September 19th Lab

The goals for this lab were to:

• Look at various fungi that make zoospores
• Observe Saprolegnia cultures that were plated over time
• Culture Allomyces from previously baited seeds
• Observe various life cycle videos

We were also going to cross Neurospora, but due to time constraints this was left to do the following week.

Fungi that make zoospores:

Initially we were supposed to look at Allomyces, but the culture did not grow so instead we looked at the Oomycte, Phytophthora. Phytophthora is not considered a fungus, but it is similar to Allomyces in that it produces zoospores. They are considered protists, and although they can cause disease, look and smell like fungi, they differ from fungi in their cell wall structure as well as having differing sequence data. Today we specifically looked at Phytophthora infestans the causal agent of Potato Blight. Unfortunately photos do not do a very good job of showing the motile zoospore, but I was able to capture some rough footage of a zoospore in action.

If you look closely in this video you can see the flagellum on this zoospore. 

Saprolegnia transfers from September 9, 12, and 18

The next thing we looked at were a series of Saprolegnia transfers that were plated on September 9, 12, and 18. It should be noted that Saprolegnia is also not a true fungus, it is instead another Oomycete. To better view the specimen I used a method Dr. Shaw had told us about in a previous lab . The goal of this method is to elevate the cover slip from the specimen so that it does not crush the sample or reduce any movement. To do this, I broke an additional cover slip and placed some fragments on a microscope slide, placed my sample in between the fragments, and then placed the whole cover slip over the entire mount. Here is what it looks like:

A simple way to elevate your cover slip is to place fragments in between the slide and the cover slip. 

Here is my drawing from the oldest (10 days old) Saprolegnia transfer. You can see sporangia and some free spores, as well as rhizoid like growth. 

10 day old Saprolegnia sample

The seven day old Saprolegnia was much better for me to see the small, motile zoospores. In this video, you can occasionally see the zoospores moving in tight circles or back and forth. 

I could not see anything from the one day old transfer. This is apparently not enough time, or I did not have enough skill, to properly see this sample. 

Culture Allomyces from baited seeds

In the lab there were seeds available that had been previously baited with Allomyces. The goal was for us to be able to somehow obtain some of the Allomyces from the seed, transfer it to an agar plate, and attempt to isolate and grow Allomyces for ourselves. I looked at my seed under the dissecting microscope and was able to see movement in the water, but no obvious zoospores. I pipetted 1 mL solution from around the seed and then transfered this to a clean PDA plate. I then sealed this plate with parafilm, took it back to my lab, and set it out to see if I could get any growth. Unfortunately, all that I was able to culture on my plate was bacteria. I will have to find a better method for transferring the fungus in question next time I try this.