جستجوی مقالات مرتبط با کلیدواژه « آنابنا » در نشریات گروه « علوم پایه »

In this study, the effect of gibberellic acid on vegetative and heterocyst cell size, inducing sugar and protein content was investigated in Anabaena at three durations (7, 14 and 21 days). According to the results, vegetative cell size did not show any significant differentiation under gibberellic acid treatments and time duration. Length and width of heterocyst cells showed a significantly different impact only with 10µM gibberellic acid at 7-day-old cultures. Algae treated with gibberellic acid had more fresh weight. Gibberellic acid induced heterocyst formation after 14 and 21 days. The amount of photosynthetic pigments increased in the 7 and 14-day cultures and decreased in the 21-day cultures. Application of gibberellic acid to the culture medium did not affect heterocyst percentage after 7 days, but it increased the heterocyst numbers in the 14 and 21-day cultures. Reducing sugar content changed dependence of gibberellic acid concentration and growth period. Treatment with gibberellic acid could increase protein content at different concentration and growth period. The results of this research showed notable effect of this plant growth regulator on Anabaena.

Since nanoparticles cause increase of serious threat to human, animals and aquatic ecosystems, toxicity of copper oxide nanoparticles (CuO-NPs) on cyanobacteria Anabaena sp. in different concentrations were studied using growth inhibition test (OECD201). The negative Zander cyanobacteria were grown in the culture medium (Z-8-N) under optimum conditions of light, temperature and aeration in growth chamber. After starting the logarithmic growth phase, samples were exposed to various concentrations of copper oxide nanoparticles at intervals of 24, 48 and 72 hours. The number of cyanobacterial cells was daily counted and analyzed based on Probit analysis. The effective concentration (EC50), no effect concentration (NOEC), specific growth rate (μ), doubling time (G), percentage growth inhibition (I%) and chlorophyll content was calculated. Treatments and control were significantly different in terms of cell density and growth inhibition percentage at specific intervals. In addition, the chlorophyll content of different treatments showed significant difference compared to control. It seems reducing the efficiency of photosynthesis is one of the routes that lead to considerable damage of copper oxide nanoparticles on Anabaena sp.

The issue of salinity stress caused by oil extraction has been one of the major environmental issues of the country in the last decade. Biological agents in oil-contaminated areas can be considered the most efficient methods. The aim of this study was to reduce salinity by cyanobacteria isolated from oil contaminated areas. Soil cyanobacterium Anabaena sp. FS 76 were collected from oil polluted areas of southern Iran (Khuzestan province) and were studied ecophysiologically for acclimation ability at combination of different salinities (up to 1%) and extremely limited irradiances (2 μmol quanta.m-2S-1) at laboratory conditions. Samples were collected from oil polluted soils at different stations of Khuzestan province (Khark) for one year. Anabaena sp.FS 76 showed common strain and was selected for next steps after preliminary identification. Salinity treatments included Salt-free medium and BG011 medium with 0.25, 0. 5, 0.75, and 1% sodium chloride which were applied before and after limited irradiance treatments. Analysis involved growth analysis, Pigments (phycocyanin, allophycocyanin, phycoerythrin) and protein and sugar content assays. Results showed that the maximum growth rate may be observed at 1% salinity. At this range of salinity. 1% NaCl not only may not decrease total sugar and protein content but also cause significant increase. In vivo absorption spectra support the presence of central and rod sections of phycobilisome. This strain has salinity amelioration ability at the laboratory conditions. This potentiality reaches to highest degrees of salinity especially at 1% probability level. The results showed examples of environmental physiology and biotechnology powerful is for future studies.

In current research two strains of Nostocaceae (Anabaena sp.FS76 and Nostoc sp. FS77) collected from paddy fields of Golestan province were studied morphologically and ultrastraucturally using optical, phase contrast, fluerosence and TEM electron microscopy. Results showed that, in comparison between strains, Anabaena sp.FS76 showed considerable fluctuations in dimensions and shapes of cells in 3th day, it seems that spatial form of this specimen changes in this day. Compression of the aggregations in liquid culture medium, decreased sharp in 8th day and stay to the similar form until the end of duration. The specimen had interesting color changes from light brown to green-brown. Generally, the length of vegetative cells and spores is more than their diameter. Vegetative cells in Anabaena sp.FS76 showed interesting shape and size variations. Vegetative cell length was more than diameter from the first to 10th day but in 10th day to end of duration this turned to the opposite and kept permanently. It seems that shapes of the thylakoides in ultrastructure analysis was not so changeable during the days and kept the relatively dense to linear configuration. In Nostoc sp.FS77, carboxysome and phosphate granules showed more various shapes in comparison with Anabaena sp. FS76.