Publication Date


Document Type


First Advisor

Frampton, Elon W.

Degree Name

M.S. (Master of Science)

Legacy Department

Department of Biological Sciences


Anacystis nidulans; Gyanophyta


Anacystis nidulans, strain 625, grown at 39 C in BG-11 medium at a light intensity of 3,000 lux was exposed to a heat stress at 47 C for 30 min in potassium phosphate buffer (0.10 M, pH 7.1) or in BG-11 medium before return to growth conditions. Cell survival was determined on samples plated at intervals on both BG-11 agar and BG-11 agar containing 0.5% (w/v) NaCl as a stressing agent for heat injured cells. Cells heat stressed in phosphate buffer continued to lose viability for 4 hours after being returned to growing conditions as evidenced by the number of survivors on the salt containing agar. After this period, there was a rapid recovery of viability which continued during the next 4 hours. BG-11 heated cells, however, started to recover viability immediately after being returned to growing conditions as evidenced by plating on salt containing agar and recovery was complete after 8 hours. Cell-free extracts from cultures labeled with [³H] uracil and heated (47 C, 30 min.) in phosphate buffer or BG-11 medium were examined for effects on the ribosomal patterns using linear sucrose gradients (5-20% w/v) containing 0.5 mM magnesium. Cells heated in phosphate buffer showed a severe reduction of the 30S ribosome peak and the 30S peak was obliterated by an apparent accumulation of breakdown material. Cells heated in BG-11 medium, however, showed only a slight reduction in the 30S ribosome peak. The 30S ribosomal components of the phosphate buffer heated cells recovered partially after 4 hours of post heating incubation. After 8 hours, both 30S and 50S ribosomal components were observed in cells labeled before heating with [¹⁴C] uracil and after heating with [³H] uracil.


Includes bibliographical references.||Includes illustrations.


v, 55 pages




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