Biomedical subjects

T Karpova

Publications and source records attributed to T Karpova.

3 recordsLinked to original sources

PubMed1999

Histidine-tagged wild-type yeast actin: its properties and use in an approach for obtaining yeast actin mutants.

Wild-type and an N-terminal 6-histidine-tagged actin have each been expressed by using a yeast strain that contains the actin gene on a plasmid and not on the chromosome. Yeast strains have also been constructed that use two plasmids, one expressing the wild-type protein and the other the 6-histidine-tagged protein. Yeast cells can be grown with either plasmid alone or with both plasmids together and appear to be normal in that the growth rates of all the yeast strains are quite similar, as is the morphology of the yeast cells. The polymerization properties of the 6-histidine-tagged actin appear almost identical to wild-type actin expressed from the chromosome. When the wild-type and 6-histidine-tagged actin are coexpressed, they can be purified by standard techniques and then separated using nickel-nitrilotriacetate chromatography. The method can be used to prepare actin mutants including those that are nonfunctional or might not support yeast growth for other reasons.

Actins↗

PubMed1999

Three-dimensional imaging by deconvolution microscopy.

Deconvolution is a computational method used to reduce out-of-focus fluorescence in three-dimensional (3D) microscope images. It can be applied in principle to any type of microscope image but has most often been used to improve images from conventional fluorescence microscopes. Compared to other forms of 3D light microscopy, like confocal microscopy, the advantage of deconvolution microscopy is that it can be accomplished at very low light levels, thus enabling multiple focal-plane imaging of light-sensitive living specimens over long time periods. Here we discuss the principles of deconvolution microscopy, describe different computational approaches for deconvolution, and discuss interpretation of deconvolved images with a particular emphasis on what artifacts may arise.

Artifacts↗

PubMed1984

Stability of recombinant plasmids containing the ars sequence of yeast extrachromosomal rDNA in several strains of Saccharomyces cerevisiae.

The mitotic stabilities of hybrid plasmid Rcp21/11, which contains the replicator of yeast rDNA, have been compared for four yeast host strains of different origins. In two related strains, Saccharomyces cerevisiae. A62-1G-P188 and 1A-P3812 from the Peterhof genetic stocks, the plasmid was much more stable than in strains DC5 and GRF18 from the USA stocks. The enhanced mitotic stability of Rcp21/11 in these two yeast strains is obviously attributable to a higher rate of integration of the plasmid into the chromosomal rDNA repeats of the hosts. The centromeric locus CEN3 was inserted into Rcp21/11 because it provides high mitotic and meiotic stability of plasmids with yeast replicators, due to an ordered distribution of plasmids throughout cell division. Using the new centromeric plasmid RcpCEN3, transformation of the four above-described yeast strains was carried out. It was found that, similarly to centromeric plasmids with other chromosomal replicators, RcpCEN3 remains in the cell as a single copy. In strains DC5, GRF18 and A62-1G-P188 the mitotic stability of RcpCEN3 was 20-50%, i.e., less than half that of plasmids containing locus CEN3 and other yeast replicators, ars1, ars2 and the 2mu DNA replicator. The mitotic stability of RcpCEN3 in strains 1A-P3812 (from the Peterhof genetic stocks) for individual clones reached 85%, i.e. close to that of the other plasmids. Genetic analysis showed that the capacity of strain 1A-P3812 to stably retain RcpCEN3 has a recessive polygenic character. We suggest that the observed differences in mitotic stability of centromeric plasmid RcpCEN3 between various yeast strains reflects the differences in activity of rDNA replicator in these strains.(ABSTRACT TRUNCATED AT 250 WORDS)

Base Sequence↗