Mutable loci and development of the organism

Brink, R. A.

doi:10.1002/jcp.1030520410

Cited by 12 publications

(8 citation statements)

References 28 publications

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“…Evidence in maize and in drosophila is consistent with this mechanism of generating variegated tissues by intrastrand crossing-over in somatic cells (23)(24)(25). For example, in maize the pr gene causes a red coloration of the pericarp.…”

Section: Looping-out Excision Theory Of Gene Selectionmentioning

confidence: 81%

“…It appears that Mp is unstable in somatic cells and that its loss from the chromosome permits pr gene expression. Furthermore, a variety of data in maize and in other plants supports the concept that directed gene loss occurs at complex or "paramutable" loci in somatic cells (23). Numerous other apparently analogous somatic variegations are known in higher organisms (24).…”

Section: Looping-out Excision Theory Of Gene Selectionmentioning

confidence: 91%

“…For example, in maize the pr gene causes a red coloration of the pericarp. When pr is linked to a transposable or episome-like controller gene, Mp, a variegated irregular red striping occurs (23). It appears that Mp is unstable in somatic cells and that its loss from the chromosome permits pr gene expression.…”

Section: Looping-out Excision Theory Of Gene Selectionmentioning

confidence: 99%

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Gene Selection in Hemoglobin and in Antibody-Synthesizing Cells

Kabat

1972

Science

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Close linkage of mutually exclusive genes occurs in the non-alpha chain hemoglobin genes and in the immunoglobulin genes of man and other mammals. The expression of one gene in the cluster precludes the expression of any other linked gene. A simple, testable theory of gene selection called "looping-out excision"which was designed only to explain this mutual exclusivity in the hemoglobin system is described. The theory is closely concordant with a wide range of previously unexplained findings concerning hematopoiesis- including the developmental changes of hemoglobins, the increases in immature or fetal forms of hemoglobin that accompany anemia, and with the distribution of adult and fetal hemoglobins among erythrocytes during normal embryogenesis and in various pathological conditions. One corollary of this theory is that erythroid tissue in the normal adult bone marrow is constantly recapitulating the developmental stages of its embryogenesis. Another corollary is that the selection from among the linked globin genes occurs independently on the two chromosomes of the diploid organism. Both of these corollaries are supported by the available data. The same theory of gene selection is also remarkably consistent with known data for immunoglobulin synthesis; it could explain not only the mutually exclusive activation of linked variable genes but also the splicing which occurs between genetically linked variable and constant region genes for the immunoglobulin polypeptide chains. The agreement between these two different tissues is considered to be strong evidence that the proposed mechanism is correct at least in broad outline. Evidence from the genetics of maize and of drosophila also supports this theory of somatic tissue variegation. On the basis of these comparisons, I suggest that looping-out excision probably occurs also in other tissues and may be one means of gene selection and activation in differentiating cells.

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Section: Looping-out Excision Theory Of Gene Selectionmentioning

confidence: 81%

Section: Looping-out Excision Theory Of Gene Selectionmentioning

confidence: 91%

Section: Looping-out Excision Theory Of Gene Selectionmentioning

confidence: 99%

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Gene Selection in Hemoglobin and in Antibody-Synthesizing Cells

Kabat

1972

Science

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“…These are called controlling elements because they tend to suppress gene action at the loci where they reside (McClintock, 1956). A mutable allele, such as the variegated pericarp allele at the P locus, is considered to be a combination of an ordinary gene and one of these accessory elements (Brink, 1958). Change from variegated to red is explained by the removal of the element from the locus either by a process called transposition or by loss of the element from the genome.…”

Section: Episomic Alternation and Local Change Of Statementioning

confidence: 99%

Attachment of wild-typeFfactor to a specific chromosomal region in a variant strain ofEscherichia coliK12: the phenomenon of episomic alternation

Richter

1961

Genet. Res.

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A variant strain ofEscherichia coliK12 (♂3) was obtained after ultra-violet irradiation. This strain differs from wild type in the possession of a preferred chromosomal site for theFfactor.When wild-type females are infected with theFfactor they are converted toF+ males which carry theFfactor in the infectious state. TheseF+ males (standard) change with low frequency toHfrmales which carry theFfactor on the chromosome. When the variant female (♀3) is infected with theFfactor it is converted to anF+ male (state II) which changes with high frequency to a specificHfrmale (state I) which carries theFfactor at the preferred site (Hfr3).Male strains carrying the preferred site alternate between the specificHfrstate and theF+ state. The mechanism of this alternation is the back-and-forth shift of theFfactor between its integrated state of multiplication at theHfr3locus and its autonomous state of multiplication. This process is termedepisomic alternation.Episomic alternation offers a physical model for regular changes in state of the gene.TheHfr3locus has two allelic forms, high rate of change and standard rate of change. The allele for high rate of change may be considered as a genetic system which occurs in two possible states, state I in which theFfactor is present atHfr3, and state II in which it is not.

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“…There continues to be keen interest in mechanisms of recombination in phages (12~, 124); in integration of DNA during bacterial conjugation (13), transformation (125,126), and transduction (66); in crossing over, so-called conversion, and other phenomena that occur during meiosis (127 to 133); and in McCllntock-type controllers (134).…”

Section: Other Areas Of Geneticsmentioning

confidence: 99%

Physiological Aspects of Genetics

Beadle¹

1960

Annu. Rev. Physiol.

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Mutable loci and development of the organism

Cited by 12 publications

References 28 publications

Gene Selection in Hemoglobin and in Antibody-Synthesizing Cells

Gene Selection in Hemoglobin and in Antibody-Synthesizing Cells

Attachment of wild-typeFfactor to a specific chromosomal region in a variant strain ofEscherichia coliK12: the phenomenon of episomic alternation

Physiological Aspects of Genetics

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