Abstract
Nucleic acid hybridization has been used in an attempt to determine the fraction of spleen DNA which is homologous to immunoglobulin messenger RNA (mRNA). Microsomes prepared from the mouse myeloma MOPC 104E and from spleens of mice hyperimmunized with Salmonella typhi were used as a source of RNA rich in immunoglobulin mRNA. It was shown that RNA extracted from microsomes contained a very limited number of RNA species and was essentially uncontaminated by other cytoplasmic and nuclear RNAs. Hyperimmune spleen DNA was hybridized with radiolabeled RNA from spleen and myeloma microsomes in the presence of unlabeled liver RNA. It was assumed that liver RNA should compete for the binding of most or all microsomal RNA species other than immunoglobulin mRNA. The amount of presumptive immunoglobulin mRNA bound indicated that spleen cells contain about 6 to 14 × 103 sequences per haploid genome for immunoglobulins of the size of the variable region of immunoglobulin polypeptide chains. The data favor germ line rather than somatic theories of the genetic basis of antibody variability.
Footnotes
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↵1 This work was supported in part by Institutional Cancer Research Grant IN-26 from the American Cancer Society, and in part by Graduate Research Training Grant CA 05040 from the National Cancer Institute, National Institutes of Health, United States Public Health Service.
- Received August 26, 1971.
- Copyright © 1972 by The American Association of Immunologists, Inc.
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