Colourblindness: not just a black and white issue

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As a ten year old, I found myself waiting impatiently outside the nurse’s office. Like most of my time in school I was unsure of why I was there. No answers were provided as I was sat down, and I was instead shown a series of odd dot patterns similar to the one you see above. Some patterns contained numbers, some didn’t. I left the room even more confused than when I’d went in. The next day my parents got a note from the school explaining that I was red-green colourblind, and that’s when my life changed forever…

Except it didn’t really.

For people already aspiring towards certain careers, such as pilot, electrician or military work, this news could be devastating. However, due to a long list of reasons (including tremors, asthma, and a potent dislike of high stress situations) running around firing a gun or cutting potentially fatal electric wires never particularly appealed to me. I decided instead to pursue science, laboratories of course famous for being happy, stress-free environments that require no intense periods of perfect hand-eye coordination.

The only difference I really noticed, fairly instantly after my diagnosis, was the reaction of other people. Anyone else with a hue-viewing deficiency will be familiar with the classic ‘What colour is this object I’m holding?’ question, and equally familiar with the resulting shock from the asker as you correctly identify it (Most kids know Coke cans are red, even if they see red differently). I’m not just talking about when I was ten years old here either.

My personal favourite question was one asked of me as I had just begun learning to drive. I remember my friend’s frown clearly, “But Joe”, they had said, concern for fellow road users filling their voice, “Aren’t you colourblind? How will you know whether the traffic lights are red and green?”

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The same goes for the walking man on pedestrian crossings.

But I cannot blame people for being confused. Colourblindness, in my life at least, has seemed to occupy an odd sort of limbo between personality quirk and a genuinely limiting condition. Indeed, the UK does not classify colourblindness as a disability. However, as colourblindawareness.org states, it can be seen as more serious in other countries. In Japan the condition can get you excluded from many potential job roles, and some countries such as Romania and Turkey even ban people from driving due to their inability to see different coloured lights.

On the flipside, people with colourblindess have occasionally found themselves sought after. In World War Two it was thought men with colourblindness were more adept at seeing through camouflage, and researchers at both Cambridge and Newcastle universities recently discovered that red-green colorblind individuals have an ability to spot differences in shades of khaki indiscernible to the average person. It makes me worry I’ve actually been wearing nothing but differing shades of beige my whole life and no-one has had the heart to tell me.

So what causes this odd biological quirk? I believe the best way to explain would be to work our way forward from the very start, which would be colour itself.

Light is a wave, and whether you can perceive the light or not is defined by the frequency at which it waves. The visible light spectrum is found sandwiched between infra-red (Which powers your remote control) and ultraviolet (Which you probably don’t want to shine on your remote control) light.

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Waves not pictured: New, Mexican, Awkward

These different ‘wavelengths’ of light all enter through the retina of your eye, where they hit a layer of cells known as ‘photoreceptors’. There are two types of these photoreceptor cells, imaginatively referred to as ‘rods’ and ‘cones’

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Scientists’ imagination is often found lacking when it comes to naming things.

Rod cells, while interesting in their own right, are not colour processors, and thus our focus today will be on cones.

There are enough processes going on in each of the six to seven million cone cells in your eye to fill a year’s worth of blogs, but the key component in these cells is inarguably a protein known as ‘Opsin’. This protein has the handy function of changing shape when being hit by light, starting off a series of events which in essence causes the cone cell to send a signal to the brain saying ‘I can see light’.

What’s more interesting is that there are multiple types of opsins, and each one only changes shape when hit by a specific range of ‘wavelengths’. This makes the cone cells sensitive to different light shades depending on which opsin they have, and together the brain can use them to determine all colour in the environment.

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S,M,L =’Short’, ‘Medium’ and ‘Long’ opsins, corresponding to what range of wavelengths they change shape in. The height of the graph shows which colour they absorb the most.

You may now see where this is going, colourblind people such as me lack one of these opsins (The ‘Medium’ one in my case), and as a result cannot absorb a specific range of light wavelengths. As you can see, M and L overlap quite alot, meaning a deficiency in one of these opsins is not as serious as a deficiency in S. Thankfully S deficiency is alot rarer, as will soon be explained…

So what is the deeper mechanism here? What causes colourblind people to have lost the ability to perceive these different frequencies from birth? Well, as it so often does, it comes down to genes…

The instructions on how to build these three opsin proteins are found in three separate genes, for simplicity (a word that produces gasps from many geneticists) let us call them opsinL, opsinM and opsinS. Genes are long sections of DNA that in most cases contain the information on how to make a single protein, the rudimentary building block for all life. These genes are packed together into 23 pairs of chromosomes, which are in turn found within every cell of our bodies. These chromosomes contain all the instructions your body needs to function, with thousands of genes for thousands of proteins, but today we’re focusing on three.

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S is on the 7th pair, and M/L are both found on pair 23, which has two variations.

While most people will know very little about chromosomes 1 through 22, the 23rd pair are much more readily recognised. The ‘X’ and ‘Y’ chromosomes, the genetic definers of sex. The presence of both long and medium wave opsins here explains one key issue with colourblindness. Why it is so much more common in men.

When our genes are passed on, things can go wrong. The machinery makes mistakes in the instructions when trying to copy them, and that means they cannot be read. This means a specific protein cannot be produced. Thankfully, as the diagram above shows, almost all our genes come with a spare set of instructions, all that is, expect the X and Y in men. If a male inherits a damaged X, he has no insurance chromosome, and his body has to work with the damaged copy. S, due to being on a non-sex chromomsome, has an insurance copy in both men and women, explaining why a deficiency is much rarer.

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The leftmost female offspring is described as a ‘carrier’ as they have the ability to pass the disease on but non of the symptoms.

And so, depending upon whether you are missing the red (long wave) or green (medium wave) opsin gene, you never experience an entire part of the visual spectrum, and have to spend an inordinate amount of time trying to work out which type of Thai curry you’ve just made. Is there anyway back from this terrible fate?

Perhaps there is, extremely sophisticated gene therapy has potentially paved the way for cures at the gene level, fixing the mistakes in the instructions so your body can produce the correct opsin protein again. Although one of the main reasons it is easier is that you can push a needle containing the fixed DNA straight into your eye for direct treatment, which some may view as a sticking point, well I guess in a way needles are always sticking points, that’s how they work. However, at the minute it’s only being used to try and regenerate damaged rods and cones in fully blind individuals, this obviously bein the more medically pressing condition.

For colourblindness, a less gruesome solution seems to have unveiled itself in recent years, and it’s admittedly fairly stylish. The company ‘Enchroma’ have begun offering glasses that users claim increase the vividness of colour in the world around them. I haven’t had a chance to get my hands on some yet, partially in the fear that I won’t ever want to take them off, mostly because of the price tag. They claim to filter out wavelengths of light, simulating a greater distinction between colours that colourblind people have not experienced before.

So while colourblindness can be a hindrance to many, I can say I’m at least partially glad I have it, as it has opened up a whole new area of biology that may not otherwise have caught my eyes.

 

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Thanks for reading my second blog, Colourblindness is a more nuanced and interesting area than many think, and is actually a good entry point into learning a lot of things about genetics, evolution and inheritance. (Did you know that the M and L opsins were originally the same gene?) If you’re interested in learning more, let me know and I may expand on it in the future.

 

The shape of knowledge: squares, cones and needles

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So, are you a square, a cone, or a needle?

I suppose the correct response is: ‘What on earth are you talking about?’ and I guess you’d be right. It is up to me to elaborate on what I mean. But first I’ll have to explain how I came up with this question in the first place…

When you start university, the subjects, or rather sub-subjects you can specialise into are laid out before you in different ‘fields’. This is an appropriate word, considering how immense the number of choices seems. You are presented with more information and specialties than you can shake an overpriced textbook at, and it’s up to you to narrow it all down to one or two if you want to progress.

If you’d taken an overall measurement of knowledge at the start of mine and anyone else’s university education, it would probably look something like this…

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    An innocent square, unburdened by student loans, deadlines, and the thought that education must end and you have to start adulting.

I believe, in terms of knowledge breadth (how many things you know about) and knowledge depth (how much you know about said things) that most people start higher education fairly similar in both, while we may be more drawn to or naturally talented in certain areas of study, the inherent structure of A-levels or other post-school education tends to leave our knowledge bases about even across the board. But what happens after the beginning of university?

Starting a degree is the first time most people feel they are developing what I’m going to refer to as a “cone of knowledge”. A phenomenon by which you begin to specialise in one core topic, at the expense of knowledge about the surrounding ones, your square will begin to taper, and end up becoming a bit more…coney.

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Symptoms include being picky over the use of the word ‘significant’ and beginning sentences with “current consensus shows…”

For example, at the end of second year, a bright-eyed and bushy-tailed me uttered the words, “Oh, Genetics looks fun, I guess I’ll choose that”. Suddenly, a class of 350 trainee scientists was pulled in different disciplinary directions, with mine whittled down to just 16. Each discipline allowed students to evolve themselves in different ways. As a budding geneticist, I occasionally worried we’d picked the educational equivalent of an evolutionary dead end.

Thankfully, me and the rest of the genetics course fell into the ‘platypus’ category of oddity, instead of, for example, the ‘dodo’ variety. The knowledge and interest I gained on genes, DNA, evolution and inheritance is most likely going to make up or be involved in a large portion of the things I talk about in the future.

So after my bachelors, having finally found a subject I felt confident and settled in, with a few months lab experience under my belt, I made the logical decision and continued in this subject area switched to a completely different field. Neuroscience.

This wasn’t a completely random decision. Like genes, brains are something I’ve always been interested in. I seem to be unstoppable drawn towards things that are irreducibly complex or complicated, or at least that’s what I tell myself while trying to untangle the wires from beneath my desk.

I had hoped, going into it, there would be some overlap between the two subjects. I knew it was possible, as my undergraduate project had involved looking at gene expression in the developing brain. But I quickly found that just because neuroscience plays by the same scientific rules, it doesn’t mean it is in anyway the same game.

Genes, as some of you may know, are small individual units of heredity made up by DNA, that tend to code for a specific protein (except when they don’t, but that’s a caveat for another time). Each one can be described as a tiny little instruction manual for one building block of an entire organism, and like tiny little instruction manuals, the directions can be difficult to read. However, science has taken great leaps in the past decade and a half in learning to decipher it.

Brains, on the other hand, pose an entirely different problem. They raise the mind boggling question of whether it is possible to understand the very thing that powers understanding. It’s the sort of thing that leads to fellow neuroscientists narrowing their eyes at each other and saying things like ‘You better not be talking about philosophy’.

To compare to genes, trying to understand the brain’s instructions may be like opening the first page and reading “To understand this manual you must have first read the manual”. It could just be something we can never achieve, due to our lack of an outsiders point of view. In other words, it feels like the darned thing won’t sit still long enough for us to work it out.

To pull this back to the shapes I’ve been mentioning, my ‘cone of knowledge’ had definitely narrowed, and was becoming more of a pointed triangle by this point. It amazed me how quickly you can put on intellectual blinkers to other subject areas when you’re in a lab environment. Sometimes it’s simply necessary to get through the volume of information on your specific topic, and I think this is why you get the occasional ‘needle’ in a lab environment.

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Disclaimer: The look of horror and general scruffiness is my personal experience of a needly lifestyle, and is not indicative of the needle population at large.

A needle tends to be the one who would perfect their topic on mastermind or university challenge but shrugs on the general knowledge round in a pub quiz because they simply don’t have time for keeping up with daily events.

Don’t get me wrong, the overwhelming number of people I’ve met in science have somehow managed to hang on to their random facts and niche interests despite the sometimes frustratingly specific information they encounter. Everyone acts a bit square at times, and everyone can get a bit needley.

But science needs those needles, it needs those finely tuned points of specificity to pop the never-ending balloons of ignorance. And if you put enough of those sharp folks together, you get a figurative bed of nails, a carpet of points that together is strong enough to hold up the weight of human advancement.

I’ve now left the world of academic research, and I’ve noticed that the switch from ‘studying’ to ‘studied’ in regards to my relationship with genetics and neuroscience has unsettled me. It sounds too historic, too final. I can feel my knowledge on the subjects fading, and I think if I don’t do something about it it will become nothing but a passing interest, something for me to regurgitate a few facts about in polite conversation.

That’s the reason I set up this blog, to hopefully preserve a knowledge of science and research that I have always enjoyed and been interested in, while also presenting it in a form people can read and (in exceptional cases) enjoy.

So while I find myself trying to fix my cone, I salute to all those people who know exactly what their shape should be.

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This entry is a bit longer than I’ll be aiming for in future weeks (although I’m aware I’m now making it longer discussing it) and this blog post began as a 200-word section for the ‘About page’. So when I try to write an actual first blog post you can expect the novel out early 2017…