24 Sept. 2009 : The darkroom hood is now being carried by Daigger (www.daigger.com). Search their site for GL-1001. Thanks to Allan Ramirez for the info. Also, the Canon G10 apparently will work with the hood and can be controlled by your PC. Expensive, but still an option. The A620 and A640 can still be had from certain Internet sites if you are looking to save money.
Features:
blue-light transilluminator
7MP digital camera operated remotely
portable darkroom hood
thermal printer
Cost of camera and darkroom assembly (in 2006): <$500
The gel documentation system in my lab is composed of a digital camera and an inexpensive, commercially produced darkroom hood. We use it with a blue-light transilluminator but it would work just as well with UV. The system is inexpensive, easy to put together and operate, and takes great photos. I've prepared this page for anyone interested in constructing a similar system.
The darkroom assembly is made from components from Spectroline's DigiCam system, available from Fisher Scientific. The darkroom hood is a simple metal unit, looking somewhat like a rectangular megaphone, that is lifted on and off the transilluminator as needed. The camera connects to the hood by means of a tube-like lens converter. A close-up lens and filter can be attached to the converter and the whole thing is threaded onto the hood. A close-up lens isn't essential but it eliminates the need to switch the camera to macro mode every time. One recommendation I can offer is to buy a couple of cheap drawer pulls from your local hardware store and attach them to the sides of the hood as handles, thus eliminating any temptation to lift the thing by the camera or lens converter.
The advantage of using a digital camera is that it provides much higher resolution than a CCD camera attached to a frame grabber. The camera we use (Canon A620) has 7MP resolution, which is more pixels than you will ever need. It also has an IR assist for focusing in the dark, which is an essential feature because the hood has no epi-illumination. And just as with a typical CCD system, this system allows you to view the sample in real time on the computer screen and control the camera (zoom, exposure, shutter release) from the computer. The control software (RemoteCapture) comes bundled with the camera and is very nice. And, you can save the camera settings as a batch file so you don't need to fiddle with the controls each time you turn it on. Photos are automatically saved to the hard drive, so there is no need to transfer images on a memory card. Beware, though, the USB cable that connects the camera to the computer is short so you may need a USB extension cable. Also, if you want to avoid changing batteries, you'll need to purchase an AC converter because the camera doesn't come with one.
Note (9/5/08): Newer camera models in the Canon A600 series may not have the flexibility to be controlled remotely from the computer. The A640 does, but the A630 and the A650is do not. Check the user's manual online to be sure it lists "shooting from a computer" or "PC-controlled shooting" in the camera specifications section. Also, make sure it has a 58mm lens adapter available; otherwise you can't connect it to the hood. Different camera models now have different adapters so be sure you know which one fits your camera. According to Canon tech support, as of September 2008 the Canon models that fit those criteria are the A640, S5is, and G9.
Our transilluminator emits blue light (480nm) and is designed for use with stains such as SYBR Green (Molecular Probes), GelStar (Cambrex) or GelGreen (Biotium). The model we use in the lab is no longer produced but similar transilluminators are available from Invitrogen and Clare Chemical. This system eliminates the dangers of working around a UV light source and is much better for recovering DNA from gels because blue light does not damage DNA to the extent that UV light does. Also, in using these new stains we have removed a potent mutagen, ethidium bromide, from the lab (note: this family of stains reportedly is much less of a safety concern than EtBr but anything that intercalates with DNA is potentially hazardous, particularly so when contained in a DMSO solution, so we treat the stains as we would EtBr).
Using a blue-light transilluminator requires an orange filter to distinguish fluorescent DNA bands from background light. Transilluminators come with an orange filter screen but any pair of blue-blocking sunglasses should work. (Note: My recent experience is that a particular shade of orange works best and that glasses manufactured specifically for this purpose work very well and are worth the price). In our system, the darkroom hood is placed directly on the transilluminator, displacing the orange screen; thus, we use an orange filter on the camera. This system also works for UV transilluminators and EtBr stain by substituting a UV/IR filter for the orange filter. Most of our photos are for documentation purposes so we did not purchase any fancy analysis software.
Equipment and source
(no endorsement is intended or implied)
Camera: any of the Canon models that use RemoteCapture and take a 58mm lens adapter
Darkroom: Spectroline Geneline Darkroom Hood with 58mm threaded camera mount, (search Fisher Scientific site for part number GL-1001)
Lens adapter: Fisher Scientific or Canon camera dealer (allows 58mm filter and close-up lens to be fitted to camera and allows connection of camera to darkroom hood); same as Canon LA-DC58F (for A640); different cameras may take a different adapter
Close-up lens: Fisher Scientific or Canon camera dealer (same as Canon 250D)
Orange 58mm filter: Quantaray YA2 (available on Amazon.com)
Total system price in 2006 (without transilluminator): $447
Thermal printer: Sony UP-D897, available from ERI, Inc. for $795 in 2006 (I've seen this same printer priced as high as $1900, so be careful where you buy it)
Blue light transilluminator with orange viewing filter. A piece of glass is placed on the blue plastic surface to prevent scratching. Yellow tape allows quick gel alignment. |
Camera assembly consisting of digital camera, 58mm lens converter, +2-diopter close-up lens, and orange filter.
Camera assembly fitted to darkroom hood and placed on transilluminator. At this point, everything is done on the computer. The hood does not come with handles but we recommend that you add them.
Low-resolution grayscale image of an agarose gel. The PCR product is a portion of cytochrome b amplified from DNA extracted from deer fecal pellets. The gel is 1.5% agarose with 1 ul of GelStar stain and 4 ul of PCR product in each lane. Size standard at right is a 100-bp ladder. Note that the fluorescent numbers on the gel tray are easily seen at this wavelength.
Real-color image of a gel used for gender determination by amplifying X- and Y-specific fragments of the amelogenin gene.