Genomic organization and developmental fate of adjacent repeated sequences in a foldback DNA clone of Tetrahymena thermophila

Journal Article · Sun Nov 01 04:00:00 EST 1987 · Genetics; (United States)

OSTI ID:5445709

Tschunko, A H; Loechel, R H; McLaren, N C; Allen, S L

DNA sequence elimination and rearrangement occurs during the development of somatic cell lineages of eukaryotes and was first discovered over a century ago. However, the significance and mechanism of chromatin elimination are not understood. DNA elimination also occurs during the development of the somatic macronucleus from the germinal micronucleus in unicellular ciliated protozoa such as Tetrahymena thermophila. In this study foldback DNA from the micronucleus was used as a probe to isolate ten clones. All of those tested (4/4) contained sequences that were repetitive in the micronucleus and rearranged in the macronucleus. Inverted repeated sequences were present in one clone. This clone, pTtFBl, was subjected to a detailed analysis of its developmental fate. Subregions were subcloned and used as probes against Southern blots of micronuclear and macronuclear DNA. DNA was labeled with (/sup 33/P)-labeled dATP. The authors found that all subregions defined repeated sequence families in the micronuclear genome. A minimum of four different families was defined, two of which are retained in the macronucleus and two of which are completely eliminated. The inverted repeat family is retained with little rearrangement. Two of the families, defined by subregions that do not contain parts of the inverted repeat are totally eliminated during macronuclear development-and contain open reading frames. The significance of retained inverted repeats to the process of elimination is discussed.

• Research Organization: Univ. of Michigan, Ann Arbor
• OSTI ID: 5445709
• Journal Information: Genetics; (United States), Journal Name: Genetics; (United States) Vol. 117:3; ISSN GENTA
• Country of Publication: United States
• Language: English

Related Subjects

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550601 -- Medicine-- Unsealed Radionuclides in Diagnostics
59 BASIC BIOLOGICAL SCIENCES
62 RADIOLOGY AND NUCLEAR MEDICINE
ANIMALS
ATP
AUTORADIOGRAPHY
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CELL DIFFERENTIATION
CHROMATIN
CILIATA
CLONING
DAYS LIVING RADIOISOTOPES
DNA
DNA SEQUENCING
DNA-CLONING
ELECTRON MICROSCOPY
INVERTEBRATES
ISOTOPES
LIGHT NUCLEI
MICROORGANISMS
MICROSCOPY
NUCLEI
NUCLEIC ACIDS
NUCLEOTIDES
ODD-ODD NUCLEI
ONTOGENESIS
ORGANIC COMPOUNDS
PHOSPHORUS 32
PHOSPHORUS ISOTOPES
PROTOZOA
RADIOISOTOPES
STRUCTURAL CHEMICAL ANALYSIS
TETRAHYMENA