Lab 3

Topic: Observation of zoosporic fungi of Chytridiomycota and Oomycota

Objectives: Several groups of fungi produce motile flagellate spores, like Chytridiomycota and Oomycota. However the zoospores differ from group to group. The goal of this experiment is: familiar with the zoosporic fungi and learn how to differentiate chytridiomycota and Oomycota from the structure of zoospores. Furthermore, learn about the life cycle of Phytophthora infestans which include the sexual and asexual life cycles and asexul life cycle of Saprolegnia mixta.

Materials:

1.         Cultures of fungi with spores. Phytophthora infestans and Saprolegnia mixta

2.         Olympus compound microscope.  One is available with an attached camera.

 3.        A kit containing microscope slides, cover slips, needles, and transfer loops.

 4.        Immersion oil and dropper bottles for water to suspend specimens. 

 5.        Lens paper for cleaning objectives, and Kim wipes for working with microscopic slides and specimens.

  6:      Bunsen burner, dissecting needle

Procedures:

1:  Agar mount slides were prepared as I descried in last report.

2: The procedures of observation the specimen under the microscope were described last report.

Observation:

Fig.1 Sporangia of P. infestans.

Fig.2 Zoospore of P.infestans.

Fig.3 Zoospore of S.mixta.

Discussions: Although the Chytridiomycota and Oomycota both zoosporic fungi, and all generate zoospores, however the structure of zoospore is quite different between these two fungi. Chytridiomycota produce small zoospores with typically single posterior whiplash flagellum, and Oomycota produce large and kidney-shape zoospores with a posterior whiplash flagellum and an anterior tinsel flagellum. The swim patterns of Chytridiomycota and Oomycota different from each other as well. Chytridiomycota swim with darting and zig-zag pattern, some of the class swim in amoeboid probing pattern, like Spizellomycetales. Oomycota swim like corkscrew-like pattern with random changes of direction, thus base on these features of the zoospores, it is easily to differentiate them under the microscopy.

In this class we also got the chance to isolate the Allomyces sp. from baited hemp seed. Follow the protocol which was provided by Dr. Shaw, I try different medium to culture it. All my culture seems got  badly contamination  of bacteria, I am in the process to subculture it, and hopefully I will get the pure culture.