Cloning And Characterization Of Differentially Expressed Genes Between Phases And Ubiquitin Genes From Gracilaria Lemaneiformis

Gracilaria lemaneiformis, the third algal cultivation industry in China, is not only an economically important agarophyte but also a good material for a variety of genetical studies. Thus, it is important to pursue basic studies on G. lemaneiformis. In this study, forward and reverse suppression subtractive hybridization (SSH) libraries were constructed between tetrasporophytes and female gametophytes of Gracilaria lemaneiformis. Genes differentially expressed between the two phases were isolated and some of them were characterized.Dot-blots were performed to screen 384 colonies randomly selected from each of the two subtracted libraries and 14 cDNAs were proved to express differentially between the two phases. The 14 clones were sequenced and deposited in GenBank under accession numbers DQ008074-87. Among them, 7 cDNAs are respectively homologous to crucial metabolic enzymes, small GTPase, RP42 homolog, and two hypothetical proteins, while the rest 7 do not have significant hits in the databases examined. The results of virtual Northern blots reveals that 11 cDNAs are differentially expressed between the two phases, including 7 genes up-regulated in tetrasporophytes, 1 expressed exclusively in tetrasporophytes and 3 up-regulated in female gametophytes.Small GTPase encoding gene and a tetrasporophyte-specific gene were selected to isolate cDNA full length sequences and to be characterized. Small GTPase of G. lemaneiformis, upregulated in female gametophytes, has high homology especially with those Rab11s from animals. Two transcripts were obtained in the RACE reaction of small GTPase encoding gene. The alignment of the two transcripts with...