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The primary and secondary spore cyst of Aphanomyces (Oomycetes, Saprolegniales)
Author(s) -
Olson L. W.,
Cerenius L.,
Lange L.,
Söderhäll K.
Publication year - 1984
Publication title -
nordic journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.333
H-Index - 33
eISSN - 1756-1051
pISSN - 0107-055X
DOI - 10.1111/j.1756-1051.1984.tb01994.x
Subject(s) - biology , zoospore , microtubule , ultrastructure , vesicle , nucleus , cyst , centriole , spore , botany , anatomy , microbiology and biotechnology , biochemistry , membrane , pathology , medicine
The ultrastructural organization of the primary (1°) and secondary (2°) cysts of Aphanomyces astaci and A. laevis is extremely similar, and similar to that of the 1° and 2° cysts of A. eutekhes as presented earlier by Hoch and Mitchell. Synchronous populations of 2° cysts can be induced by mechanical shock and encystment appears to be essentially instantaneous. The cyst coat–wall appears to be formed extremely rapidly from material from the peripheral vesicles with flocculent content. After encystment the microtubule cytoskeleton found in the zoospore is maintained in the 1° and 2° cyst (i.e. the single microtubules which extend along the pyriform nucleus from the ki–netosomes–centrioles and the bundles of closely appressed microtubules are retained). The peripheral vesicles with granular content found in the zoospore are not seen in the 1° or 2° cyst. Multivesicular bodies and lomasomes are observed in the 1° and 2° cyst which are not found in the zoospore. The peripheral cisternae of the zoospore are lost upon encystment and may be formed from dictyosome–derived vesicles during excystment of the 1° and 2° cyst. The U–body of A. astaci has a paracrystalline content while the U–body of A laevis and A eutekhes has a tubular content. A microbody–lipid body complex (sensu Powell) is found in the 1° and 2° cysts of A laevis but not in A astaci or A eutekhes. The significance of the presence of a microbody–lipid body complex in a biflagellate zoospore is discussed.