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101.
Isolation of cadmium sensitive mutants in Chlamydomonas reinhardtii by transformation/insertional mutagenesis 总被引:1,自引:0,他引:1
Abstract An arg7, cw15, mt+ strain of Chlamydomonas reinhardtii (CC1618) was transformed with pARG7.8, a plasmid containing the wild-type ARG7 gene. Over 2300 arg+ transformants were selected on TAP media. Upon subsequent analysis on TAP plus cadmium plates, five of the transformants failed to grow at a level of 400 μM cadmium and were designated as cadmium sensitive (Cds ) mutants. Hybridization data indicated that vector (pBR329) sequences were present in these five mutants, but not in the untransformed parental strain. Two of the mutants have been back crossed to an arg7, cw15, Cd+ , mt− strain (CC425) and found to have progeny which always cosegregate the arg+ and Cds phenotypesin these two mutants results from the insertion of the plasmid pARG7.8 into a gene involving cadmium detoxification, and it provides a method by which to clone the interrupted gene(s). 相似文献
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One electron micrographs, negatively stained multicatalytic proteinase molecules are viewed end-on (ring shaped) or side-on (rectangular shaped). For aurothioglucose, ammonium molybdate- and phosphotungstate-stained molecules, the dimensions measured are consistent. In contrast, uranyl acetate-staining reveals ring-shaped particles which vary in diameter between 12 and 16 nm. This is due to a partial collapse and substantial flattening of the structure. Digital image analysis of side-on views of the particles reveals a tripartite, reel-shaped structure. Within the ring-like, end-on projections of ammonium molybdate-stained molecules six local centres of mass can be discerned; their position appears to depart, however, from a true six-fold symmetry. 相似文献
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Eric Dexter Stephen M. Bollens Jeffery Cordell Ho Young Soh Gretchen Rollwagen-Bollens Susanne P. Pfeifer Jérôme Goudet Séverine Vuilleumier 《Biological invasions》2018,20(6):1577-1595
The rate of aquatic invasions by planktonic organisms has increased considerably in recent decades. In order to effectively direct funding and resources to control the spread of such invasions, a methodological framework for identifying high-risk transport vectors, as well as ruling out vectors of lesser concern will be necessary. A number of estuarine ecosystems on the North American Pacific Northwest coast have experienced a series of high impact planktonic invasions that have slowly unfolded across the region in recent decades, most notably, that of the planktonic copepod crustacean Pseudodiaptomus inopinus. Although introduction of P. inopinus to the United States almost certainly occurred through the discharge of ballast water from commercial vessels originating in Asia (the species’ native range), the mechanisms and patterns of subsequent spread remain unknown. In order to elucidate the migration events shaping this invasion, we sampled the genomes of copepods from seven invasive and two native populations using restriction-site associated DNA sequencing. This genetic data was evaluated against spatially-explicit genetic simulation models to evaluate competing scenarios of invasion spread. Our results indicate that invasive populations of P. inopinus exhibit a geographically unstructured genetic composition, likely arising from infrequent and large migration events. This pattern of genetic patchiness was unexpected given the linear geographic structure of the sampled populations, and strongly contrasts with the clear invasion corridors observed in many aquatic systems. 相似文献
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Schoepf Verena Cornwall Christopher E. Pfeifer Svenja M. Carrion Steven A. Alessi Cinzia Comeau Steeve McCulloch Malcolm T. 《Coral reefs (Online)》2018,37(4):1169-1180
Coral Reefs - Reef-building corals are surrounded by complex microenvironments (i.e. concentration boundary layers) that partially isolate them from the ambient seawater. Although the presence of... 相似文献
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