Lab Day 10 - Hamburgers, ELISA, and Yogurt

Today, we looked at the results for our food purity test.  between the Bovine albumin and the goat anti-bovine albumin, there appeared a small whitish strip.  This indicates a reaction.  There was no such strip between the Bovine albumin and either of the other goat antibodies (anti-horse and anti-swine).  This means that our Bovine albumin must have been pure.  The results for the hamburger extract were the same, indicating that the hamburger extract must have been pure cow.  We therefore effectively tested the purity of the food.

We also performed an ELISA test (Enzyme Linked Immunosorbent Assay).  For this experiment, we worked with Theresa and Elanie.  

We had 6 little wells: two marked positive, two negative, one marked “8”, and another “47”.  First, we added 50 micro liters of purified antigen to each well, letting it sit for about 5 minutes to allow the proteins to bind to the walls of the wells by hydrophobic interaction.  We then washed it out with buffer solution.

Next, we added the serum and control samples.  The positive control was added to the wells marked positive.  The negative control was added to the wells marked negative.  Each serum sample was added to the wells marked “8” and “47”.  These we also let sit for 5 minutes.  If the serum contains the correct antibodies for the virus antigen, then they will bind to the antigen in the wells.  After 5 minutes, we empties the wells again, and washed them with buffer.  

Then we added 50 mictoliters of secondary serum (marked SA).  If the serum antibodies have bound to the virus antigen, the secondary antibodies will bind to the serum antibodies.  We let this sit for 5 minutes before emptying it and washing it with buffer.

We then added 50 micro liters of the enzyme substrate to each well.  If the primary antibody is present in the serum, the wells will turn blue, indicating a positive result.  If it remains colorless, however, then it was a negative test, indicating that there were no antibodies.

The two positive control wells tested positive, while the negative control wells were negative.  The well marked “47” was also negative, and the well marked “8” was positive.  All the positive wells turned a distinct blue color.

In addition to this experiment, we did one other, mostly for fun.  We made Yogurt!  We wanted to compare the results of using heated vs. unheated milk, so we inoculated heated and unheated milk with a small bit of Yoplait yogurt.  We then placed them in incubators.

Before we left, we did one last thing.  Dr. Pathakamuri demonstrated how UV light can be used to sterilize water.  Using a UV flashlight, he stuck it into a glass of water.  We then inoculated the UV radiated water, and we inoculated regular water.  Tomorrow, we'll see which is the cleaner.