Radioautographic visualization of differences in the pattern of (/sup 3/H)uridine and (/sup 3/H)orotic acid incorporation into the RNA of migrating columnar cells in the rat small intestine
The epithelium of rat small intestine was radioautographed to examine whether RNA is synthesized by the salvage pathway as shown after (/sup 3/H)uridine injection or by the de novo pathway as shown after (/sup 3/H)orotic acid injection. The two modes of RNA synthesis were thus investigated during the migration of columnar cells from crypt base to villus top, and the rate of synthesis was assessed by counting silver grains over the nucleolus and nucleoplasm at six levels along the duodenal epithelium - that is, in the base, mid, and top regions of the crypts and in the base, mid, and top regions of the villi. Concomitant biochemical analyses established that, after injection of either (5-/sup 3/H)uridine or (5-/sup 3/H)orotic acid: (a) buffered glutaraldehyde fixative was as effective as perchloric acid or trichloroacetic acid in insolubilizing the nucleic acids of rat small intestine; (b) a major fraction of the nucleic acid label was in RNA, that is, 91% after (/sup 3/H)uridine and 72% after (/sup 3/H)orotic acid, with the rest in DNA; and (c) a substantial fraction of the RNA label was in poly A/sup +/ RNA (presumed to be messenger RNA). In radioautographs of duodenum prepared after (/sup 3/H)uridine injection, the count of silver grains was high over nucleolus and nucleoplasm in crypt base cells and gradually decreased at the upper levels up to the villus base. In the rest of the villus, the grain count over the nucleolus was negligible, while over the nucleoplasm it was low but significant.
- Research Organization:
- McGill Univ., Montreal, Quebec
- OSTI ID:
- 5822725
- Journal Information:
- J. Cell Biol.; (United States), Vol. 98:5
- Country of Publication:
- United States
- Language:
- English
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RNA
BIOSYNTHESIS
SMALL INTESTINE
AUTORADIOGRAPHY
BIOCHEMISTRY
CELL CONSTITUENTS
CHEMICAL ANALYSIS
DNA
EPITHELIUM
OROTIC ACID
RATS
SILVER
TRACER TECHNIQUES
TRITIUM COMPOUNDS
URIDINE
ANIMAL TISSUES
ANIMALS
AZINES
BODY
CARBOXYLIC ACIDS
CHEMISTRY
DIGESTIVE SYSTEM
ELEMENTS
GASTROINTESTINAL TRACT
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
HYDROXY COMPOUNDS
INTESTINES
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
MAMMALS
METALS
NUCLEIC ACIDS
NUCLEOSIDES
NUCLEOTIDES
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANS
PYRIMIDINES
RIBOSIDES
RODENTS
SYNTHESIS
TISSUES
TRANSITION ELEMENTS
URACILS
VERTEBRATES
550201* - Biochemistry- Tracer Techniques