جستجوی مقالات مرتبط با کلیدواژه "anabaena" در نشریات گروه "محیط زیست"

Paddy fields are terrestrial ecosystems that represent a favorable environment for the growth of blue-green algae. Members of genus Anabaena Bory ex Bornet et Flahault are most important genera of filamentous heterocystous blue-green algae in these terrestrial ecosystems. In present study, Anabaena specimens were obtained from paddy field soils of seven main rice cultivation provinces situated in north, centre, south, west and east of Iran from April 2008 to May 2010. For isolation and identification of these taxa, algal cultures carried out by growing the specimens in nitrate free BG-11 medium. Identification was carried out by morphometric and molecular methods (16S rRNA gene sequencing). Thirty six morphological characters and numerical taxonomic methods were used for classifying the several species of this genus. Numerical taxonomic studies were performed on 34 populations of 13 Anabaena morphospecies. A cluster analysis and principal component analysis performed using MVSP software and rate of resemblance among the species recognized. The results showed that populations of each species are placed close to each other and separate from the other species only base on morphological characters.

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.