# X-RAY DAMAGE & REPAIR OF PRIMATE CELL & DNA SEQUENCES

> **NIH NIH R01** · ALBERT EINSTEIN COLLEGE OF MEDICINE · 1988 · $213,820

## Abstract

Examining x-ray damage and repair of cellular DNA at the base
sequence level required obtaining homogeneous populations of DNA
sequences from the irradiated cells.  We demonstrated the
feasibility of this in studies on highly repetitive component alpha
DNA sequence prepared from irradiated monkey CV-l cells.  The
system is being used to evaluate the time course of repair of alpha
DNA and the influence of caffeine on repair.

We now extend the studies to alpha DNA residing in irradiated
plasmids transfected into host cells.  This approach permits
studies on x-ray damage and repair of homogeneous populations
cloned genes.  Eventually, it should provide a host cell react-
ivation system for detecting and evaluating the activity of
individual DNA repair enzymes and the transfected genes which code
for them.  Plasmids serve as surrogate targets for cellular DNA.
Damage to plasmid sequences are verified before transfection; the
time course of repair is followed, in unirradiated cells, thereby
avoiding interference from radiation damage to cell functions.
With the host cell reactivation scheme, residual DNA strand and
base damage will be scored at the base sequence level in cells of
repair proficient and repair deficient constitution (e.g., AT and
XP).

The topology of plasmids carrying x-ray damaged DNA sequences must
be taken into account, as in our report on expression of genes
coding for chloramphenicol acetyltransferase in cells transfected
with pSV2CAT.  Information on the relationship of plasmid form and
the repair of specific sequences can now be attained.  Together
with data on x-ray inactivation of gene expression, the studies we
propose with circular plasmids provide a model for studying x-ray
effects on DNA in the chromatin, where the DNA is also arranged in
closed loops.

Residual unrepaired damage in sequences transfected into AT cells
are of special interest because certain DNA repair deficiencies in
AT are believed to be present in as many as 5% of all persons dying
of cancer before age 45 years.

## Key facts

- **NIH application ID:** 3174095
- **Project number:** 2R01CA036492-04A2
- **Recipient organization:** ALBERT EINSTEIN COLLEGE OF MEDICINE
- **Principal Investigator:** ROBERT E BASES
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1988
- **Award amount:** $213,820
- **Award type:** 2
- **Project period:** 1984-01-01 → 1991-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/3174095

## Citation

> US National Institutes of Health, RePORTER application 3174095, X-RAY DAMAGE & REPAIR OF PRIMATE CELL & DNA SEQUENCES (2R01CA036492-04A2). Retrieved via MORVS 2026-10-25 from https://api.morvs.ai/grant/nih/3174095. Licensed CC0.

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