title: Differences in mRNA levels in Anabaena living freely or in symbiotic association with Azolla.
abstract: Azolla is a small water fern in whose leaf cavities the filamentous nitrogen-fixing cyanobacterium Anabaena azollae is symbiotically associated. Using cloned genes from Anabaena 7120 for glutamine synthetase (GS), ribulose-1,5-bisphosphate (RuBP) carboxylase, nitrogenase and the 32-kd protein of photosystem II, mRNA levels of the corresponding genes in the Anabaena endosymbiont were studied by Northern hybridization. In RNA isolated from the endosymbiont there is a 10-fold reduction of GS transcript levels, a greater than 5-fold increase in 32-kd transcript levels and a greater than 5-fold decrease in RuBP carboxylase transcript levels, compared with levels in the free-living Anabaena azollae. In the endosymbiont and in heterocysts of the free-living Anabaena azollae the nif H, nif D, and nif K genes are transcribed from a single nif HDK operon.
authors.forename: S A
authors.initials: SA
authors.lastname: Nierzwicki-Bauer
authors.forename: R
authors.initials: R
authors.lastname: Haselkorn
mesh_terms: D002734:Chlorophyll / Q000235:genetics; D003001:Cloning, Molecular; D000458:Cyanobacteria / Q000235:genetics* / Q000502:physiology; D005796:Genes; D005974:Glutamate-Ammonia Ligase / Q000235:genetics; D045342:Light-Harvesting Protein Complexes; D009591:Nitrogenase / Q000235:genetics; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D018521:Plant Physiological Phenomena; D010940:Plant Proteins / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics* / Q000302:isolation & purification; D012273:Ribulose-Bisphosphate Carboxylase / Q000235:genetics; D013559:Symbiosis; D014158:Transcription, Genetic
chemical_list: D045342:Light-Harvesting Protein Complexes; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D010940:Plant Proteins; D012333:RNA, Messenger; D002734:Chlorophyll; D009591:Nitrogenase; D012273:Ribulose-Bisphosphate Carboxylase; D005974:Glutamate-Ammonia Ligase