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 The three-dimensional organization of polytene nuclei in male Drosophila melanogaster with compound XY or ring X chromosomes.

Genetics ◽  
1989 ◽  
Vol 121 (2) ◽  
pp. 293-311
Author(s):  
D Mathog ◽  
J W Sedat
Keyword(s):  
Drosophila Melanogaster ◽  
Salivary Glands ◽  
X Chromosome ◽  
Genetic Regulation ◽  
Polytene Chromosomes ◽  
Three Dimensional ◽  
X Chromosomes ◽  
Frequent Failure ◽  
Polytene Nucleus ◽  
Polytene Nuclei

Abstract The three-dimensional organization of polytene chromosomes within nuclei containing rearranged X chromosomes was examined in male Drosophila melanogaster. Salivary glands of third instar larvae containing either an inverted X chromosome (YSX.YL, In(1)EN/O) or a ring X chromosome (R(1) 2/BSYy+) were fixed, embedded, and serially sectioned. The nuclei in contiguous groups of cells were modeled and analyzed. We find that for both genotypes the three-dimensional behavior at each euchromatic locus is independent of the orientation of the chromosome on which it resides, independent of the behavior of loci not closely linked to it, and not similar in neighboring cells. The preference for right-handed chromosome coiling noted in previous studies is shown to be independent of homologous pairing. However, a relation between the extent of chromosome curvature and the handedness of chromosome coiling is present only in homologously paired chromosomes. The attached-XY chromosome has two previously undescribed behaviors: a nearly invariant association of the euchromatic side of the proximal heterochromatin/euchromatin junction with the nucleolus and a frequent failure of this site to attach to the chromocenter. The relative chromosome arm positions are often similar in several neighboring cells. The size of these patches of cells, assuming that they represent clones, indicates that such arrangements are at best quasi-stable: they may be maintained over at least one, but less than four, cell divisions. The observed nuclear organization in salivary glands is inconsistent with the idea that position in the polytene nucleus plays a major role in the normal genetic regulation of euchromatic loci.

scholarly journals SITE-SPECIFIC INSTABILITY IN DROSOPHILA MELANOGASTER: EVIDENCE FOR TRANSPOSITION OF DESTABILIZING ELEMENT

Genetics ◽  
1982 ◽  
Vol 101 (3-4) ◽  
pp. 461-476
Author(s):  
Todd R Laverty ◽  
J K Lim
Keyword(s):  
Drosophila Melanogaster ◽  
X Chromosome ◽  
Lethal Mutation ◽  
Chromosome Rearrangements ◽  
Chromosome Break ◽  
Secondary Mutation ◽  
X Chromosomes ◽  
Site Specific ◽  
Normal Sequence ◽  
Lethal Mutations

ABSTRACT In this study, we show that at least one lethal mutation at the 3F-4A region of the X chromosome can generate an array of chromosome rearrangements, all with one chromosome break in the 3F-4A region. The mutation at 3F-4A (secondary mutation) was detected in an X chromosome carrying a reverse mutation of an unstable lethal mutation, which was mapped in the 6F1-2 doublet (primary mutation). The primary lethal mutation at 6F1-2 had occurred in an unstable chromosome (Uc) described previously (Lim 1979). Prior to reversion, the 6F1-2 mutation had generated an array of chromosome rearrangements, all having one break in the 6F1-2 doublet (Lim 1979, 1980). In the X chromosomes carrying the 3F-4A secondary lethal mutation the 6F1-2 doublet was normal and stable, as was the 3F-4A region in the X chromosome carrying the primary lethal mutation. The disappearance of the instability having a set of genetic properties at one region (6F1-2) accompanied by its appearance elsewhere in the chromosome (3F-4A) implies that a transposition of the destabilizing element took place. The mutant at 3F-4A and other secondary mutants exhibited all but one (reinversion of an inversion to the normal sequence) of the eight properties of the primary lethal mutations. These observations support the view that a transposable destabilizing element is responsible for the hypermutability observed in the unstable chromosome and its derivaties.

scholarly journals Hybrid dysgenesis-induced quantitative variation on the X chromosome of Drosophila melanogaster.

Genetics ◽  
1990 ◽  
Vol 124 (3) ◽  
pp. 627-636
Author(s):  
C Q Lai ◽  
T F Mackay
Keyword(s):  
Drosophila Melanogaster ◽  
X Chromosome ◽  
Quantitative Traits ◽  
Natural Populations ◽  
Quantitative Variation ◽  
Hybrid Dysgenesis ◽  
X Chromosomes ◽  
Bristle Number ◽  
Seven Generations ◽  
Polygenic Variation

Abstract To determine the ability of the P-M hybrid dysgenesis system of Drosophila melanogaster to generate mutations affecting quantitative traits, X chromosome lines were constructed in which replicates of isogenic M and P strain X chromosomes were exposed to a dysgenic cross, a nondysgenic cross, or a control cross, and recovered in common autosomal backgrounds. Mutational heritabilities of abdominal and sternopleural bristle score were in general exceptionally high-of the same magnitude as heritabilities of these traits in natural populations. P strain chromosomes were eight times more mutable than M strain chromosomes, and dysgenic crosses three times more effective than nondysgenic crosses in inducing polygenic variation. However, mutational heritabilities of the bristle traits were appreciable for P strain chromosomes passed through one nondysgenic cross, and for M strain chromosomes backcrossed for seven generations to inbred P strain females, a result consistent with previous observations on mutations affecting quantitative traits arising from nondysgenic crosses. The new variation resulting from one generation of mutagenesis was caused by a few lines with large effects on bristle score, and all mutations reduced bristle number.

Spontaneous formation of compound X chromosomes in Drosophila melanogaster.

Genetics ◽  
1988 ◽  
Vol 119 (1) ◽  
pp. 95-103
Author(s):  
R J Morrison ◽  
J D Raymond ◽  
J R Zunt ◽  
J K Lim ◽  
M J Simmons
Keyword(s):  
Drosophila Melanogaster ◽  
X Chromosome ◽  
The Other ◽  
X Chromosomes ◽  
Multiple Factors ◽  
Spontaneous Formation ◽  
Chromosome Attachment ◽  
Recombination Experiments ◽  
Attachment Process

Abstract Males carrying different X chromosomes were tested for the ability to produce daughters with attached-X chromosomes. This ability is characteristic of males carrying an X chromosome derived from 59b-z, a multiply marked X chromosome, and is especially pronounced in males carrying the unstable 59b-z chromosomes Uc and Uc-lr. Recombination experiments with one of the Uc-lr chromosomes showed that the formation of compound chromosomes depends on two widely separated segments. One of these is proximal to the forked locus and is probably proximal to the carnation locus. This segment may contain the actual site of chromosome attachment. The other essential segment lies between the crossveinless and vermilion loci and may contain multiple factors that influence the attachment process.

scholarly journals MEIOTIC BEHAVIOR OF COMPOUND AUTOSOMES IN FEMALES OF DROSOPHILA MELANOGASTER: INTERCHROMOSOMAL EFFECTS AND THE SOURCE OF SPONTANEOUS NONSEGREGATION

Genetics ◽  
1980 ◽  
Vol 96 (2) ◽  
pp. 455-470
Author(s):  
Hideh Harger ◽  
David G Holm
Keyword(s):  
Drosophila Melanogaster ◽  
X Chromosome ◽  
Inverse Correlation ◽  
Proximal Region ◽  
Crossing Over ◽  
X Chromosomes ◽  
Repulsion Phase ◽  
Base Level ◽  
Exchange Processes ◽  
Spontaneous Frequency

ABSTRACT In females of Drosophila melanogaster, compound autosomes enter the repulsion phase of meiosis uncommitted to a particular segregation pattern because their centromeres are not restricted to a bivalent pairing complex as a consequence of crossing over. Their distribution at anaphase, therefore, is determined by some meiotic property other than exchange pairing, a property that for many years has been associated with the concept of nonhomologous pairing. In the absence of heterologous rearrangements or a free Y chromosome, C(3L) and C(3R) are usually recovered in separate gametes, that is as products of meiotic segregation. Nevertheless, there is a regular, albeit infrequent, recovery of reciprocal meiotic products (the nonsegregational products) that are disomic and nullosomic for compound thirds. The frequency of these exceptions, which is normally between 0.5 and 5.0%, differs for the various strains examined, but remains constant for any given strain. Since previous studies have not uncovered a cause for this base level of nonsegregation, it has been referred to as the spontaneous frequency. In this study, crosses between males and females whose X chromosomes, as well as compound autosomes, are differentially marked reveal a highly significant positive correlation between the frequency of compound-autosome nonsegregation and the frequency of X-chromosome nondisjunction. However, an inverse correlation is found when the frequency of nondisjunction is related to the frequency of crossing over in the proximal region of the X chromosome. These findings have been examined with reference to the distributive pairing and the chromocentral models and interpreted as demonstrating (1) that nonsegregational meiotic events arise primarily as a result of nonhomologous interactions, (2) that forces responsible for the segregation of nonhomologous chromosomes are properties of the chromocentral region, and (3) that these forces come into expression after the exchange processes are complete.

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 MALE-STERILIZING INTERACTIONS BETWEEN DUPLICATIONS AND DEFICIENCIES FOR PROXIMAL X-CHROMOSOME MATERIAL IN DROSOPHILA MELANOGASTER

Genetics ◽  
1981 ◽  
Vol 99 (1) ◽  
pp. 49-64
Author(s):  
Rezaur Rahman ◽  
Dan L Lindsley
Keyword(s):  
Drosophila Melanogaster ◽  
X Chromosome ◽  
Male Fertility ◽  
Primary Spermatocyte ◽  
Single Factor ◽  
X Chromosomes ◽  
Recessive Lethal ◽  
Lethal Mutations ◽  
Y Chromosomes ◽  
Chromosome Material

ABSTRACT The genetic limits of sixty-four deficiencies in the vicinity of the euchromatic-heterochromatic junction of the X chromosome were mapped with respect to a number of proximal recessive lethal mutations. They were also tested for male fertility in combination with three Y chromosomes carrying different amounts of proximal X-chromosome-derived material (BSYy+, y+Ymal126 and y  +  Ymal  +). All deficiencies that did not include the locus of bb and a few that did were male-fertile in all male-viable Df(1)/Dp(1;Y) combinations. Nineteen bb deficiencies fell into six different classes by virtue of their male-fertility phenotypes when combined with the duplicated Y chromosomes. The six categories of deficiencies are consistent with a formalism that invokes three factors or regions at the base of the X, one distal and two proximal to bb, which bind a substance critical for precocious inactivation of the X chromosome in the primary spermatocyte. Free duplications carrying these regions or factors compete for the substance in such a way that, in the presence of such duplications, proximally deficient X chromosomes are unable to command sufficient substance for proper control of X-chromosome gene activity preparatory to spermatogenesis. We conclude that there is no single factor at the base of the X that is required for the fertility of males whose genotype is otherwise normal.

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.

scholarly journals FITNESS EFFECTS OF EMS-INDUCED MUTATIONS ON THE X CHROMOSOME OF DROSOPHILA MELANOGASTER. II. HEMIZYGOUS FITNESS EFFECTS

Genetics ◽  
1977 ◽  
Vol 87 (4) ◽  
pp. 775-783
Author(s):  
Joyce A Mitchell ◽  
Michael J Simmons
Keyword(s):  
Drosophila Melanogaster ◽  
X Chromosome ◽  
Induced Mutations ◽  
Fitness Effect ◽  
X Chromosomes ◽  
Fitness Effects ◽  
Induced Mutants ◽  
Time Changes

ABSTRACT X chromosomes mutagenized with EMS were tested for their effects on the fitness of hemizygous carriers. The tests were carried out in populations in which treated and untreated X chromosomes segregated from matings between males and attached-X females; the populations were maintained for several generations, during which time changes in the frequencies of the treated and untreated chromosomes were observed. From the rates at which the frequencies changed, the fitness effects of the treated chromosomes were determined. It was found that flies hemizygous for a mutagenized chromosome were 1.7% less fit per mm EMS treatment than those hemizygous for an untreated chromosome. Since the same flies were only 0.5% per m m less viable than their untreated counterparts, the total fitness effect of an X chromosome carrying EMS-induced mutants is three to four times greater than its viability effect. By comparing the heterozygous effect of a mutagenized X chromosome on fitness with the corresponding hemizygous effect, the dominance value for the chromosome is estimated to be about 0.25.

Dependence on genie balance for synaptonemal complex formation in Drosophila melanogaster

Genome ◽  
1988 ◽  
Vol 30 (2) ◽  
pp. 258-264 ◽  
Author(s):  
T. M. Grishayeva ◽  
Y. F. Bogdanov
Keyword(s):  
Drosophila Melanogaster ◽  
Synaptonemal Complex ◽  
X Chromosome ◽  
Central Element ◽  
Sharp Decrease ◽  
Electron Microscopic Examination ◽  
Electron Microscopic ◽  
X Chromosomes ◽  
Ovary Cells ◽  
Synaptonemal Complexes

Electron microscopic examination of gonads of Drosophila melanogaster with different genotypes, including a metafemale 3X;2A and an intersex XXY;3A, have revealed that the formation of synaptonemal complexes is controlled by the genie balance, i.e., the ratio of X chromosomes to autosomes. The Y chromosome is not involved in the genetic control of the formation of precursors of the central element of synaptonemal complexes in males, nor does it disturb their formation in [Formula: see text] females. Hyperploidy for sections 1 – 3A and 18A – 20 of the X chromosome does not lead to the appearance of synaptonemal complexes in males and does not interfere with their formation in females. Females hyperploid for extensive regions of the X chromosome (sections 1 – 11A, 11A – 20, and 8C – 20) are fertile and show apparently normal formation of synaptonemal complexes. Hyperploidy for sections 8C – 11A of the X results in a sharp decrease in the viability of females, in abnormal differentiation of ovary cells, and in the lack of synaptonemal complexes. These data suggest a possible important role for the sections 8C – 11A in the genic balance controlling the formation of synaptonemal complexes in D. melanogaster. The lack of synaptonemal complexes in hypoploid females may be the result of abnormal cell differentiation in gonads.Key words: Drosophila melanogaster, synaptonemal complex, sex chromosomes, genic balance.

Sign in / Sign up

Export Citation Format

Share Document