. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. CO2 ASSIMILATION IN HYDROTHERMAL VENT SYMBIONTS 113 DNA DNA was extracted from homogenized gill tissue ( g wet wt) and from the "purified" bacterial fraction ( g wet wt). It was deproteinized, purified by repeated washings after binding to hydroxylapatite, and dialyzed. These procedures, as well as methods for estimating base composition, genome size, and relative proportion of more rapidly renaturing DNA, were as described previously (Nelson et ai, 1984). RESULTS Electron donor Figure 1 represents the data
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. CO2 ASSIMILATION IN HYDROTHERMAL VENT SYMBIONTS 113 DNA DNA was extracted from homogenized gill tissue ( g wet wt) and from the "purified" bacterial fraction ( g wet wt). It was deproteinized, purified by repeated washings after binding to hydroxylapatite, and dialyzed. These procedures, as well as methods for estimating base composition, genome size, and relative proportion of more rapidly renaturing DNA, were as described previously (Nelson et ai, 1984). RESULTS Electron donor Figure 1 represents the data of experiments testing the capacity of two sulfur com- pounds, Na2S and Na2S2O3, to support CO2 incorporation in mussel gill and in worm trophosome homogenates. It appears that the Bathymodiolus gill tissue can utilize thiosulfate but not sulfide while the pattern is reversed in the Riftia trophosome tissue. In both cases poisoned samples ( glutaraldehyde) and homogenized host tissues (mussel mantle or worm vestimentum) showed CO2 incorporation which did not increase beyond the "zero time" level. For Bathymodiolus (data not shown) these values were less than nmol CO2 mg"1 protein in assay mixtures supplemented with400MA/Na2S2O3. While the enhancing effects of thiosulfate and sulfide were reproducible, a certain degree of variability was observed in both cases in the activity of the unsupplemented preparations. This correlated with the length of the preincubation period which pre- ceded the introduction of the radioactive substrate. The results in Figure 1 were obtained after approximately 15 min of preincubation. When this period was increased to 75 min, no activity was detected in the mussel preparations without thiosulfate. In addition to electron donor specificity, other differences between the two active preparations were in the reaction's duration and linearity. Whereas the activity of mussel gill tissue was linear for 2 to 3 h or more, that of the R
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
