Biological Oxygen (c) 2005 Richard Katz


Not too long after I started working in biology laboratories, I got a job growing yeast. It turned out, a year or so later, that the answer to the main research question depended on how you grew the yeast, in particular, the air supply. In looking back on the yeast studies, it would appear that the air supply -- and the yeast oxygen demand -- was the most interesting part of the whole thing.

That was thirty-five years ago. In looking ahead, it appears to me that oxygen demand is the most interesting part of brain function.*

I. The Yeast

The lady scientist growing those yeast, back in 1969 or so, was as much of a scientist as anybody else. She had her degrees, her publications, her assistant professorship at Penn, her career path; and I never would have hooked up with a job as one of her technicians, not in a million years, if God hadn't invented nepotism. My girlfriend's mother was a full Professor who ran a big lab at the same biophysics Institute as the yeast lady. I had had a menial technician's job at Cornell, the summer before I met my girlfriend, Laura, the daughter of the Professor back at Penn. Not long after I had been to Laura's house to Meet the Parents (both of whom were full Professors, at Penn) her mom asked me if I wanted another job, like I had at Cornell.

The job turned out to be the worst job I ever had. The lab she fixed me up with worked with beef heart mitochondria; the biggest part of the job was butchering up beef hearts. Disgusting. I had had lots of experience with disgusting jobs, because I had grown up on a farm. Mud, pesticides, machinery -- didn't matter, you worked sunup to sundown and they paid you in the dark, on the farm, and you didn't complain because it was your own family farm.

After a few months, the beef heart mitochondria lady let it be known that I would learn more if I switched jobs and worked for her friend the yeast lady down the hall. I think the idea here is that technicians at an Institute are chattels, and you deploy them where they'll do the most good, but with a definite eye toward the technician's development. Not a bad system; a bit feudal and patriarchal, perhaps, but not a bad system at all.

I started work in the yeast lady's laboratory thinking everything was just fine, totally under control, nothing to worry about, certainly not the bubbles in the carboy growing the yeast. Everything was according to the way it's supposed to be in The Literature. But imagine that you're staring right at the problem, and you (and your superior) have absolutely no idea that there's a problem. The yeast lady was doing it all just right, but her yeast (and everybody else's yeast) have a much higher demand for oxygen than her equipment could supply.

Equipment? You mean that one cheesey little sparger? Hah!! You could have all the spargers in the world bubbling away, it turned out, and the oxygen needle wouldn't budge off zero. A culture of fast growing yeast demands oxygen at such a clip that you have to dose them with oxygen from a tank of compressed gas. Gases don't diffuse into or dissolve in liquids worth a damn, kinetically speaking, including yeast culture medium. Ask the fish in Lake Erie.

It had never occurred to the lady scientist growing her yeast that the yeast needed -- were demanding -- more oxygen. In fact, when you stop to think about it, it's a problem that compounds itself: The more the yeast demand and get, the more yeast you have, and the more oxygen they'll demand! They don't get better at it, there just get to be more of them. But you'd never know that, until you supply more oxygen; and all of that probably only occurred to me because I grew up trying to get a good yield growing foodstuffs on a farm. To all the city slickers, it was just a matter of if it ain't broke, don't fix it.

Now what's that got to do with thinking, or thinking hard? With the brain, you'll never know you could consume more oxygen, until you find someone somewhere who demands more oxygen. And we did.

II. The Brain

I always maintained a connection to that lab, right up to the present. Not to the particular laboratory run by the yeast lady; after she fired me, for being uppity and wanting to do my own experiments, her boss -- the Boss -- the Director of the Institute -- picked up my meager salary, and gave me a desk out in the hall. I improvised a lab bench, on a table I moved into the hallway. I measured the oxygen in a yeast culture, the same kind of yeast culture that the yeast lady and microbiologists all over the world use for growing experimental batches of yeast and bacteria, and got a reading of a solid zero. NO oxygen in the culture medium. That's like measuring the hemoglobin in your blood and finding that it's zero, that there's zero oxygen being carried from your lungs to the rest of your body. You're dead. The yeast weren't dead, though; as it was said on Monty Python's Flying Circus, they're only resting. **

One night I got the idea to construct an iron lung for a yeast culture. A friend of mine, Jim Geogalas, and I went into the lab thinking we would customize a pHStat so it would regulate oxygen instead of pH. The Boss came by on his way back to his lab down the hall. My buddy and I probably looked like we were two guys destroying an expensive pHStat, when in fact we were only, well, cannibalizing it. The Boss grimaced, the sort of expression that shows slight annoyance, mostly pity, and not a trace of what I would call criticism or reproof. ***

The Boss really swung into action. He is one of the pioneers in biophysics, so equipment modification was his long suit. Modification, hell, the Boss designed and built equipment just to be able to do this or that experiment, over the years. He'd been doing that since before I was born; he'd been one of the scientists who helped win the War. So he didn't bat an eyelash at what we were doing. He just told us to stop destroying the perfectly good pHStat, and come see him in the morning.

Next day he told me what it was I had been trying to do, and how one would do that electronically (they had just invented integrated circuits a few years before.) He sketched a schematic of how to do it. He told me to take that rough sketch over to the electronics shop, down the hall, and the boys in the shop would know what to do with it. A week or so later I got back a shiny little aluminum box. Armed with that box, I could dip an oxygen electrode in my yeast culture and the dissolved oxygen reading would be somewhere safely between 5% and 20%, because the shiny little aluminum box would give it a shot of oxygen now and then to keep it that way. If you kept a wide range like that, you could even keep track of the rate the yeast dragged the oxygen concentration back down -- the rate of respiration. Measuring that rate of respiration -- the rate of oxygen consumption -- led to the realization that, "My God, these poor things were gasping for breath, all these years!"

Now skip ahead thirty years.

The Boss is measuring oxygen consumption in brain, in situ. Here's a picture of Britton Chance and his Cogniscope. Notice the headset in Figure 0.



Now look at Figure 1, which shows the oxygen consumption at the prefrontal cortex of an ordinary brain (mine, in fact) answering ordinary social and moral questions. Note the excursions of the pen in the 0.5 to 1.0 micromolar range.



Now look at Figure 2, which shows the oxygen consumption at the prefrontal cortex of a trained brain -- a Division One Scrabble Player solving eight letter anagrams. Note the excursions of the pen into the five micromolar range.


What we want to do now, in 2005, is CREATE oxygen demand in the brain! If yeast can suck oxygen out of the water like a freight train climbing a hill -- power under the hood -- why not go looking for a way to get trainees' and students' brains to get up to that level of oxygen demand? Power under the hat. Brainpower!****

Richard Katz October 2005






*Perhaps my published scientific findings from thirty-five years ago, about acquisition and loss of rotenone sensitivity in Candida yeast mitochondria (the main research question) will help cure Parkinson's disease in humans; perhaps not. "The Literature" doesn't really reach back that far (1971), and so it is very unlikely that any current day researcher's literature search is going to unearth the fact that complex I of the mitochondrial electron transport chain is poisoned by rotenone when the yeast cells are growing, and is insensitive to rotenone if they aren't. Rotenone can cause Parkinson's.

**To this day I don't know of a word to use to describe their state of oxygenation. The Literature usually just says the culture was "sparged" or "aerated" and gives the rate of airflow in liters of air per minute. Any auto mechanic would immediately recognize this setup as being totally halfassed. Modern fuel systems are sophisticated, and the modern mechanic measure oxygen with a sensor that's built in to the car. The Boss would probably use the word "hypoxic"; never asked him.

***I got the idea from then on that, at least with guys like him, really good leaders, it's okay to fuck things up as long as you're experimenting, or as he always put it, you're working. He'd ask you, "What are you working on?" and it meant what experiments are you doing.

****We can approach these higher levels of cognition during the process of imparting expertise via short unadorned digital video sequences accompanied by Quicktime text tracks. This is spelled out at .