Tri-n-butyltin Research Articles

Tri-n-butyltin increases intracellular Ca2+ in mouse thymocytes: a flow-cytometric study using fluorescent dyes for membrane potential and intracellular Ca2+.

Effects of tri-n-butyltin (TBT) on mouse thymocytes were examined using a flow-cytometer and fluorescent dyes for membrane potential and intracellular Ca2+ ([Ca2+]i). TBT at concentrations from 1 x 10(-7) M to 3 x 10(-7) M caused hyperpolarization in thymocytes during 30 min. after drug application in a time- and dose-dependent manner. Further increase in TBT concentration (to 1 x 10(-6) M) made hyperpolarization of thymocytes more profound within 5 min. after application, thereafter gradually depolarized them during the next 25 min. TBT at 3 x 10(-8) M or more (up to 1 x 10(-6) M) increased the [Ca2+]i of thymocytes. After reaching maximum [Ca2+]i at the various TBT concentrations used within 5 min. after drug application, the [Ca2+]i slightly decreased in a time-dependent manner. Effects of TBT on membrane potential and the [Ca2+]i were greatly reduced under nominal external Ca(2+)-free condition. Results suggest that TBT can promote Ca(2+)-influx to thymocytes, resulting in hyperpolarization by activation of Ca(2+)-dependent K+ current. The increase in [Ca2+]i by TBT may be related to its cytotoxic action on thymocytes.

In vitro activation of lipophilic tributyltins by superoxide produces tributylstannyl superoxo radicals, proposed initiators of lipid peroxidation: an EPR model study.

Tri-n-butyltin(TBT) compounds having the chemical formula (C4H9)3SnX are broad-spectrum biocidal agents whose toxic effect is primarily at the membrane level. Red blood cells (RBC) exposed to micromolar concentrations of tributyltin compounds (TBTX) undergo morphological changes and hemolysis. Determination of the mechanism of action whereby TBT elicits membrane damage continues to be a challenging endeavor. Because xenobiotic TBT+ and endogenous O2.- have been found to penetrate and alter RBC membrane function, it is hypothesized that they may combine chemically within the RBC hydrophobic lipid bilayer during TBT insult to initiate lipid peroxidative processes. The present study has been designed (1) to determine if TBT+ and O2.- combine chemically in aprotic media and, if so, (2) to characterize any free-radical complex(es) generated. The reactions of the membrane-active TBTX compounds (X = OCH3, Cl, Br, or I) with O2.- have been investigated in the aprotic solvent system cis-dicyclohexano-18-crown-6 ether/DMSO using EPR techniques. When incremental amounts of each TBT halide were added to O2.- solutions at room temperature, the EPR signal characteristic of O2.- diminished in intensity and disappeared when a 1:1 O2.-/TBT+ mole ratio was attained. Although the same phenomenon was observed for all TBT halides used, only the KO2/TBTI reaction produced detectable amounts of a new oxygen-centered free-radical complex. The EPR spectral parameters calculated from the product anisotropic frozen glass spectra were gx = 2.054, a(x) = 31.7 G, gy = 2.021, gz = 2.002, gav = 2.026.(ABSTRACT TRUNCATED AT 250 WORDS)

Combined effects of tri-n-butyl tin (TBT) and diuron on marine periphyton communities detected as pollution-induced community tolerance

The effects of combined toxicity were studied, using marine periphyton communities exposed to mixtures of tri-n-butyl tin (TBT) and diuron (3-(3,4-dichlorophenyl)-1,1-dimethylurea, DCMU) in indoor aquaria during four weeks. The experimental design of the study followed a central composite design (CCD) and utilized dose-response surface methodology for evaluation of the results. The detection of pollution-induced community tolerance (PICT) was accomplished by short-term (1 h) tests on inhibition of photosynthesis. Both single-toxicant and two-toxicant short-term tests were used. Two tentative measures of tolerance are proposed to achieve convenient comparisons of the tolerances from the two-toxicant tests. With the detection of PICT, effects of the long-term exposure were recorded on diatom species richness, chlorophyll a accumulation and copepod abundance. The decrease of diatom species richness was accompanied by an increased tolerance (PICT), which was detectable by all tolerance measures used. Primary effects on microalgae were recorded as a decrease in chlorophyll a at higher toxicant concentrations. At lower concentrations, primary effects on copepods were found, which resulted in reduced grazing and increased chlorophyll a content.

Accumulation and persistence of tri-n-butyltin in pink and chum salmon fry cultured in marine net-pens

Pink salmon ( Oncorhynchus gorbuscha) and chum salmon ( O. keta) fry cultured in tri-n-butyltin (TBT) treated marine net-pens for 20–68 days were tested just prior to release into the ocean to determine whether TBT contamination had occurred and, if so, to what extent. Exposed fry contained 0.2–7.3 μg TBT/g fish at the time of release; TBT concentrations varied substantially among the netpen populations. Unusually high mortalities or poor growth rates were not observed. TBT was not detected in the returning adults.

Determination of tri-n-butyltin in oysters by reaction—gas chromatography of hydride derivatives

A reaction—gas chromatography method for determining tri-n-butyltin (TBT) as the hydride derivative has been adapted to allow determination of TBT in oysters. The extraction method has been modified to prevent fouling of the hydride formation reactor and the gas chromatography has been made faster by employing a different column and temperature program. The detection limit is 3–6 ng/g in oyster tissue. Apparent recoveries of TBT from oyster tissue at 25 and 125 ng/g levels are 107 and 97%, respectively.

Mechanisms of Tri-N-Butyltin Bioaccumulation by Marine Phytoplankton

We examined uptake of tri-n-butyltin (TBT) by three genera of marine microalgae and one genus of cyanobacterium. There was a linear relationship between external concentrations of TBT and cell burdens in the microalgae Nannochloris sp., Chaetoceros gracilis, and the cyanobacterium Synechococcus sp. (PR-6). The relationship between external TBT concentrations and cell TBT burdens was distinctly nonlinear for Isochrysis galbana. Competitive binding experiments showed a decrease of approximately 88% of the total bound radiolabeled TBT to I. galbana in the presence of a 200-fold excess of unlabeled TBT. No significant decrease of bound TBT was observed for Nannochloris sp. These studies demonstrate that either partitioning or binding may control bioaccumulation of TBT by marine phytoplankton.

Occurrence of tri-n-butyltin-caused imposex in the North Pacific marine snail Nucella lima in Auke Bay, Alaska

Like female dog whelks (Nucella lapillus) in the Atlantic Ocean, females of the Pacific gastropod N. lima respond to low concentrations of tri-n-butyltin (TBT) by growing a penis and vas deferens. This condition, termed imposex, was found to occur in N. lima collected from August 1987 to May 1988 along a TBT pollution gradient associated with a marina in Auke Bay, Alaska. The suite of symptoms characteristic of imposex in N. lima was slightly different than in N. lapillus. Imposex, as measured by relative penis size (RPS) of females to males, increased from 0.0 to 34.27 along this gradient and as measured by vas deferens sequenceindex (VDS) increased similarly from 0.0 to 4.29. Concentrations of TBT in N. lima increased from below detection limits (about 0.010 μg Sn g-1 dry tissue wt) to 0.065 μg Sn g-1 dry tissue wt along the gradient. The gradient was determined by measuring TBT in whole-body tissues of bay mussels (Mytilus edulis). Concentrations of TBT in mussels increased from below detection limits to 0.833 μg Sn g-1 dry tissue wt in mussels from within the marina that was the major local source of TBT. Imposex, tissue TBT burden, and position along a TBT pollution gradient are significantly correlated (P<0.01) in N. lima. TBT was tested as a causative agent for imposex by exposing snails at a distant control site to TBT paint. After 1 mo exposure, 33% of the females grew a penis ranging in size from 0.2 to 0.8 mm. Our results generally corroborate those found for N. lapillus and indicate that imposex in N. lima is caused by environmental TBT exposure. We suggest that the RPS in the genus Nucella may be useful in monitoring TBT in coastal waters worldwide.

The reaction of (9- [formula omitted])-9-deoxo-9-hydroximinoerythromycin a with alkaline n-bromosuccinimide

(9- E )-9-Deoxo-9-hydroximinoerythromycin A (2) was reacted with N-bromosuccinimide in aqueous sodium bicarbonate to give 9-deoxo-11-deoxy-9,11-epoxy-9-nitroso-3′-des- N -methylerythromycin A (5) which was converted into 3′-des- N -methyl-9-deoxo-9-hydroximinoerythromycin A (7) with tri n-butyl tin hydride.

A technique for assessing the preventative efficacy against decay fungi of preservative treatments applied to wood

A method is described in which test blocks with envelope preservative treatments can be challenged by selected test fungi previously established on an untreated feeder block. The progress of the test fungus through the treated zone is monitored using novel baits or sensors inserted in holes drilled into blocks to within predetermined distances of the face being challenged. Preliminary results show the method to be discriminating. Three-minute immersion treatment with 5% pentachlorophenol retarded colonisation for a longer period than 1% tri n-butyltin oxide, particularly when penetration was in the tangential direction.

Degradation of Tributyl Tin and Dibutyl Tin Compounds in Environmental Waters

The degradation of tri-n-butyl tin (TBT) and di-n-butyl tin (DBT) compounds in river and sea water samples was studied. In river water (Daini Neya River), TBT was degraded with time, and the concentration of inorganic tin increased. DBT was also degraded with time, and the concentrations of n-butyl tin (MBT) compounds and inorganic tin (the degradation products) increased. The half lives of TBT and DBT were about 11 days and 5 days, respectively. In seawater from Sakaisenboku Harbour (one of the most polluted areas in Osaka Bay), TBT and DBT were degraded in a manner similar to that in Daini Neya River water, but in seawater from other areas of Osaka Bay these compounds were little degraded.

Determination of tri-n-butyltin and di-n-butyltin in fish as hydride derivatives by reaction gas chromatography.

A method is described for the determination of tri-n-butyltin (TBT) and di-n-butyltin (DBT) by reaction gas chromatography. The method involves formation of hydride derivatives of TBT and DBT in a packed reactor inside the injection port of a gas chromatograph (GC). Following hydride formation, the hydrides are separated on a wide bore capillary column (5% phenylmethylsilicone) and detected with a flame photometric detector (FPD) equipped with a 600-nm filter. The method is sensitive to approximately 100 pg of TBT injected (as Sn) and its application to the determination of TBT and DBT in salmon tissue is described. For this application, organotins are extracted with a methanol/methylene chloride mixture and the extracts are cleaned up on a small silica gel column prior to reaction GC. For 18 salmon samples analyzed, TBT levels ranged from < 5 to 188 ppb (as Sn) with an average recovery of 93%. The method may have applications for other organometallic pesticides and environmental pollutants that can undergo hydridization.

Tri- n-butyltin: A membrane toxicant

Increased use of the biocidal compound tri- n-butyltin (TBT) in antifouling paints has prompted research aimed at determining the mechanism for TBT toxicity. Past investigations indicate that the primary cellular target for TBT is the cell membrane. Erythrocyte suspensions treated with TBT concentrations ≧ 5 μM undergo hemolysis described by a sigmoidal kinetic pattern. Transformation of cell shape from discocyte to echinocyte occurs at TBT concentrations ≧ 0.1 μM , indicating that the compound enters the outer membrane bilayer. TBT at concentrations ≧ 10 μM forms electron-dense aggregates that are intercalated within plasma membranes as viewed in ultrathin sections by transmission electron microscopy. Qualitative X-ray microanalysis of these aggregates confirms the presence of tin. The size of these structures can be modified by either 10 mM cyanide or 2,3-dimercaptopropanol (British Anti-Lewisite, BAL). Adding 10 mM cyanide to hemolytic TBT concentrations resulted in a synergistic stimulation of hemolysis attributable to high cyanide anion concentrations in or near the cell membrane. The elevated cyanide anion levels are thought to contribute to membrane lysis. The lipophilic dimercapto compounds BAL, dithiothreitol, and 2,3-dimercaptosuccinate are effective inhibitors of TBT-induced lysis. Water-soluble 2,3-dimercapto-1-propane sulfonate, a BAL analog, was largely ineffective as an inhibitor. The detailed molecular mechanism for TBT-induced membrane lysis is not yet clear. Cellular ATP depletion could be induced by TBT as well as by delipidation of anionic phospholipids or even formation of tributylstannylperoxy radicals, resulting in lipid peroxidation.

Toxicity of tri- n-butyl-tin to chinook salmon, Oncorhynchus tshawytscha, adapted to seawater

The median lethal concentrations (LC 50s) of tri- n-butyl-tin oxide (TBTO) to juvenile chinook salmon, Oncorhynchus tshawytscha, adapted to seawater were determined in a static renewal bioassay. LC 50s were 54, 20, and 1.5 μg TBTO/l after exposures for 6, 12, and 96 h, respectively. LC 50s decreased logarithmically with time for exposures between 12 and 96 h. Also determined were the average tri- n-butyl-tin (TBT) concentrations in liver, brain, and muscle tissues of salmon that died during the bioassay: 7.0, 3.5, and 0.52 μg TBT/g wet weight tissue, respectively. TBT concentrations in liver, brain, and muscle tissues of salmon that survived until day 4 of the bioassay were 4300, 1300, and 200 times exposure concentrations, respectively. Our results implicate TBT exposure as the cause of death of chinook salmon exposed to TBT-treated marine net pens at one aquaculture facility.

Accumulation of butyltins in muscle tissue of chinook salmon reared in sea pens treated with tri-n-butyltin

Muscle tissue of chinook salmon, Oncorhyncus tshawytscha, reared for 3 to 19 months in sea pens treated with an antifouling biocide, tri-n-butyltin (TBT), contained organotin concentrations of 0.28–0.90 μg g −1 (as TBT). Organotins are present in some pen-reared salmon sold in the United States: eleven of 15 salmon advertised as aquaculture products and purchased from public markets contained organotin concentrations of 0.081–0.20 μg g −1. Most common cooking practices do not effectively destroy or remove butyltins from salmon muscle tissue. We believe this is the first evidence of entry of organotins into the human diet in the United States.

α - Benzenesulfonyl free radicals

Allylic α-halosulfones give, on reduction with tri n-butyl tin hydride, sizeable amounts of dimers. It so appears that free radicals can indeed be formed α to an arenesulfonyl group and coupling can occur during tin hydride reduction of halides.

Dependence of Delayed Luminescence upon Adenosine Triphosphatase Activity in Chlorella

Delayed luminescence and fluorescence yield after illumination by a short flash were measured in Chlorella pyrenoidosa in the presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea. Addition of tri-N-butyl-tin (TNBT), a specific inhibitor of ATPase, drastically increases the life-time of the reduced photosystem II primary acceptor Q(-) and decreases the intensity of delayed luminescence. This indicates a slowing of the charge recombination between the oxidized donor and reduced acceptor of photosystem II centers. No inhibition is observed in isolated chloroplasts when the membrane is permeable to ions, i.e. in the presence of Gramicidin D and KCl.It is suggested that there exists in dark-adapted algae a permanent proton gradient which stimulates the charge recombination process. This proton gradient results from the hydrolysis of a pool of ATP by membrane-bound ATPases and collapses after the addition of TNBT. The long lifetime of this proton gradient (several hours) indicates that the ATP probably comes from the mitochondria.The rate of the back reaction occurring from state S(3) (as defined by Kok, Forbush, and McGloin 1970 Photochem Photobiol 11: 457-475) is more dependent upon the pH gradient than for state S(2).

Evidence for Hydrogen Abstraction by Classical Radicals in the Norbornenyl-Nortricyclyl System

Studies of product compositions and deuterium-label rearrangements at various concentrations of tri-n-butyltin hydride in the reductions of exo-and endo-5-bromonorbornene and 2-bromonortricyclcne to mixtures of norbornene and nortricyclene lead to three main conclusions: (i) at least two radical intermediates contribute to product formation; (ii) each intermediate yields predominantly (80% or more) one product; and (iii) nortricyclene is predominantly derived from a symmetrical intermediate. This constitutes strong evidence for hydrogen abstraction by classical (i.e., single-product) norbornenyl and nortricyclyl radicals. It is argued that the norbornenyl-nortricyclyl system is exceptionally well suited for the generation of a nonclassical (dual-product) radical; hence, the existence of a nonclassical radical in any other system is rather unlikely.