請用此 Handle URI 來引用此文件: http://hdl.handle.net/11455/70941
標題: Influences of nitrogen deficiency on the transcript levels of ammonium transporter, nitrate transporter and glutamine synthetase genes in Isochrysis galbana (Isochrysidales, Haptophyta)
作者: Kang, L.K.
Hwang, S.P.L.
Gong, G.C.
Lini, H.J.
Chen, P.C.
Chang, J.
關鍵字: Isochrysis
gene expression
nitrogen
ammonium transporter
transporter
glutamine synthetase
diatom skeletonema-costatum
cylindrotheca-fusiformis bacillariophyceae
chlamydomonas-reinhardtii
marine diatom
fresh-water
plants
expression
phytoplankton
phosphate
membrane
期刊/報告no:: Phycologia, Volume 46, Issue 5, Page(s) 521-533.
摘要: Three DNA fragments belonging to genes involved in nitrogen uptake and assimilation, including a nitrate transporter gene (IgNrt2), an ammonium transporter gene (IgAmt), and a glutamine synthetase gene (IgglnII, were obtained from the marine haptophyte, Isochrysis galbana. Based on alignments of the deduced amino acid sequences, the IgNRT2 fragment shared 47%,, identity with the Cylindrotheca fusiformis (Bacillariophyceae) nitrate transporter, the IgAMT fragment shared 48%, identity with the C. fusiformis ammonium transporter, and the IgGSII fragment shared 61% identity with Skeletonema costatum (Bacillariophyceae) glutamine synthetase. Southern hybridization indicated that both IgNrt2 and IgAmt may have more than one copy in the genome of L galbana, but only a single copy was detected for IgglnII. The transcript abundances of these three genes under various nitrogen-supply conditions were monitored simultaneously by quantitative real-time polymerase chain reaction (PCR). In the presence of ammonium, both IgNrt2 and IgAmt were severely repressed with mean mRNA concentrations of 0.67 and 3.45 mu mol (mol 18S rRNA)(-1). IgNrt2 and IgAmt mRNA transcripts increased 41-fold and 8.3-fold, respectively, in the presence of nitrate, and increased 160-fold and 15-fold, respectively, in the ni trogen-depleted condition. The mRNA level of IgglnII was low in cells grown in the presence of ammonium [3.98 mu mol (mol 18S rRNA)(-1)], but mild increases in the range of 2- to 4-fold were observed in cells grown in both nitrate-containing and nitrogen-depleted cultures. Our results demonstrated that the expression patterns of IgNrt2, IgAmt, and IgglnII shared a common trend with their homologous genes in diatoms and green algae under various nitrogen-supply conditions. This group of genes could be used as indicators in natural environments to estimate the degree of nitrogen deficiency and chemical forms of nitrogenous nutrients in use on a species-specific basis.
URI: http://hdl.handle.net/11455/70941
ISSN: 0031-8884
文章連結: http://dx.doi.org/10.2216/06-44.1
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