post on. I’m getting a lot of enjoyment out of blogging, so I’ll post as often as I reasonably can…

One last quick note on using this blog: I try to put title tags on most special bits of posts, like images and links. And…bits of text like this, which you might think of as “inline footnotes”. If you hover over anything with that thick-dotted-underline, you should see some additional information. As of a week or two ago, if you click on them, the entire extra text will pop up in a separate box where you can read it all, assuming you don’t have javascript turned off. I haven’t yet gotten around to going back and doing this to the previous bits like this, but I will eventually.

So, again, welcome. Comments, questions, and suggestions will help me improve the blog, and are therefore strongly encouraged. Oh, yes, and please vote for me. Otherwise, I’m going to have to resort to selling blood plasma and begging outside of scientific conferences. Thanks.

Libel! Blasphemy! Slander!…

Injustice! Perfidy! HUMBUG!

Periodically, someone puts up a “could you pass a grade-school science class” quiz. The one linked to the image below goes to one that I just broke down and took, purely out of curiousity. Take a look at this outrage!:

JustSayHi - Science Quiz

Oh, sure, it LOOKS good, but what you don’t see is that it only gave me a 96%, implying that I missed one (it was a short quiz)! Sure, the quiz was very much in the modern fashion for “standardized testing” (aka the “No Child Left Awake” project) where the emphasis is on memorizing stuff for a test rather than actual comprehension. So, I thought, maybe I hadn’t correctly memorized which word was correct for one of the word-memorization questions. But, no, according to the “answer sheet”, the one I supposedly got wrong was this one:

(Note: If you’re planning to actually take that quiz, do so now before you read on and I give away one of the answers…)

“How do mammals respire?”

The options were:

  • Aerobically
  • Anaerobically
  • Both aerobically and anaerobically

Come on, I may hardly ever concern myself with perverse eukaryotic systems but…never mind just “mammals”, as far as I know, all eukaryotes (animals, plants, and fungi) only possess aerobic (oxygen-requiring) respiratory systems.

However, the “answer sheet” for the quiz claims that the answer is “Both aerobically and anaerobically”.

So….they’re wrong. I’m pretty sure what what they were intending to ask, given this answer, is “what kind of metabolism do mammals have?”, in which case their answer is correct.

See, “respiration” is only one part of the cellular energy-generating system. Specifically, it’s our friend, the Electron Transport Chain, which (to grossly oversimplify) harnesses the energy of oxygen sucking electrons off the end of the chain various biochemicals to recharge molecules of ATP. That’s not the only way a cell can get ATP, though. What the quiz authors are presumably alluding to is that there are non-oxygen-requiring biochemical pathways that animal cells can take to make energy – such as the one your muscles use when they can’t get enough oxygen, which involves production of lactic acid, which in turn gets blamed for the “burn” sensation you get when you work your muscles hard.

So, the authors of this quiz are bad, bad people, besmirching my reputation and harming my precious self-esteem by giving me less than 100% on that quiz!

On a related subject: breathing causes cancer in Sprague-Dawley™ rats!

No, seriously, it’s true – try raising one group of Sprague-Dawley™ rats with air, and one group with no air, and examing both populations 150 days later. I guarantee you’ll find many more cancerous growths in the “with air” group than in the group that was denied air to breathe…

What brought this outburst on? It was this blog article. “No, It’s for Real: Aspartame Causes Cancer”, the post proclaims. They’re talking about This study(pdf). Go ahead, take a look, but in particular, look at the tables of actual data, not the paper’s abstract. In particular, take a look at Figure 1, especially “D” and “E” (showing survival rates for the different groups of Sprague-Dawley™ rats as the study progressed), and at the number of “tumor-bearing animals” in Table 2.

Notice that at around 120 days on the survival graphs, the groups with the highest percentage of members still alive were the groups receiving the most aspartame in their feed. It’s worth noting that the highest-Aspartame group there was getting roughly the equivalent of a human drinking <em>thousands</em> of cans of diet soda every day. Also note, in fairness, that both graphs seem to show little difference between the groups, so rather than assuming that Aspartame makes Sprague-Dawley™ rats live longer, I would tend to assume that there’s really not much difference.

Notice also that in terms of the percentage of Sprague-Dawley™ rats that developed one or more tumors, there were fewer of them in the group that got the equivalent of 500 mg/kg of aspartame: which scaled up to human terms means about 200-250 cans of diet soda EVERY DAY worth of aspartame.

You may be wondering why I keep mentioning Sprague-Dawley™. It’s because this is a particular commercially-bred strain of rat that’s popular with labs for this kind of thing. One point that isn’t always mentioned is this: Sprague-Dawley™ rats are known to be prone to developing cancer spontaneously. This can be handy if you’re doing studies of “borderline” carcinogens. The hope is that if something has even a tiny ability to cause cancer, you’ll be able to measure the effect in a population of critters known to get cancer at the drop of a metaphorical hat, when in a human population the incidence might be so rare that you can’t distinguish it from random chance. To my admittedly-not-big-on-the-biochemistry-of-perverse-eukaryotes mind, this study really seems to show that there’s little or no effect – and certainly no dose-dependent effect – of aspartame even on cancer-prone lab rats.

I don’t know what it is, but “artificial sweeteners”, and especially aspartame, seem to generate such passionate hatred in some people. It reminds me a great deal of people’s reactions to “genetically modified” crops. People just really want to hate it. The authors of this paper are obviously trying REALLY hard to show somehow that aspartame is a dangerous poison, despite the inconclusive-appearing actual results. Though I suppose one could argue that they showed Aspartame to be at least as much of a deadly poison as Expired JellO®.

And now that I have exposed my readers to several times the Recommended Daily Allowance of Humbug, I bid you all a good night – I have Art History and Philosophy to attend in the morning…