Heat-shock protein 90 may be involved in differentiation of the female gametophytes in Griffithsia japonica (Ceramiales, Rhodophyta)

A cDNA library from a mixed population of female and male gametophytes of G riffithsia japonica Okamura was constructed, and a cDNA clone, designated G jFP-1 (G. japonica female predominant-1), was isolated by differential scre ening of the cDNA library. The transcript corresponding to GjFP-1 was abund ant in female gametophytes, but only basal levels of the transcript were de tected in male and tetrasporangial thalli. Determination of the nucleotide sequence of GjFP-1 identified a putative open reading frame encoding 313 am ino acids and a 3' untranslated region of 116 nucleotides. The deduced amin o acid sequence of GjFP-1 for the putative open reading frame shared high, homology with the previously reported amino acid sequences of heat shock pr otein 90 (hsp90). RNA blot hybridization analysis for the transcripts of he at-shocked G. japonica and DNA hybridization analysis for the genomic DNA o f G. japonica with GjFP-1 as a probe suggested that GjFP-1 is a cDNA clone for the hsp90 gene in G. japonica. In situ hybridization for the GjFP-1 tra nscript again showed a differential specificity of the transcript in female gametophytes. The data reported here suggest a possibility of hsp90 functi on linked to the development of;he female gametophytes in G. japonica.