How animals help us understand disease

Glow-in-the-dark jellyfish (Aequorea victoria) by Frans LantingGlow-in-the-dark jellyfish are just one of many animals helping scientists understand human disease

For all the weird and wonderful diversity of the animal kingdom, at the genetic level many species have a surprising level of similarity.

As a result we can learn a lot about the inner workings of our own human cells by studying other animals, and not all of them are mammals as you might expect.

In the 2013 Christmas lectures at the Royal Institution, titled Life Fantastic, I discuss a menagerie of creatures that help explain where life comes from and how we grow and age.

I also show how the knowledge we gain from the natural world is helping to inform our understanding of human development and disease.

‘Hero’ worms

The first animal to have its genome sequenced was a tiny but wonderful species of nematode worm called Caenorhabditis elegans in 1998. Since then this simple worm has helped to inform a wide range of research topics, from ageing to cancer.

Measuring just one millimetre long, these worms are nearly impossible to see without the aid of a microscope, but their transparency allows scientists to see inside a living creature without the aid of x-rays, MRI scans, or any other technology.

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Life fantastic

Blind cave dwelling fish (c) Inaki Relanzon

See the curious life-forms thriving in poisonous underwater caves

Watch ‘chimpanzee fire’ fungus glow in dark African forest floors

Meet the rock ‘n’ roll salamander with an unusual escape tactic

But we would not have been able to make our greatest discoveries with C. elegans without the help of a fascinating jellyfish.

Aequorea victoria jellyfish produce a glow-in-the-dark protein called GFP (green fluorescent protein) which has allowed scientists to trace the movement of specific proteins through the body by using it as a visible ‘tag’.

Using GFP to highlight specific patterns of gene expression, I can track the impact of this on the rest of the organism over the worm’s lifespan and transfer this knowledge to how similar genes work in more complicated organisms, like ourselves.

I certainly would not have been able to begin to understand some cancer-associated genes without the help of GFP.

Secrets of sleep

Our biological clock – or circadian clock – is an internal mechanism which regulates almost every aspect of our physiology and behaviour.

One of the ways in which it does this in humans is by exposure to the light/dark cycle of day and night, without which our internal clock becomes out of sync with the external world.

So what would happen to our body’s everyday routine, if we lived in a pitch black cave?

Mexican tetra blind cavefish by Gerard LaczMany cave dwelling creatures like this blind Mexican cave fish are pale and lack eyes

Blind Mexican cave fish live in complete darkness their entire lives, and yet they have still developed an internal body clock that helps to govern their feeding patterns.

By identifying and understanding the genes which control their body clocks we may be able to shed light on how our genetic makeup contributes to our internal ‘clock’ and better understand sleep disorders.

Mending mussels

Mussels have an impressive ability to cling to surfaces such as rocks and boats without being washed away by powerful waves.

This is due to an extremely adhesive protein which, thanks to its super sticking properties, has become our inspiration for a new synthetic bio-adhesive for use in surgical procedures and repairing wounds.

Other types of tissue healing agents have been around for decades but often have unwanted side effects or are unsuitable for use on wet tissue.

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Dr Alison Woollard standing next to pictures of butterflies

The secrets to some of the greatest questions in biological and medical sciences could still be out there swimming in the sea or hiding underground”

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Dr Alison Woollard
University of Oxford

Adhesives derived from the mussel’s protein, however, are much stronger under wet conditions and, because they are fully synthetic, are much less likely to cause allergic reactions.

They can even be modified to degrade over specific time periods to suit a patient’s recovery needs.

Regenerating salamanders

Salamanders have remarkable regeneration abilities. As well as repairing their hearts, brains and spines, they are known for being able to re-grow entire limbs like their tail and are one of the very few vertebrates that are able to do this.

If we can figure out how they do this we may be able to develop a treatment that would assist the healing of wounds in humans.

It is thought that the capability for tissue regeneration exists in the genes of many other animals but has simply been turned off as a result of evolution.

Whilst re-growing limbs in humans is an ambitious aspiration, if we could find a way to reactivate the regenerative process we may at least be able to improve treatments for heart and liver diseases or reduce scarring from surgery.

Healing hearts

Heart failure affects around 750,000 UK people, and whilst more people are now surviving heart attacks, they often have to live with a reduced quality of life due to severely damaged cardiac tissue.

To help tackle heart disease scientists have turned to a species popular with tropical aquarium owners known as zebrafish.

Zebrafish are able to repair up to 20% of their heart muscle within weeks of damage occurring and, with time, are able to return a wounded heart to almost its original condition.

Zebra danio / (Brachydanio rerio) / Zebrafish by H ReinhardtCould tiny zebrafish unlock the secrets of how to repair human hearts?

Researchers have managed to identify a molecule in zebrafish which tells certain stem cells in an embryo whether to become a heart muscle cell or a blood vessel cell.

This discovery tells us more about the origins of cells in an adult heart, taking us one step closer to being able to make new heart muscle cells in order to repair damage caused by a heart attack.

We may even one day be able to offer an alternative to transplant operations which, for many patients, are currently their only hope of a healthy heart.

This is merely a tiny snapshot of the vast wealth of biological secrets waiting to be unlocked in the animal world.

In some cases research is still in the early stages and there are countless species with unique genetic properties that we’ve yet to put under the microscope.

The secrets to some of the greatest questions in biological and medical sciences could still be out there swimming in the sea or hiding underground.

The 2013 Royal Institution Christmas Lectures, titled Life Fantastic, begin on BBC Four at 20:00 on Saturday 28 December.

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