In my life as a scientist, I am continually struck by the modest miracle of the microscopic writ large. I think about this every time I streak a solution of invisible bacteria onto a Petri plate and come in the next morning to a sea of pale colonies scattered across the agar surface. Or when I amplify DNA from a clear droplet of liquid in the PCR machine and end up with a string of violent pink bands bristling on the gel under UV. Yesterday, my benchmate and I were marvelling at yet another manifestation of the tiny made tangible: E.coli transformed with a man-made DNA plasmid encoding a fluorescent tag called mCherry, so bright that after overnight growth, the bugs glow ruby red even by daylight:
The color became more intense after she spun the bacteria down in a centrifuge:
And, true to the laws of color mixing, when I miniprepped the DNA for her as a favor, the blue tracking dye turned a lovely shade of lavender:
It’s little observations like these that add a dash of wonder to my everyday lab experiences. But I was thinking this morning as I walked across the Quad, leaves fluttering down around me in the crisp air, that nature is the master of crafting invisible components into a gloriously omnipresent whole. The ochre and scarlet of autumn leaves are just conglomerates of microscopic pigment molecules; the blades of grass are mere chains of microscopic proteins. Even the mould that stubbornly sprouts up in the interstices of my bathroom tiles between bleach attacks is just another manifestation.
But nature does this so effortlessly. And we have become so divorced from the natural world that repeating its tricks in the lab seems like something original and clever.
Lovely ending.
To me, colors from pigments are pretty, but the unpigmented scales of butterflies that create color by interference are quite magical.
Ooh…(quick google)…I didn’t know that! What a wonderful idea; and I’m trying and failing to find a lab analogy for that.
I’m sure Stephen will be along in a minute to say something about diffraction, or Fresnel lenses…
At least Stephen has managed to teach me that proteins wouldn’t have color if you could get a camera small enough to see them. Which is so dreadfully disappointing.
Yeah, I know. We should complain to the Management.
OK, I’m here. What do you want me to do?
I could start by pointing out that this colour change malarkey was not such a doddle for nature. It did take a few billion years of evolution. Any natural system worth a candle would have sorted it out much quicker!
It’s worth waiting a few billion years to be able to shoof through autumn leaves. While commenting on Nature Network.
A few billion years…not sure I could persuade my funding body to stretch to that. But it’s a good point. I should have said that nature made it appear effortless.
On lab analogy to butterfly scales: I think there is some experimentation by printer companies putting OVERLAPPING dots of black ink on paper, varying the distance between the drops of ink to generate color. I forget where I read that.
David – I think there are optical illusions like this, no? Pictures made up of dots that seem coloured?
Regarding butterfly scales – bird feathers play some similar tricks too. Budgies, for example, only produce black and yellow pigments, but can be coloured blue or green due to some reflection and refraction malarkey.
And there’s RPG using his new word again… shoof. 🙂
My Dad is an emeritus professor of art, and he one of the courses he used to teach was one all about color. One of the exams he always set was the simple command: “make a grey disappear”. He didn’t issue any other instructions, and would come home with armfuls of art to grade (and for us kids to admire). It was amazing how many different ways there are of tricking the eye into thinking that something isn’t there, just by the context.
That printing thing sounds amazing – I just can’t picture how it would work.
make a grey disappear
Heh. Am I allowed to paint over it with black?
Only if you don’t mind getting an ‘F’.
I have to turn my head until my darkness disappears.
I’d like to add that now I can see those pics, they are lovely.
And ‘shoof’ is a perfectly cromulent word, thankyouverymuch.
Silver tabby cats have amazing hair. They actually change color over the zed axis, with ginger on the bottom and then either black or silver. If you rub them the wrong way the characteristic pattern goes completely haywire. (Plus the cat will sulk.)
The biggest color-when-it-ain’t-there magic is the peripheral vision – where there are few, if any, color receptors. I’m color blind (deuteranomalous to be precise) so my brain sometimes colors things in central vision areas that are grey, sometimes without cognitive cues, and sometimes with (like a woodgrain pattern on a grey table – it SHOULD be brown, says my brain, so it LOOKS brown).
As to how the “butterfly-scale” printer works, I have a dim and unreliable memory about the ink being thicker than usual, so it didn’t dry flat, and the irregular surface somehow created the interference.
If we’re getting into colour perception, this is a pretty cool optical illusion (?) that I came across recently. It’s quite remarkable.
Explanation anyone?
God, that’s weird. I’d almost say that the program is anticipating when you’d be likely to mouse over and it’s an animation changing from B&W to color! But it works even when you approach it unpredictably.
Relatively tire the receptors for the color complementary to the one you want to see after swapping the black and white image in. Move your eyes, and the images no longer line up, and your brain takes the easiest option and shows you “truth”.
Stay on the black dot after bringing the black and white photo in via the mouseover() call… even without moving focus the photo will gradually resolve to black and white.
And ‘shoof’ is a perfectly cromulent word, thankyouverymuch.
It embiggens me to hear that.
make a grey disappear
Am I allowed to use the “hue” slider in Photoshop?
Wintle, you were that kid in the back row, weren’t you?
He still is, Jenny.
Very cool – it’s always amazing to step back and see what nature does so (apparently) effortlessly. This is much the same as with the brain…once I start thinking about how it works, I’m just in awe.
Stephen – love those types of illusions. David gave a great explanation. I seem to recall something similar being discussed a few weeks ago, but can’t remember who posted it.
The weirdest thing that ever happened to me with optical illusions happened in a darkroom. I had read, earlier that morning, a paper in Nature about light perception. I wish I could remember exactly what it was but the upshot was a suggestion that if you see a bright light in the dark in a particular way, the brain can sometimes, under the right conditions, make it look as if a single light is oscillating to the right and left. So there I was in the darkroom with a particularly robust Western blot on the bench in front of me, with one band so efficiently detected by the chemiluminescent solution that it glowed bright green. I was just fiddling with the x-ray film when out of the corner of my eye, the band started to flash right and left, seemingly almost two inches apart and regular as clockwork.
I am a pretty suggestible person, but I hadn’t been thinking about the paper, and I definitely wasn’t imagining it.
How fast was it oscillating?
Quite leiesurely…maybe swapping every half second?
Perhaps the Western Faeries were signalling to you?
It’s so cool when things are visibly happening in the lab. I’m still amazed when I add developing solution to a particularly strong band on my Western blot membrane (usually b-actin) and it sometimes start glowing directly, the bands appearing as I drop the solution over them. It is kind of beautiful.
Talking about leaves, I read in the paper this morning that European leaves tend to turn mostly yellow in the fall, which is because the green color disappears and the yellow becomes visible. North American leaves on the other hand mostly turn red, which is due to a new dye produced in the leaves, maybe to ward of pests of various kinds. Cool!
Hi Anna, that’s really interesting about the leaves. We certainly have mostly yellow leaves here in London, and I was hypothesizing that it had something to do with the lack of extreme seasonal temperatures here.
Wintle, you were that kid in the back row, weren’t you?
I was not. I behaved myself in school. It’s only as an (alleged) adult that I’ve become difficult.
I could make the grey disappear by turning the lights out, you know.
Jenny
I mean, it’s an interesting post and I love the colour of the pellet – don’t get me wrong – but I have been thinking about grey for way too long and drawing a blank. A complete tabula rasa sort of 😉
Now that you, Ã…sa, mention and talk about colors really cause relax.
Especially the red and blue colors.
Asa, the idea is that you put a grey panel between two colored panels such that when you stare at the entire composition, you can only see one of the colors. There are a number of different solutions. I’m sure my Dad could explain it in terms of ‘values’ and which specifically are required to do the job, but I think the students just used trial and error, placing panels next to each other until the magic occurred. It was a pass/fail exam, because there was nothing in between!
What if you took the grey panel, broke it up into thousands of tiny microscopic grey panels, and arranged them in overlapping dots as David mentioned above? Or alternatively, interleaved them with dots of another colour (say, dark blue) so that from any reasonable viewing distance, the whole thing appears the other colour?
I think I may have worn out my welcome in this topic now. And failed your dad’s course several times in a row.
Jenny> aha, I think I understand now. That is truly fascinating though. I remember something like that at the Science museum when I was young 😉
thanks for explaining it! no more lost sleep over cofusing thoughts!
Richard, it didn’t matter how the students achieved it, so long as it ‘worked’. Keeping in mind that he taught this course in a time when you couldn’t do this on a computer – you’d have to be able to cut up your tiny pieces with scissors and glue then on. A bit fiddly!
I should ask him what the craziest pass looked like.
Richard, it didn’t matter how the students achieved it, so long as it ‘worked’.
In that case, I’m returning to my black spraypaint solution.
I seem to remember some other optical illusion where colours appear in a black and white photograph – but I don’t think it was the amazing one Stephen posted way up there…^