Introduction. This week in lab, we simultaneously learned baiting techniques and were able to observe motile fungi. We first observed motile zoospores from a baited culture of Saprolegnia sp., which is a freshwater mould in the class Oomycota. We then attempted to isolate Allomyces, a chytrid water mould, from a baited soil sample. Lastly, we were able to observe the Riddell mounts from the previous week.
Zoospores
Zoospores are asexual spores that posssess a flagella for locomotion. I tried to
observe these from a culture of a
Saprolegnia sp. [S1; trans. 9.ix.2012]. This proved to be a
very difficult task. I did see tiny organisms swimming erratically in samples
of this culture, but after comparing to some of my classmate’s zoospores
(particularly to the size of the organisms), I came to the conclusion that I
was probably observing some sort of bacterium. I looked at several different
cultures of Saprolegnia sp. of
various ages, but had no luck. It wasn’t until I tried the Phytophthora sp. cultures (trans. 17.ix.2012) that I actually saw zoospores.
This gave me so much satisfaction that I decided to take an extremely high
quality video in order to share this glorious experience with the rest of the
world (Video 1). I was actually able to see, but not capture with video, the flagella of these spores.
Video 1.
The dark spots zooming around in circles and changing directions are most likely zoospores (40x).
Allomyces Isolation (attempt)
In this part of the lab, we were supposed to isolate Allomyces from seeds (popcorn or hemp) that had been previously submerged in a soil sample/ distilled water solution. Seeds placed in this solution acted as a bait for fungal growth. The first step was to see whether or not we could observe any mitospores around the seed. After observing this, we were supposed to then try to isolate these mitospores. I definitely was not successful at any of these tasks. I was not able to see any zoospores, so, under the direction of Dr. Shaw, I transferred the seeds to a micro petri dish filled with DS solution. I then labeled the petri dish, sealed it with parafilm, and placed it in a box in the back of the room so as to check on it next week. Perhaps then I will be able to isolate and culture the Allomyces at that time.
In this part of the lab, we were supposed to isolate Allomyces from seeds (popcorn or hemp) that had been previously submerged in a soil sample/ distilled water solution. Seeds placed in this solution acted as a bait for fungal growth. The first step was to see whether or not we could observe any mitospores around the seed. After observing this, we were supposed to then try to isolate these mitospores. I definitely was not successful at any of these tasks. I was not able to see any zoospores, so, under the direction of Dr. Shaw, I transferred the seeds to a micro petri dish filled with DS solution. I then labeled the petri dish, sealed it with parafilm, and placed it in a box in the back of the room so as to check on it next week. Perhaps then I will be able to isolate and culture the Allomyces at that time.
Riddell Mounts
The last thing I accomplished in this lab was observing the Riddell mounts I made of Aspergillus flavus and A. paraciticus from the previous week. Hyphae were definitely prolific on the cover slips (Fig. 1), but I was not able to locate many conidiophores. I’m not sure if the photos I took depict conidiphores or just balls of conidia that clustered together when I made my slide mount (Figs. 2, 3). It definitely looks like Fig. 3 is structured like a conidiophore, but I would really need a professional opinion on this to feel comfortable saying that with any degree of certainty. My A. paraciticus culture was very difficult, and actually impossible in most cases, to observe because there was so much condensation inside on the petri dish. I took a couple of pictures (Fig. 4), but mostly I was not able to see anything on those coverslips.
The last thing I accomplished in this lab was observing the Riddell mounts I made of Aspergillus flavus and A. paraciticus from the previous week. Hyphae were definitely prolific on the cover slips (Fig. 1), but I was not able to locate many conidiophores. I’m not sure if the photos I took depict conidiphores or just balls of conidia that clustered together when I made my slide mount (Figs. 2, 3). It definitely looks like Fig. 3 is structured like a conidiophore, but I would really need a professional opinion on this to feel comfortable saying that with any degree of certainty. My A. paraciticus culture was very difficult, and actually impossible in most cases, to observe because there was so much condensation inside on the petri dish. I took a couple of pictures (Fig. 4), but mostly I was not able to see anything on those coverslips.
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| Fig. 1 Aspergillus flavus hyphal growth on cover slip. Riddell Mount, 40x. |
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| Fig. 2 A. flavus conidia and perhaps conidiophore? Or maybe just a bubble with clusters of conidia on the periphery? Riddell mount, 40x. |
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| Fig. 3 Again, A. flavus and a putative conidiophore. Riddell mount, 40x. |
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| Fig. 4 A. paraciticus conidia and perhaps conidiophore. Several drops of condensation can be seen on the slide. Riddell mount, 40x. |
Conclusion
I feel like I can recognize the zoospores from other organisms because of their more or less spheroidal shape and their flagella. However, since I did not have any luck with Allomyces, I am still uncomfortable with what these types of mitospores should look like. As for my Riddell mounts, I understand how to do them and what they should look like, I just need more practice.
All for now.
Nice.
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