Ca2+ signal transduction related to neutral lipid synthesis in an oil-producing green alga Chlorella sp. C2.
Changes in the cytosolic Ca(2+) levels and the role of Ca(2+) signal transduction in neutral lipid synthesis in Chlorella sp. C2 under nitrogen starvation conditions were investigated. The results detected by using the scanning ion-selective electrode technique demonstrate that nitrogen starvation induced significant Ca(2+) influx across the plasma membrane into cells. Ca(2+) fluorescence imaging and flow cytometry were used to estimate the effect of this Ca(2+) influx on the generation of the Ca(2+) signal, and the results showed that the cytosolic Ca(2+) concentration increased transiently and then remained at a stable, high level when the cells were exposed to nitrogen starvation. However, the increase could be inhibited by pre-treatment with the Ca(2+) channel blockers ruthenium red, verapamil and GdCl3, indicating that both the influx of Ca(2+) from the extracellular space via Ca(2+) channels that are localized in the plasma membrane and the release of Ca(2+) from intracellular calcium storage via the internal calcium store were required for the generation and transduction of the Ca(2+) signal. During nitrogen starvation, neutral lipid synthesis in Chlorella sp. C2 in response to stress conditions was also inhibited to differing degrees by pre-treatment with the three Ca(2+) channel blockers, demonstrating the regulation of Ca(2+) via these Ca(2+) channels in neutral lipid synthesis. The results suggested that by transduction of extracellular stress signals into the cell and the regulation of the Ca(2+) signal in neutral lipid synthesis, Ca(2+) signal transduction played important roles in the response mechanism of Chlorella sp. C2 to nitrogen starvation.
Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, Hubei, China.
Hui
H
Chen
Yunming
Y
Zhang
Chenliu
C
He
Qiang
Q
Wang
D002118:Calcium / Q000378:metabolism*; D000460:Chlorophyta / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D005682:Gadolinium / Q000494:pharmacology; D009584:Nitrogen / Q000172:deficiency; D010938:Plant Oils / Q000378:metabolism*; D012430:Ruthenium Red / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D014700:Verapamil / Q000494:pharmacology
D010938:Plant Oils; D012430:Ruthenium Red; D005682:Gadolinium; D014700:Verapamil; D009584:Nitrogen; C038958:gadolinium chloride; D002118:Calcium
Ca2+ channel; Ca2+ signal transduction; Chlorella sp. C2; Neutral lipid synthesis; Nitrogen starvation