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Arsenic (+3 oxidation state) methyltransferase and the methylation of arsenicals in the invertebrate chordate Ciona intestinalis
Author(s) -
Nava Gerardo Manuel,
Lee David Y.,
Cai ShiYing,
Boyer James L.,
HernándezZavala Araceli,
Thomas David J.,
Gaskins H. Rex
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.796.1
Subject(s) - ciona intestinalis , chordate , arsenic , ciona , biotransformation , methylation , methyltransferase , biology , arsenite , chemistry , biochemistry , gene , genome , enzyme , organic chemistry
The biotransformation of inorganic arsenic (iAs) involves methylation by an arsenic (+3 oxidation state) methyltransferase ( AS3MT ), yielding methyl arsenic (MA), dimethyl arsenic (DMA), and trimethylarsenic (TMA). To identify molecular mechanisms that coordinate arsenic biotransformation, we are using a comparative genomic approach focused on the invertebrate chordate, Ciona intestinalis . Bioinformatic analyses were used to annotate an AS3MT gene in Ciona . RT‐PCR analysis from replicate animals demonstrated constitutive expression of AS3MT in branchial sac (BS), gastrointestinal tract (GIT), and heart. Also, replicate animals were exposed to zero (control) or 1 ppm of iAs (as arsenite) in sea water during 24 h or 5 d. Hydride generation‐atomic absorption spectrometry was used to measure iAs, MA, DMA, and TMA concentrations in BS, GIT, and heart. Methylated metabolites were detected in each of the tissues at both 24 h and 5 d in Ciona specimens exposed to iAs compared with controls ( P < 0.01). Average total speciated As concentrations were highest in the BS (3705 ng/g) followed by heart (1019 ng/g) and GIT (835 ng/g) after 5 d. Thus Ciona metabolizes iAs to its methylated metabolites, consistent with the presence of an AS3MT ortholog in its genome, making this basal chordate a useful model to examine the evolution of As detoxification. (This abstract does not reflect U.S. EPA policy.)