Videotape: Conidium Ontogeny in Hyphomycetes
This tape is meant to be used as a teaching aid in conjunction with the textbook The Fifth Kingdom.
After a title sequence meant to be reminiscent of a phialide in action, followed by acknowledgments, the tape begins by showing how the specially designed thin culture chambers used in the filming of this movie are filled with medium, inoculated, sealed and incubated. A set of interesting sound effects - which tend to hold student attention - make their debut here, and pop up at intervals throughout the rest of the tape.
Now it's on to the time-lapse sequences that form the body of the tape. Note that more extensive discussions of the different ontogenies can be found in chapter 4 of The Fifth Kingdom. Note also that in the commentary which follows, the titles of some of the modes of development, and the names of one or two of the fungi involved, have been up-dated, to be in line with current thinking.
This mode, by far the commonest among conidial fungi, is defined, then illustrated by time-lapse sequences of the development of multiple conidia in several different anamorphic fungi.
- Nodulisporium hinnuleum (with sound effects). Note that the particular pattern of retrogressive conidium ontogeny demonstrated in this sequence has not been formally described in the literature. To my knowledge, it has not been observed in any other genera.
- Beauveria bassiana - blastic-sympodial (sound effects). This is one of the commonest kinds of conidium ontogeny, found in 360 of the 1250 known genera of Hyphomycetes.
- Basipetospora anamorph of Monascus ruber - blastic-retrogressive (sound effects). This ontogeny is rare, having been observed in only 6 of the 1250 known genera of Hyphomycetes. Note the intrusion of fast-growing assimilative hyphae in one of the sequences.
- Cladobotryum varium - blastic-retrogressive. This is a very long and rather impressive sequence. Watch as more than 50% of the left-hand conidiogenous cell is gradually retrogressively converted into large conidia.
- Gonatobotryum apiculatum - blastic-synchronous (sound effects). This is also fairly rare, having been observed in only 29 of the 1250 known genera of Hyphomycetes. Note how a large number of primary conidia 'blow out' in perfect synchrony, beautifully spaced over the surface of the apical vesicle. Note also that secondary conidia, which form in acropetal chains, are not synchronous.
- Phialophora lagerbergii - blastic-phialidic (sound effects). This is a common and successful mode of conidium ontogeny, having been reported in 260 of the 1250 known genera of Hyphomycetes, including some of the most successful of all anamorphs, such as Penicillium, Aspergillus, Trichoderma, etc. Note that the conidiogenous cell does not become either longer or shorter during the formation of many conidia.
- Chalara anamorph of Ceratocystis paradoxa - blastic-phialidic (sound effects). Note the rapid laying down of cross-walls and side walls in what begins as an upwardly moving column of cytoplasm. This kind of phialide is rather different from that in Phialophora.
This mode is defined, then illustrated by time-lapse sequences of Geotrichum candidum.
- Geotrichum candidum - thallic-arthric. (The striking sound effects in these sequences are guaranteed to wake up any sleeping students). Note that surface tension causes the newly seceded conidia to clump. Note also that Geotrichum is a yeast, though it does not look very like one. This points up that many yeasts are effectively conidial fungi, the cells of the average budding yeast beginning life as conidia, and proceeding to become conidiogenous cells as they reproduce.