The biotransformations and biomobility of monomethlarsonate and dimethylarsinate in the marine environment
department or school: Science, Faculty of
department or school: Chemistry, Department of
data provider: DSpace
degree campus: UBCV
creator: Nelson, John Christian
issued: 2009-04-09T00:00:00
issued: 1994
related degree: Doctor of Philosophy - PhD
degree grantor: University of British Columbia
description: The biotransformations and the biomobility of monomethylarsonate (MMA) and dimethylarsinate (DMA) in the marine environment were investigated. The biotransformations were studied by exposing blue mussels (Mytilus edulis) to either [³H]-MMA or [³H]-DMA in seawater tanks. Metabolic products including arsenobetaine ((CH₃)₃As⁺CH₂COO⁻) were identified in both the seawater and the mussels by using chromatographic techniques. The HPLC columns were coupled to a scintillation counter which acted as the detector. Arsenobetaine was also produced in seawater tanks which did not contain mussels which indicates that arsenobetaine is biosynthesized by microscopic organisms which are naturally occurring in seawater. It is likely that the arsenobetaine found in mussels is not a metabolic product of the mussels. The biomobility ofDMA and MMA was studied by measuring the rate at which these arsenicals diffused through liposomes as models for biological membranes. (Previously studies have shown that both DMA and MMA enter cells via slow passive diffusion.) Traditional techniques employing both radiolabelled permeants and liposomal membranes showed that DMA was much more permeable to the membranes than MMA. A ¹H-NMR spectroscopic technique employing shift agents to differentiate the spectroscopic signals of the permeant on either side of the liposomal membrane, was developed to measure the rate of diffusion of molecules across membranes. This technique was applied to DMA and MMA. Permeability coefficients of(5.8 ± 1.0) x 10⁻⁸ cm s⁻¹ and (7.8 ± 2.7) x10⁻⁹ cm s⁻¹ at 24°C were measured for the neutral forms of DMA and MMA, respectively. In addition, the effects ofpH, temperature, and membrane composition on the diffusion coefficients for DMA and MMA through the liposomal membrane were investigated. It was determined that only the neutral form of these weak acids permeates across the membrane and that cholesterol decreases the rate of permeation of DMA.
aggregated CHO: https://circle.library.ubc.ca/rest/handle/2429/7002
extent: 3628068 bytes
format: application/pdf
note: THE BIOTRANSFORMATIONS AND BIOMOBU.ITY OFMONOMETI[YLARSONATE AND DIMETHYLARSINATE IN THE MARINEENVIRONMENTbyJOHN CHRISTIAN NELSONB. Sc., University ofBritish Columbia, Canada, 1989A THESIS SUBMITTED IN PARTIAL FULFILLMENTOF THE REQUIREMENTS FOR THE DEGREE OFDOCTOR OF PHILOSOPHYinTHE FACULTY OF GRADUATE STUDIESDEPARTMENT OF CHEMISTRYWe accept this thesis as conformingto the required standardTHE UNWERSITY OF BRITISH COLUMBIA1993(c) John Christian Nelson, 1993In presenting this thesis in partial fulfilment of the requirements for an advanceddegree at the University of British Columbia, I agree that the Library shall make itfreely available for reference and study. I further agree that permission for extensivecopying of this thesis for scholarly purposes may be granted by the head of mydepartment or by his or her representatives, It is understood that copying orpublication of this thesis for financial gain shall not be allowed without my writtenpermission.(Signature)___________________________Department of Ce\ 5[The University of British ColumbiaVancouver, CanadaDate 4J7DE-6 (2/88)11ABSTRACTThe biotransformations and the biomobility of monomethylarsonate (MMA) anddimethylarsinate (DMA) in the marine environment were investigated.The biotransformations were studied by exposing blue mussels (Mytilus edulis) toeither[3H1-MMA or[3H]-DMA in seawater tanks. Metabolic products includingarsenobetaine ((CH)A.sCH2COOjwere identified in both the seawater and themussels by using chromatographic techniques. The HPLC columns were coupled to ascintillation counter which acted as the detector. Arsenobetaine was also produced inseawater tanks which did not contain mussels which indicates that arsenobetaine isbiosynthesized by microscopic organisms which are naturally occurring in seawater. It islikely that the arsenobetaine found in mussels is not a metabolic product of the mussels.The biomobility of DMA and MMA was studied by measuring the rate at whichthese arsenicals diffused through…
has type: Thesis/Dissertation
date issued: 1994-05
is shown at: 10.14288/1.0061713
language: eng
degree discipline: Chemistry
provider: Vancouver : University of British Columbia Library
publisher: University of British Columbia
rights: For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
scholar level: Graduate
type: Text
identifier URI: http://hdl.handle.net/2429/7002