SINGLE-LOCUS MODIFICATION OF POSITION-EFFECT VARIEGATION IN <i>DROSOPHILA MELANOGASTER</i>. I. WHITE VARIEGATION

Spofford, Janice B.

doi:10.1093/genetics/57.4.751

Cited by 46 publications

(14 citation statements)

References 5 publications

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“…The regression lines have nearly identical slope, but expression in males is consistently higher than in females at any one development time. We attribute this difference to the presence of the largely heterochromatic Y chromosome, in accordance with the interpretations of Gowen & Gay (1934) and of Spofford (1976). The effects of supernumerary heterochromatic elements also must be independent of their effects on development time, since their presence relieves variegation without accelerating development.…”

Section: Discussionsupporting

confidence: 83%

“…This results in a heritable somatic inactivation of the gene in cell clones within a tissue, visible as mosaic expression. The phenomenon has been most extensively documented in Drosophila melanogaster (Baker, 1968;Spofford, 1976). There is a cis-trans relationship between the variegating gene and the breakpoint in the chromosomal rearrangement at which the euchromatin and heterochromatin are joined; m-dominance is the basis for proofs of the position effect nature of variegation (Spofford, 1976), and, in fact, the variegating allele can be rescued in a normal sequence chromosome by recombination between the locus and the breakpoint (Demerec & Slizynska, 1973;Judd, 1955).…”

Section: Introductionmentioning

confidence: 99%

“…Extra heterochromatin, elsewhere in the genome, also affects the expression of the variegating gene; the presence of a Y chromosome, or other heterochromatic elements, suppresses variegation, while deletion of these elements enchances it (Gowen & Gay, 1934). Thus, XXY females and XYY males are almost fully revertant to wild type, while XO males show more extreme variegation than XY males (Spofford, 1976). Deletion of histone genes has also been reported to suppress variegation (Moore et al 1979;Moore et al 1983;Sinclair et al 1983).…”

Section: Introductionmentioning

confidence: 99%

“…In the few cases studied, position-effect variegation exhibits a polarized spreading of inactivation, such that the loci further from the breakpoint are inactivated less frequently than those closer to it (Spofford, 1976). Inactivation of genes may be accompanied by heterochromatinization of the normally euchromatic segment on which they are located; this may be cytologically visible in the polytene chromosomes of the salivary glands, extending up to 65-80 bands from the break point (Hartman-Goldstein, 1967;Spofford, 1976).…”

Section: Introductionmentioning

confidence: 99%

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A correlation between development time and variegated position effect inDrosophila melanogaster

Michailidis¹,

Murray²,

Graves³

1988

Genet. Res.

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SummaryPosition-effect variegation is a phenomenon in which cell-autonomous genes, normally expressed in all cells of a tissue, are expressed in some cells but not in others, leading to a mosaic tissue. Variegation occurs when a normally euchromatic gene is re-positioned close to heterochromatin by chromosome rearrangement. The extent of variegation is known to be influenced by a number of environmental and genetic factors. In the courss of investigations of the influence of the pH of larval medium on the extent of eye-colour variegation in In(1)ωm4 Drosophila melanogaster, we have found that the extent of variegation depends on development time. Flies reared at pH 2·6 develop slowly and show more extreme variegation than those reared at higher pH. This effect, as well as variations within the pH treatments, can be accounted for by differences in development time. The observed regression relationship between variegation and development time also appears to accommodate the influences of temperature on both variables. We suggest that development time may account causally for the reported influences of a number of environmental agents (temperature, crowding, chemicals) on variegation. Ways in which this might occur are discussed in the context of models of the molecular basis of differential gene activity.

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Section: Discussionsupporting

confidence: 83%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A correlation between development time and variegated position effect inDrosophila melanogaster

Michailidis¹,

Murray²,

Graves³

1988

Genet. Res.

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“…Chromosomal inversions are important drivers of genome structure evolution in natural populations (Said et al 2018). Inversions have the potential to disrupt genes at breakpoints, generate linkage blocks that cannot be broken by recombination, and cause positional effects on adjacent chromatin (Allshire et al 1994;Spofford 1976). In this study, we observed signi cant gene expression differences in genes located close to the inversion breakpoint regions, such as TraesCS2A03G1276800 and TraesCS2A03G1280400 (Table S5), but we currently do not know if these differences are caused by position effects.…”

Section: Discussionmentioning

confidence: 99%

High-resolution mapping of SrTm4, a recessive resistance gene to wheat stem rust

Li¹,

Luo²,

Zhang

et al. 2023

Preprint

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Race Ug99 of Puccinia graminis f. sp. tritici (Pgt), the causal agent of wheat stem (or black) rust is one of the most serious threats to global wheat production. The identification, mapping, and deployment of effective stem rust resistance (Sr) genes are critical to reduce this threat. In this study, we generated SrTm4 monogenic lines and found that this gene confers resistance to North American and Chinse Pgt races. Using a large mapping population (9,522 gametes), we mapped SrTm4 within a 0.06 cM interval flanked by marker loci CS4211 and 130K1519, which corresponds to a 1.0-Mb region in the Chinese Spring reference genome v2.1. Physical map of the SrTm4 region was constructed with 11 overlapping BACs from the resistant T. monococcum PI 306540. The comparison of the 754-kb physical map with the genomic sequence of Chinese Spring and the discontinuous BAC sequence of DV92 revealed a 593-kb chromosomal inversion in PI 306540. Within the candidate region, we identified an L-type lectin-domain containing receptor kinase (LLK1), which was disrupted by the proximal inversion breakpoint, as a potential candidate gene. Two diagnostic dominant markers were developed to detect the inversion breakpoints. In a survey of T. monococcum accessions, we identified only 10 domesticated T. monococcum subsp. monococcum genotypes, mainly from the Balkans, carrying the inversion and showing similar mesothetic resistant infection types against Pgt races. The high-density map and the tightly linked molecular markers developed in this study are useful tools to accelerate the deployment of SrTm4-mediated resistance in wheat breeding programs.

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Position effect variegation in Drosophila: Towards a genetics of chromatin assembly

Eissenberg

1989

BioEssays

138

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The formation of a highly condensed chromosome structure (heterochromatin) in a region of a eukaryotic chromosome can inactivate the genes within that region. Genetic studies using the fruitfly Drosophila melanogaster have identified several essential genes which influence the formation of heterochromatin. My purpose in this review is to summarize some recent work on the genetics of heterochromatin assembly in Drosophila and a recent model for how chromosomal proteins may interact to form a heterochromatic structure.

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SINGLE-LOCUS MODIFICATION OF POSITION-EFFECT VARIEGATION IN DROSOPHILA MELANOGASTER. I. WHITE VARIEGATION

Cited by 46 publications

References 5 publications

A correlation between development time and variegated position effect inDrosophila melanogaster

A correlation between development time and variegated position effect inDrosophila melanogaster

High-resolution mapping of SrTm4, a recessive resistance gene to wheat stem rust

Position effect variegation in Drosophila: Towards a genetics of chromatin assembly

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