scholarly journals P element transposition contributes substantial new variation for a quantitative trait in Drosophila melanogaster.

Genetics ◽  
1992 ◽  
Vol 131 (1) ◽  
pp. 73-78
Author(s):  
A Torkamanzehi ◽  
C Moran ◽  
F W Nicholas
Keyword(s):  
Drosophila Melanogaster ◽  
Quantitative Trait ◽  
Spontaneous Mutation ◽  
Additive Genetic Variance ◽  
P Element ◽  
Response To Selection ◽  
Stock Selection ◽  
Bristle Number ◽  
Cumulative Response ◽  
Cumulative Selection

Abstract The P-M system of transposition in Drosophila melanogaster is a powerful mutator for many visible and lethal loci. Experiments using crosses between unrelated P and M stocks to assess the importance of transposition-mediated mutations affecting quantitative loci and response to selection have yielded unrepeatable or ambiguous results. In a different approach, we have used a P stock produced by microinjection of the ry506 M stock. Selection responses were compared between transposition lines that were initiated by crossing M strain females with males from the "co-isogenic" P strain, and ry506 M control lines. Unlike previous attempts to quantify the effects of P element transposition, there is no possibility of P transposition in the controls. During 10 generations of selection for the quantitative trait abdominal bristle number, none of the four control lines showed any response to selection, indicative of isogenicity for those loci affecting abdominal bristle number. In contrast, three of the four transposition lines showed substantial response, with regression of cumulative response on cumulative selection differential ranging from 15% to 25%. Transposition of P elements has produced new additive genetic variance at a rate which is more than 30 times greater than the rate expected from spontaneous mutation.

scholarly journals P-element-induced mutation and quantitative variation in Drosophila melanogaster: lack of enhanced response to selection in lines derived from dysgenic crosses.

1988 ◽  
Vol 51 (3) ◽  
pp. 231-238 ◽  
Author(s):  
A. Torkamanzehi ◽  
C. Moran ◽  
F. W. Nicholas
Keyword(s):  
Drosophila Melanogaster ◽  
Phenotypic Variation ◽  
Quantitative Variation ◽  
P Element ◽  
Response To Selection ◽  
Induced Mutation ◽  
Bristle Number ◽  
Reciprocal Crossing

SummaryDysgenic and non-dysgenic base populations were made by reciprocal crossing of Harwich (P) and Canton-S (M) strains. From each cross, two up and two down selection lines were established, with selection on abdominal bristle number for ten generations. The intensity of selection was 10 out of 50 individuals from each sex. Mean bristle number, phenotypic variation and heritabilities were compared between dysgenic and non-dysgenic populations under selection. Except for an anomalous non-dysgenic downline in which a mutation of large effect occurred, all lines showed similar responses to selection. These results contrast with the results reported by Mackay (1984, 1985) in which substantial increases were obtained for response to selection, phenotypic variation and heritability in the dysgenic compared to non-dysgenic lines. There are some indications that the higher response in our aberrant non-dysgenic downline is the result of transposition. Possible explanations for the occurrence of transposition and dysgenesis in the lines derived from nondysgenic crosses are discussed.

Effects of Single P-Element Insertions on Bristle Number and Viability in Drosophila melanogaster

Genetics ◽  
1996 ◽  
Vol 143 (1) ◽  
pp. 277-292 ◽  
Author(s):  
Richard F Lyman ◽  
Faye Lawrence ◽  
Sergey V Nuzhdin ◽  
Trudy F C Mackay
Keyword(s):  
Drosophila Melanogaster ◽  
Quantitative Trait Loci ◽  
Quantitative Trait ◽  
Genetic Locus ◽  
P Element ◽  
Powerful Method ◽  
Spontaneous Mutations ◽  
Absolute Value ◽  
P Elements ◽  
Bristle Number

Abstract Single P-element mutagenesis was used to construct 1094 lines with P[lArB] inserts on all three major chromosomes in an isogenic background previously free of P elements. The effects of insertions on bristle number and on viability were assessed by comparison to 392 control lines. The variance and effects of P-element inserts on bristle number and viability were larger than those inferred from spontaneous mutations. The distributions of effects on bristle number were symmetrical and highly leptokurtic, such that a few inserts with large effects caused most of the increase in variance. The distribution of effects on viability were negatively skewed and platykurtic. On average, the effects of P-element insertions on bristle number were partly recessive and on viability were completely recessive. P-element inserts with large effects on bristle number tended to have reduced viability, but the correlation between the absolute value of the effects on bristle number and on viability was not strong. Fifty P-element inserts tagging quantitative trait loci (QTLs) with large effects on bristle number were mapped cytogenetically. Two P-element-induced scabrous alleles and five extramacrochaetae alleles were generated. Single P-element mutagenesis is a powerful method for identifylng QTLs at the level of genetic locus.

scholarly journals Genetic and Molecular Analysis of smooth, a Quantitative Trait Locus Affecting Bristle Number in Drosophila melanogaster

Genetics ◽  
1997 ◽  
Vol 146 (2) ◽  
pp. 607-618
Author(s):  
Petra zur Lage ◽  
Antony D Shrimpton ◽  
Andrew J Flavell ◽  
Trudy F C Mackay ◽  
Andrew J Leigh Brown
Keyword(s):  
Quantitative Trait Locus ◽  
Quantitative Trait ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Allelic Variation ◽  
P Element ◽  
Selection Line ◽  
Element Insertion ◽  
Bristle Number ◽  
Trait Locus

A semi-lethal, sterile allele of the smooth locus (2-91.5), sm3, was discovered in an artificial selection line for low abdominal bristle number that had been started from a P-M dysgenic cross. The fitness effects and extremely low bristle number phenotype of the allele could not be separated by recombination from a P-element insertion at cytological location 56E, and precise excision of the P element at this site was associated with reversion to wild type. The smooth gene was cloned using the P-element insertion as a tag. The gene encodes a 2.6-kb transcript derived from 10 exons and covers a genomic region of at least 80 kb. The Drosophila smooth gene shares substantial sequence identity with a group of RNA binding proteins, with the closest relationship being to the human heterogeneous nuclear ribonucleoprotein L gene. The smooth gene is by definition an abdominal bristle number quantitative trait locus, but further work is required to discern whether naturally occurring allelic variation at this locus is a source of genetic variation for abdominal bristle number in natural populations.

scholarly journals Response to Selection in Synthetic Lines of Drosophila Melanogaster

1973 ◽  
Vol 26 (3) ◽  
pp. 613 ◽  
Author(s):  
RR Howe ◽  
JW James
Keyword(s):  
Drosophila Melanogaster ◽  
Base Population ◽  
Response To Selection ◽  
Bristle Number ◽  
Experimental Analyses

Response to selection in synthetic lines has been examined by both theoretical and experimental analyses. Synthetic lines were founded from 20 base lines of D. melanogaster all derived from the same base population and which had been selected for high sternopleural bristle number.

Mutations in ash1 and trx enhance P-element-dependent silencing in Drosophila melanogaster

Genome ◽  
2016 ◽  
Vol 59 (8) ◽  
pp. 527-540
Author(s):  
Allen McCracken ◽  
John Locke
Keyword(s):  
Drosophila Melanogaster ◽  
Spontaneous Mutation ◽  
Position Effect ◽  
P Element ◽  
Position Effect Variegation ◽  
Genetic Modifiers ◽  
Gypsy Element ◽  
P Elements ◽  
Opposite Action ◽  
Dose Dependent

In Drosophila melanogaster, the mini-w+ transgene in Pci is normally expressed throughout the adult eye; however, when other P or KP elements are present, a variegated-eye phenotype results, indicating random w+ silencing during development called P-element-dependent silencing (PDS). Mutant Su(var)205 and Su(var)3-7 alleles act as haplo-suppressors/triplo-enhancers of this variegated phenotype, indicating that these heterochromatic modifiers act dose dependently in PDS. Previously, we recovered a spontaneous mutation of P{lacW}ciDplac called P{lacW}ciDplacE1 (E1) that variegated in the absence of P elements, presumably due to the insertion of an adjacent gypsy element. From a screen for genetic modifiers of E1 variegation, we describe here the isolation of five mutations in ash1 and three in trx that enhance the E1 variegated phenotype in a dose-dependent and cumulative manner. These mutant alleles enhance PDS at E1, and in E1/P{lacW}ciDplac, but suppress position effect variegation (PEV) at In(1)wm4. This opposite action is consistent with a model where ASH1 and TRX mark transcriptionally active chromatin domains. If ASH1 or TRX function is lost or reduced, heterochromatin can spread into these domains creating a sink that diverts heterochromatic proteins from other variegating locations, which then may express a suppressed phenotype.

scholarly journals Mapping and characterization of P-element-induced mutations at quantitative trait loci in Drosophila melanogaster

1993 ◽  
Vol 61 (3) ◽  
pp. 177-193 ◽  
Author(s):  
Chaoqiang Lai ◽  
Trudy F. C. Mackay
Keyword(s):  
Drosophila Melanogaster ◽  
Physical Mapping ◽  
Hybridization Analysis ◽  
P Element ◽  
Complementation Test ◽  
Induced Mutations ◽  
Element Insertion ◽  
Bristle Number ◽  
Chromosomal Bands

SummaryX chromosomes derived from crosses of inbred P and M Drosophila melanogaster strains that had extreme effects on abdominal and/or sternopleural bristle number in males, were further analyzed to determine their effects in females and to map the loci at which the mutations occurred. Seven lines that had on average 3.9 fewer sternopleural bristles than wildtype in males had average homozygous sternopleural bristle effects of −2·2. The bristle effects were partially recessive, with an average degree of dominance of −0·60. Physical mapping of the sternopleural bristle effects of these lines placed them all at approximately 24·7 cM. These mutations are apparently allelic on the basis of a complementation test, and deficiency mapping indicates they occur within chromosomal bands 8A4; 8C6. In situ hybridization analysis of the sites of P element insertions of these lines suggests that mutations probably resulted from excision of P elements at 8C on the original inbred P strain chromosome. Two additional lines, NDC(19) and DP(146), had reduced numbers of sternopleural and abdominal bristles. NDC(19) males had 9·7 fewer abdominal and 8·6 fewer sternopleural bristles than wildtype. The corresponding homozygous abdominal and sternopleural bristle number effects were −5·8 and −3·8, respectively; with the abdominal bristle effect completely recessive and the sternopleural bristle effect nearly additive. DP(146) males had 6·2 fewer abdominal and 4·1 fewer sternopleural bristles than wildtype, with homozygous abdominal bristle effects of −4·3 and sternopleural bristle effects of −2·0. Abdominal bristle effects of this line were partially recessive whereas the sternopleural bristle effects were additive. Physical mapping showed effects on both bristle traits segregated jointly in these two lines, with the NDC(19) mutation closely linked to y and the DP(146) mutation 0·17 cM from it. Complementation tests and deficiency mapping also indicate the mutations in lines NDC(19) and DP(146) are at closely linked but separate loci within chromosomal bands 1B2; 1B4–6 and 1B4–6; 1B10 respectively, with some epistatic effects. In situ hybridization analysis of sites of P element insertion suggest that the NDC(19) mutation, which may be a scute allele, was probably caused by a P element insertion in the IB region; the DP(146) mutation is also associated with an insertion at IB.

scholarly journals Mapping quantitative trait loci affecting sternopleural bristle number in Drosophila melanogaster using changes of marker allele frequencies in divergently selected lines

1998 ◽  
Vol 72 (2) ◽  
pp. 79-91 ◽  
Author(s):  
SERGEY V. NUZHDIN ◽  
PETER D. KEIGHTLEY ◽  
ELENA G. PASYUKOVA ◽  
ELENA A. MOROZOVA
Keyword(s):  
Drosophila Melanogaster ◽  
Quantitative Trait Loci ◽  
Candidate Genes ◽  
Allele Frequency ◽  
Quantitative Trait ◽  
Permutation Test ◽  
Average Distance ◽  
Marker Allele ◽  
Bristle Number ◽  
Trait Loci

Quantitative trait loci (QTLs) responsible for variation in sternopleural bristle number in crosses between the laboratory lines of Drosophila melanogaster OregonR and CantonS were mapped using information from allele frequency changes of two families of retrotransposon markers in divergently selected populations. QTL effects and positions were inferred by likelihood, using transition matrix iteration and Monte Carlo interval mapping. Individuals from the selected populations were genotyped for markers spaced at an average distance 4.4 cM. Four QTLs of moderate effect ranging from 0·6 to 1·32 bristles accounted for most of the selection response. A permutation test of the correspondence between the mapped QTLs and the positions of bristle number candidate genes suggested that alleles at these candidate genes were no more strongly associated with selected changes in marker allele frequency than were randomly chosen positions in the genome.

scholarly journals Genotype-Environment Interaction at Quantitative Trait Loci Affecting Sensory Bristle Number in Drosophila melanogaster

Genetics ◽  
1998 ◽  
Vol 149 (4) ◽  
pp. 1883-1898 ◽  
Author(s):  
Marjorie C Gurganus ◽  
James D Fry ◽  
Sergey V Nuzhdin ◽  
Elena G Pasyukova ◽  
Richard F Lyman ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Quantitative Trait Loci ◽  
Quantitative Trait ◽  
Rank Order ◽  
Recombinant Inbred Lines ◽  
Environment Interaction ◽  
Genotype Environment Interaction ◽  
Bristle Number ◽  
A Genome ◽  
Trait Loci

AbstractThe magnitude of segregating variation for bristle number in Drosophila melanogaster exceeds that predicted from models of mutation-selection balance. To evaluate the hypothesis that genotype-environment interaction (GEI) maintains variation for bristle number in nature, we quantified the extent of GEI for abdominal and sternopleural bristles among 98 recombinant inbred lines, derived from two homozygous laboratory strains, in three temperature environments. There was considerable GEI for both bristle traits, which was mainly attributable to changes in rank order of line means. We conducted a genome-wide screen for quantitative trait loci (QTLs) affecting bristle number in each sex and temperature environment, using a dense (3.2-cM) marker map of polymorphic insertion sites of roo transposable elements. Nine sternopleural and 11 abdominal bristle number QTLs were detected. Significant GEI was exhibited by 14 QTLs, but there was heterogeneity among QTLs in their sensitivity to thermal and sexual environments. To further evaluate the hypothesis that GEI maintains variation for bristle number, we require estimates of allelic effects across environments at genetic loci affecting the traits. This level of resolution may be achievable for Drosophila bristle number because candidate loci affecting bristle development often map to the same location as bristle number QTLs.

scholarly journals Polygenic mutation in Drosophila melanogaster: estimates from response to selection of inbred strains.

Genetics ◽  
1994 ◽  
Vol 136 (3) ◽  
pp. 937-951 ◽  
Author(s):  
T F Mackay ◽  
J D Fry ◽  
R F Lyman ◽  
S V Nuzhdin
Keyword(s):  
Drosophila Melanogaster ◽  
Artificial Selection ◽  
Inbred Strains ◽  
Response To Selection ◽  
Environmental Variance ◽  
Rapid Responses ◽  
Bristle Number ◽  
Mutational Variance ◽  
Selection Of ◽  
New Mutations

Abstract Replicated divergent artificial selection for abdominal and sternopleural bristle number from a highly inbred strain of Drosophila melanogaster resulted in an average divergence after 125 generations of selection of 12.0 abdominal and 8.2 sternopleural bristles from the accumulation of new mutations affecting bristle number. Responses to selection were highly asymmetrical, with greater responses for low abdominal and high sternopleural bristle numbers. Estimates of VM, the mutational variance arising per generation, based on the infinitesimal model and averaged over the responses to the first 25 generations of selection, were 4.32 x 10(-3) VE for abdominal bristle number and 3.66 x 10(-3) VE for sternopleural bristle number, where VE is the environmental variance. Based on 10 generations of divergent selection within lines from generation 93, VM for abdominal bristle number was 6.75 x 10(-3) VE and for sternopleural bristle number was 5.31 x 10(-3) VE. However, estimates of VM using the entire 125 generations of response to selection were lower and generally did not fit the infinitesimal model largely because the observed decelerating responses were not compatible with the predicted increasing genetic variance over time. These decelerating responses, periods of response in the opposite direction to artificial selection, and rapid responses to reverse selection all suggest new mutations affecting bristle number on average have deleterious effects on fitness. Commonly observed periods of accelerated responses followed by long periods of stasis suggest a leptokurtic distribution of mutational effects for bristles.

scholarly journals Effects of P element insertions on quantitative traits in Drosophila melanogaster.

Genetics ◽  
1992 ◽  
Vol 130 (2) ◽  
pp. 315-332 ◽  
Author(s):  
T F Mackay ◽  
R F Lyman ◽  
M S Jackson
Keyword(s):  
Drosophila Melanogaster ◽  
Quantitative Traits ◽  
P Element ◽  
Host Strain ◽  
Sex Dimorphism ◽  
Environmental Variance ◽  
P Elements ◽  
Lethal Mutations ◽  
Bristle Number ◽  
Recessive Effects

Abstract P element mutagenesis was used to construct 94 third chromosome lines of Drosophila melanogaster which contained on average 3.1 stable P element inserts, in an inbred host strain background previously free of P elements. The homozygous and heterozygous effects of the inserts on viability and abdominal and sternopleural bristle number were ascertained by comparing the chromosome lines with inserts to insert-free control lines of the inbred host strain. P elements reduced average homozygous viability by 12.2% per insert and average heterozygous viability by 5.5% per insert, and induced recessive lethal mutations at a rate of 3.8% per insert. Mutational variation for the bristle traits averaged over both sexes was 0.03Ve per homozygous P insert and 0.003Ve per heterozygous P insert, where Ve is the environmental variance. Mutational variation was greater for the sexes considered separately because inserts had large pleiotropic effects on sex dimorphism of bristle characters. The distributions of homozygous effects of inserts on the bristle traits were asymmetrical, with the largest effects in the direction of reducing bristle number; and highly leptokurtic, with most of the increase in variance contributed by a few lines with large effects. The inserts had partially recessive effects on the bristle traits. Insert lines with extreme bristle effects had on average greatly reduced viability.

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