WAR  of  the  MICROWORLDS  

How do I kill Thee?   Let me count the Ways!   (# 2)

Myzocytiopsis humicola - biflagellate zoospores track down a nematode by following leakage chemicals from the body orifices (mouth, anus, vaginal orifice).  The zoospore encysts on the nematode's cuticle and penetrates into the body cavity by means of a fine penetration peg.  The contents of the zoospore are transferred into the host to initiate the infection thallus.   The thallus secretes enzymes into the body cavity that digest the host organs and these are absorbed by the fungus for growth.   An elongate thallus eventually fills the body cavity of the host and at maturity it becomes divided into a number of segments.  Each thallus segment enlarges and morphs into a zoosporangium containing many zoospores for near term dispersal.  The zoosporangium develops an exit tube that passes through the ematode's cuticle to the exterior  through which the zoospores escape to chase down additional nematodes.   Thick walled sexual spores are also produced to take care of long term persistence. OOMYCOTA.

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      ABOVE LEFT - biflagellate zoospore tracking nematode.  ABOVE RIGHT - three stages in zoospore development.  Lower arrow: recent encystement.  Upper left arrow:  peg has penetrated the host cuticle. Upper right arrow:  contents of zoospore transferred into host to initate thallus. Note: zoospore is now empty of protoplasm.

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Above - nematode 's shell' filled wirth thallus segments (zoosporangia) of parasite.  Each zoosporangium develops an exit tube to the etxterior and the zoospores swim off to attack another host.

Images copyright George Barron mostly from MycoAlbum CD (contains this picture and a 1000 more)

Comment on MyoAlbum CD by JS ' I think the Mycoalbum is fantastic and a really useful resource for teaching. It is really a wonderful set of images'

(see www.mycographics.com)