scholarly journals HETEROZYGOUS EFFECTS ON FITNESS OF EMS-TREATED CHROMOSOMES IN DROSOPHILA MELANOGASTER

Genetics ◽  
1978 ◽  
Vol 88 (3) ◽  
pp. 575-590
Author(s):  
Michael J Simmons ◽  
Emily W Sheldon ◽  
James F Crow
Keyword(s):  
Drosophila Melanogaster ◽  
X Chromosome ◽  
Heterozygous Condition ◽  
Homozygous Condition ◽  
Fitness Effects ◽  
Lethal Mutations ◽  
Induced Mutants ◽  
Heterozygous Carriers ◽  
Different Doses ◽  
Over Time

ABSTRACT The heterozygous effects on fitness of second chromosomes carrying mutants induced with different doses of EMS were ascertained by monitoring changes in chromosome frequencies over time. These changes were observed in populations in which the treated chromosomes, as well as untreated competitors, remained heterozygous in males generation after generation. This situation was achieved by using a translocation which links the second chromosome to the X chromosome; however, only untranslocated second chromosomes were mutagenized. Chromosomes were classified according to their effects on viability in homozygous condition. A preliminary homozygosis identified completely lethal chromosomes; secondary tests distinguished between drastic (viability index < 0.1) and nondrastic chromosomes. Chromosomes that were nondrastic after treatment were found to reduce the fitness of their heterozygous carriers by 3-5%. The data show that flies homozygous for these chromosomes were about 2.7% less viable per treatment with 1 mm EMS than flies homozygous for untreated chromosomes. By comparing the fitness-depressing effects of nondrastic EMS-induced mutants in heterozygous condition with the corresponding viability-depressing effects measured by Temin, it is apparent that the total fitness effects are several times larger than the viability effects alone. Completely lethal chromosomes derived from the most heavily treated material reduced fitness by 11% in heterozygous condition; approximately half of this reduction was due to the lethal mutations themselves.

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.

scholarly journals FITNESS EFFECTS OF EMS-INDUCED MUTATIONS ON THE X CHROMOSOME OF DROSOPHILA MELANOGASTER. I. VIABILITY EFFECTS AND HETEROZYGOUS FITNESS EFFECTS

Genetics ◽  
1977 ◽  
Vol 87 (4) ◽  
pp. 763-774
Author(s):  
Joyce A Mitchell
Keyword(s):  
Drosophila Melanogaster ◽  
X Chromosome ◽  
Strongly Correlated ◽  
Induced Mutations ◽  
X Chromosomes ◽  
Heterozygous Condition ◽  
Fitness Effects ◽  
Sucrose Solutions ◽  
Discrete Generation ◽  
Males And Females

ABSTRACT Drosophila melanogaster X chromosomes were mutagenized by feeding males sucrose solutions containing ethyl methanesulfonate (EMS); the concentrations of EMS in the food were 2.5 mm, 5.0 mm, and 10.0 mm. Chromosomes were exposed to the mutagen up to three times by treating males in succeeding generations. After treatment, the effective exposures were 2.5, 5.0, 7.5, 10.0, 15.0, and 30.0 mm EMS. X chromosomes treated in this manner were tested for effects on fitness in both hemizygous and heterozygous conditions, and for effects on viability in hemizygous and homozygous conditions. In addition, untreated X chromosomes were available for study. The viability and heterozygous fitness effects are presented in this paper, and the hemizygous fitness effects are discussed in the accompanying one (Mitchell and Simmons 1977). Hemizygous and homozygous viability effects were measured by segregation tests in vial cultures. For hemizygous males, viability was reduced 0.5 percent per mm EMS treatment; for homozygous females, it was reduced 0.7 percent per mm treatment. The decline in viability appeared to be a linear function of EMS dose. The viabilities of males and females were strongly correlated. Heterozygous fitness effects were measured by monitoring changes in the frequencies of treated and untreated X chromosomes in discrete generation populations which, through the use of an X-Y translocation, maintained them only in heterozygous condition. Flies that were heterozygous for a treated chromosome were found to be 0.4 percent less fit per m m EMS than flies heterozygous for an untreated one.

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 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.

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 GENETICS OF ACETYLCHOLINESTERASE IN DROSOPHILA MELANOGASTER

Genetics ◽  
1976 ◽  
Vol 83 (3) ◽  
pp. 517-535
Author(s):  
Jeffrey C Hall ◽  
Douglas R Kankel
Keyword(s):  
Drosophila Melanogaster ◽  
Ache Activity ◽  
Normal Activity ◽  
Deletion Mapping ◽  
Structural Locus ◽  
Heterozygous Condition ◽  
Small Segment ◽  
The Third ◽  
Lethal Mutations ◽  
Segmental Aneuploidy

ABSTRACT Genes in Drosophila melanogaster that control acetylcholinesterase (AChE) were searched for by segmental aneuploidy techniques. Homogenates of flies containing duplications or deletions for different segments were assayed for enzyme activity. A region on the third chromosome was found for which flies having one does consistently gave lower AChE activity than euploid flies, which were in turn had lower activity than flies with three doses. The activity differences were in the approximate ratio 1:2:3. Fine structure deletion mapping within this region revealed a very small segment for which one-dose flies have approximately half-normal activity. To obtain putative AchE-null mutations, lethal mutations within this region were assayed. Four allelic lethals have approximately half-normal activity in heterozygous condition. These lethals probably define the structural locus (symbol: Ace) for AChE.

scholarly journals Genomewide Clonal Analysis of Lethal Mutations in the Drosophila melanogaster Eye: Comparison of the X Chromosome and Autosomes

Genetics ◽  
2007 ◽  
Vol 177 (2) ◽  
pp. 689-697 ◽  
Author(s):  
Gerald B. Call ◽  
John M. Olson ◽  
Jiong Chen ◽  
Nikki Villarasa ◽  
Kathy T. Ngo ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
X Chromosome ◽  
Clonal Analysis ◽  
Lethal Mutations

scholarly journals CORRELATIONS BETWEEN CHROMOSOME SEGMENTS AND FITNESS IN DROSOPHILA MELANOGASTER. I. THE X CHROMOSOME AND EGG PRODUCTION

Genetics ◽  
1977 ◽  
Vol 85 (4) ◽  
pp. 721-732
Author(s):  
William Chapco
Keyword(s):  
Drosophila Melanogaster ◽  
X Chromosome ◽  
Egg Production ◽  
Position Effect ◽  
X Chromosomes ◽  
Heterozygous Condition ◽  
Coupling Phase ◽  
Isogenic Lines ◽  
Apparent Relationship ◽  
Chromosome Segments

ABSTRACT Unmarked segments within the X chromosomes of four different Drosophila melanogaster isogenic lines were assessed with respect to egg production. By making a series of crosses among original and derived recombinant lines, it was possible to estimate parameters representing additive, dominance and interaction effects of the segments. It was shown that whereas most of the segments were additive for egg production when homozygous, they all displayed dominance in the heterozygous condition. Two of the strains were characterized by intersegmental interaction. A possible position effect was detected for these same two strains, with flies in the coupling phase laying more eggs than those in the repulsion configuration. There was no apparent relationship between the number of eggs laid and the amount of heterozygosity within the X chromosome.

scholarly journals LETHALITY PATTERNS AND MORPHOLOGY OF SELECTED LETHAL AND SEMI-LETHAL MUTATIONS IN THE ZESTE-WHITE REGION OF DROSOPHILA MELANOGASTER

Genetics ◽  
1972 ◽  
Vol 72 (4) ◽  
pp. 615-638 ◽  
Author(s):  
M P Shannon ◽  
T C Kaufman ◽  
M W Shen ◽  
B H Judd
Keyword(s):  
Drosophila Melanogaster ◽  
Salivary Gland ◽  
X Chromosome ◽  
Pattern Analysis ◽  
Salivary Gland Chromosome ◽  
Developmental Genetics ◽  
Morphological Attributes ◽  
White Region ◽  
Lethal Mutations ◽  
Complementation Groups

ABSTRACT Aspects of the developmental genetics of lethal and semi-lethal mutants representing 13 complementation groups (cistrons) in the 3A-3C region of the X chromosome of Drosophila melanogaster are given. Each of these cistrons is associated with a particular chromomere in the salivary gland chromosome. Mutants within each cistron have similar lethality patterns and morphological attributes, and the characteristics of a given cistron are distinct with respect to other cistrons. These results provide additional evidence that only one function is associated with each chromomere.—The results of the lethality pattern analysis are also compared with previous studies of lethal mutants of Drosophila.

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