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131.
The present study reports the isolation and characterization of a cadmium-containing glycoprotein from the water-soluble fraction of an aquatic insect. The isolated glycoprotein contained 0·67% cadmium, 62·1% carbohydrate, and 37·2% protein. The glycoprotein appears to be involved in the detoxification of cadmium, because species insensitive to cadmium contain five times the amount of the glycoprotein as do species sensitive to cadmium. 相似文献
132.
Richard D. Maca Adrianne Hakes 《Biochemical and biophysical research communications》1977,74(4):1660-1666
A new approach was used to evaluate the role of surface sialyl transferase activity in the regeneration of surface sialic acid (SSA) on cultured lymphoma cells (Raji). Cells which were made deficient in SSA by neuraminidase treatment were incubated for 18 hours in medium containing CMP, a potent inhibitor of surface sialyl transferase activity. In these cultures, the amount of regenerated SSA was not significantly less than for the controls, even though the surface sialyl transferase activity on these cells was inhibited by an average of 95%. Conversely, emetine, an inhibitor of protein synthesis, effectively inhibited SSA regeneration. Thus, these results support the concept that surface sialo-proteins are largely, if not entirely, synthesized intracellularly instead of being assembled on the cell surface by the surface located transferase system. 相似文献
133.
Beate Nürnberger Richard G. Harrison 《Evolution; international journal of organic evolution》1995,49(2):266-275
The spatial population structure of the pond-living water beetle Dineutus assimilis (Coleoptera: Gyrinidae) was investigated through a field study of population dynamics and dispersal, with a concurrent assessment of the spatial distribution of mitochondrial DNA (mtDNA) restriction-fragment-length polymorphism (RFLP). A comprehensive 2-yr survey within a 60-km2 study area revealed pronounced fluctuations in local abundances, including extinctions and colonizations. The recapture of marked individuals showed that dispersal among ponds is frequent in both males and females and connects populations on a large geographic scale (maximum observed flight distance: 20 km). The population structure of D. assimilis is thus characterized by both pronounced genetic drift and frequent gene flow. Together, these two forces generate a pattern of very local and transient genetic differentiation. Mitochondrial DNA samples collected within a few kilometers indicate highly significant spatial structure, if newly founded demes or those that experienced recent bottlenecks are included. These results based on four demes within the study area were placed into a regional context by further samples collected at distances of 100 km and 200 km. Fst estimates computed on increasing spatial scales were variable but showed no increasing trend. Thus, gene flow exerts a strong homogenizing force over a wide geographic range but is counteracted locally by genetic drift. These findings highlight the need to supplement estimates of Fst with additional data to arrive at valid interpretations of the genetic information. More generally, this study raises questions about how to capture the relevant features of dynamic, subdivided populations to understand their evolutionary dynamics. 相似文献
134.
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137.
James E. Fleming Paula S. Melnikoff Klaus G. Bensch 《Biochimica et Biophysica Acta (BBA)/General Subjects》1984,802(2):340-345
Several hundred proteins have been resolved on two-dimensional gels of extracts of [35S]methionine-labeled adult Drosophila melanogaster. 27 of these polypeptides disappear from the gel pattern after feeding the K+ ionophore nonactin. These proteins have been identified as mitochondrial, since the two-dimensional gel pattern of extracts of isolated mitochondria correlates well with the pattern of the proteins missing from that of nonactin-treated flies. Nine new proteins also appear on the two-dimensional gels of the extracts from the nonactin-treated flies. Apparently, these nine proteins are precursors of the mature mitochondrial forms. These particular data support the concept that processing of many of the cytoplasmically synthesized mitochondrial proteins requires a specific membrane potential, and that some of these proteins are modified intramitochondrially. However, using [35S]methionine incorporation techniques, not all labeled polypeptides disappear from mitochondria during such treatment. Feeding similarly radiolabeled flies with chloramphenicol, an inhibitor of mitochondrial protein synthesis, results in the disappearance of only one protein from the gel pattern with the concurrent appearance of a ‘new’ high-molecular-weight polypeptide. Collectively, these data show that a specific group of [35S]methionine-labeled mitochondrial proteins can be identified by selective inhibition of mitochondrial function in whole cell protein maps of adult D. melanogaster. 相似文献
138.
139.
James Appleyard 《BMJ (Clinical research ed.)》1982,285(6351):1352-1353
140.
Richard v. König-Warthause 《Journal of Ornithology》1854,2(3):249-253
Ohne ZusammenfassungVergl. Naumannia. 1852, II, S. 40, und 1853, II, S. 154. 相似文献