J.M Espinosa Lara

Instituto Politécnico Nacional

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Frank Traganos

Memorial Sloan Kettering Cancer Center

Zbigniew Darżynkiewicz

New York Medical College

P Loyola Abitia

Instituto Politécnico Nacional

Andrzej Myc

Ludwik Hirszfeld Institute of Immunology and Experimental Therapy

Jaime Hernández

University of California, Santa Cruz

Sarai Luna

Medical College of Wisconsin

Myron R. Melamed

Westchester Medical Center

R. Escamilla

Universidad Nacional Autónoma de México

J.D Quintana Hau

Universidad de Guadalajara

Rayner Rodrı́guez

University of Miami

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Instituto Politécnico Nacional

New York Medical College

Cancer Research Institute

Catalyst Foundation

Memorial Sloan Kettering Cancer Center

Westchester Medical Center

John Wiley & Sons (United States)

Universidad de Guadalajara

University of Surrey

Prostate Cancer Research

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DNA stainability in aneuploid breast tumors: Comparison of four DNA fluorochromes differing in binding properties

Cytometry (1992)

Andrzej Myc Frank Traganos J.M Espinosa Lara Myron R. Melamed Zbigniew Darżynkiewicz

The aim of this study was to evaluate whether or not the differences in chromatin structure between diploid stromal cells or lymphocytes, which are often used as DNA ploidy standard, and aneuploid breast tumor cells can significantly affect the estimates of the DNA index of these tumors. To this end, the DNA content estimates of 34 aneuploid breast tumors, differing in size, degree of differentiation, and presence or absence of estrogen and progesterone receptors and metastases, were compared using four common DNA fluorochromes: DAPI, Hoechst 33342, propidium iodide, and acridine orange. These dyes differ in their mode of interaction with DNA (binding to minor groove or intercalation) and for each of them binding to DNA is restricted to a different degree by nuclear proteins. It was expected, therefore, that if differences in chromatin structure play a role in DNA content estimates, the DNA index of the measured tumors may vary depending on the dye. The cell nuclei were isolated from the tumors using a detergent-based procedure and stained with each of the dyes and the DNA index was estimated using peripheral blood lymphocytes as a DNA content standard. For each of the tumors, the DNA index estimates with all four dyes correlated very well. When the results obtained with individual dyes were compared in pairs, the correlation coefficients (r) of DNA indices were all above 0.96 (correlation at p less than 0.001). The best concordance was seen between specimens stained with Hoechst 33342 and DAPI (r = 0.99), and the least between those stained with Hoechst 33342 and propidium iodide (r = 0.96). The data indicate that DNA content analysis of unfixed nuclei, utilizing the above fluorochromes, is not significantly biased by differences in chromatin structure of the measured cells.

Acridine orange

DAPI

Propidium iodide

Nuclear DNA

10.1002/cyto.990130409

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Rat DNA polymerase beta substitutes the repairing activity of DNA polymerase I in the lethal effect of UV light.

PubMed (2006)

R. Escamilla J.M Espinosa Lara J.D Quintana Hau Sarai Luna P Loyola Abitia

The aim of this work was to search if the rat DNA polymerase beta can substitute the capability of DNA polymerase I to repair damage caused by the UV light in Escherichia coli. The oriC origin of replication from p beta 5 was replaced by the rep origin from pSC101 and named p beta 6. The presence of pol beta in the new construct was verified by PCR. E. coli polA-1 (WP6) was transformed with p beta 6. A protein with size similar to DNA Pol beta (40 kDa) was shown in the cell free extracts carrying pbeta5. In WP6/p beta 6 cell free extracts a slightly smaller protein was observed instead of the 40 kDa. DNA Pol beta was revealed by western analysis, with polyclonal antibodies, in strains with p beta 5. Yet, it was not detected in the western from WP6/p beta 6. A moderate change in UV resistance was observed in strains carrying p beta 5. However, in polAl carrying p beta 6 (WP6/p beta 6), irradiated with 60-90 J/m2 of UV light, the viability was increased by more than four orders of magnitude, when compared with the polA1 (WP6) strain, reaching approximately the same UV resistance as the strains with DNA polymerase I. The results suggests that probably Pol beta is rapidly degraded in the cell free extracts from WP6/p beta 6 and, it repairs the lethal effect of the UV light in E. coli.

DNA polymerase beta

BETA (programming language)

DNA polymerase I

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