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K Kucharczyk

Publications and source records attributed to K Kucharczyk.

15 recordsLinked to original sources
PubMed2001

Multitemperature single-strand conformation polymorphism.

Changes of gel temperature during single-strand conformation polymorphism (SSCP) electrophoresis increase the sensitivity of mutation detection in polymerase chain reaction (PCR) products and significantly reduce the overall time and costs of analysis. Based on these findings, a new method for single nucleotide polymorphism (SNP) and point mutation detection--multitemperature single-strand conformation polymorphism (MSSCP) was devised. In order to control the gel temperature with 0.1 degrees C accuracy during electrophoresis, new equipment was developed. We demonstrated that increasing the gel temperature by 8 degrees C or decreasing it by 10 degrees C from 23 degrees C led to the disappearance of all electrophoretic differences between five alleles of exon 8 of the human p53 gene during the SSCP analysis. The interesting result was the detection of two additional SNPs (out of seven analyzed) in exon 7 of the human PAH gene during a one hour MSSCP electrophoresis. This result is better than that obtained by three classical SSCP analyses of the same samples at different but constant gel temperatures. We advocate the MSSCP technology as a fast, reliable, and cost-effective tool for the screening and preselection stage of genomics surveys, especially when a high variability of the analyzed DNA fragment is expected.

Acrylic Resins↗
PubMed1991

Response of Escherichia coli cell membranes to induction of lambda cl857 prophage by heat shock.

Heat shock induces protein aggregation in Escherichia coli and E. coli (lambda cl857). The aggregates (S fraction) appear 15 min post-induction and are separable from membranes by sucrose density-gradient centrifugation. The S fraction quickly disappears in wild type strains but persists in rpoH mutant with concomitant quick inner membrane destruction. We propose that: (1) the disappearance of the S fraction reflects a rpoH-dependent processing, (2) the membrane destruction explains the lethality of the rpoH mutation at elevated temperatures; and (3) the protection of the inner membrane integrity is an important physiological function of the heat-shock response. We assume that the S fraction of aggregated proteins represents the signal inducing the heat-shock response. The prophage thermo-induction results in an increase (35 min post-induction) in the A fraction resembling that of the adhesion zones of the membranes. This fraction is greater than the corresponding fraction from uninduced cells. The increase is mediated by the lambda late genes, since it is absent in the induced E. coli (lambda cl857 Qam21). Since heat shock is widely used for induction of the lambda promoters in expression vectors it is possible that the formation of the protein aggregates (though transient in WT strains) and/or the fragility of membranes in rpoH mutants may be the cause of poor expression of cloned genes or may lead to mistaken localization of their expression products.

Bacterial Outer Membrane Proteins↗
PubMed1977

The cell cycle in the small intestine transplanted beneath the kidney capsule in syngenic mice.

Transplantation of a small fragment of the ileum beneath the kidney capsule in syngenic mice results in the formation of a cyst lined with proliferating intestinal epithelium. The duration of the cell cycle in the epithelium was determined (using tritiated thymidine and the FLM method) as 14.5 h, as compared with 11.5 h in the intestinal epithelium in situ. We conclude that the intestinal content has little effect on the cell cycle of epithelial cells of the small intestine.

Animals↗
PubMed1977

Lamina propria macrophages of intestine of the guinea pig. Possible role in phagocytosis of migrating cells.

The macrophages of lamina propria were commonly found both in the small and the large intestine of guinea pigs, mice, rats, and in human duodenum. The frequency of macrophage occurrence was highest in the lamina propria of villous apices of the small intestine and beneath the lining epithelium of the large intestine. In the cytoplasm of lamina propria macrophages localized in those regions, Feulgen-positive (DNA-containing) granules could be observed particularly in the guinea pig intestine. Autoradiography of the latter, 3 to 5 days after [3H]thymidine injection, showed the coincidence of occurrence of labeled Feulgen-positive granules in the macrophage cytoplasm with the appearance of labeled epithelial cells and sheath-fibroblasts in the region of lamina propria containing the highest accumulation of macrophages, i.e., at the apices of villi of the small intestine and beneath the lining epithelium of the large intestine. Labeled nuclei of macrophages were observed scarcely and much less frequently than were labeled cytoplasmic granules. No labeled Feulgen-positive granules could be seen in macrophages 1/2 hr, 1, 2, and 7 days after [3H]thymidine injection. It is suggested that the lamina propria macrophages may play a role in the phagocytosis of some migrating cells of the intestinal mucosa, most probably of the sheath-fibroblasts and/or intraepithelial lymphocytes.

Animals↗