caa a22 4500 378854135 CHVBK 20180305123330.0 cr unu---uuuuu 161128e20030905xx s 000 0 eng 10.1515/BOT.2003.044 doi (NATIONALLICENCE)gruyter-10.1515/BOT.2003.044 Ultrastructural Study of Zoosporogenesis in the Siphonous Green Alga Derbesia tenuissima (Chlorophyta) [Elektronische Daten] [S.-H. Lee, T. Motomura, T. Ichimura] Based on transmission electron microscopy observation, zoosporogenesis in the siphonous multinucleate green alga Derbesia tenuissima can be divided into five stages. In vegetative sporophytes and Stage 1 sporangia, the cytoplasm was distinguished as two regions, the inner region of chloroplasts and the outer region of nuclei. In Stage 1 sporangia, the chloroplasts differentiated into amyloplasts and contained large starch grains. In Stage 2 sporangia, several meiotic nuclei with synaptonemal complexes were observed in the apical and the subapical portions of a sporangium. The width of a synaptonemal complex was 103±5 (mean ± standard deviation) nm (n = 20). In Stage 3 sporangia, the plug complex that was composed of 4 layers as observed with transmission electron microscopy, was formed between the sporangium and the main axis. In Stage 4 sporangia, the following conspicuous characters were observed: 1) differentiation of nuclei into two types, 2) de novo appearance of centrioles (flagellar basal bodies) on the type 2 nuclei (large), 3) decrease in the number of the type 1 nuclei (small), 4) development of cleavage furrows and vesicles, 5) formation and elongation of flagellar axonemes, and 6) development of three characteristic bands on the flagellar basal bodies. In Stage 5 sporangia, differentiation of flagella and flagellar bands was completed. Each stephanokont zoospore of D. tenuissima had about 80 flagella, about 16 nuclei and many chloroplasts. Copyright © 2003 by Walter de Gruyter GmbH & Co. KG Hydrobiology nationallicence Mycology, fungi nationallicence Botany & plant sciences nationallicence Lee S.-H aut Motomura T. aut Ichimura T. aut Botanica Marina Walter de Gruyter 46/5(2003-09-05), 438-449 0006-8055 46:5<438 2003 46 botm https://doi.org/10.1515/BOT.2003.044 text/html Onlinezugriff via DOI 1 research article jats NATIONALLICENCE 856 40 https://doi.org/10.1515/BOT.2003.044 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Lee S.-H aut NATIONALLICENCE 700 1- Motomura T. aut NATIONALLICENCE 700 1- Ichimura T. aut NATIONALLICENCE 773 0- Botanica Marina Walter de Gruyter 46/5(2003-09-05), 438-449 0006-8055 46:5<438 2003 46 botm CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-gruyter