Isolation and characterization of phase-specific cDNAs from sporophytes and gametophytes of Porphyra purpurea (Rhodophyta).

摘要

The red alga Porphyra purpurea has a life cycle that alternates between shell-boring, filamentous sporophytes and free-living, foliose gametophytes. The significant differences between these two phases suggest that many genes should be developmentally regulated and expressed in a phase-specific manner. In this thesis, I prepared and screened subtracted cDNA libraries specific for the sporophyte and gametophyte of P. purpurea. This involved the construction of cDNA libraries, followed by the removal of common clones through subtractive hybridization. Of twenty putative phase-specific cDNAs selected from each subtracted library for further study, eight unique clones were obtained for the sporophyte and seven for the gametophyte. After confirming their phase-specificities by northern hybridizations, these 15 phase-specific cDNAs were sequenced and the deduced amino acid sequences were used to search protein data banks. The proteins encoded by two cDNAs from each phase were identified. One sporophyte-specific cDNA encodes an elongation factor 1