Dark Reader - Performance

	Dark Reader Performance

Click on a button for more information about using the Dark Reader to view specific fluorophors.
The Dark Reader is a non-UV blue light transilluminator that uses a novel patented technology to visualize fluorescently stained DNA, RNA, proteins and other biological samples. Dark Reader devices use a visible blue light source that excites fluorophors between about 420 and 500 nm. This range includes many popular dyes such as fluorescein, SYBR Green, SYBR Gold, AttoPhos, GelStar, GelGreen, SYPRO Orange and red-shifted GFP variants. The Dark Reader also works with dyes maximally excited above 500 nm such as rhodamines, ethidium bromide and RFP.
Detect less than 100 pg of DNA
Using a unique combination of filters, the Dark Reader is at least as sensitive as a UV transilluminator for the detection of many dyes. For example, using SYBR Gold stain it is possible to see, by eye, less than 100 pg of DNA.

				430 ng - 0.84 ng of lambda DNA, cut with HindIII, was subjected to electrophoresis and stained with SYBR Gold. The gel was viewed on either a DARK READER (DR) or a 312 nm UV transilluminator (UV). By eye it is possible to see band 3 in lane 10 which contains 110 pg of DNA. Using a CCD system it is possible to detect tens of picograms of DNA.
Much More Sensitive than UV
All our Dark Reader products, including the Hand Lamps, are particularly effective for viewing fluorophors in places where UV light cannot reach - through glass and plastic.

		The superior ability of the Dark Reader to `see` through plastic is obvious in the photographs left. Note how the UV-induced glow from the centrifuge tube itself, especially on the 312 nm box, masks the fluorescence from the solution.
		Identical fluorescein solutions, in 1.5 mL centrifuge tubes, were placed on either a DARK READER transilluminator, a 360 nm UV hand lamp or a 312 nm UV transilluminator.
Head to Head: DR vs Laser Scanner
					How does a $700 Dark Reader (DR) stack up against a $90,000 laser scanner-based imaging system? Remarkably well! The graph on the left shows the results of a side- by-side comparison of a Dark Reader transilluminator (coupled with a basic CCD camera) and a laser scanner system. 100 uL samples of a serial dilution of fluorescein were placed in a 96-well plate and imaged using either the DR or laser scanner.

The Dark Reader performs as well as the laser scanner and can be used to reliably detect fluorescein down to about 1 nM or 0.1 pmol. (Incidentally, it took over 100 times as long to collect the laser scanner data - 540 sec- as it did the DR data - 4 sec.)
Monitor DNA Migration in Real Time
			The Dark Reader GelHead allows DNA bands to be visualized in real time as they migrate through a gel using either GelGreen, SYBR Green or GelStar as a stain. Lambda DNA cut with SauI/StyI was incubated briefly with SYBR Green I stain and loaded on a 1% agarose gel in a DR GelHead and electrophoresed at 5 V/cm. The extent of migration of the DNA fragments was monitored in 'real time' and recorded using a CCD camera at the time points indicated.

Detect Green Fluorescent Proteins
			Drs. Jim McManaman and Vern Shellman at the University of Colorado are using a red-shifted GFP variant (EGFP from ClonTech) to monitor protein expression. They have found the DR Hand Lamp to be a powerful and unique tool for the detection of EGFP during electrophoresis. The photograph on the left shows several EGFP preparations during native gel electrophoresis. Using a UV hand lamp, the GFP was undetectable.

						Using a DR transilluminator, the fluorescence from EYFP (ClonTech) expression in bacterial colonies is easily detectable. On the other hand, using a UV transilluminator, it is very difficult to distinguish between those colonies expressing EYFP and those that are not.