Study On Patterns Of NO On The Growth Of Three Marine Microalgae

Nitric Oxide (NO) is a small gaseous molecule and free radical, also is an important signalling and regulatory molecule in animals, plants, and microorganisms. The research on NO have attracted great attention of researchers from a vast array of fields including Chemistry, Molecular biology, and Medicine at present. However, the research about NO in Oceanological field, especially in marine phytoplankton is rarely reported except a few reports by our laboratory. Otherwise, the Dust Storms and the Red Tides with high frequency have very important influence on atmosphere and ocean environment in the past years. Since dust storm particles enrich much heavy metal element and have the quality of transportation, the interaction of the Dust Storms and the ocean also have attracted attention of researchers from atmosphere and ocean fields. The dust storm particles contain various elements such as As,Sb,Se (Selenium),Cu,Pb,Zn,Cd and so on. It is necessary to study the effect laws of Se element on marine phytoplankton growth, for the purpose of understanding the influence of dust storms on oceanic ecological system. Therefore, this paper chooses three marine algae namely Chaetoceros gracilis , Haeterosigma akashiwo and Nitzschia closterium f. minutissima to discuss the laws of NO and Se(IV) effect on the growth of marine phytoplankton from chemical point of view. During Chaetoceros gracilis cultivation process, nitric oxide of different concentrations is added only one time or twice a day. During Haeterosigma akashiwo and Nitzschia closterium f. minutissima cultivation process, the different high concentration of nitric oxide is added only once or once a day and the different concentration of Se(IV) is added only one time. This paper also discusses the variation of nitric oxide in Nitzschia closterium f. minutissima solution through ISO-NOPMC NO microsensors. The conclusions are as follows:(1) The growth of C. curvisetus could be obviously promoted or inhibited during the cultivation process in NO enriched media of different concentrations. That is consistent with the results of our larabory originally. The reseults also have positive proof of the concept of NO threshold in marine phytoplankton.(2) The exogenous high concentration NO have two types effect on marine algae that are competitive and interrelated. When 1.4×10-6mol/L NO is added only once, it inhibit the algae growth originally. But with NO decaying from 1.4×10-6mol/L NO to 10-8~10-9mol/L that belong to the threshold.of promotion the algae growth, NO promote the growth of algae. The inhibition─promotion effects is the characters of the threshold of high concentration NO. In the threshold of low concentration NO, its primary characters is the promotion effects.(3) When adding 1.4×10-6mol/L of NO once a day, the growth of Haeterosigma akashiwo and Nitzschia closterium f. minutissima is restricted. The growth period of algae is shortened, the growth curves of algae change from from sigmoid to the type of peak value or the type of linearity.(4) When adding 1.4×10-6mol/L of NO twice a day, the growth curves of Nitzschia closterium f. minutissima present step type, that provides more proof for the threshold of NO in existence.(5) The exogenous Se(IV) have important effect on the growth of The growth of algae could be obviously promoted or inhibited during the cultivation process in Se(IV) enriched media of different concentrations. The effect of Se(IV) on marine phytoplankton is similar to trace element on organism.(6) When 1.4×10-9mol/L NO is added twice each day, it alleviate the Se(IV) toxicity of Haeterosigma akashiwo and Nitzschia closterium f. minutissima. The function of NO may be relate to free radical scavenging activities and antioxidant capacity.The conclusions above show the patterns of NO effect on the growth of marine phytoplankton. These results can provide the experimental basis of further study on chemical dynamics of NO on the growth of marine phytoplankton, which is important to the marine chemistry and marine biogeochemistry. Besides, This paper also study on the effect of inorganic element selenium─a component in dust storms on the growth of marine phytoplankton. These results make a good outset to study the effect of dust storms on the marine ecological system (including red tides).