Distributions of iron, phosphorus and sulfur along trichomes of the cyanobacteria Trichodesmium.
The nonheterocystous cyanobacterium Trichodesmium fixes C and N concurrently during the light period in tropical and subtropical oceans. Synchrotron mapping of Fe, P and S in trichomes of Trichodesmium erythraeum Erhenberg IMS 101 (CCMP 1985) collected during exponential and senescent growth revealed that 16% of trichomes contained sections of up to 25 cells with ca. 2-fold elevated Fe and S but ca. 2-fold lowered P in comparison to neighboring trichome sections. The correlation between Fe and S in these trichomes was moderate to strongly positive (R > 0.35), while the correlation between Fe and P was moderate to strongly negative (R < 0.35). Higher Fe in theses trichome sections might indicate the presence of nitrogenase. Increase in S in conjunction with Fe is likely driven by other S-containing compounds in addition to Fe-S proteins. Furthermore, the concurrent increase in S and decrease in P in these Fe-rich trichome sections might indicate a switch from P- to S-containing compounds. Diurnal changes and growth phase-related differences in the correlation between Fe and P both point to Trichodesmium's ability to re-allocate elements depending on their physiological need. Concurrent P depletion and Fe and S enrichment in trichome sections is a strong indication that Trichodesmium is able to develop special trichome regions consisting of multiple cells with a unique chemical composition. Whether these cells are uniquely dedicated to N2-fixation (i.e., diazocytes) is an open question.
Bigelow Laboratory for Ocean Sciences, 60 Bigelow Drive, East Boothbay, Maine 04544, USA. jnuester@bigelow.org.
Jochen
J
Nuester
Matthew
M
Newville
Benjamin S
BS
Twining
D000458:Cyanobacteria / Q000737:chemistry / Q000254:growth & development / Q000378:metabolism* / Q000648:ultrastructure; D007501:Iron / Q000032:analysis* / Q000378:metabolism; D009586:Nitrogen Fixation; D010758:Phosphorus / Q000032:analysis* / Q000378:metabolism; D013455:Sulfur / Q000032:analysis* / Q000378:metabolism
D010758:Phosphorus; D013455:Sulfur; D007501:Iron