Sequencing and analysis of a genomic fragment provide an insight into the Dunaliella viridis genomic sequence.
Dunaliella is a genus of wall-less unicellular eukaryotic green alga. Its exceptional resistances to salt and various other stresses have made it an ideal model for stress tolerance study. However, very little is known about its genome and genomic sequences. In this study, we sequenced and analyzed a 29,268 bp genomic fragment from Dunaliella viridis. The fragment showed low sequence homology to the GenBank database. At the nucleotide level, only a segment with significant sequence homology to 18S rRNA was found. The fragment contained six putative genes, but only one gene showed significant homology at the protein level to GenBank database. The average GC content of this sequence was 51.1%, which was much lower than that of close related green algae Chlamydomonas (65.7%). Significant segmental duplications were found within this fragment. The duplicated sequences accounted for about 35.7% of the entire region. Large amounts of simple sequence repeats (microsatellites) were found, with strong bias towards (AC)(n) type (76%). Analysis of other Dunaliella genomic sequences in the GenBank database (total 25,749 bp) was in agreement with these findings. These sequence features made it difficult to sequence Dunaliella genomic sequences. Further investigation should be made to reveal the biological significance of these unique sequence features.
Sun
Xiao-Ming
XM
Shanghai Key Laboratory of Bio-energy Crops, School of Life Sciences, Shanghai University, Shanghai 200444, China.
Tang
Yuan-Ping
YP
Meng
Xiang-Zong
XZ
Zhang
Wen-Wen
WW
Li
Shan
S
Deng
Zhi-Rui
ZR
Xu
Zheng-Kai
ZK
Song
Ren-Tao
RT
D000818:Animals; D001482:Base Composition; D002696:Chlamydomonas / Q000235:genetics; D000460:Chlorophyta / Q000235:genetics*; D030561:Databases, Nucleic Acid; D018745:Genome, Plant; D012091:Repetitive Sequences, Nucleic Acid; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid