scholarly journals High levels of fitness modifiers induced by hybrid dysgenesis in Drosophila melanogaster

1986 ◽  
Vol 48 (2) ◽  
pp. 89-94 ◽  
Author(s):  
Benjamin J. Fitzpatrick ◽  
John A. Sved

SummaryWild-type chromosomes of D. melanogaster mutagenized by passage through a single generation of hybrid dysgenesis have been compared against identical chromosomes passed through a reciprocal, non-dysgenic cross. Fitness of the chromosome in homozygous condition has been examined in population cages using the technique of balancer chromosome equilibration. The results indicate that amongst chromosomes with no lethal or visible mutation, more than 50% have suffered a measurable decline in fitness. The magnitude of this decline is estimated to be in the range 10–20%.

Genetics ◽  
1986 ◽  
Vol 112 (4) ◽  
pp. 755-767
Author(s):  
S H Clark ◽  
M McCarron ◽  
C Love ◽  
A Chovnick

ABSTRACT DNA extracts of several rosy-mutation-bearing strains were associated with large insertions and deletions in a defined region of the molecular map believed to include the rosy locus DNA. Large-scale, intragenic mapping experiments were carried out that localized these mutations within the boundaries of the previously defined rosy locus structural element. Molecular characterization of the wild-type recombinants provides conclusive evidence that the rosy locus DNA is localized to the DNA segment marked by these lesions.—One of the mutations, ry  2101, arose from a P-M hybrid dysgenesis experiment and is associated with a copia insertion. Experiments are described which suggest that copia mobilizes in response to P-M hybrid dysgenesis.—Relevance of the data to recombination in higher organisms is considered.


1979 ◽  
Vol 34 (3) ◽  
pp. 303-315 ◽  
Author(s):  
A. N. Wilton ◽  
J. A. Sved

SUMMARYPopulation cages were set up containing an X-chromosome balancer, and either a single wild-type chromosome(homozygous cages) or a mixture of wild-type chromosomes(heterozygous cages). The balancer chromosome was eliminated more rapidly from the heterozygous cages, indicating that chromosome heterozygotes are at an advantage over chromosome homozygotes. The disadvantage of X-chromosome homozygosity in the female is estimated to be about 40%. From earlier studies it is known that the average disadvantage of homozygosity for either of the two major autosomes of D. melanogaster is approximately 80%. Since these autosomes are both about twice as long as the X chromosome, the disadvantage per unit length is similar for both chromosomal types.Both X-chromosomal and autosomal heterosis can be explained by either dominance or overdominance at individual loci. However, a dominance model can only explain the similarity if many of the X-linked loci (about 50%) are limited in expression to the female.


1986 ◽  
Vol 6 (5) ◽  
pp. 1520-1528 ◽  
Author(s):  
D Y Chang ◽  
B Wisely ◽  
S M Huang ◽  
R A Voelker

A hybrid dysgenesis-induced allele [su(s)w20] associated with a P-element insertion was used to clone sequences from the su(s) region of Drosophila melanogaster by means of the transposon-tagging technique. Cloned sequences were used to probe restriction enzyme-digested DNAs from 22 other su(s) mutations. None of three X-ray-induced or six ethyl methanesulfonate-induced su(s) mutations possessed detectable variation. Seven spontaneous, four hybrid dysgenesis-induced, and two DNA transformation-induced mutations were associated with insertions within 2.0 kilobases (kb) of the su(s)w20 P-element insertion site. When the region of DNA that included the mutational insertions was used to probe poly(A)+ RNAs, a 5-kb message was detected in wild-type RNA that was present in greatly reduced amounts in two su(s) mutations. By using strand-specific probes, the direction of transcription of the 5-kb message was determined. The mutational insertions lie in DNA sequences near the 5' end of the 5-kb message. Three of the seven spontaneous su(s) mutations are associated with gypsy insertions, but they are not suppressible by su(Hw).


1976 ◽  
Vol 29 (4) ◽  
pp. 375 ◽  
Author(s):  
JA Sved

Male.recombination and female sterility, two aspects of hybrid dysgenesis in D. melanogaster, have been studied in crosses between a locally collected wild population and laboratory strains. Dysgenesis occurs in the Fl hybrid of such crosses only if the wild type is used as maie parent and the laboratory strain as female, suggesting an interaction between genotype and cytoplasm. However the results from further crosses are difficult to interpret in terms of a conventional genotype--cytoplasm model, and suggest that for dysgenesis to occur it is necessary-that the wild-type chromosomes be contributed by the male parent. Furthermore, receipt of any of the three major wild-type chromosomes in crosses to laboratory females is sufficient to cause hybrid dysgenesis.


Genetics ◽  
1988 ◽  
Vol 119 (1) ◽  
pp. 75-83
Author(s):  
H Roiha ◽  
G M Rubin ◽  
K O'Hare

Abstract DNA from the singed gene of Drosophila melanogaster was isolated using an inversion between a previously cloned P element at cytological location 17C and the hypermutable allele singed-weak. Five out of nine singed mutants examined have alterations in their DNA maps in this region. The singed locus is a hotspot for mutation during P-M hybrid dysgenesis, and we have analyzed 22 mutations induced by P-M hybrid dysgenesis. All 22 have a P element inserted within a 700-bp region. The precise positions of 10 P element insertions were determined and they define 4 sites within a 100-bp interval. During P-M hybrid dysgenesis, the singed-weak allele is destabilized, producing two classes of phenotypically altered derivatives at high frequency. In singed-weak, two defective P elements are present in a "head-to-head" or inverse tandem arrangement. Excision of one element results in a more extreme singed bristle phenotype while excision of the other leads to a wild-type bristle phenotype.


Genetics ◽  
1982 ◽  
Vol 101 (3-4) ◽  
pp. 417-429
Author(s):  
Nita N Scobie ◽  
Henry E Schaffer

ABSTRACT A set of 1,000 "mutation accumulation" lines of Drosophila melanogaster, which originated from two different wild-type, lethal-bearing second chromosomes (Yamaguchi and Mukai 1974; Mukai and Cockerham 1977), was examined for evidence of a mutator factor by using the occurrence of recessive visible mutations and male recombination to identify its presence. The 1,000 lines were screened at approximately generation 240 for the presence of recessive visible mutations at twelve loci, by outcrossing to a balanced multiply marked second chromosome stock (Muller's "12ple" Bowling Green). Twenty-three lines were found to carry a visible mutation at one of the loci. Seventeen of these lines carried a mutation of either the dp or the vg locus. Mutations found in three lines, two at the dp locus and one at the vg locus, demonstrated instability as revertants to the wild type and were recovered and verified in these three cases. The three revertant lines, and three lines showing no reversion, were tested for their ability to induce male recombination. Male recombination was observed in the three lines in which revertants were recovered. Male and female sterility assays indicated conclusively that these "hybrid dysgenic" characteristics could not be used to identify lines potentially carrying mutator factors, whereas the consistent ability of the lines to induce high rates of reversion and male recombination was successful in determining that the "mutation accumulation lines" do possess mutator factors.


Genetics ◽  
1985 ◽  
Vol 109 (1) ◽  
pp. 95-117
Author(s):  
Stephen B Daniels ◽  
Margaret McCarron ◽  
Carol Love ◽  
Arthur Chovnick

ABSTRACT Utilizing the method of P-M hybrid dysgenesis-mediated gene transfer to insert rosy locus DNA into various chromosomal locations, we recovered a transformed strain that carries an ry  + transposon inserted in or near the scalloped locus in polytene section 13F on the Χ chromosome. The resultant product, when stabilized, behaves as a homozygous and hemizygous viable and fertile extreme scalloped allele associated with wild-type expression of the rosy locus. We have labeled this allele, sdry+  +. This allele has been destabilized by subsequent P-M hybrid dysgenesis, and mutations were recovered that exhibit alterations in the rosy and/or scalloped phenotypes. Representative samples of all phenotypic classes have been characterized by Southern blot analyses of restricted DNA. The most common events are excisions of DNA wholly internal to the transposon and representing sections of rosy DNA. In addition to loss of rosy locus function, such excisions affect the scalloped locus expression.—A second dysgenesis experiment was carried out involving an ry  + transposon inserted in polytene section 16D on the Χ chromosome. A minimal estimate of the relative frequency of imprecise excisions, determined in this experiment is 75%.—A successful pilot experiment is described that utilizes dysgenic perturbation of the sdryry  + allele to select for small deletions of the 5' noncoding region of the rosy locus.


1986 ◽  
Vol 6 (5) ◽  
pp. 1520-1528
Author(s):  
D Y Chang ◽  
B Wisely ◽  
S M Huang ◽  
R A Voelker

A hybrid dysgenesis-induced allele [su(s)w20] associated with a P-element insertion was used to clone sequences from the su(s) region of Drosophila melanogaster by means of the transposon-tagging technique. Cloned sequences were used to probe restriction enzyme-digested DNAs from 22 other su(s) mutations. None of three X-ray-induced or six ethyl methanesulfonate-induced su(s) mutations possessed detectable variation. Seven spontaneous, four hybrid dysgenesis-induced, and two DNA transformation-induced mutations were associated with insertions within 2.0 kilobases (kb) of the su(s)w20 P-element insertion site. When the region of DNA that included the mutational insertions was used to probe poly(A)+ RNAs, a 5-kb message was detected in wild-type RNA that was present in greatly reduced amounts in two su(s) mutations. By using strand-specific probes, the direction of transcription of the 5-kb message was determined. The mutational insertions lie in DNA sequences near the 5' end of the 5-kb message. Three of the seven spontaneous su(s) mutations are associated with gypsy insertions, but they are not suppressible by su(Hw).


Genetics ◽  
1986 ◽  
Vol 114 (3) ◽  
pp. 897-918
Author(s):  
Gail M Simmons

ABSTRACT Three populations of Drosophila melanogaster from northern California were surveyed for the ability to produce and resist gonadal dysgenesis in the P-M system of hybrid dysgenesis. Males from all three populations produced low to moderate levels of gonadal dysgenesis in crosses to Oregon-R M females. Most females had the P cytotype, but the M cytotype occurred occasionally. The three populations could not be statistically differentiated from one another, but were easily distinguished from populations from Australia and Wisconsin on the basis of gonadal dysgenesis potential. The California populations had higher levels of M cytotype than did the Wisconsin population. Thirteen Χ chromosomes and 11 pairs of autosomes were extracted from one of the California populations, using a modification of the standard balancer chromosome technique to suppress hybrid dysgenesis during extraction. All lines produced strongly skewed sterility distributions in crosses to M-strain females, and mean levels of sterility were less than 50%. There was evidence of nonadditive interactions between the autosomes. Most extraction lines had the P cytotype, but M and intermediate cytotypes were observed. Some of the intermediate cytotypes were stable over time. Lines were tested at two different times after extraction. Some lines evolved higher sterility potential as they were kept in the laboratory, even in the presence of P cytotype. The results point out a number of deficiencies in current genetic and population genetic models of hybrid dysgenesis and imply that gonadal dysgenesis is unlikely to be an important evolutionary force in this population.


Genetics ◽  
1996 ◽  
Vol 143 (3) ◽  
pp. 1339-1347
Author(s):  
Alfred M Handler ◽  
Sheilachu P Gomez

Abstract Function of the Drosophila melanogaster hobo transposon in tephritid species was tested in transient embryonic excision assays. Wild-type and mutant strains of Anastrepha suspensa, Bactrocera dorsalis, B. cucurbitae, Ceratitis capitata, and Toxotrypana curvicauda all supported hobo excision or deletion both in the presence and absence of co-injected hobo transposase, indicating a permissive state for hobo mobility and the existence of endogenous systems capable of mobilizing hobo. In several strains hobo helper reduced excision. Excision depended on hobo sequences in the indicator plasmid, though almost all excisions were imprecise and the mobilizing systems appear mechanistically different from hobo. hobe-related sequences were identified in all species except T. curvicauda. Parsimony analysis yielded a subgroup including the B. cucurbitae and C. capitata sequences along with hobo and Hermes, and a separate, more divergent subgroup including the A. suspensa and B. dorsalis sequences. All of the sequences exist as multiple genomic elements, and a deleted form of the B. cucurbitae element exists in B. dorsalis. The hobo-related sequences are probably members of the hAT transposon family with some evolving from distant ancestor elements, while others may have originated from more recent horizontal transfers.


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