List of Articles Heterocyst

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  1 - The effect of continuous illumination and photoperiods on growth and heterocyst frequency of cyanobacterium Fischerella ambigua from Golestan province
  Fereshte Vakili Kayvan Ghorchibeigi Neda Soltani Shadman Shokravi
  10.30495/iper.2006.690227
  The effect of limited continuous irradiance and photoperiods on survival, growth and heterocyst frequencies of cyanobacterium Fischerella ambigua collected from paddy-fields of Golestan province have been studied at laboratory condition. After soil collection and cultur More

  The effect of limited continuous irradiance and photoperiods on survival, growth and heterocyst frequencies of cyanobacterium Fischerella ambigua collected from paddy-fields of Golestan province have been studied at laboratory condition. After soil collection and culture, sample were isolated, purified, and incubated under 2μEm-2s-1 continuous irradiance with no carbon dioxide addition. The photoperiods were 2, 4, 6, 8 hours darkness each day. Survival, growth and heterocyst frequencies were studied in each treatment using optical density and chlorophyll measurements. Results showed that this cyanobacterium can survive under relatively short times of darkness (2 and possibly 4hours). The highest specific growth rate was related to 2hours dankness daily. 6 and 8hours darknesses cause relative similar results. 8hours darkness daily showed the highest degree of stress and cause sharp drop in growth. Chlorophyll production and morphological behaviors of aggregations showed unpredictable irregular fluctuations independent of photoperiods. We saw highest amount of heterocyst frequency and better regular patterns of heterocyst production at continuous irradiance but correlation between growth and heterocyst production differ completely at this condition. Manuscript profile
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  2 - Identification of some heterocystous cyanobacteria isolated from rice fields of Mazandaran province with emphasis on multi-genic approach
  Sara Kabirnataj Ghorban Ali Nematzadeh Ahmad Farhad Talebi Meisam Tabatabai Prashant Singh
  Background & Objectives: In the past, the classification of cyanobacteria was only based on the morphological characteristics; however other markers such as accurate molecular methods have been recently used. This study aimed to identify several heterocystous cyanob More

  Background & Objectives: In the past, the classification of cyanobacteria was only based on the morphological characteristics; however other markers such as accurate molecular methods have been recently used. This study aimed to identify several heterocystous cyanobacteria by polyphasic taxonomy and to investigate the multigenic approach in enhancing the accuracy of  cyanobacterial identification. Materials & Methods: After analyzing the morphological features and initial identification, the 16SrRNA gene along with tufA, rbcL, psbA, and rpoC1 functional genes were used to evaluate the taxonomic status and phylogenetic relationships. For this purpose, after DNA extraction, amplification and sequencing of gene fragments, the exact position of the strains was determined by making phylogenetic trees, based on the corresponding genes using MEGA software. Results: Among  the functional genes studied, the rpoC1 gene was able to discriminate genera very well, a result that completely confirmed 16SrRNA phylogenetic results. Finally based on the results, 4 samples from the Desmonostoc genus and 2 samples from the Calothrix genus were introduced.  Conclusion: The results of this study demonstrate the ability of the rpoC1 gene to discriminate genera correctly and confirm the morphological and phylogenetic results of 16SrRNA gene analysis. A phylogenetic study using the rpoC1 gene marker helps to clarify phylogenetic relationships among cyanobacteria. Moreover, it provides further evidence of their chloroplast origin and the presence of different evolutionary pathways among them. Manuscript profile