Zebra fish ears - Dr Tanya Whitfield

Tanya -  They don't have an outer ear, a pinna like we do, and they don't have a middle ear system, but they do have the equivalent of our inner ear and they do use their ears for both hearing, so they're sensitive to sound - although they're not sensitive to quite the same range or frequencies that people are.   And they also use them for as a balance organ which is exactly what our own inner ears are useful too, so we remain upright partly because we're constantly sensing whether we're the right way up, using our inner ears.

Kat -  And tell me about some of the work you're doing with zebra fish.  How are you using zebra fish to try and find how the ears work?

Tanya -  The subject I was talking about today was our work, looking for small molecules that can actually affect the way the ear develops and functions in the embryo.  The fish particularly good for that because the embryos are small which means we can treat them with different compounds, different small molecules, and see whether those have any effect on the developing ear.  Specifically, we've been using a gene expression marker which is abnormally expressed in one of our zebra fish strains to see whether we can restore the normal expression of that gene, after we've treated with chemical compounds.

Kat -  So when this fish don't have their ears developing properly, they make this marker that you can see and then you're looking for things that will turn it back to normal.

Tanya -  Exactly, yes.  And we can do this in not a high throughput, but a sort of medium throughput format, so we can screen plates of about 80 chemicals at any one time and so, we've completed a screen of over 2,000 chemicals and of those, we found 40 different compounds that give the effect that we want.

Kat -  So, what are some of the similar problems in human hearing that mimic what you see in your fish and do you think any of the things that you've discovered could be useful for human hearing or balance disorders?

Tanya -  We're at the very basic end of research so it's very early days to say that yet, but the fish with the abnormal gene expression I was talking about actually also has swollen ears as a developmental defect and in fact, too much fluid inside the ear is a problem in some clinical conditions for example, something called Meniere's disease which is actually quite a common disorder and for which the causes a largely unknown and some syndromes such as Pendred syndrome which is an ion imbalance syndrome which causes problem in the ear and in the thyroid gland.  But the idea is, a long-term goal is to identify new lead compounds that might be used in a drug development process.