TY - JOUR
T1 - Phytochelatin concentrations in the equatorial Pacific
AU - Ahner, Beth A.
AU - Lee, Jennifer G.
AU - Price, Neil M.
AU - Morel, Francois M. M.
N1 - Funding Information:
A special thanks to the captain and crew of the R/V Moana ¼ave, and to Kenneth Bruland, the chief scientist, Geoffrey Smith, Mark Wells and the other members of the Bruland laboratory who made our participation on this cruise and the collection of trace metal clean samples possible. Also, a special thanks to Michelle DuRand and Jeffery Dusenberry for the ßow cytometry data, to Giacomo DiTullio for the divinyl chl a measurements and to Gregory Cutter for the use of his Go-ßo bottles. We would also like to thank William Sunda and an anonymous reviewer for thoughtful comments on the manuscript. Funding of this project was provided by NSF, ONR and EPA.
PY - 1998/11
Y1 - 1998/11
N2 - Phytochelatin, an intracellular metal-binding polypeptide synthesized in eucaryotic algae in response to metals such as Cd and Cu, was measured in particulate samples collected from the equatorial Pacific. The concentrations in these samples (normalized to total particulate chl a) were unexpectedly high compared to laboratory culture data and were on average slightly more than in coastal areas where the metal concentrations are typically much greater. In part, the high field concentrations can be explained by the low cellular concentrations of chlorophyll a resulting from very low ambient Fe, but laboratory experiments provide a possible explanation for the rest of the difference. At low concentrations of inorganic Cd (Cd' = 3 pM), increasing amounts of phytochelatin were induced by decreasing Zn concentrations in the culture medium of two diatoms: Thalassiosira weissflogii, a coastal species, and T. parthenaia, an isolate from the equatorial Pacific. In all previous studies, phytochelatin production has been directly correlated with increasing metal concentrations. Decreasing Co also resulted in higher phytochelatin concentrations in T. weissflogii and Emiliania huxleyi. Replicating the field concentrations of Zn, Co, and Cd in the laboratory results in cellular concentrations (amol-1 cell) that are very similar to those estimated for the field. Contrary to the expectation that high metal concentrations in the equatorial upwelling would cause elevated phytochelatin concentrations, there was no increase in phytochelatin concentrations from 20°S to 10°N - near surface samples were roughly the same at all stations. Also, most of the depth profiles had a distinct subsurface maximum. Neither of these features is readily explained by the available Zn and Cd data. Incubations with additions of Cd and Cu performed on water sampled at four separate stations induced significantly higher concentrations of phytochelatins than those in controls in a majority of the samples. The differences between metal additions and controls were greater within the upwelling zone, where water presumably has had less time to accumulate biogenic complexing agents. However, the uniformity of phytochelatin concentrations in and out of the upwelling region suggests that the phytoplankton or the biota are successfully maintaining a tight control over the trace metal chemistry both intra- and extracellularly across a wide range of oceanic conditions.
AB - Phytochelatin, an intracellular metal-binding polypeptide synthesized in eucaryotic algae in response to metals such as Cd and Cu, was measured in particulate samples collected from the equatorial Pacific. The concentrations in these samples (normalized to total particulate chl a) were unexpectedly high compared to laboratory culture data and were on average slightly more than in coastal areas where the metal concentrations are typically much greater. In part, the high field concentrations can be explained by the low cellular concentrations of chlorophyll a resulting from very low ambient Fe, but laboratory experiments provide a possible explanation for the rest of the difference. At low concentrations of inorganic Cd (Cd' = 3 pM), increasing amounts of phytochelatin were induced by decreasing Zn concentrations in the culture medium of two diatoms: Thalassiosira weissflogii, a coastal species, and T. parthenaia, an isolate from the equatorial Pacific. In all previous studies, phytochelatin production has been directly correlated with increasing metal concentrations. Decreasing Co also resulted in higher phytochelatin concentrations in T. weissflogii and Emiliania huxleyi. Replicating the field concentrations of Zn, Co, and Cd in the laboratory results in cellular concentrations (amol-1 cell) that are very similar to those estimated for the field. Contrary to the expectation that high metal concentrations in the equatorial upwelling would cause elevated phytochelatin concentrations, there was no increase in phytochelatin concentrations from 20°S to 10°N - near surface samples were roughly the same at all stations. Also, most of the depth profiles had a distinct subsurface maximum. Neither of these features is readily explained by the available Zn and Cd data. Incubations with additions of Cd and Cu performed on water sampled at four separate stations induced significantly higher concentrations of phytochelatins than those in controls in a majority of the samples. The differences between metal additions and controls were greater within the upwelling zone, where water presumably has had less time to accumulate biogenic complexing agents. However, the uniformity of phytochelatin concentrations in and out of the upwelling region suggests that the phytoplankton or the biota are successfully maintaining a tight control over the trace metal chemistry both intra- and extracellularly across a wide range of oceanic conditions.
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U2 - 10.1016/S0967-0637(98)00043-0
DO - 10.1016/S0967-0637(98)00043-0
M3 - Article
AN - SCOPUS:0032213213
SN - 0967-0637
VL - 45
SP - 1779
EP - 1796
JO - Deep-Sea Research Part I: Oceanographic Research Papers
JF - Deep-Sea Research Part I: Oceanographic Research Papers
IS - 11
ER -