Guillardia

Guillardia is a genus of flagellate cryptomonad algae belonging to the family Geminigeraceae, containing a secondary plastid within a reduced cytoplasmic compartment that contains a vestigial nucleomorph. There is only one characterised member of this genus, Guillardia theta. Guillardia theta was the first cryptophyte to have its nuclear genome sequenced. The genome contains 87 Mbp, encoding around 24,840 genes. The complete nucleomorph and plastid genomes have been sequenced, containing 551 kbp and 121 kbp respectively. Two anion-conducting channelrhodopsins were isolated from Guillardia theta that hyperpolarize neuronal membrane potential and are potent inhibitors of neural activity.