scholarly journals Chromosomal basis of dosage compensation in Drosophila: I. Cellular autonomy of hyperactivity of the male X-chromosome in salivary glands and sex differentiation

1969 ◽  
Vol 14 (2) ◽  
pp. 137-150 ◽  
Author(s):  
S. C. Lakhotia ◽  
A. S. Mukherjee
Keyword(s):  
Drosophila Melanogaster ◽  
Salivary Glands ◽  
X Chromosome ◽  
Metabolic Activity ◽  
Dosage Compensation ◽  
Rna Synthesis ◽  
Sex Differentiation ◽  
Chromosome 3 ◽  
Normal Male ◽  
Developmental Physiology

Morphology and the rate of RNA synthesis of the X-chromosome in XX/XO mosaic larval salivary glands of Drosophila melanogaster have been examined. For this purpose the unstable ring-X was utilized to produce XX and XO nuclei in the same pair of glands. The width of the X-chromosome and the left arm of the 3rd chromosome (3L) of larval salivary glands was measured and the rate of RNA synthesis by them was studied upon the use of [3H]uridine autoradiography in such XX (female) and XO (male) nuclei developing in a female background (i.e. otherwise genotypically XX). In such mosaic glands the width of the single X-chromosome of male nuclei is nearly as great as that of the paired two X's of female nuclei, as is also the case in normal male (X Y) and female (XX). The single X of male nuclei synthesizes RNA at a rate equal to that of the paired two X's of female nuclei and nearly twice that of an unpaired X of XX nuclei. Neither the developmental physiology of the sex nor the proportion of XO nuclei in a pair of mosaic salivary glands of an XX larva has any influence on these two characteristics of the male X-chromosome.It is suggested that dosage compensation in Drosophila is achieved chiefly, if not fully, by a hyperactivity of the male X, in contrast to the single X inactivation in female mammals, that this hyperactivity of the male X is expressed visibly in the morphology and metabolic activity of the X-chromosome in the larval salivary glands of the male, and that this hyperactivity and therefore dosage compensation in Drosophila in general is not dependent on sex-differentiation, but is a function of the doses of the X-chromosome itself.

scholarly journals Chromosomal basis of dosage compensation in Drosophila: II. The DNA replication patterns of the male X-chromosome in an autosome—X insertion in D. melanogaster

1970 ◽  
Vol 15 (3) ◽  
pp. 301-307 ◽  
Author(s):  
S. C. Lakhotia
Keyword(s):  
Drosophila Melanogaster ◽  
Salivary Glands ◽  
Functional Morphology ◽  
X Chromosome ◽  
Dosage Compensation ◽  
Compensation Mechanism ◽  
Replication Pattern ◽  
Early Completion ◽  
Single Male ◽  
Autosomal Segment

SUMMARYThe functional morphology and the replication pattern of the male X-chromosome in an autosome-X insertion stock (T(1;3) 05) of Drosophila melanogaster have been examined. In larval salivary glands carrying this insertion neither the enlargement and pale staining of the single male X, nor the characteristic early completion of replication cycle, as revealed by 3H-TdR autoradiography is in any way changed. The normal properties of the inserted autosomal segment are also unaltered. The results appear to support a ‘piecemeal’ type of dosage compensation mechanism in Drosophila operating through the male.

Studies on Nucleolar RNA Synthesis in Drosophila Melanogaster

1972 ◽  
Vol 11 (3) ◽  
pp. 689-697
Author(s):  
H. M. KRIDER ◽  
W. PLAUT
Keyword(s):  
Drosophila Melanogaster ◽  
Salivary Glands ◽  
Rna Synthesis ◽  
First Generation ◽  
Nucleolus Organizer ◽  
Fifth Generation ◽  
Autoradiographic Analysis ◽  
Temporally Correlated ◽  
Nucleolar Rna ◽  
Nucleolus Organizers

The influence of conditions resulting in bobbed phenotypes on nucleolar RNA synthesis and the formation of constrictions at nucleolus organizers was examined in larval tissues of Drosophila melanogaster. By means of [3H]uridine incorporation and autoradiographic analysis, a mutation at the bobbed locus was shown to limit the rate of nucleolar RNA synthesis in salivary glands of XO larvae. The formation of constrictions at the organizer sites of a 4-nucleolus-organizer stock was monitored in dividing neuroblast cells stained with acridine orange. Loss of the ribosomal cistrons had been reported by other workers when such stocks were maintained for several generations. In the first generation in our work, constrictions were visible at only 2 of the 4 nucleolus organizers. This situation persisted until the fifth generation, when constrictions appeared at all 4 of the organizer sites. An increase in the rate of nucleolar RNA synthesis in the salivary glands was temporally correlated with the appearance of the extra constrictions. We interpret these observations to mean that 2 of the organizers of the 4-nucleolus-organizer stock were caused to function through the loss of ribosomal RNA cistrons; thus the functional status of an organizer would appear to be subject to control.

Quantitative Genetics of Drosophila Melanogaster. II. Heritabilities and Genetic Correlations between Sexes for Head and Thorax Traits.

Genetics ◽  
1988 ◽  
Vol 119 (2) ◽  
pp. 421-433
Author(s):  
D E Cowley ◽  
W R Atchley
Keyword(s):  
Drosophila Melanogaster ◽  
Sexual Dimorphism ◽  
Genetic Analysis ◽  
X Chromosome ◽  
Dosage Compensation ◽  
Imaginal Disc ◽  
Genetic Correlations ◽  
Body Parts ◽  
Quantitative Genetic ◽  
Males And Females

Abstract A quantitative genetic analysis is reported for traits on the head and thorax of adult fruit flies, Drosophila melanogaster. Females are larger than males, and the magnitude of sexual dimorphism is similar for traits derived from the same imaginal disc, but the level of sexual dimorphism varies widely across discs. The greatest difference between males and females occurs for the dimensions of the sclerotized mouthparts of the proboscis. Most of the traits studied are highly heritable with heritabilities ranging from 0.26 to 0.84 for males and 0.27 to 0.81 for females. In general, heritabilities are slightly higher for males, possibly reflecting the effect of dosage compensation on X-linked variance. The X chromosome contributes substantially to variance for many of these traits, and including results reported elsewhere, the variance for over two-thirds of the traits studied includes X-linked variance. The genetic correlations between sexes for the same trait are generally high and close to unity. Coupled with the small differences in the traits between sexes for heritabilities and phenotypic variances, these results suggest that selection would be very slow to change the level of sexual dimorphism in size of various body parts.

scholarly journals Puffing activity in Drosophila melanogaster Meig. political chromosomes after exposure to microwave radiation

2018 ◽  
Vol 23 ◽  
pp. 393-398
Author(s):  
M. N. Sheyka ◽  
V. Yu. Strashnyuk
Keyword(s):  
Drosophila Melanogaster ◽  
Salivary Glands ◽  
Power Density ◽  
Microwave Radiation ◽  
X Chromosome ◽  
Polytene Chromosomes ◽  
Early Embryogenesis ◽  
Wild Type ◽  
Ocular Micrometer ◽  
Outbred Strain

Aim. The aim of the work was to study the effect of microwave radiation of varying intensity on the polytene chromosomes puffing activity in larvae salivary glands of Drosophila melanogaster. Methods. The wild type outbred strain Oregon-R was used as the material. Microwave radiation with a frequency of 36.64 GHz and a power density of 0.1 and 1 W / m2 was used. Exposure to microwaves was applied in early embryogenesis after 3-hour oviposition. Exposure time was 30 sec. The puff sizes were studied on the squashed preparations of larvae salivary glands stained with acetoorcein. Dimensions of four puffs were investigated^ 2B5-6 (X chromosome); 62E, 71CE and 72CD (chromosome 3L). The measurements were carried out using an ocular-micrometer. Results. There were no significant changes in the size of the puffs in any of the four loci studied, regardless of the applied power density. Conclusions. Microwave radiation in early embryogenesis at a frequency of 36.64 GHz, a power density of 0.1 and 1 W/m2, and an exposure of 30 sec does not have a significant effect on the puff sizes in the Drosophila polytene chromosomes. Keywords: Drosophila melanogaster Meig., giant chromosomes, puff sizes, non-ionizing radiation.

Modification of the Drosophila heterochromatic mutation brownDominant by linkage alterations.

Genetics ◽  
1994 ◽  
Vol 136 (2) ◽  
pp. 559-571 ◽  
Author(s):  
P B Talbert ◽  
C D LeCiel ◽  
S Henikoff
Keyword(s):  
Drosophila Melanogaster ◽  
X Chromosome ◽  
Genetic Locus ◽  
Special Property ◽  
Chromosome Rearrangements ◽  
Chromosome 3 ◽  
Heterochromatin Formation ◽  
Chromosome Arm ◽  
Translocation Breakpoints

Abstract The variegating mutation brownDominant (bwD) of Drosophila melanogaster is associated with an insertion of heterochromatin into chromosome arm 2R at 59E, the site of the bw gene. Mutagenesis produced 150 dominant suppressors of bwD variegation. These fall into two classes: unlinked suppressors, which also suppress other variegating mutations; and linked chromosome rearrangements, which suppress only bwD. Some rearrangements are broken at 59E, and so might directly interfere with variegation caused by the heterochromatic insertion at that site. However, most rearrangements are translocations broken proximal to bw within the 52D-57D region of 2R. Translocation breakpoints on the X chromosome are scattered throughout the X euchromatin, while those on chromosome 3 are confined to the tips. This suggests that a special property of the X chromosome suppresses bwD variegation, as does a distal autosomal location. Conversely, two enhancers of bwD are caused by translocations from the same part of 2R to proximal heterochromatin, bringing the bwD heterochromatic insertion close to the chromocenter with which it strongly associates. These results support the notion that heterochromatin formation at a genetic locus depends on its location within the nucleus.

scholarly journals Autosomal and X-Linked Additive Genetic Variation for Lifespan and Aging: Comparisons Within and Between the Sexes in Drosophila melanogaster

2016 ◽  
Vol 6 (12) ◽  
pp. 3903-3911 ◽  
Author(s):  
Robert M Griffin ◽  
Holger Schielzeth ◽  
Urban Friberg
Keyword(s):  
Drosophila Melanogaster ◽  
Genetic Variation ◽  
X Chromosome ◽  
Dosage Compensation ◽  
Genetic Variance ◽  
Additive Genetic Variance ◽  
Conclusive Evidence ◽  
Substitution Lines ◽  
Chromosome Substitution Lines ◽  
Sexually Antagonistic Selection

Abstract Theory makes several predictions concerning differences in genetic variation between the X chromosome and the autosomes due to male X hemizygosity. The X chromosome should: (i) typically show relatively less standing genetic variation than the autosomes, (ii) exhibit more variation in males compared to females because of dosage compensation, and (iii) potentially be enriched with sex-specific genetic variation. Here, we address each of these predictions for lifespan and aging in Drosophila melanogaster. To achieve unbiased estimates of X and autosomal additive genetic variance, we use 80 chromosome substitution lines; 40 for the X chromosome and 40 combining the two major autosomes, which we assay for sex-specific and cross-sex genetic (co)variation. We find significant X and autosomal additive genetic variance for both traits in both sexes (with reservation for X-linked variation of aging in females), but no conclusive evidence for depletion of X-linked variation (measured through females). Males display more X-linked variation for lifespan than females, but it is unclear if this is due to dosage compensation since also autosomal variation is larger in males. Finally, our results suggest that the X chromosome is enriched for sex-specific genetic variation in lifespan but results were less conclusive for aging overall. Collectively, these results suggest that the X chromosome has reduced capacity to respond to sexually concordant selection on lifespan from standing genetic variation, while its ability to respond to sexually antagonistic selection may be augmented.

scholarly journals A different level of X-chromosomal transcription in an In(1)BM2 (reinverted) strain and in its hyperploid derivatives resolves an X-coded regulatory activity for dosage compensation in Drosophila

1986 ◽  
Vol 48 (2) ◽  
pp. 65-75 ◽  
Author(s):  
A. S. Mukherjee ◽  
Mita Ghosh
Keyword(s):  
Dosage Compensation ◽  
Rna Synthesis ◽  
Normal Male ◽  
Temperature Sensitive ◽  
Gene Complex ◽  
Regulatory Activity ◽  
Hypomorphic Mutation ◽  
Feulgen Cytophotometry ◽  
Mutant Male ◽  
Mutant Chromosome

SummaryThe transcriptional competence of the X-chromosome of a mutant strain of Drosophila melanogaster, [in(1)BM2 (reinverted)], and of hyperploid derivatives with different additional segments of the X-chromosome has been examined. The single X in the mutant male shows twice as much puffiness and RNA synthesis as does that in the normal male, revealing a level of X-coded activity in addition to the normal male and female levels. Feulgen cytophotometry reveals no duplication of DNA content in the mutant X. When duplication for the segments 1A-3E, 9A-20F, 11A-20F and 16A-20F of the X-chromosome are combined in the male with the mutant chromosome, the super-hyperactivity of the mutant X is completely abolished. In combination with the Bs. Y duplication, which contains 16A7-B2, the two-fold activity is also completely suppressed.The mutant chromosome can appear in three discrete manifestations, namely, highly flabby, intermittently flabby and normal, suggesting a leaky nature of the mutant. The effect is also temperature-sensitive. Our results suggest that there may be a modulator gene complex (M+) in the 16A7-B2 region as well as regulators elsewhere on the X, which in combination influence the hyperactivity of the male X in Drosophila. We suggest that the In(1)BM2 (reinverted) chromosome carries a hypomorphic mutation of M+(Mm). The results presented here and earlier data on various X-chromosomal and autosomal hyperploids are discussed in the light of a model for dosage compensation in Drosophila.

scholarly journals Chromosomal basis of dosage compensation in drosophila: IX. cellular autonomy of the faster replication of the x chromosome in haplo-x cells of drosophila melanogaster and synchronous initiation

1977 ◽  
Vol 74 (1) ◽  
pp. 168-180 ◽  
Author(s):  
RN Chatterjee ◽  
AS Mukherjee
Keyword(s):  
Drosophila Melanogaster ◽  
Salivary Glands ◽  
X Chromosome ◽  
Initial Phase ◽  
X Chromosomes ◽  
Initiation Of Replication ◽  
A Genome ◽  
The Mean ◽  
Early Replication ◽  
X Cells

[(3)H]Thymidine labeling patterns have been examined in gynandric mosaic salivary glands of drosophila melanogaster. The Ring-X stock, R(1) w(ve)/In(1)dl 49, l (1) J1 y w lz(s), was used for this purpose. 365 labeled XX2A and 40 labeled XO2A nuclei were obtained from a total of 624 nuclei in nine pairs of mosaic salivary glands. It was observed that in all but those nuclei which had DD, 1C, and 2C patterns, the X chromosome of the XO2A nuclei always had fewer sites labeled than the X chromosomes of the XX2A nuclei, for a given pattern of the autosomes in either sex. Such asynchronous labeling of the X chromosome in the XO2A (male) nuclei was observed regardless of the proportion of the XO2A cells (2.0-73.7 percent), in the mosaic glands. Moreover, while the frequency of [(3)H]thymidine labeling for all of the 39 replicating units except the two late replicating sites (3C and 11A) in the X chromosome of the XO2A nuclei, was consistently lower than in the X chromosome of the XX2A nuclei, the mean number of grains on the X chromosome was relatively (to autosomes) similar in both XX2A and XO2A cells. The results, therefore, suggest that, as in XY2A larval glands, the X chromosome in the XO2A cells also completes the replication earlier than autosomes and that the XO2A nuclei show cellular autonomy with respect to the early replication of the X chromosome, like its counterpart, RNA transcription. Absence of the asynchrony during the initial phase (DD-2C) further completes the replication earlier but that the rate of replication of its DNA is possibly faster, and (b) that there might be a common regulation with respect to the initiation of replication of different chromosomes in a genome.

scholarly journals A Role for siRNA in X-Chromosome Dosage Compensation in Drosophila melanogaster

Genetics ◽  
2012 ◽  
Vol 191 (3) ◽  
pp. 1023-1028 ◽  
Author(s):  
Debashish U. Menon ◽  
Victoria H. Meller
Keyword(s):  
Drosophila Melanogaster ◽  
X Chromosome ◽  
Dosage Compensation

scholarly journals Transcription in X-chromosomal segmental aneuploids of Drosophila melanogaster and regulation of dosage compensation

1981 ◽  
Vol 38 (2) ◽  
pp. 103-113 ◽  
Author(s):  
Jayashree Prasad ◽  
Ashish K. Duttagupta ◽  
A. S. Mukherjee
Keyword(s):  
Drosophila Melanogaster ◽  
Dosage Compensation ◽  
Genetic Locus ◽  
Normal Male ◽  
Chromosomal Dna ◽  
Male And Female ◽  
Nuclear Variation ◽  
The Individual ◽  
Per Gene

SUMMARYTranscription of X chromosomal DNA has been examined autoradio-graphically in various 1X2A and 2X2A normal larvae and 1X2A (+ X fr) and 2X2A (+ X fr) segmental aneuploid larvae of species Drosophila melanogaster. The segmental aneuploids contained duplications for the segment 9A–11A and 15D–ISA of the X chromosome. Results show that in the aneuploid male containing 9A–11A duplicaton both the homologous segments involved in the aneuploidy are autonomously hyperactive; their combined activity, measured by X/A grain ratio, is found to be nearly 70% more than the activity in normal male and about 100% more than that in diplo-X female. In the aneuploid female, containing the aneuploid segment 15D–18A and having three doses of the segment of the X chromosome, the activity was over 100% more than the diplo-X activity. The per gene dose activity for the two segments in the aneuploid male and female, respectively, is also significantly higher than their male and female counterparts. The possible role of lack of contiguity of the genetic segments and an intra-nuclear variation has been ruled out by appropriate analysis. We, therefore, interpret these findings to be due to an autonomous expression of the X linked compensatory genes, resulting from a primary modulation in the organization of the entire X chromosome. The autosomal signal then renders the individual genetic locus hyperactive.

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