12am house light

Figure 2: Tan and wild type Sordaria fimicola mating agar

will not protect the skin once a certain amount of UV radiation is reached. All in all, I am attempting to relate melanin, skin pigmentation and cancercausing UV light damage.

MATERIALS AND METHODS:

Part 1: Growing/Mating Spores In order to compare skin pigmentation and melanin production to the effects of UV rays, I used the fungus sordaria fimicola in two types: tan and wild. First, I used growth agar to grow spores from the fungus on plates and incubated them for one week at room temperature. To collect the spores, I took plugs out of each growth agar plate to be used in sordaria-mating agar plates, made with 3.41 grams of mating agar and 100mL of water. I used a sterilized plug tool and transferred the plugs from the growth agar onto mating agar plates using a loop, proceeding to incubate these for one week at room temperature. Part 2: Finding Concentration/Dilution Series Next, I set up six 15 mL test tubes each with 9 mL of distilled water. In one of these tubes, I poured the water onto one of the tan-type mating agar plates, scraped the plate to loosen the spores, and poured the water and spore mixture back into the test tube. I repeated this for the wild-type. To find the concentration of the spores in the two tubes, I used a corpuscle-counting chamber to

Figure 3. Removing plugs from growth agar with a loop.

count the spores from four squares under a microscope and averaged the number. Since the number of spores is calculated in cubic millimeters, I converted this into cubic centimeters so the average spore count per box multiplied with 104 is equal to the concentration. This came to be 2.5 x 105 for the tan-type and 6 x 104 for the wild-type. Next, I set up a dilution series with the remaining test tubes (3 tubes per fungus type). I poured one milliliter of the original tan-type tube into the second tube that had 9 mL of water and then poured one milliliter of that tube into the 3rd tube. I repeated this step with the wild-type.

Part 3: UV Exposure Finally, I set up the exposure growth plates. I made a growth environment with 2 grams of growth agar and 200 mL of distilled water to pour into twenty plates that would be exposed to UV radiation (2 controls). Then, for the concentration of each type, 3 plates were set up for one, five and ten minute intervals. Therefore, eighteen plates were made with the growth agar and a 100 microliter sample of the specific concentration of a spore type. Then, I exposed these samples to the UV light box under germicidal UV for their labeled time frames with the dish covers off and allowed them to either grow or die overnight in a drawer at room temperature with parafilm around the edges. I then analyzed these results by relating the amount of melanin to the amount of growth versus death of the spores because the protective nature of melanin in the two types of the fungus is