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ARE CYTOPLASMIC POCKETS (MTR/POCKET) PRESENT IN ALL PHOTOSYNTHETIC EUGLENOID GENERA? 1
Author(s) -
Shin Woongghi,
Brosnan Stacy,
Triemer Richard E.
Publication year - 2002
Publication title -
journal of phycology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.85
H-Index - 127
eISSN - 1529-8817
pISSN - 0022-3646
DOI - 10.1046/j.1529-8817.2002.01208.x
Subject(s) - biology , photosynthesis , phototroph , chloroplast , botany , euglena , biochemistry , gene
In 1985, the existence of a cytoplasmic pocket formed from the reservoir membrane in the photosynthetic euglenoid Colacium was described. A band of reinforcing microtubules (MTR) derived from the ventral flagellar root lined the pocket, and a dense fibrillar mesh was associated with the membrane. A comparison of bodonid cytostomes, colorless euglenoid cytostomes, and the reservoir pocket found in Colacium suggested that the three structures were homologous and that photosynthetic euglenoids arose from phagotrophic ancestors. MTR/pockets have since been reported in other photosynthetic euglenoids, including Euglena , Eutreptia , Eutreptiella , Cryptoglena , Tetreutreptia , and Phacus. We found MTR/pockets in three additional taxa, Lepocinclis, Trachelomonas , and Strombomonas , thereby demonstrating the presence of this complex in representatives of all the major photosynthetic genera. A comparison of the MTR/pocket complex across genera indicated a reduction in structural complexity that was consistent with recent phylogenetic schemes based on molecular characters. Three alternative hypotheses of the origin of MTR/pockets in phototrophic euglenoids are presented and discussed.