Cadmium: A toxin and a nutrient for marine phytoplankton. Doctoral thesis
Although cadmium is known to be very toxic, it exhibits nutrient-like vertical concentration profiles in the open ocean. Cadmium enhances the growth of the marine diatom Thalassiosira weissflogii, a chlorophyte and some prymnesiophytes at inorganic zinc and cadmium concentrations typical of surface seawater. Detailed studies of T. weissflogii show that cadmium is also regulated like a nutrient over a wide range of external inorganic cadmium (5-500pM) and inorganic zinc (2-16pM) concentrations. The cellular cadmium concentration is maintained at relatively constant levels both through uptake and, at high inorganic cadmium concentrations (5nM), export of cadmium, most likely complexed to the metal-binding polypeptide phytochelatin. Cadmium may play an essential role in carbon uptake under conditions of zinc limitation. The same low level of inorganic cadmium that enhances the growth of T. weissflogii restores the activity of carbonic anhydrase, thought to be the key enzyme limiting growth at low zinc. Cadmium coelutes with a least one of the multiple isoforms of carbonic anhydrase produced by T. weissfiogii and covaries with activity of this isoform. The substitution of cadmium for zinc in carbonic anhydrase links the geochemical cycle of cadmium to those of zinc and carbon.
- Research Organization:
- Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
- OSTI ID:
- 371326
- Report Number(s):
- AD-A-308002/5/XAB; TRN: 62390129
- Resource Relation:
- Other Information: TH: Doctoral thesis; PBD: Jun 1995
- Country of Publication:
- United States
- Language:
- English
Similar Records
Metabolic responses to subacute toxicity of trace metals in a marine microalga (Thalassiosira weissflogii) measured by calorespirometry
Control of Cd concentrations in a coastal diatom by interactions among free ionic Cd, Zn, and Mn in seawater