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Newly fertilized eggs of the oyster Crassostrea virginica were exposed to 0.2 microM Cd and sampled during the first 24 hr of embryonic and larval development for determination of the temporal patterns of total bioaccumulated and metallothionein (MT)-bound Cd concentrations and the concentrations of MT mRNA. In comparison with controls, exposure to this(More)
The relationship between metallothionein (MT) induction and cytotoxicity was examined in isolated oyster hemocytes exposed in vitro to cadmium, copper, and zinc. In all cases MT induction increased to peak levels with increased metal dose, then declined with continued increases in dose. The effectiveness of these metals as inducers of MT was cadmium >(More)
A quantitative assay based on competitive reverse transcription polymerase chain reaction (RT-PCR) was developed for metallothionein (MT) mRNA of the mollusc Crassostrea virginica and applied to analysis of MT mRNA of hemocytes. The assay was based on titration of a competitive external standard cRNA derived from the coding region of the oyster MT mRNA.(More)
Two low-molecular-mass cadmium-induced, cadmium-, zinc-binding proteins were purified from the oyster Crassostrea virginica using procedures that included acetone precipitation, Sephadex gel chromatography, and anion-exchange and reverse-phase high-performance liquid chromatography. Although they could be cleanly separated from each other, they exhibited(More)
The ability of metallothionein (MT) to modulate DNA binding by a two-finger peptide of Tramtrack (TTK), a CCHH zinc transcription factor, was investigated using metal-bound and metal-deficient forms of rabbit MT-2 and the TTK peptide. Thionein inhibited DNA binding by zinc-bound TTK, and Zn-MT restored DNA-binding by zinc-deficient apo-TTK. "Free" zinc at(More)
One-week-old larvae of the mollusc Crassostrea virginica, an oyster, were exposed to Cd concentrations ranging from the control with no added Cd to 0.2 microM CdCl2 for 24 hr. Concentration-dependent increases in total cadmium accumulation, cytosolic and metallothionein-bound Cd concentrations, and levels of the MT mRNA were detectable over this range of(More)
The primary structure of metallothioneins (MT) of a mollusc, the oyster Crassostrea virginica, was determined by molecular cloning and mass spectrometry of purified proteins. The cloning strategy included PCR amplification of the responsible cDNAs from total cDNA using completely degenerate oligonucleotides (derived from the N-terminal amino acid sequence)(More)
High kinetic reactivity and high metal affinity of the metal-binding sites of metallothionein are characteristics that would facilitate involvement of the thionein-zinc metallothionein couple in metal transfer or exchange reactions. Studies demonstrating thionein-metallothionein-mediated activation or inhibition of various zinc metalloenzymes and(More)
In order to better understand the interplay between metallothionein (MT) and reactive oxygen species (ROS) in oyster hemocytes, studies of the hydrogen peroxide (H2O2) scavenging properties of MT were carried out in a cell-free system. Mammalian MT is involved in protection against oxidative stress by virtue of its ability to scavenge free radicals;(More)