Guillardia theta | Hanusia phi

Introduction

• Guillardia described by Hill and Wetherbee; type species Guillardia theta (marine; Hill and Wetherbee 1990)
• Hanusia described by Deane et al; types species Hanusia phi (marine; Deane et al. 1998)

Characteristics

• Type of biliprotein: PE545
• Nucleomorph free in periplastidial space
• Light microscopy: reddish cryptophytes, one plastid with a pyrenoid
• Ultrastructure of Gullardia: sheet-like inner periplast component, longitudinal plates (SPC), gullet, non-keeled rhizostyle (Gillott and Gibbs 1983; Hill and Wetherbee 1990)
• Ultrastructure of Hanusia: sheet-like inner periplast component, rosulate scales (SPC), furrow, keeled rhizostyle (Gillott and Gibbs 1983; Deane et al. 1998)

Discussion of Phylogenetic Relationships

Since only one strain of each genus has been examined thus far, there is insufficient data to identify potential dimorphisms or inconsistencies in systematics (Marin et al. 1998; Deane et al. 2002; Hoef-Emden et al. 2002). Guillardia theta strain CCMP327 was the model cryptophyte chosen for first nuclear genome sequencing projects. Its complete nucleomorph and plastid genomes have been sequenced (Douglas and Penny 1999; Douglas et al. 2001).

References

Deane JA, Hill DRA, Brett SJ, McFadden GI (1998) Hanusia phi gen. et sp. nov. (Cryptophyceae): characterization of 'Cryptomonas sp. φ'. Eur. J. Phycol. 33: 149-154

Deane JA, Hill DRA, Brett SJ, McFadden GI (2002) Cryptomonad evolution: Nuclear 18S rDNA phylogeny versus cell morphology and pigmentation. J. Phycol. 38: 1236-1244

Douglas SE, Penny SL (1999) The plastid genome of the cryptophyte alga, Guillardia theta: Complete sequence and conserved synteny groups confirm its common ancestry with red algae. J. Mol. Evol. 48: 236-244

Douglas SE, Zauner S, Fraunholz M, Beaton M, Penny S, Deng LT, Wu X, Reith M, Cavalier-Smith T, Maier UG (2001) The highly reduced genome of an enslaved algal nucleus. Nature 410: 1090-1096

Gillott MA, Gibbs SP (1983) Comparison of the flagellar rootlets and periplast in two marine cryptophytes. Can. J. Bot. 61: 1964-1978

Hill DRA, Wetherbee R (1990) Guillardia theta gen. et sp. nov. (Cryptophyceae). Can. J. Bot. 68: 1873-1876

Marin B, Klingberg M, Melkonian M (1998) Phylogenetic relationships among the Cryptophyta: analyses of nuclear-encoded SSU rRNA sequences support the monophyly of extant plastid-containing lineages. Protist 149: 265-276