The X chromosome

Chromosomes carry the genetic code that determines the characteristics of a living thing. They are fascinating due to the varied factors they determine, the sometimes negative effects they can have and their complexity. Equally interesting are the stories of their discoveries. This series will explore the history of specific chromosomes and their impact on science.

Humans typically have 23 pairs of chromosomes. One of these is comprised of our sex-determining chromosomes, X and Y. Taryn Cain starts this series off by looking at the X chromosome.

When cytologist Hermann Henking looked down his microscope in 1891, he was surprised to see that approximately half of his fire wasps had a spare chromosome floating around. Confused and intrigued, he named his lonely chromosome the “X element”.

By this point scientists already knew about cells; they knew that heritable material must come from these cells and they were aware that humans came from a sperm and an egg. What they didn’t know was how sex was determined while in the womb. Many theories have abounded throughout history.

Sperm of a mouse as seen under a microscope.

Sperm of a mouse as seen under a microscope.

Aristotle was sure that a hot and sweaty father during conception would bring forth a son. Galen believed a man’s right testicle would result in a son. Hippocrates thought it was the domination of a man’s semen over that of a woman’s that would bring him a son. In more modern times, Geddes and Thomson believed that good times would bring on a daughter whereas adversity would give you a son; a metabolic belief of sex determinism which persisted until the 1920s.

An unborn baby's genetic inheritance. (credit: Wellcome Library, London)

An unborn baby’s genetic inheritance. (credit: Wellcome Library, London)

After its discovery, the idea that the X chromosome was somehow responsible for sex determination grew quickly. However, it still took until the middle of the next century to be universally accepted. The X was briefly thought to be male determining until 1906 when this idea was put to rest by the same scientist who discovered the Y chromosome.

Part of the confusion came from the fact that the XX female and XY male combination aren’t standard amongst life on earth:

  • Henking’s fire wasps have XX females and XO males
  • Birds and butterflies have ZW females and ZZ males
  • A Platypus has 5X5X females and 5X5Y males
  • Roundworms have XX hermaphrodites and XO males

Of course, some species don’t rely on sex chromosomes for gender determination at all. Gender in humans isn’t purely determined by chromosomes alone either.

Illustration of a duck-billed platypus.

Illustration of a duck-billed platypus.

Over 200 million years ago the X and Y chromosomes were much like any other chromosome. As the first mammals were beginning to evolve, so were the X and Y chromosomes, drifting away from each other until they had little in common and barely spoke. The Y degenerated into the friendless chromosome we know today, being a third of the size of the X, whereas the X has remained relatively unchanged for the last 150 million years.

Human’s love to categorise things and we also like polarising opinions. This is why there are winners and losers, why you are a cat or a dog person and why your toilet roll must either face towards the back or the front. A similar thought process is at work with the X and Y chromosomes.

Ishihara charts for testing colour blindness.

Ishihara charts for testing colour blindness.

The X is often referred to as the ‘female’ chromosome; it is more accurately described as a ‘human’ chromosome. All of us, regardless of gender, have an active X chromosome in all of our cells. If you are female you were likely born with two Xs, so your cells will express one or the other. If you’re male, you likely only have one, so all your cells are the same.

This is the reason behind the higher incidence of autoimmune disease in women, the greater death rates of men and the male specific X chromosome disorders, such as colour blindness and Duchenne muscular dystrophy. That’s not to say that women are immune from these disorders. Usually when women are affected by them, it’s because they have inherited two mutant Xs, or one X chromosome has dominated the other during foetal development.

Meiosis. (credit: MRC NIMR, Wellcome Images)

Meiosis. (credit: MRC NIMR, Wellcome Images)

In 1992, the Human Genome Project (HGP) began sequencing each of our chromosomes. The X chromosome was sequenced by 250 scientists in 3 countries including the UK, with the nearly complete sequence being released in March 2005. The X was found to contain 155 million base pairs and 1100 genes, 50 of which are shared with the Y.

Along the way, some surprising things were discovered about the X. No one expected the X chromosome to contain genes for testis development, nor that the human X and dog X would be virtually identical. The HGP opened up a whole new door for exploring the path of human evolution.

The human genome library on display at Wellcome Collection.

The human genome library on display at Wellcome Collection.

In 2007, a complete printed library of the human genome, including the sex chromosomes, was given to Wellcome Collection, containing 118 books with over 3 billion characters. This genome library is still on display in our galleries today.

A look inside one of the books in the human genome library.

A look inside one of the books in the human genome library.

Taryn is a Visitor Experience Assistant at Wellcome Collection.

Contemplating the Contemporary: Sculpture

Contemporary art is all around us, but we often still ask: “Is it art?” In the first of a new blog series exploring how and why we make art, Guillaume Vandame looks at sculpture in our Medicine Now gallery and beyond for Contemplating the Contemporary.

Contemporary art of the twenty-first century is driven in part by advancements and innovations in the practice of sculpture. In particular, artists are interested in using mixed media, found objects and ready-mades, triumphed by artists such as Robert Rauschenberg and Marcel Duchamp, and at the same time, developing highly sophisticated forms of fabrication, as exemplified by Jeff Koons, Damien Hirst and Takashi Murakami. These contemporary strategies to making sculpture are continued with some of the artists featured in the Medicine Now gallery. Click each image for more information.

Robert Rauschenberg, Canyon. 1959. (© 2014 Robert Rauschenberg Foundation/Licensed by VAGA, New York, NY)

Marcel Duchamp, Bicycle Wheel. 1951. (© 2014 Artists Rights Society (ARS), New York / ADAGP, Paris / Estate of Marcel Duchamp)

Jeff Koons, Pink Panther. 1988. (© 2014 Jeff Koons)

Takashi Murakami, Fire sculpture. 2013. (© 2013 Takashi Murakami / Kaikai Kiki Co., Ltd. All Rights Reserved.)

Damien Hirst, Mother and Child (Divided). 1993-2007. (© Damien Hirst and Science Ltd.)

In the first space in Medicine Now, on the theme of Obesity and Genetics, there are two sculptures produced by John Isaacs and Rob Kesseler. Isaacs’ sculpture is striking and one of the first works visitors recognise in the gallery. I Can’t Help the Way I Feel was produced in 2004 and made predominantly from wax. Wax and wax-like materials such as fibreglass plastic have been investigated by a range of contemporary artists from Duane Hanson to Ron Mueck, predominantly in the pursuit of hyperrealism and strange, uncanny representations of the body.

John Isaacs, I Can Not Help The Way I Feel. 2003. (Courtesy of Wellcome Collection, London.)

Duane Hanson, Man on Mower. 1995. (© Estate of Duane Hanson/Licensed by VAGA/New York, NY)

Ron Mueck, A Girl. 2006. (© National Gallery of Canada.)

Despite its popularity as a material, this is not your typical wax sculpture of a famous celebrity you would find at Madame Tussaud’s. John Isaacs’s sculpture, in effect, could represent anyone and, at the same time, serves as an allegory of obesity; the ultimate visualisation of excessive consumption, corpulence and greed. The sculpture is pulsating and visceral, a quality which Isaacs exaggerates and seizes as an opportunity to strike our imagination about the possibilities of obesity. Perhaps the most terrifying aspect represented through its amorphous curves and folds is the anonymity of such a sculpture which could at once appear realistic and unknown. In this way, Isaacs presents a subject which is less about itself and more about our own critical reception and attitudes towards body image and its relationship to space.

Shown together with Kesseler’s, Bud, from 2002, the two sculptures deliberate ideas of consumption and the body. In contrast to Isaacs, who is much more hands on and appreciates the materiality and humanity of sculpture, Kessler presents a sculpture with no trace of his body and emphasises the sophisticated processes of creating new media through its fabrication.

Rob Kesseler, Bud. 2002. (Courtesy of the artist and Wellcome Collection, London.)

The sculpture is a glass vessel, shaped like a wine glass, missile or trophy, and filled with genetically modified soy beans. Kessler’s exploration of genetic modification considers some of the multifaceted positions surrounding the subject.

On one level, there are the unknown consequences of genetic modification. In particular, there is the concern that genetically modified foods could adversely affect our health while having an unforeseen impact on the environment. On another level, there are the obvious advantages of genetic modification: accelerated food production could yield a surplus which could eradicate hunger and world poverty.

Kesseler’s slickness and austere minimalism is used to great effect with this work of art and is a characteristic which follows some of the other key works in Medicine Now, including sculptures by Mauro Peruchetti, Annie Cattrell and Luke Jerram. The act of reducing an object to its most basic form is used to demonstrate the spiritual essence or physicality of a work of art, as spearheaded with modernist masters such as Donald Judd, Carl Andre and Richard Serra. In other cases it is used to emphasise ideas of industrialisation, consumerism and mechanical reproduction, exemplified by the gaudy, oversized sculptures of cheeseburgers, ice cream and cake by Claes Oldenburg, comparable to Peruchetti’s series of deliciously coloured  jelly babies made from polyurethane. Everyday life, through both subject matter and material, thus becomes a central focus of contemporary sculpture displayed in Medicine Now and remains an integral aspect of international artists working today.

Annie Cattrell, SENSE. 2001-2003. (Courtesy of the artist and Wellcome Collection, London.)

Donald Judd, Untitled (Stack). 1967. (© Helen Acheson Bequest (by exchange) and gift of Joseph Helman)

Luke Jerram, Swine Flu Virus (H1N1). (Courtesy of the artist and Wellcome Collection, London.)

Mauro Perucchetti, Jelly Baby 3. 2004. (Courtesy of the artist and Wellcome Collection, London.)

Claes Oldenburg, Floor Cake. 1962. (© 2014 Claes Oldenburg.)

Guillaume is a Visitor Experience Assistant at Wellcome Collection.

Object(s) of the month: Origin and Fossil Necklace

Who are we? Where did we come from? Where are we going? Aside from sounding like the ramblings of a philosophy student at three in the morning these are the ever pertinent questions addressed by two artworks currently on display at Wellcome Collection. This month Charlie Morgan takes a look at how these objects may offer answers to those questions.

Regular visitors to Medicine Now will be familiar with Origin by Daniel Lee. The looped video shows an animated Coelacanth-type fish evolve through reptiles and primates into a modern human: the scales disappear, the tails get shorter and, eventually, the body stands upright. By using smooth linking manipulated photos as opposed to clunky still images we are able to experience evolution as a fluid process and not just as a series of isolated points throughout history. Four floors up and in our Foreign Bodies: Common Ground exhibition, another piece does something very similar.

Origin by Daniel Lee

Origin by Daniel Lee

Katie Paterson is an award-winning Scottish artist who for six months was in residence at the Sanger Institute in Cambridgeshire. Here she became interested in genomic archaeology and after sourcing 170 different fossils (the oldest of which is a mere 3.5 billion years old) she had them carved into identically shaped beads and strung up on a necklace. The result is the first fashion accessory to document the history of life on earth and the first to ask the question “does my dinosaur stomach stone match my shoes?”

In Origin, the Coelacanth that starts the video emerged about 350-400 million years ago; in Fossil Necklace it would probably only appear about halfway down the right hand side. Fossil Necklace instead begins with the first single celled bacterial organisms to populate earth around 3.6 billion years ago. Since then, the earth and the living creatures that reside on it have developed, changed and evolved. As Katie Paterson notes, the only real links we have between them all is the DNA that the Sanger Institute studies and the fossils that she has collected.

Fossil Necklace by Katie Paterson

Fossil Necklace by Katie Paterson

While Fossil Necklace ends with the occurrence of written records approximately five thousand years ago, it also gives us a basis to pose questions about the future. Through Fossil Necklace we encounter five mass extinction events. These include the Late Devonian extinction which wiped out 75% of life on earth, but which was then topped by the aptly named ‘Great Dying’ and a whopping 95%. The most recent mass extinction was the most famous, the K/T extinction, which resulted in the death of the dinosaurs and a subsequent abundance of competing “whodunnit?” theories. 65 million years later and in an age of uncontested human dominance, a number of scientists are speculating a future – or, more accurately, an already underway – sixth extinction event: the Holocene extinction. We’ve already seen the death of the Dodo, the Auroch and the Mammoth to name but three amongst many, many others but it’s now estimated that “nearly 20,000 species of animals and plants around the globe are considered high risks for extinction in the wild”. How many of our present day creatures will soon just be fossils on a necklace?

Likewise Origin, by emphasising the various stages of human evolution (and as a result emphasising the ways in which those stages have adapted in order to survive), allows us to ask questions about what the future might hold for humanity. There is no shortage of theories; transhumanism anticipates a future merging of humanity with technology; a scientist has predicted we’ll soon be growing beaks; and one visitor to Foreign Bodies has suggested that the X-Men might be the most realistic prediction of future evolution. There is not much evidence to suggest humans are currently moving towards a new anatomical form or that we’ll soon be self-healing or shape shifting. Still, faced with constant fluctuations in the environment, climate and inhabitants of earth, both Fossil Necklace and Origin suggest we can be sure of one thing: something’s going to change.

Charlie Morgan is a Visitor Services Assistant at Wellcome Collection and Foreign Bodies: Common Ground is on until 16th March.

Around the World in 80 Days – Part 6: Germany

Over the course of four months, Barry Gibb visited our major overseas programmes in Africa and Asia to make a film about Wellcome Collection’s Art in Global Health project. In the latest of his diary entries, Barry makes a brief stop somewhere a little closer to home: Berlin.

As a researcher back in the early 90s, I spent several months living and working in Berlin, Germany, doing a spot of ad-hoc science at the Max-Planck-Institute for Molecular Genetics. I remember buses that ran like clockwork, the intense cold and Tacheles, a huge department store that had become a squat and home to some of the most amazing art and raves.

Back at Tegel Airport, memories began fighting their way through the treacle of time as I made my way to meet Katie Paterson, the artist-in-residence at the Wellcome Trust Sanger Institute in the UK (who, before you ask, lives in Germany ­– hence my being here and not back home!).

Arriving at Katie’s place, she and her partner immediately welcomed me into the space in which Katie thinks and creates; a cubic, entirely white room. Whilst often filled with materials and objects of inspiration (offering clues to Katie’s cerebral interests), today the contents of this room were minimal – perfect for our interview.

Despite the studio being right beside a main road, we were a few storeys up – far enough away from the traffic to stop noise being too much of an issue. And, thanks to large windows all across this street facing wall, I was able to place Katie looking directly into a flood of natural light, making the most of a sunny day and her unusually bright, blue eyes.

Katie P

The interview itself was an opportunity to gather material for the film but also to gain a deeper insight into how Katie sees the world. As it turns out, she is interested in nothingness, the absence of things: space and time. Within the context of her apartment, beyond the studio, this manifests itself in meteorite fragments and rocks of varying texture, a physical map of the moon, books about space. At the Sanger Institute, her discussions with scientists led her down a path of inquiry into the genetic heritage of humanity; where did the first humans emerge, how did they spread across the planet?

In Katie’s own words, “I believe work being undertaken in genome sequencing at the Sanger Institute can allow us to penetrate questions of existence: contemplate who we are, where we have come from and how we relate to one another, and enable us to be part of a complex decision-making process about the possible direction of our species.”

After the interview, with a deeper respect for Katie and her work, there followed a filming challenge – how do you show the internal creative processes of a person who, when not busy creating their works, spends her increasingly rare moments of tranquility deep in thought, formulating ideas? Shots of Katie simply staring into space seemed a little hackneyed so, fortunately, Katie shared that she keeps written notes, notes she was prepared to add to. Bingo.

There are so many nuances of human behavior, even within the simplest of actions, that I now knew we’d have enough coverage of Katie ‘thinking’. Wide and mid shots, macro shots, the pencil moving across the page, the eyes as they pause and consider. Finally, Katie introduced me to their two new kittens, fragile lumps of fluff with legs. These had nothing to do with DNA and human heritage but everything to do with fun and the promise of moments of levity between those deeper thoughts.

The next morning came all too quickly. Leaving for the airport at 4am, time suddenly felt very present. I was about to travel across countries and time zones, flying beneath stars that still filled the dark sky, bathing the planet in light from millions of years in the past. This sudden, profound awareness of space and time, I have called, the Paterson Effect.

Barry J Gibb

Barry J Gibb is a Science Multimedia Producer at the Wellcome Trust.

Read Barry’s previous diary entries.

Find out more about Art in Global Health on the Wellcome Collection website.

Object of the Month: You Spin Me Right Round

'Palindrome' by William Cobbing

Wellcome Images/William Cobbing 2003

It has become a cliché to say that when Charles Darwin published On The Origin of Species in 1859, he turned our view of the world on its head. But this is quite literally the case, for as the philosopher Daniel Dennett explains in his absorbing read Darwin’s Dangerous Idea, Darwin’s theory of evolution threatened to invert the ‘cosmic pyramid’ or ‘great chain of being’ (that traditionally placed God at the top, Creator of all things), by suggesting that design, or at least a semblance of it, could manifest by itself out of mere ordered matter if only given time. This, of course, was the philosophical implication, but Darwin himself was far more modest in his writing, diligently side-stepping the loaded question of how life itself began to demonstrate how the wonderful variety of life on Earth could have descended from earlier, simpler, pre-existing organisms through an algorithmic process he dubbed natural selection, and which avoided the need for an omniscient Creator, guiding the process along.

Despite over 150 years of accumulated evidence, the truth of evolution is still difficult for many people to accept, but nowhere in our exhibitions are its paradigm-changing qualities more succinctly expressed than in this fascinating (and quite frankly, bizarre) artwork by William Cobbing, on display in Medicine Now. Entitled ‘Palindrome’, it is a modified artificial skeleton of a human, with its parts reversed – it has a skull for a pelvis, and a pelvis for a skull. ‘What has this got to do with evolution?’ I hear you say. Well, when it comes down to it, rather a lot.

Cobbing was inspired by a book by the late author J. G. Ballard, ‘The Atrocity Exhibition’, wherein one of the characters, a doctor called Travis, imagines that ‘the bones of the pelvis may constitute the remains of a last sacral skull.’ In a scientific sense this is utter tripe, but what Cobbing has quite cleverly revealed in this artwork is that many parts of our bodies, when they originally evolved in our ancestors, may have served a very different purpose. Genetic research has suggested that our fingers and toes, for instance, may have originally evolved as the fins of fish that swam in the oceans over 100 million years ago. If this seems completely ridiculous, then genetics has shown the very same genes are perhaps responsible. An innocuous-sounding gene called HoxD-13 is present both in the DNA of four-limbed animals with a spinal cord (tetrapods), and a type of antipodean fish called Australian lungfish. In the fish, it controls the growth of the upper fins from the lower fins, but in animals, it controls the growth of fingers and toes from hands and feet, or claws from paws elsewhere. (Mutations in this gene are known to lead to the development of fused or extra digits.) The ubiquity of this gene means that it is highly unlikely it evolved independently in every single species that possesses it. Rather, it eludes to the common descent of all tetrapods (including us) from organisms that swam in our seas hundreds of millions of years ago.

Clues to our fishy ancestry also come from evolutionary developmental biology. Even without knowledge of DNA, genes or chromosomes, Darwin knew that embryonic development provided a tantalising hint as to our evolutionary origins. In The Descent of Man (1871), Darwin compared the embryos of dogs and humans at equivalent stages of development to demonstrate our (albeit distant) common ancestry. He pointed out the atavisms or evolutionary throwbacks expressed in foetuses that betray our common ancestry, which are later hidden as the embryo develops further, such as an ancestral tail. We now know that as fish and human embryos develop, genes are activated which control the development of structures called pharyngeal arches. In humans they become part of the pharynx, but in fish they go on to support the gills (this observation has led to the rather amusing assertion that human embryos have gills, which, I’m sorry to report, is not the case).

In a slightly different sense, our genome is chock-a-block with palindromes – sequences of DNA bases that read the same back to front, and which have been linked with the multiplication of oncogenes, genes responsible for cancer.

Chris Sirrs is a Visitor Services Assistant at Wellcome Collection. Look out for our special ‘Darwin’ themed tours of the Medicine Man and Medicine Now galleries on the Wellcome Collection tours page.

An extra yummy Packed Lunch

Donut design. flickr.com/jek-a-go-go

Donut design. flickr.com/jek-a-go-go

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When I heard that the latest Packed Lunch would be on food psychology, I immediately became very hungry. As the hours counted down the thought of ‘packed lunch’ and ‘food’ led me to an extra large helping of fish and chips…and a cheesecake.

Why do I lack such willpower when it comes to food? Is it something inherent in me, or is it the fault of those nasty devils in the kitchen, wafting their delicious smells of steaks and pies across our building? According to Professor Jane Wardle, health psychologist and Director of the Cancer Research UK Health Behaviour Centre at UCL, it’s a bit of both.

Wardle’s research focuses on the psychological factors influencing obesity.

Weight is highly heritable (we tend to resemble our biological parents), so for years people assumed that weight changes were almost entirely the result of your genes, and there have been several findings to support this. For example, researchers from the Wellcome Trust Sanger Institute and colleagues found that people with a specific variant of a gene called FTO were heavier. But though there have been several headlines about the ‘obesity gene’ over the years, many appear to make only a small amount of difference in weight. It’s likely that a plethora of genes are involved in a web of interactions.  And their influence is likely to be affected by external factors too.

Moreover, the ballooning of obesity cases over the last 25 years belies a purely genetic influence. Such a rapid rise can’t all be due to genetic changes. So what is?

Lifestyle changes have made a difference, as is the rise in convenience foods and 24/7 advertising. And we react strongly to cues like the smell of food (as anyone who’s walked past a bakery will know) – something food outlets actively take advantage of.

Wardle thinks that some people are naturally more “food responsive”, getting more of a kick out of eating than others. These people may therefore be more vulnerable to the presence of a tasty treat or the devilish advertising around them. Be it a sweet or a savoury tooth, some people are more easily affected by external influences and less able to resist temptation.

In one experiment, Wardle gave a group of 8-12 year old children their favourite food for lunch. They were told they could to eat as much as they liked. The kids were then taken to a room to do puzzles – next to a large plate of sweets and biscuits. Again, the kids were told they could eat as many of these as they liked.

The researchers weighed the plate of sweets and biscuits before and after the experiment. Given that the children should have all been full, surely most of the treats would go untouched? The results were surprising. Some kids indeed ate little or none of the food, but others ate a lot. Their relative fullness appeared to have no effect on how much they ate.

Interestingly, the experiment showed that a child’s body weight was a good predictor of how much they would eat: those with larger weights were more likely to eat more, despite being ‘full’.

Wardle theorises that people vary in the strength or recognition of ‘full’ signals in their body: those who have weaker ‘stop’ signals will easily eat more than they need to. And this doesn’t mean they binge on donuts and KFC – the amount that they overstep might just be a small amount each meal, so they don’t notice. But over time this leads to a gain in weight.

Can we find ways to help people notice their internal stop signals, or consciously change their eating behaviours? The only intervention that has worked so far is the rather extreme vertical banded gastroplasty (VBG), also known as stomach stapling. Wardle also warned that, when it comes to dieting, anything that involves mentally resisting temptation is only a short-term fix and does not tend to change long-term behaviour.

One thing Wardle is experimenting with is ‘unconscious training’ using a cognitive task that trains subjects to unconsciously look away from a ‘bad word’. By replacing the words with pictures of food, she is looking at whether a few minutes of brain training could set you up to ignore food temptations for the rest of the day.

In the meantime, what can I do to cut down the calories and resist that mid-afternoon cake break? Wardle ended her talk with a few practical tips:

1)   go for regular meals at the same time and place to reduce impulse eating

2)   make each meal gradually healthier

3)   make them gradually a little smaller

4)   weigh yourself every day and plot this on a graph so you can track your progress.

I’m putting away that Mars bar right now…