Incubation experiments

A number of negative reports have also arisen from incubation experiments. It has been pointed out that methylation of MesPb 1 species to Me4Pb may arise through a sulphide-mediated disproportionation68-70. MesPbOAc has been incubated with both sterilized and unsterilized lake sediments and in all cases similar amounts of Me4Pb were evolved, i.e. disproportionation without biomethylation can account for the results71. Use of labelled carbon and lead in a series of attempted biomethylation in cultures produced no evidence of biomethylation but did confirm that sulphide-promoted disproportionation is possible72. 

A blank and also a sterile solution containing Pb2+ of methyllead compounds showed no Pb content in the methanolic solution after the same treatment. The author concluded that Me4Pb was produced in the biomethylation of Pb2+ by bacteria123. Thompson and Crerar122 also observed that about 0.03% of lead as Pb(NC>3)2 underwent methylation and trimethyllead acetate, (CH3)3PbOAc, was methylated nearly quantitatively in incubation experiments with marine sediments from the British Columbia coastline. 

Incubation experiment with soil from arable field in Denmark, peas and mycorrhizal inocula at 10°C or 15°C... 

Few, if any, studies appear to demonstrate the persistence of short-chain fatty acids in archaeological residues, either esterilied to glycerol or in the free state (see, however, Mirabaud et al., 2007). Short-term laboratory incubation experiments provide empirical data demonstrating the speed at which hydrolysis takes place (Dudd and Evershed, 1998 Dudd et al., 1998). Once released from the glycerol backbone, these fatty acids are both more soluble and thus... 

Aliphatic ethers with branched side chains such as MTBE (methyl t-butyl ether), especially, deactivate enzymes only to a very small degree in incubation experiments for example, the BAL mentioned above has a half-life h/2 of up to 500 h in aqueous-organic two-phase systems (see Fig. 3.1.6) [21]. This may not hold true for a special enzyme/solvent combination under process conditions. When incubated at higher temperatures or even in the presence of the substrate benzaldehyde the deactivation of the enzyme is much higher (see Table 3.1.2)... 

Zeddel, A., Majcherczyk, A. Huttermann, A. (1994). Degradation and mineralization of polychlorinated biphenyls by white-rot fungi in solid-phase and soil incubation experiments. In Bioremed tation of Chlorinated and Polycyclic Aromatic Hydrocarbon Compounds, ed. R. E. Hinchee, A. Leeson, L. Semprini S. K. Ong, pp. 436-40. New York Lewis Publishers. 

One may hypothesize that the mobilization and accumulation of Mn we observed during stratification was linked to the degradation of organic matter. The degradation rate reaches a maximum in the bathylimnion during summer, as indicated by the sharp increase in conductivity. This process facilitates the release of Mn under suboxic, rather than anoxic, conditions, and is consistent with the incubation experiments reported here. 

Microbial transformations of DOM were also studied by incubation experiments. The DOM extracted from maize straw and forest floors was incubated for 90 days and samples taken before and after incubation were analyzed by Py-FIMS and complementary UV absorbance, fluorescence emission spectroscopy, FTIR-spectroscopy, 1H NMR spectroscopy, and 13C natural abundance (Kalbitz et al., 2003). The Py-FI mass spectra showed increases in the proportions of phenols and lignin monomers at the expense of lignin dimers and alkylaromatics during... 

Barriuso, E., W. Koskinen, and B. Sorenson (1992c). Modification of atrazine desorption during field incubation experiments. Sci. Total Environ., 123/124 333-344. 

The stereochemistry of the reaction catalyzed by the lysine 2,3-aminomutase in C. subterminah SB4 was elucidated in detail by Aberhardt and Gould [32]. Incubation experiments with cell-free extracts of C. subterminah SB4 and (2RS)-[3-13C,2-lsN]lysine and NMR spectroscopy of the isolated /Mysine as the di-N-phthaloyl ethyl ester derivative revealed that the amino group migrates in an intramolecular reaction to position 3S in /Mysine 25. 

The stereochemistry of 43 was established to be S by comparing the optical rotation of an authentic sample derived from (R)-//-tyrosine hydrochloride with //-tyrosine hydrochloride isolated from edeine A and B [62], Incubation experiments with [lsN]tyrosine revealed that the [15N]amino group in //-tyrosine is lost, suggesting a reaction mechanism similar to that of an ammonia lyase [62]. This finding is supported by further incubation experiments with (2RS,3R)-[3-3H]tyrosine and (2RS,3S)-[ 3-3H tyrosine in combination with (2RS)-[3-14C]tyrosine. Determination of the 3H/14C ratios of the isolated //-tyrosine 43 leads to the conclusion that the pro-3 S hydrogen is lost in the course of the reaction whereas the pro-3R hydrogen is retained (Scheme 1.6.14). A similar incubation experiment with (2S)-[2-3H]tyrosine proceeds with a loss of most of the tritium label from C2. 

Gymnodinium sp. - globosa single cells incubation experiments Tang et al. (2001)... 

Noctiluca scintillans (Macartney) Kofoid Swezy cf. globosa single cells and colonies incubation experiments and microscopy Hansen (1992, 1995), Jakobsen and Tang (2002), Weisse et al. (1994)... 

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