Claude Rouleau

Fast and high-yield synthesis of radioactive CH3203Hg(II)

A simple and fast synthesis of radioactive methylmercury is presented. It is based on the methylation of inorganic 203Hg(II) by methylcobalamin and isolation of resulting CH3203Hg(II) in a single extraction step. Time required is less than 4 hours and the final yield is ⩾90%.

Transport and subcellular distribution of intranasally administered zinc in the olfactory system of rats and pikes

Zinc is an essential element, which can act as a neuromodulator and also is bound in zinc proteins in the brain. The olfactory bulb contains high concentrations of zinc. In the present study, 65Zn(2+) was applied on the olfactory epithelium of rats and pikes and the transport of the metal in the olfactory system was then examined. Administration of 65Zn(2+) in the nasal cavity of rats or the olfactory chambers in pikes resulted in an uptake of the metal in the olfactory epithelium and a transport of the metal along the primary olfactory neurons to their terminations in the olfactory bulbs. Low levels of 65Zn(2+) passed these terminals and continued into the interior of the bulbs. In the rats 65Zn(2+) was also detected in the anterior parts of the olfactory cortex. Subcellular fractionations of the olfactory mucosa and olfactory bulb of rats given 65Zn(2+) intranasally showed that the metal is bound both to particulate cellular constituents and to cytosolic components in these tissues. Gel chromatography indicated that some of the zinc in the cytosol is bound to metallothionein in the olfactory mucosa and bulb. Inhalation of zinc-containing dusts or fumes occurs in some work-places and may imply high exposure of the nasal tissues. It is not known whether neurotoxicity may be related to uptake of zinc in the olfactory system. However, this is an issue which deserves attention, since zinc dysregulation has been implied to play a role in Alzheimers disease. In addition, impairment of the sense of smell and degenerative changes of the olfactory tissues have been seen in early stages of some neurodegenerative disorders.

Bioaccumulation and biotransformation of pyrene and 1‐hydroxypyrene by the marine whelk Buccinum undatum

The fates of a phenolic contaminant and its hydrocarbon precursor have rarely been compared, especially in an invertebrate species. Two groups of Buccinum undatum were exposed to equimolar amounts of pyrene and 1-hydroxypyrene over 15 d through their diets. Tissue extracts from the muscle and visceral mass were analyzed by liquid chromatography with fluorescence and mass spectrometry detection. Nine biotransformation products were detected in animals from both exposures. These included 1-hydroxypyrene, pyrene-1-sulfate, pyrene-1-glucuronide, pyrene glucose sulfate, two isomers each of pyrenediol sulfate and pyrenediol disulfate, and one isomer of pyrenediol glucuronide sulfate. These compounds represent a more complex metabolic pathway for pyrene than is typically reported. Diconjugated metabolites were as important in animals exposed to pyrene as in those exposed to 1-hydroxypyrene. Biotransformation products represented >90% of the material detected in the animals and highlight the importance of analyzing metabolites when assessing exposure. A mean of only 2 to 3% of the body burden was present in muscle compared with the visceral mass of both groups. The analytical methods were sufficiently sensitive to detect biotransformation products both in laboratory control whelks and in those sampled offshore. The tissue distribution of [(14)C]pyrene was also studied by autoradiography. Radioactivity was present primarily in the digestive and excretory system of the whelks and not in the gonads or muscle tissue.

Synthesis of radioactive tributyl[113Sn]tin of high specific activity for use in environmental fate studies

A method of synthesis of tributyl[ 113 Sn]tin, (n/C 4 H 9 ) 3 113 Sn(IV), from commercially available inorganic 113 Sn(IV) is presented. Inorganic tin is first extracted in diethyl ether and reacted with C 4 H 9 MgCl to produce tetrabutyltin, (C 4 H 9 ) 4 113 Sn, which is then debutylated with HgCl 2 . The resulting tributyl[ 113 Sn]tin chloride is isolated from the reaction mixture by successive extractions with hexane and aqueous Na 2 S 2 O 3 . The yield is 40-60% and the product obtained is >98% pure. It has the same specific activity as the starting 113 Sn(IV), i.e. up to 550 MBq mg -1 Sn, making it suitable for use in environmental fate and toxicology studies at concentrations relevant of those found in the aquatic environment.