Weak Chemiluminescent Western Blot Signals: Possible Cause 3 – Wrong Membrane Placement

How to Place the Blot on the C-DiGit Blot ScannerSo, we’ve talked about how the substrate rate of reaction can cause weak Western blotting signals and how the amount of substrate used can affect signals on chemiluminescent Western blots. But, there are other possible causes of weak signals.

The third possible cause of weak signals is the blot membrane placement for imaging on the detection systems, since systems may vary as to how the blot should be placed on the scanning surface. Why is this important? Well, if the blot is placed incorrectly, you may or may not be able to visualize bands. If bands are visualized, they will be substantially reduced in signal.

As an example, LI-COR has two imaging systems for chemiluminescent Western blots: the Odyssey® Fc Dual-Mode Imaging System and the C-DiGit® Blot Scanner. Blot membrane placement depends on which one you use.

For the Odyssey Fc Dual-Mode Imaging System, the membrane needs to be placed FACE UP on the imaging tray.

However, for the C-DiGit Blot Scanner, the membrane needs to be placed on the scanning surface FACE DOWN. (For a quick video demonstrating this, watch “How to Place Your Blot on the C-DiGit Blot Scanner“.) Below is an experiment we did to look at the performance differences between imaging the blot correctly (protein side down) and imaging the blot protein side up on the C-DiGit Scanner. (Images are normalized to the Lookup Table (LUT) of the correctly imaged blot.)

Correctly Imaged Blot Incorrectly Imaged Blot
Images Correctly Imaged Chemiluminescent Blot on C-DiGit Scanner Incorrectly Imaged Chemiluminescent Blot on C-DiGit Scanner
Conditions:
Substrate SuperSignal® West Dura1 SuperSignal® West Dura1
Imaging Method Blot imaged protein side facing down Blot imaged protein side facing up
Performance LOD – 156 ng LOD – 625 ng

1SuperSignal West Dura results are comparable to those obtained with WesternSure® PREMIUM Chemiluminescent Substrate.

For more hints and tips, stay tuned to future blog posts. And if you would like to try some FREE Western Blot Analysis Software, download Image Studio™ Lite today!

Related posts:
Weak Signals on Chemiluminescent Western Blots: Possible Cause 1 – Substrate Rate of Reaction
Weak Signals on Chemiluminescent Westerns: Possible Cause 2 – Not Enough Substrate

Using Image Studio™ Lite Software: Image Display and Analysis

Okay, if you followed the last post on creating a work area and importing images into Image Studio Lite, you are now ready to learn how to easily alter the image display. You can adjust the way the image is displayed in Image Studio Lite by using the “Choose Display Assistant” or chooser.

Once you have imported your Western blot image and have adjusted it to be just how you like it, you can now add shapes and begin analysis in Image Studio Lite. Luke Miller (of ImageJ tutorial fame) also wrote some really informative, helpful instructions on how to use Image Studio Lite.

Wow! That was pretty easy, wasn’t it? If you haven’t yet, GO!, download a copy of this free Western Blot analysis software from LI-COR now! To see all of the tutorial videos and support documents, visit the Image Studio Support page.

(And, again, bonus brownie points for telling your friends about Image Studio Lite! :-))

Image Studio Lite – A Dream Come True, Without the Unicorn

Create a Work Area and Import an Image into this Free Western Blot Analysis Software

In this series of posts, you will discover how easy it is to use Image Studio™ Lite. This free Western blot analysis software from LI-COR® allows you to easily create your own work area and then import images from numerous sources. So, if you have an old film scan, or an image from another chemiluminescent Western blot imaging system, try using this free Western blot analysis software. In subsequent posts, we will talk about the other functionalities of Image Studio Lite.

The first video in this post will show you how to open Image Studio Lite software and create a work area. (If you need to find out the installation requirements for Image Studio Lite, see the 17-Jul-13 Post, Computer Requirements to Get Started with Free LI-COR® Image Studio Lite Software).

This second video walks through the steps needed to import an image into Image Studio Lite. Image Studio Lite analyzes images in the tif, png, or jpeg format as well as images acquired with past versions of the Odyssey® or Pearl® imaging systems software.

Download FREE Image Studio Lite Western Blot Analysis Software from LI-COR and get started right away! (Bonus points for telling your friends about it too! :-))

Image Studio Lite – A Dream Come True without the Unicorn!

Multiplex Western Blotting System Turbo-Charges Western Blot Results Output

Example of Multiplex Western Blotting using the MPX Blotting SystemMultiplex Western blotting is a powerful tool that allows you to get more out of your Western blots. Multiplex detection becomes possible when you utilize the MPX™ (Multiplex) Blotting System and LI-COR IRDye® near-infrared fluorescent dye-labeled secondary antibodies.

Multiplex Westerns can be imaged on any of the Odyssey® Imagers and provide results for a possible maximum of 48 targets on a single membrane — 24 per channel with two-color detection — and the option for quantitative analysis, saving you time and reagents! The MPX Blotting System can be used if you need to optimize:

  • Primary antibodies – to determine the primary antibody that has the right specificity and the right dilution for use
  • Antibody incubation times
  • Blocking conditions – which blocking buffer will give you the optimum results
  • Secondary antibodies – what dilutions is best to use without getting a lot of non-specific binding?
  • Or just about anything else you need to optimize!

Watch this 4 minute video on how easy it is to get the most out of multiplexing with the MPX Blotting System. You can also download the handy MPX Blotter User Guide.

WesternSure® Chemiluminescent Western Blotting Reagents from LI-COR®

WesternSure Chemiluminescent Western Blotting ReagentsDetect your Western Blots with Confidence! Use NEW! WesternSure® Chemiluminescent Reagents from LI-COR!

Now, in addition the great imaging systems for chemiluminescent Western blots, LI-COR Biosciences offers chemiluminescent Western blotting substrates and HRP-conjugated secondary antibodies for use in performing your BEST chemiluminescent Western blots ever. And, the WesternSure Pen is used to annotate visible protein ladders prior to chemiluminescent Western blot detection.

WesternSure chemiluminescent Western blotting reagents offer the best performance available when compared to other competitive products on the market. WesternSure PREMIUM Chemiluminescent Substrate is a highly sensitive enhanced substrate for detecting horseradish peroxidase (HRP) on immunoblots.

WesternSure HRP-conjugated secondary antibodies (Goat anti-Mouse and Goat anti-Rabbit) are compatible with a variety of chemiluminescent substrates and are optimized for use with WesternSure PREMIUM chemiluminescent substrates.

Happy Blotting!

No Darkroom? No Problem! Get the LI-COR® C-DiGit® Western Blot Scanner !

C-DiGit Blot Scanner - a Compact Personal Chemiluminescent Imaging System
Are you doing chemiluminescent Western blots? Have you ever found yourself with a blot that is ready to image, but the darkroom is busy or the developer is broken?

FINALLY, image at your convenience. Keep your C-DiGit Blot Scanner on your lab bench, at your desk, or anywhere you choose (look left and see just how small and portable the C-DiGit Western Blot Scanner really is!). It can truly be YOUR personal chemiluminescent Western imager!

The C-DiGit Chemiluminescent Western Blot Scanner maintains the simplicity of film exposures without the mess of the darkroom. You perform all of the same steps, without buying film and spending time in the darkroom. The C-DiGit Scanner gives you a complete digital replacement for film – keeping the advantages of film and eliminating many of the drawbacks – saving you time AND money!

Watch this short video and then visit our website to get your very own C-DiGit Blot Scanner!

NEW! IRDye® Goat Anti-Mouse IgM Secondary Antibodies from LI-COR®!

IRDye Dye-labeled Goat anti-Mouse AntibodiesOur IRDye secondary antibody line is growing! We have recently added IRDye Goat anti-Mouse IgM (μ chain specific) secondaries labeled with:

  • IRDye 800CW (PN 926-32280)
  • IRDye 680RD (PN 926-68180) or
  • IRDye 680LT (PN 926-68080).

Just like all of the LI-COR IRDye secondary antibodies, these are highly cross-adsorbed secondary antibody conjugates suitable for a variety of applications (see the table below).

IRDye 800CW secondary antibodies are the antibodies of choice for a wide variety of applications in the 800 nm channel (see the list below). IRDye 800CW secondary antibodies can be used for 2-color detection when multiplexed with IRDye 680RD or IRDye 680LT secondary antibodies.

IRDye 680RD secondary antibodies are the antibodies of choice for In-Cell Western Assay and Western blot applications in the 700 nm channel. These antibodies can be used for 2-color detection when multiplexed with IRDye 800CW secondary antibodies. These antibodies are our most universal use 700 nm channel antibodies. Start using IRDye 680RD first over other 700 nm dyes. Dilution working range 1:10,000 – 1:40,000.

IRDye 680LT secondary antibodies have been proven the brightest signal for Western blot detection in the 700 nm channel and are comparable to Alexa Fluor 680 secondary antibodies. Choose IRDye 680LT secondary antibodies to get high signal and for specific uses of detection in the 700nm channel. These antibodies are not recommended when getting up and running on system. Once established near-infrared protocols are optimized with IRDye 680RD, IRDye 680LT can be used to optimize signals in the 700 channel. Dilution range 1:20,000 – 1:40,000. Note: optimization may be required with IRDye 680LT.

Application IRDye 800CW
Secondaries
IRDye 680RD
Secondaries
IRDye 680LT
Secondaries
Western Blot
In-Cell Western™ Assay Not Recommended
On-Cell Western Assay Not Recommended
Protein Array
Immunohistochemistry
Microscopy
2D Gel Detection
Tissue Section Imaging
Small Animal Imaging Not Recommended
Virus Titration Assay Not Known Not Known
FRET-based Assay Not Known Not Known


Note: Now, as of December 15, 2014, you can also get 0.1 mg sizes of all of our IRDye dye-labeled secondary antibodies. Check out our complete listing here and our new filtering tool!

Reprobe Fluorescent Westerns with NewBlot™ Western Blot Stripping Buffers

NewBlot Stripping Buffer IconNewBlot Western Blot Stripping Buffers are specially formulated for use with IRDye® infrared dyes (680RD, 680LT, and 800CW only) and the Odyssey® Infrared Imaging Systems to help you save time and money on recreating samples. NewBlot Stripping Buffer allows you to reuse the same blot by stripping and reprobing up to two fluorescent antibodies simultaneously.

So, you may ask, what’s so great about NewBlot Stripping Buffer?

  • Effectively removes antibodies, yet gentle enough to retain immobilized proteins
  • Strips blots at room temperature in 20 minutes or less without an unpleasant odor
  • Allows you to reuse the same blot up to 3X! (see the data below!)
  • Offers qualitative analysis after stripping

In the example below, beta tubulin and ERK2 were run on a gel and transferred to Immobilon®-FL PVDF membrane. They were probed with primary antibodies rabbit anti-beta-tubulin and mouse anti-ERK2 and then with IRDye 680 Goat anti-Rabbit (red) and IRDye 800CW Goat anti-Mouse (green), respectively. NewBlot PVDF Stripping Buffer was used to strip the blot, which was then reprobed with the fluorescent secondary antibodies. This was repeated 2 more times. As you can see from the series of images, there is very little apparent loss of signal in either channel in the third blot as compared to the original blot.
Example of using NewBlot Stripping Buffer on PVDF Membranes

NewBlot is available in two ‘flavors’: one for stripping nitrocellulose membranes and the other for stripping PVDF membranes.

Get more power out of your blot with NewBlot Western Blot Stripping Buffers!

Note: On August 25, 2014, we launched two new Western blot stripping buffers: NewBlot™ IR Stripping Buffer for infrared Western blots on either PVDF OR nitrocellulose membranes; and, WesternSure® ECL Stripping Buffer for chemiluminescent Western blot stripping and reprobing. BOTH do not require hazardous shipping charges, unlike many other Western stripping buffers.

Which Western Blot Detection Method Should You Use?

Western blots can be detected with fluorescent, chemiluminescent, or colorimetric methods. Which Western blot detection method should you choose? Find out how the three common Western blot detection methods compare to each other in terms of time, sensitivity, and other important factors. The, choose what works best for your research.

Fluorescent detection: Fluorescent detection uses secondary antibodies labeled with fluorescent dyes, rather than enzymes. No substrates are needed.

Enzymatic detection: Chemiluminescent and colorimetric methods use secondary antibodies labeled with enzyme reporters such as horseradish peroxidase (HRP). Signal-generating substrates are used.

Fluorescent detection uses NIR fluorescent dyes to generate a signal.
Secondary antibodies are labeled with dyes such as IRDye 800CW or IRDye 680RD
• Digital imaging reveals target protein signals with high sensitivity
• Quantitative (signal is proportional to the amount of target protein present)
• Stable fluorescent signals are stable
Multiplex detection of multiple protein targets without stripping and re-probing

Chemiluminescent detection
uses the horseradish peroxidase (HRP) enzyme and a luminescent substrate.
• Enzymatic reaction produces light that is detected by film exposure, or digital imaging with CCD camera
• Multiple exposures typically required to capture optimal signals and avoid signal saturation
• Very sensitive
• Cannot be multiplexed
• May not be quantitative

Colorimetric detection uses the alkaline phosphatase enzyme.
• Enzyme converts a soluble chromogenic substrate to a colored, insoluble product that precipitates onto the membrane and produces colored bands
• Development of the blot is stopped by washing away the soluble substrate
• Simple and cost-effective
• Limited sensitivity

Comparison of Chemiluminescence and Infrared Fluorescence
Detection for Western Blotting
Chemiluminescence IR Fluorescence
Sensitivity +++ +++
Linear Dynamic Range 10-50 fold >4000 fold
Multiplex Detection No Yes
Signal Stability Hours Months – Years
Enzyme Conjugate HRP
Substrate Luminol-based None Needed
Detection/Documentation Film Exposure/Digital Imaging Digital Imaging
Membrane Compatibility Nitrocellulose or PVDF Nitrocellulose or PVDF

Monitor Protein Levels and Phosphorylation with Quantitative Multiplexed Western Blots

Molecular profiling reveals diversity of stress signal transduction cascades in highly penetrant Alzheimer’s disease human skin fibroblasts.

Mendonsa, G., et al. PLoS ONE 4(2): e4655. doi:10.1371/journal.pone.0004655

Aberrant signal transduction is associated with Alzheimer’s disease (AD). In skin fibroblasts of AD patients, exaggerated signal transduction occurs in response to bradykinin (BK), an inflammatory neuropeptide. BK-induced PKC signaling causes stimulation of tau phosphorylation on serine residues in AD fibroblasts, but not in normal skin fibroblasts. Quantitative Western blotting with multiplex fluorescent detection (Odyssey Imager; LI-COR Biosciences) was used to monitor protein levels and phosphorylation.

To explore the roles of inflammatory and oxidative stress in AD pathology, this study profiled the effects of these stresses on MAPK signaling cascades in human skin fibroblasts of familial AD patients. AD fibroblasts of different genetic origins express presenilin (PS-1 or PS-2) mutated at a variety of sites. These mutations caused diverse responses to stress induced by BK or H2O2, with unique profiles of stress-induced MAPK activation, caspase-3 cleavage, and survival pathway activation. These results indicate that AD research must consider a broad spectrum of inflammatory, oxidative, and other stress factors and intracellular signaling responses.
Reduced ERK activation in PS-1 (M146L) Alzheimer's disease fibroblasts stimulated with bradykinin.

Figure 1. Reduced ERK activation in PS-1 (M146L) Alzheimer’s disease fibroblasts stimulated with bradykinin (BK). These fibroblasts carry a mutation in presenilin-1 associated with aberrant signaling. Mutant and control human skin fibroblasts were treated with 250 nM BK and immunoblotted for active and total ERK. Odyssey Imager was used, and fold activation was quantified. Total ERK is shown in green, and phospho-ERK in red; overlapping signals (active ERK) are shown in yellow. ERK activation was greatly reduced in PS-1 (M146L) AD fibroblasts. Graphs show mean + S.E. *p < 0.05 and **p < 0.005; n = 4. doi:10.1371/journal.pone.0004655