Ultrastructure of the flagellar apparatus in the green flagellate Spermatozopsis similis

• Published in: Plant systematics and evolution 1984-01, Vol.146 (3/4), p.145-162
• Main Authors: Melkonian, M, Preisig, H.R
• Format: Article
• Language: English
• Subjects: Algae; algae and seaweeds; Biological and medical sciences; Body regions; Chlorophycota; Flagella; Fundamental and applied biological sciences. Psychology; Green algae; Materials; Microtubules; phylogeny; Plant cytology, morphology, systematics, chorology and evolution; Retraining; Root systems; Terminator regions; Thallophyta; ultrastructure; Zoospores
• ISSN: 0378-2697; 1615-6110
• DOI: 10.1007/BF00989542

The ultrastructure of the flagellar apparatus of the naked, biflagellate green alga Spermatozopsis similis Preisig & Melkonian has been studied in detail using an absolute configuration analysis. The two basal bodies are displaced by 350nm in the 1/7 o'clock direction and do not overlap proximally. They are interconnected by a principal distal connecting fibre consisting of a bundle of 5—8 nm filaments and possibly two proximal striated connecting fibres. The flagellar root system is cruciate (5-2-5-2 or 4-2-4-2 system) and contains a prominent continuous system I fibre overlying the two opposite two-stranded roots. A system II fibre is absent. Pronounced structural differences have been observed in the flagellar apparatus ultrastructure at two types of flagella orientation: During backward swimming basal bodies are parallel, the distal connecting fibre is extremely contracted; during forward swimming basal bodies assume various angles (from 20° to 180°) and the connecting fibre is about five times longer compared to the contracted state. The function of the connecting fibre as a contractile organelle and the mechanism of its contraction are discussed. On the basis of the flagellar apparatus ultrastructure, Spermatozopsis similis is related to Chlamydomonas-type green algae.