|
OUR TEAM
Error creating thumbnail: File missing
LAB 5 WRITE-UP
SYBR Green Dye
A fluorescent DNA dye that binds all dsDNA and is measured by the change in fluorescence throughout. The dye is used in the PCR reaction in order to detect double stranded DNA. This allows experimenters to quantify the amount of DNA being produced.
Single-Drop Fluorimeter
An instrumentation that is able to detect fluorescence. The quantity is proportional to the number of molecules being deteced.
Error creating thumbnail: File missing
How the Fluorescence Technique Works
A technique that detects light in a molecule much similar to a spectrometer. It uses an ultraviolet light and excites the electrons causing the molecules to emit light.
Procedure
Smart Phone Camera Settings
First Phone:
- Type of Smartphone: iPhone 5s
- Flash: Off
- ISO setting: 800
- White Balance: Auto
- Exposure: Highest Setting
- Saturation: Highest Settings
- Contrast: Lowest Settings
Additional Phone:
- Type of Smartphone: Galaxy Samsung S3
- Flash: Off
- ISO setting: 800
- White Balance: Auto
- Exposure: Highest Setting
- Saturation: Highest Setting
- Contrast: Lowest Setting
Calibration
First turn on the Blue LED switch in order to activate the excitation light. Also make sure the camera is open with the settings listed above. From there place the pone on the cradle with 90 degree angle from the slide. Make sure to adjust the height of phone and/or fluorimeter in order to take pictures of the drops. Lastly, the cradle should be as close to the fluorimeter as possible with having a clear picture still.
- Distance between the smart phone cradle and drop =
4.5 cm
Solutions Used for Calibration
| Initial Concentration of 2X Calf Thymus DNA solution (micrograms/mL) |
Volume of the 2X DNA solution (μL) |
Volume of the SYBR GREEN I Dye solution (μL) |
Final DNA concentration in SYBR Green I solution (μg/mL)
|
| 5 |
80 |
80 |
2.5
|
| 2 |
80 |
80 |
1
|
| 1 |
80 |
80 |
0.5
|
| 0.5 |
80 |
80 |
0.25
|
| 0.25 |
80 |
80 |
0.125
|
| 0 |
80 |
80 |
0
|
Placing Samples onto the Fluorimeter
- On the first two rows of the slide, place one drop (the pipette is calibrated to 80 microlitres) of SYBR Green.
- Add a second drop of the diluted calf thymus DNA on top of the first drop on the slide. We now have a sample!
- Adjust the slide such that the blue LED light is using the drop to focus on the other side of the drop.
- Use the camera's timer to take a picture after closing the light box (this prevents as much outside light as possible from contaminating our data).
- Remove the box, being careful not to knock the smartphone out of position.
- Use the pipette to remove the entire 160 microlitre drop from the slide, then move the slide into the next position and use the next concentration standard.
- Repeat as needed.
Data Analysis
Representative Images of Samples
Negative Signal

Positive Signal

Image J Values for All Samples
| PCR Product TUBE LABEL
|
Diluted Volume (µL)
|
SYBR GREEN Volume (µL)
|
INTDEN 1
|
INTDEN2
|
INTDEN3
|
AVERAGE INTDENS VALUE
|
| A1 |
80 |
80 |
2716687 |
3229970 |
3340085 |
3095581
|
| A2 |
80 |
80 |
1451878 |
2568844 |
8446955 |
4155892
|
| A3 |
80 |
80 |
3862714 |
8011744 |
1600043 |
4491500
|
| B1 |
80 |
80 |
9856858 |
5058003 |
3108259 |
6007707
|
| B2 |
80 |
80 |
6862644 |
5685363 |
6783718 |
6443908
|
| B3 |
80 |
80 |
6287959 |
7119245 |
9598254 |
7668486
|
| + |
80 |
80 |
11779932 |
7973600 |
11270538 |
10341357
|
| - |
80 |
80 |
4371681 |
2482949 |
1977785 |
2944138
|
|
| Fitting a Straight Line
Linear Regression of PCR Results
Interpretation
Based on the results from the image analysis, the intensity in the green coloration in patient B was higher than patient A. Due to the fact that false positives and negatives were controlled for, it can be confidently said that patient B's DNA indicated a positive result for gene detection test. Patient A did not test positive. According to the calibration, it should be noted that the concentration of DNA is positively correlated to the green intensity of the SYBR Green dye; thus the high intensity in patient B's amplified DNA would be expected to increase with increased concentration of DNA.
|