On Chlorogloeopsis fritschii (Cyanophyta/Cyanobacteria) from thermal springs in Slovakia and from a saline lake in Tunisia
The life cycle of Chlorogloeopsis fritschii (Cyanophyta/Cyanobacteria, Nostocales/Stigonematales) was studied in cultures isolated from fields in Allahabad, India, thermal springs in Slovakia, Central Europe and a saline lake in Tunisia, Northern Africa. As in the genera Nostoc, Trichormus or Nodularia, in C. fritschii all vegetative cells were able to transform into akinetes. Two types of germination of akinetes were distinguished. One type represented akinetes undergoing equal cell division and hormogonia formed without heterocytes that developed later. The second type was quite different and is unique in this group of cyanophytes. The akinetes divided asymmetrically into a smaller part to be transformed into a heterocyte, and a bigger one which divided again into two equal parts as vegetative cells. No substantial morphological differences were found among cultures of the species isolated from India, Slovakia or Tunisia, although the places of origin are ecologically different and geographically quite distant.