Nitrogen fixation and colonization by associative cyanobacteria in the aerial roots (pneumatophores) of black mangrove trees was evaluated in situ at Balandra lagoon, Baja California Sur, Mexico, for 18 consecutive months. Year-round vertical zonation of cyanobacterial colonization was determined along the pneumatophores. The bottom part close to the sediment was colonized mainly by nonheterocy...

Some N2-fixing cyanobacteria form symbiosis with diverse protists. In the plankton two groups of diazotrophic symbioses are described: (1) a collective group of diatoms which associate with heterocystous cyanobacteria (Diatom Diazotroph Associations, DDA), and (2) the microalgal prymnesiophyte Braarudosphaera bigelowii and its relatives which associate with the unicellular cyanobacterium Candid...

Cyanobacteria may possess several enzymes that are directly involved in dihydrogen metabolism: nitrogenase(s) catalyzing the production of hydrogen concomitantly with the reduction of dinitrogen to ammonia, an uptake hydrogenase (encoded by hupSL) catalyzing the consumption of hydrogen produced by the nitrogenase, and a bidirectional hydrogenase (encoded by hoxFUYH) which has the capacity to bo...

Homeostatic systems for essential and non-essential metals create the cellular environments in which the correct metals are acquired by metalloproteins while the incorrect ones are somehow avoided. Cyanobacteria have metal requirements often absent from other bacteria; copper in thylakoidal plastocyanin, zinc in carboxysomal carbonic anhydrase, cobalt in cobalamin but magnesium in chlorophyll, ...

Glucose-6-phosphate dehydrogenase (G6PDH) is a key enzyme involved in fixed carbon dissimilation in photosynthetic microorganisms ; in heterocystous cyanobacteria it may also be implicated in the supply of reductant to nitrogenase. In crude cell-free extracts of the N,-fixing cyanobacterium Anabaena variabilis G6PDH activity was reversibly deactivated by the thiol agent dithiothreitol in the pr...

Avian vacuolar myelinopathy (AVM) is a newly discovered bird disease, which is killing bald eagles (Haliaeetus leucocephalus) and waterfowl in the southeastern United States. Surveys were conducted to investigate exotic macrophytes (e.g. Hydrilla verticillata) as a substrate for attachment by toxic cyanobacteria that may be associated with the incidence of AVM. While the specific cause of the d...