Tuesday, 27 March 2012

Shedding Light on Body Clocks & Brains

Last week, on a sunny Friday afternoon I was in the basement of a UCL building performing my first public talk on my PhD and the effect of light on body clocks. This was the last session of Bite-sized lunchtime lectures this term, which allow early career researchers at UCL to talk about their research interests to the general public.

By the time I took to the stage the room had standing space only, a really successful turn-out. We even had a class of biology students from Norway! Apparently, my nerves were only noticable when I held the 96-well plate and you could see my hands shaking. Quite lucky really, as I felt like I was shaking like a leaf the entire way through.

After the presentation I got some really good questions, which I will re-type up here for everyone's benefit.

A huge thank you to the Bite-sized team for their help and feedback: Hilary, Kim, Laura and Matthew. Thank you also to Simon, who had to hear the presentation a few too many times! Thanks also to those who came and supported me.

And for those of you who missed it, or want to see it again, here it is:

0:00 Intro to talk
1:44 Chronotherapy - asthma & cancer
2:36 How body clocks work
4:35 Using light to help our body clocks
6:25 Zebrafish - development, regeneration and cancer research
7:44 My PhD research
9:40 Glowing zebrafish
10:34 Rhythms in light sensitive zebrafish brains
11:49 Conclusion

Questions - please feel free to ask more in the comments section below

As rats are nocturnal, how does testing drugs on them during the day effect them?
This is a really important point. Not all drugs are effected by time of day, but a lot of them are, and unfortunately a lot of pharmaceutical companies only test for drug effects (and side effects) during the day, which is the rat's sleeping time, not during the dark phase, when the rat's are more active. So the results are be more aligned with giving humans drugs during the night, which happens less frequently.

A few drugs have been deemed to toxic when trialled during the day, when they can be less toxic and effective during the night, and so we are losing drug candidates.

Does period3 have any other role in the zebrafish?
Period3 is a gene that signals time of day information throughout the cell, we don't know of any other role it is playing in the cell.

How did you measure gene expression, when you weren't doing the bioluminescent recording?
Good question. I mushed up the brain, to break all the cells open, and allow access to the messenger RNA molecule. This is an intermediate molecule we can measure when the gene is being expressed into protein.

We can determine how much messenger RNA is in the brain by using qPCR, quantitative polymerase chain reaction. This effectively doubles the amount of the RNA exponentially until enough can be detected, and then we can work backwards and find out how much we had to begin with.

How long can a zebrafish brain stay in culture? Will it behave in culture the same as in the body?
That's a good point. I've kept zebrafish brain regions in culture for two weeks, and the rhythms are still strong, so I think they could go for longer without any change in media. Eventually, the nutrients in the media will get used up, and the waste products will build up and so the cells will die. However, biologists can keep cells alive for decades by replenishing the media and giving the cells space to grow.

Cells and brains and other tissue cultures won't necessarily be the same in culture as they are in the body, so we try where possible to examine rhythms in both.

If light exposure during the day is so important, should schools be getting students to spend more time outside and less inside in the classroom?
Sometimes staying indoors can't be avoided, and that's why using effective lighting indoors is important. However, where possible everyone should try and spend enough time outdoors, from young people to the elderly.

How long is enough time outside?
It can vary from person to person, and on the time of year, but as a rough estimate I would aim for a couple of hours.

Is this also effective for jet lag?
Yes, light in the morning of your destination will help you synchronise to the new time zone quickly. A bike ride in the morning has been shown to be most effective, perhaps not what you really want to do to recover from a 12 hour flight, but you'll thank me later.

What does this light research mean for people with disabilities/limited vision?
The cells in the eye that are responding to this blue light are actually not the rods or cones or cells commonly associated with vision. So you can have blind people, who are visually blind, but not time blind. Their eyes can still use light to synchronise their body. Therefore, exposure to light is important for everyone including the disabled.


Enjoy this blog post? Check out my other posts from body clock related Bite-sized lunchtime talks:
Clocks make you fit, evolutionarily speaking and UCL researchers are mapping our happiness across the week


  1. You just became the catalyst of my get outside more scheldule. I love this blog!!

    And thank the zebrafish for me. :)

  2. Well done, Helen. An excellent talk indeed!

  3. I have waited 6 months for another post - how much longer shall I wait?