11 replies to this topic

[DustinL]

I recently did an experiment looking at Arabidopsis grown under continuous red, far-red, and blue lights. To do this, I had to borrow some space in the programmable specific wavelength light chambers of a neighboring lab. I want to try different combinations of continuous wavelengths, but for such a preliminary experiment I can't really ask the lab to let me take over one of their chambers. So I was thinking I could use colored cellophane, just as a very primitive experiment. I was wondering if anyone knew of cheap filters I could cut up to get even dispersion of each color when placed over a box in a regular light chamber, or if anyone knew the wavelengths of light transmitted by some cellophanes. Does anyone have any better ideas for how to do this cheaply given that I only have access to a white-light chamber, and single chambers of red, far-red, and blue?

Thanks,
Dustin

[K.B.]

I think you may be looking for something like this - http://en.wikipedia.org/wiki/Color_gel

[HomeBrew]

Or use colored bulbs?

[DustinL]

Thank you both for the ideas. unfortunately, I still can't find the precise wavelengths the colored gels filter, and I don't have a free chamber here to put colored bulbs in. Does anyone with experience in theater lighting or photography know somewhere you can find datasheets on available colored gels?

[hobglobin]

it depends also how exactly you have to separate wavelengths...those filters will filter out some and pass several other wavelengths...i.e. you will get a mixture. And it depends on the light source of course, as all bulb and tube types have a different spectrum....
And finally they will reduce light intensity, don't know if it's then enough for plant growth...if this is of no importance (short experiment) LEDs might work, as now several different and with quite narrow wavelength spectrum exist

[perneseblue]

Oddly enough, I actually have a friend who built miniature light chambers for Aradopsis using LEDs. He built different chambers for specific light frequencies. So the LED idea does work and there isn't as much of a heating with LEDs so you have better control over temperature and light intensity.

[DustinL]

perneseblue, on Jul 15 2010, 01:57 AM, said:

Oddly enough, I actually have a friend who built miniature light chambers for Aradopsis using LEDs. He built different chambers for specific light frequencies. So the LED idea does work and there isn't as much of a heating with LEDs so you have better control over temperature and light intensity.

I like the idea of LEDs you both posted. I'd have to buy a bunch of parts, and if I'm here long enough (I have one more rotation with another lab after this, probably) then I may do just that so my mentoring postdoc and I can keep doing these experiments. For now it's too short notice to build a mini-chamber, so I'll give it a shot with the cellophane, even though it's going to give a mixture of wavelengths; I knew it would, but I was hoping to filter it as much as possible. And regarding intensity, we're going to look into that today and figure out if reduced intensity could explain some of the marked phenotypes we saw.

Thanks!

[K.B.]

You may try using spectrophotometer to measure absorbance curve of those cellophane filters.

[DustinL]

K.B., on Jul 15 2010, 01:20 PM, said:

You may try using spectrophotometer to measure absorbance curve of those cellophane filters.

The only thing I've ever used a spec for (a Nanodrop) was to quantify nucleic acids. And I think this is the only spec we have in the lab. Any suggestions on how to set it up for such a use? I really like the idea of doing that to at least have an idea of what the filters transmit.

[K.B.]

Which model of Nanodrop do you have? 1000 or 2000? First one has path length between 0.2 and 1.0 mm, the other - 0.05-1.0 mm. I'm pretty sure you can make this measurement with Nanodrop 1000 but I would not risk it with Nanodrop 2000 (unless you know the thickness of cellophane and it's less than 0.05 mm).

If you want to do it - pick "UV-Vis" from the main menu, zero on water, place piece of cellophane (eg. 5x5mm or smaller) on the top of drop of water on Nanodrop pedestal, place another drop of water on the top of cellophane, lower the upper pedestal (lid/arm) and measure.

[hobglobin]

Or if someone has in your department a UV/VIS spectrometer or somewhere else you can rent it. It should be something like this one here  e_pma12.pdf   1.62MB   155 downloads, though there are many companies and lots of different machines, mostly unfortunately not cheap...

[DustinL]

K.B., on Jul 15 2010, 04:11 PM, said:

Which model of Nanodrop do you have? 1000 or 2000? First one has path length between 0.2 and 1.0 mm, the other - 0.05-1.0 mm. I'm pretty sure you can make this measurement with Nanodrop 1000 but I would not risk it with Nanodrop 2000 (unless you know the thickness of cellophane and it's less than 0.05 mm).

If you want to do it - pick "UV-Vis" from the main menu, zero on water, place piece of cellophane (eg. 5x5mm or smaller) on the top of drop of water on Nanodrop pedestal, place another drop of water on the top of cellophane, lower the upper pedestal (lid/arm) and measure.

KB, that's exactly what I needed to know. Thank you! I'll give this a shot once I get my hands on the cellophane now that I know how to test it (and as long as the lab that shares it with us is ok with it).