Dosage compensation of sex-linked genes in Drosophila melanogaster

Faizullin, L. Z.; Гвоздев, В. А.

doi:10.1007/bf00267534

Cited by 26 publications

(8 citation statements)

References 25 publications

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“…This model is not consistent with the conclusions reached by ourselves [28] and by Stewart and Merriam [29] that metafemales (3X;2A) are compensated-conclusions that were at odds with those of Faizullin and Gvosdev [30] and of Ananiev et a1 [31], These authors observed a distinct increment in X-linked gene function mediated by the presence of the extra X chromosome. The most reasonable explanation seems to be that in metafemales, the presence of an extra dose of X-linked genes may be buffered by mechanisms of genetic homeostasis other than the one that normally operates to equalize gene products in males and females.…”

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confidence: 70%

The relationship between gene dosage, gene expression, and sex in Drosophila

Lucchesi

1982

Dev. Genet.

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In Drosophila, the ratio of the number of X chromosomes to sets of other chromosomes initiates a series of events which result in sexual differentiation. In addition, this ratio establishes dosage compensation, a mechanism which equalizes the products of X-linked genes in males and females. The present review discusses possible genetic entities responsible for the interpretation of chromosomal sex and subsequent sex-mediated regulation during development.Key words: Drosophila, sex chromosomes, gene dosage, gene expression INTRODUCTIONIn Drosophila melanogaster, females have two X chromosomes; males have a single X and a Y. The genetic information contained by the Y chromosome i s not involved in the determination of sex. It is mostly concerned with spermatogenesis and is, therefore, necessary for male fertility. In this particular species of fruit flies, the Y chromosome also bears a cluster of ribosomal RNA cistrons. Sex is determined by the balance of X chromosomes and autosomes in the genome [ 13, and it is generally assumed that there are X-linked female-determining elements whose products are additive [2,3]. In an XX embryo, these products reach the threshold necessary to initiate sexual differentiation along a female mode. When a single X chromosome is present, the threshold is not reached and differentiation proceeds along the male mode It has long been known that, in addition to these purported sex determining genes, the X chromosome contains genes coding for basic metabolic steps or for morphological or physiological products of equal importance to males and females. With few exceptions,* the levels of these gene products are equivalent in the two sexes, leading to the notion that a mechanism exists for the compensation of gene dosage differences that normally occur between males and females.The seminal observation was reported by H.J. Muller at the Sixth International Congress of Genetics [6]. He had noted that the hypomorphic eye color mutant allele white-apricot (Mp) 276Lucchesi deficiency encompassing the gene and bearing, therefore, a single Wa allele had less pigment than homozygous females; males with an extra does of Wa had substantially darker eyes than hemizygous males. The equalization of gene products between chromosomally normal males and females led Muller to postulate the existence of a mechanism of dosage compensation for X-lined genes. He further stated that, although uncovered and more readily studied with mutants, the mechanism must operate on wild-type alleles. Validation of this point came much later with the quantitation of the activity of X-linked enzymes [7].There have been four major landmarks in the study of dosage compensation in Drosophila. The first was the evidence gathered by Mukherjee and Beerman [8] that chromosomal RNA synthesis along the single polytenic X chromosome of male larval salivary glands and the paired X chromosomes of females are equivalent, suggesting that dosage compensation is a transcriptional phenomenon. Another landmark was the demonstration that ge...

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contrasting

confidence: 70%

The relationship between gene dosage, gene expression, and sex in Drosophila

Lucchesi

1982

Dev. Genet.

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“…Inconsistent with the above conclusion are some results published by Faizullin and Gvozdev [13]. These authors reported that intersexes selected for their more extreme male phenotype exhibited a 30% increase in X-chromosome activity over sexually intermediate intersexes with levels of X-chromosome activity characteristic of compensation.…”

Section: In Tro D U Ct I0 Nsupporting

confidence: 51%

“…The correlation between the sexual differentiation and X-chromosome activity levels of triploid intersexes reported by Faizullin and Gvozdev [13] remains to be discussed. A possible explanation may be found in the fact that these authors used specific activity levels of X-linked enzymes as a measure of X-chromosome activity.…”

Section: Discussionmentioning

confidence: 91%

Phenogenetics of triploid intersexes in Drosophila melanogaster

1985

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Triploid intersexes homozygous for a mutant (msl-2) known to impede the hyperactivation of the X chromosome in diploid males differentiate into adults, sexually indistinguishable from their heterozygous sibs. A shift toward female sexual differentiation mediated by manipulating the rearing temperature is accompanied by an apparent increase in the level of an X-linked gene product. This unexpected result is rationalized in terms of differential lethality of individuals at the two extremities of the distribution of X-activity levels in intersexes raised at a particular temperature. No evidence of a mosaicism comparable to the sexual mosaicism exhibited could be found with respect to an X-linked gene product in triploid intersexes.

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“…Although in such females some genes are down-regulated(13) by a mechanism other than that of dosage compensation, a number of . loci respond proportionately to the increase in their dosage (14) and are responsible, presumably, for reducing viability. The mechanism of dosage compensation, therefore, operates within a very narrow range of activity.…”

Section: Introductionmentioning

confidence: 99%

Dosage compensation in Drosophila and the ‘complex’ world of transcriptional regulation

Lucchesi

1996

BioEssays

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The purpose of this review is to draw attention to the mechanism of dosage compensation in Drosophila as a model for the study of the regulation of gene activity through the modulation of transcription. Dosage compensation resembles some mechanisms of transcriptional regulation, found in widely divergent organisms, that do not play a role in the activation of silent genes but determine the level of activity of genes that have been induced through the action of specific activators. It differs from other known regulatory mechanisms in that its effect is to achieve, on average, a twofold change in gene activity levels. This review introduces the notion that, in order to yield such a defined level of regulation, the mechanism of dosage compensation in Drosophila, and perhaps in Caenorhabditis as well, incorporates elements that govern both transcriptional enhancement and repression within the same multi-protein regulatory complex.

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Dosage compensation of sex-linked genes in Drosophila melanogaster

Cited by 26 publications

References 25 publications

The relationship between gene dosage, gene expression, and sex in Drosophila

The relationship between gene dosage, gene expression, and sex in Drosophila

Phenogenetics of triploid intersexes in Drosophila melanogaster

Dosage compensation in Drosophila and the ‘complex’ world of transcriptional regulation

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