Interactions of cadmium, zinc, and phosphorus in marine Synechococcus : field uptake, physiological and proteomic studies
Interactions of cadmium, zinc, and phosphorus in marine Synechococcus : field uptake, physiological and proteomic studies
Date
2011-06
Authors
Cox, Alysia D.
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Date Created
Location
Costa Rica Upwelling dome
DOI
10.1575/1912/4645
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Keywords
Primary productivity
Biogeochemistry
Knorr (Ship : 1970-) Cruise KN182-05
Biogeochemistry
Knorr (Ship : 1970-) Cruise KN182-05
Abstract
A combination of uptake field studies on natural phytoplankton assemblages and
laboratory proteomic and physiological experiments on cyanobacterial isolates were
conducted investigating the interactions of cadmium (Cd), zinc (Zn), and phosphorus (P)
in marine Synechococcus. Enriched stable isotope field uptake studies of 110Cd in the
Costa Rica Upwelling dome, a Synechococcus feature, showed that uptake of Cd occurs
in waters shallower than 40 m, correlates positively with chlorophyll a concentrations
and is roughly equivalent to the calculated upwelling flux of cadmium inside the dome.
In laboratory experiments, Synechococcus WH5701 cells exposed to low picomolar
quantities of free Cd under Zn deficiency show similar growth rates to no added Cd
treatments during exponential growth phase, but show differences in relative abundances
of many proteins involved in carbon and sulfur metabolism suggesting a great metabolic
impact. During stationary phase, chronic Cd exposure in this coastal isolate causes an
increase in relative chlorophyll a fluorescence and faster mortality rates. The interactions
of acute Cd exposure at low picomolar levels with Zn and phosphate (PO4
3-) were
investigated in Synechococcus WH8102, an open ocean isolate. The presence of Zn
appears vital to the response of the organism to different PO4
3- concentrations.
Comparisons with literature transcriptome analyses of PO4
3- stress show similar increases
in relative abundance of PO4
3- stress response proteins including a PO4
3- binding protein
and a Zn-requiring alkaline phosphatase. A bacterial metallothionein, a Zn-associated
protein, appears to be correlated with proteins present under low PO4
3- conditions.
Together, these experiments suggest that the interactions of Cd and Zn can affect
Synechococcus and play a role in the acquisition of PO4
3-.
Description
Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution June 2011
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Citation
Cox, A. D. (2011). Interactions of cadmium, zinc, and phosphorus in marine Synechococcus : field uptake, physiological and proteomic studies [Doctoral thesis, Massachusetts Institute of Technology and Woods Hole Oceanographic Institution]. Woods Hole Open Access Server. https://doi.org/10.1575/1912/4645