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 THE INTERCELLULAR DISTRIBUTION OF MUTATIONS INDUCED IN OOCYTES OF DROSOPHILA MELANOGASTER BY CHEMICAL AND PHYSICAL MUTAGENS

Genetics ◽  
1979 ◽  
Vol 92 (1) ◽  
pp. 151-160
Author(s):  
H Traut
Keyword(s):  
Drosophila Melanogaster ◽  
Mitomycin C ◽  
Mutation Frequency ◽  
Lethal Mutation ◽  
X Rays ◽  
Mutagenic Treatment ◽  
X Chromosomes ◽  
Recessive Lethal ◽  
Lethal Mutations ◽  
X Irradiation

ABSTRACT When females of Drosophila melanogaster are treated with chemical or physical mutagens, not only in one but also in both of the two homologous X chromosomes of a given oocyte, a recessive sex-linked lethal mutation may be induced. A method is described that discriminates between such "single" and "double mutations." A theory is developed to show how a comparison between the expected and the observed frequency of double mutations yields an indication of the intercellular distribution (random or nonrandom) of recessive lethal mutations induced by mutagenic agents in oocytes and, consequently, of the distribution (homogeneous or nonhomogeneous) of those agents.—Three agents were tested: FUdR (12.5, 50.0 and 81.0,μg/ml), mitomycin C (130.0 μg/ml) and X rays (2000 R, 150 kV). After FUdR feeding, no increase in the mutation frequency usually observed in D. melanogaster without mutagenic treatment was obtained (u=0.13%, namely three single mutations among 2332 chromosomes tested). After mitomycin C feeding, 104. single and three double mutations were obtained. All of the 50 mutations observed after X irradiation were single mutations. The results obtained in the mitomycin C and radiation experiments favor the assumption of a random intercellular distribution of recessive lethal mutations induced by these two agents in oocytes of D. melanogaster. Reasons are discussed why for other types of mutagenic agents nonrandom distributions may be observed with our technique.

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.

Cytogenetics of Notch Mutations Arising in the Unstable X Chromosome Uc of Drosophila melanogaster

Genetics ◽  
1987 ◽  
Vol 115 (4) ◽  
pp. 701-709
Author(s):  
Dena Johnson-Schlitz ◽  
J K Lim
Keyword(s):  
Drosophila Melanogaster ◽  
In Situ Hybridization ◽  
X Chromosome ◽  
Cytological Analysis ◽  
Specific Chromosome ◽  
Site Specific ◽  
Normal Sequence ◽  
Chromosome Breaks ◽  
Notch Locus

ABSTRACT A derivative of the unstable X chromosome, Uc, isolated in 1978 is still unstable and exhibits most of the genetic properties characteristic of the original Uc. This derivative, Df(1)cm-In, contains an inversion of the genes between bands 6F1-2 and 3D3-5 and a lethal deficiency between 6D5-7 and 6F1-2. This chromosome generated Notch mutations at a rate of 3.47 ± 0.32% during seven consecutive generations. Cytological analysis of 50 Notch mutations of independent origin in the Df(1)cm-In chromosome showed that all of the 50 had an apparently identical deletion involving the region between 3D3-5 and 3C7-8 of the X chromosome. The results of in situ hybridization indicated that the extent of deletion in all of the 20 Notch deficiencies sampled from the 50 mentioned above involves about 10 kb of the sequences from the 3′ end of the Notch locus. In addition to hypermutability and the accumulation of site-specific chromosome breaks, the Df(1)cm-In chromosome reinverts its inversion to the normal sequence and exhibits use of the existing chromosome breakpoints to generate new rearrangements.

Site-specific X-chromosome rearrangements from hybrid dysgenesis in Drosophila melanogaster

Science ◽  
1980 ◽  
Vol 210 (4468) ◽  
pp. 427-429 ◽  
Author(s):  
R Berg ◽  
W. Engels ◽  
R. Kreber
Keyword(s):  
Drosophila Melanogaster ◽  
X Chromosome ◽  
Chromosome Rearrangements ◽  
Hybrid Dysgenesis ◽  
Site Specific

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.

scholarly journals Cytogenetic and complementation analyses of recessive lethal mutations induced in the X chromosome of Drosophila by three alkylating agents

1974 ◽  
Vol 24 (1) ◽  
pp. 1-10 ◽  
Author(s):  
J. K. Lim ◽  
L. A. Snyder
Keyword(s):  
Drosophila Melanogaster ◽  
Salivary Gland ◽  
X Chromosome ◽  
Alkylating Agents ◽  
Complementation Analysis ◽  
Ethyl Methanesulphonate ◽  
Induced Mutations ◽  
Recessive Lethal ◽  
Lethal Mutations

SUMMARYSalivary-gland chromosomes of 54 methyl methanesulphonate- and 50 triethylene melamine-induced X-chromosome recessive lethals in Drosophila melanogaster were analysed. Two of the lethals induced by the mono-functional agent and 11 of those induced by the polyfunctional agent were found to be associated with detectable aberrations. A complementation analysis was also done on 82 ethyl methanesulphonate- and 34 triethylene melamine-induced recessive lethals in the zeste-white region of the X chromosome. The EMS-induced lethals were found to represent lesions affecting only single cistrons. Each of the 14 cistrons in the region known to mutate to a lethal state was represented by mutant alleles, but in widely different frequencies. Seven of the TEM-induced lethals were associated with deletions, only one of which had both breakpoints within the mapped region. Twenty-six of the 27 mutations in which only single cistrons were affected were mapped to 7 of the 14 known loci. One TEM- and two EMS-induced mutations were alleles representing a previously undetected locus in the zeste-white region.

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 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.

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