P-element-induced male recombination can be produced in Drosophila melanogaster by combining end-deficient elements in trans.

Abstract Male recombination, not normally present in Drosophila melanogaster, can be produced at high rates when target P elements at homologous sites are combined in the presence of transposase protein. We have produced a set of elements by in situ deletion of a particular insertion and have found elements that have deletions stretching into either end. Elements were tested in pairs to see whether they complement each other in their ability to induce recombination. The combination of elements that are deficient for the same end produces very little recombination, but the combination of a right-end and a left-end element can generate recombination values higher than given by two complete P[CaSpeR] elements at homologous sites. This strongly suggests that "hybrid" P elements, containing ends from two different elements, can be recognized by transposase protein. We have also examined genotypes containing a normal and an end-deficient element and found that they yield reasonably high levels of recombination. We interpret the resultant gametes from such genotypes as showing that the majority of events in this genotype derive from the association of complementary ends from the same element, whereas the complementary ends from elements in trans associate in only a minority of cases.

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Chromosome interactions in P-M dysgenic male recombination of Drosophila melanogaster

Genetics Research ◽

10.1017/s0016672300030913 ◽

1992 ◽

Vol 60 (3) ◽

pp. 165-174

Author(s):

P. Eggleston ◽

K. A. Exley

Keyword(s):

Drosophila Melanogaster ◽

Recombination Breakpoint ◽

P Element ◽

Chromosome 2 ◽

Male Recombination ◽

P Elements ◽

Element Array ◽

Recombination Breakpoints ◽

Map Distance

SummaryThe frequency, distribution and structure of P elements on the second and third chromosomes of Texas 1, a wild-type inbred strain of Drosophila melanogaster, were investigated by in situ hybridization. These autosomes were isolated individually and used as P-element donors to study the frequency and distribution of male recombination events generated on recipient chromosomes which were originally devoid of P sequences. The P-element array of chromosome 2 was shown to generate higher male recombination frequencies on chromosome 3 than vice versa, despite having fewer P factors and fewer P elements in general. This is likely to be due to the presence and distribution of specific P-deletion derivatives, which vary in their ability to repress P mobility. The male recombination generated on recipient chromosomes is associated with the insertion of donated P sequences, but only in a small minority of cases could a novel P-element site be detected at, or near, the recombination breakpoint. The majority of such breakpoints appear to be associated either with unsuccessful P insertion, or with the action of P transposase attracted by P elements newly inserted elsewhere on the recipient chromosome. Recent evidence also suggests that a small proportion of the breakpoints may be associated with the action of P transposase alone. Male recombination breakpoints appear to be distributed effectively at random along the recipient autosomes, and their frequency of occurrence was shown to correlate with the physical length of DNA available between markers, as revealed by the polytene map distance.

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The relationship between P elements and male recombination in Drosophila melanogaster.

Genetics ◽

10.1093/genetics/124.2.317 ◽

1990 ◽

Vol 124 (2) ◽

pp. 317-329

Author(s):

A Duttaroy ◽

M McCarron ◽

K Sitaraman ◽

G Doughty ◽

A Chovnick

Keyword(s):

Drosophila Melanogaster ◽

Hot Spot ◽

The Other ◽

P Element ◽

Male Recombination ◽

P Elements ◽

Selective System ◽

Element Mobilization ◽

The Relationship ◽

Initial Binding

Abstract P element dysgenesis associated male recombination in Drosophila was examined with a selective system focused upon 5% of the standard female genetic map divided into eight recombination segments. We found no correspondence between P element mobilization events and recombination in males in the intervals monitored. We defined two adjacent short genetic and molecular regions, one devoid of male recombination and the other acting as a "hot spot" for exchange in the absence of supporting P element insertion and excision activity. These data suggest that, even in the presence of mobilizing P elements, transposase may be active at non-P element sites, and that the genome may harbor sequences ranging from highly responsive to completely unresponsive to transposase action. A viewpoint is presented wherein P elements, with sequences that bind transposase, serve to focus the recombination action of transposase to encompass a region of DNA radiating outward from the initial binding site. We suggest that this region is measured in terms of chromosomal segments rather than limited to P element sequences.

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Germ-line and somatic recombination induced by in vitro modified P elements in Drosophila melanogaster.

Genetics ◽

10.1093/genetics/124.2.331 ◽

1990 ◽

Vol 124 (2) ◽

pp. 331-337 ◽

Cited By ~ 2

Author(s):

J A Sved ◽

W B Eggleston ◽

W R Engels

Keyword(s):

Drosophila Melanogaster ◽

Germ Line ◽

Somatic Cells ◽

Chromosome Breakage ◽

P Element ◽

Male Germ Line ◽

Male Recombination ◽

P Elements ◽

Somatic Recombination

Abstract The P element insertion delta 2-3(99B) has previously been shown to activate incomplete P elements elsewhere in the genome. We show that this element, in conjunction with a second incomplete P element, P[CaSpeR], also induces recombination in the male germ line. The recombination is induced preferentially in the region of the P[CaSpeR] element. Recombinant chromosomes contain the P[CaSpeR] element in more than 50% of cases, and alternative models of transposon replication and preferential chromosome breakage are put forward to explain this finding. As is the case with male recombination induced by P-M dysgenic crosses, recombination appears to be premeiotic in a high proportion of cases. The delta 2-3(99B) element is known to act in somatic cells. Correspondingly, we show that the delta 2-3(99B)-P[CaSpeR] combination elevates the incidence of somatic recombination.

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Localization of P elements, copy number regulation, and cytotype determination in Drosophila melanogaster

Genetics Research ◽

10.1017/s0016672300028822 ◽

1990 ◽

Vol 56 (1) ◽

pp. 3-14 ◽

Cited By ~ 35

Author(s):

C. Biémont ◽

S. Ronsseray ◽

D. Anxolabéhère ◽

H. Izaabel ◽

C. Gautier

Keyword(s):

Drosophila Melanogaster ◽

Copy Number ◽

Chromosomal Location ◽

Inbred Lines ◽

P Element ◽

P Elements ◽

Left And Right ◽

Element Activity ◽

Copy Number Regulation

SummarySeventeen highly-inbred lines of Drosophila melanogaster extracted from an M′ strain (in the P/M system of hybrid dysgenesis) were studied for their cytotype and the number and chromosomal location of complete and defective P elements. While most lines were of M cytotype, three presented a P cytotype (the condition that represses P-element activity) and one was intermediate between M and P. All lines were found to possess K.P elements and only eight to bear full-sized P elements. Only the lines with full-sized P elements showed detectable changes in their P-insertion pattern over generations; their rates of gain and of loss of P-element sites were equal to 0·12 and 0·09 per genome, per generation, respectively. There was no correlation between these two rates within lines, suggesting independent transpositions and excisions in the inbred genomes. The results of both Southern blot analysis and in situ hybridization of probes made from left and right sides of the P element strongly suggested the presence of a putative complete P element in region 1A of the X chromosome in the three lines with a P cytotype; the absence of P copy in this 1A region in lines with an M cytotype, favours the hypothesis that the P element inserted in 1A could play a major role in the P-cytotype determination. Insertion of a defective 2 kb P element was also observed in region 93F in 9 of the 13 M lines. The regulation of the P-element copy number in our lines appeared not to be associated with the ratio of full-length and defective P elements.

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P-Element-Induced Recombination in Drosophila melanogaster: Hybrid Element Insertion

Genetics ◽

10.1093/genetics/144.4.1601 ◽

1996 ◽

Vol 144 (4) ◽

pp. 1601-1610 ◽

Cited By ~ 4

Author(s):

Yasmine H M Gray ◽

Mark M Tanaka ◽

John A Sved

Keyword(s):

Single Unit ◽

Target Site ◽

P Element ◽

High Tendency ◽

Male Recombination ◽

P Elements ◽

Element Insertion ◽

Hybrid Element ◽

In Trans ◽

The Right

It has previously been shown that the combination of two deleted P elements in trans, one containing the left functional end and the second element the right functional end, can lead to high levels of male recombination. This finding strongly suggests that P-element, ends from different chromosomes can become associated, followed by “pseudo-excision.” We show that two different processes are involved in resolving the pseudo-excision event: (1) the excised P-element ends continue to function as a single unit (Hybrid Element) and insert at a nearby site in the chromosome or into the element itself [Hybrid Element Insertion (HEI)] and (2) free ends that do not contain P elements repair and rejoin [(Hybrid Excision and Repair (HER)]. Both types of resolution can lead to recombination, and this paper concentrates on the HEI class. One type of HEI event predicts the exact reverse complementary duplication of an 8-bp target site, and we have confirmed the existence of such a structure in six independently derived recombinant chromosomes. There is also a high tendency for insertion events to occur within a few bases of the original 8-bp target site, including six apparent cases of insertion into the exact site.

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Targeted transposition at the vestigial locus of Drosophila melanogaster.

Genetics ◽

10.1093/genetics/138.4.1127 ◽

1994 ◽

Vol 138 (4) ◽

pp. 1127-1135

Author(s):

T R Heslip ◽

R B Hodgetts

Keyword(s):

Drosophila Melanogaster ◽

Position Effect ◽

Regulatory Region ◽

Current Method ◽

P Element ◽

Opposite Orientation ◽

Position Effects ◽

P Elements ◽

In Trans ◽

In Cis

Abstract Targeted transposition is the replacement of one P element with another. We are exploiting this unique property of P elements to study the complex regulatory domain of the Dopa decarboxylase (Ddc) gene in Drosophila melanogaster. P element constructs targeted to the same site in the genome will be subjected to the same position effect. This allows the subtle effects typical of most mutations in the Ddc regulatory region to be measured in the absence of the variable influences of position effects which are associated with the current method of germline transformation. We have investigated some of the parameters affecting targeted transposition of a Ddc transposon, P[Ddc], into a P element allele at the vestigial locus. These events were detected by an increased mutant vg phenotype. The location of the donor transposon in cis or in trans to the target had little effect on the frequency of targeting. Likewise, the mobility of different donor elements, as measured by their rate of transposition to a different chromosome, varied nearly 20-fold, while the rate of targeted transposition was very similar between them. All targeted alleles were precise replacements of the target P element by P[Ddc], but in several cases the donor was inserted in the opposite orientation. The targeted alleles could be described as the result of a replicative, conversion-like event.

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The maternally inherited regulation of P elements in Drosophila melanogaster can be elicited by two P copies at cytological site 1A on the X chromosome.

Genetics ◽

10.1093/genetics/129.2.501 ◽

1991 ◽

Vol 129 (2) ◽

pp. 501-512 ◽

Cited By ~ 5

Author(s):

S Ronsseray ◽

M Lehmann ◽

D Anxolabéhère

Keyword(s):

Drosophila Melanogaster ◽

X Chromosome ◽

P Element ◽

P Elements ◽

Element Activity ◽

High Level ◽

Regulatory Properties ◽

Cellular Condition

Abstract Two P elements, inserted at the cytological site 1A on an X chromosome from an Drosophila melanogaster natural population (Lerik, USSR), were isolated by genetic methods to determine if they are sufficient to cause the P cytotype, the cellular condition that regulates the P family of transposable element. The resulting "Lerik P(1A)" line (abbreviated "Lk-P(1A)") carries only one P element in situ hybridization site but genomic Southern analysis indicates that this site contains two, probably full length, P copies separated by at least one EcoRI cleavage site. Because the Lk-P(1A) line shows some transposase activity, at least one of these two P elements is autonomous. The Lk-P(1A) line fully represses germline P element activity as judged by the GD sterility and snw hypermutability assays; this result shows that the P cytotype can be elicited by only two P element copies. However, the Lk-P(1A) line does not fully repress delta 2-3(99B) transposase activity in the soma, although it fully represses delta 2-3(99B) transposase activity in the germline (delta 2-3(99B) is an in vitro modified P element that produces a high level of transposase activity in both the germline and the soma). The germline regulatory properties of the Lk-P(1A) line are maternally transmitted, even when the delta 2-3(99B) element is used as the source of transposase. By contrast, the partial regulation of delta 2-3(99B) somatic activity is chromosomally inherited. These results suggest that the regulatory P elements of the Lk-P(1A) line are inserted near a germline-specific enhancer.

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Structure, frequency and distribution of P elements in relation to P—M hybrid dysgenic male recombination in Drosophila melanogaster

Genetics Research ◽

10.1017/s0016672300028123 ◽

1989 ◽

Vol 53 (3) ◽

pp. 163-171 ◽

Cited By ~ 1

Author(s):

K. A. Exley ◽

P. Eggleston

Keyword(s):

Drosophila Melanogaster ◽

Egg Production ◽

Polytene Chromosomes ◽

Element Distribution ◽

Hybrid Dysgenesis ◽

P Element ◽

Male Recombination ◽

P Elements ◽

Egg Hatchability ◽

The Third

SummaryThe frequency and distribution of P elements were investigated in the third chromosomes of two wild-type strains of Drosophila melanogaster using in situ hybridization of biotinylated probes to the polytene chromosomes. The relationship between these data and the extent of hybrid dysgenesis was determined through assays of egg production, egg hatchability (F2 embryo lethality), snw destabilization and male recombination along the third chromosome. The results suggest that P-element distribution, frequency and structure are all contributory factors in the regulation of hybrid dysgenesis. Texas 6 was shown consistently to be a stronger P strain than Texas 1, eliciting greater reductions in fertility, more extensive snw destabilization and higher frequencies of male recombination. Clustering of male recombination events, arising from pre-meiotic crossing over, was evident among the dysgenic progeny of each strain. Male recombination and snw destabilization were independently distributed among the dysgenic males studied, suggesting that these traits represent separate P-mediated functions. The third chromosome male recombination maps produced by the two strains differed significantly from each other and from the published female meiotic and polytene chromosome maps. Male recombination breakpoints were associated with the original distribution of P sequences in the two strains and the results suggest that this relationship may be closer for potentially complete P factors than for P sequences in general. An analysis of sub-lines derived from individual recombinant males revealed that chromosomal breakpoints could also be associated with novel insertions following P-element transposition.

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Transposable element-induced response to artificial selection in Drosophila melanogaster: molecular analysis of selection lines.

Genetics ◽

10.1093/genetics/125.4.803 ◽

1990 ◽

Vol 125 (4) ◽

pp. 803-811 ◽

Cited By ~ 1

Author(s):

A E Shrimpton ◽

T F Mackay ◽

A J Brown

Keyword(s):

Drosophila Melanogaster ◽

Artificial Selection ◽

Genetic Variance ◽

Selection Response ◽

P Element ◽

Induced Response ◽

Phenotypic Variance ◽

P Elements ◽

Insertion Sites

Abstract Artificial selection lines for abdominal bristle score of Drosophila melanogaster established from P-M hybrid dysgenic crosses showed increases in selection response, heritability and phenotypic variance compared to similar lines started from nondysgenic crosses. To determine whether this increased genetic variance could be due to enhanced transposition of P elements following the dysgenic cross, the cytological locations (sites) of P elements were determined by in situ hybridization for the whole genome of samples of 20 individuals from the parental P strain, 20 individuals from each of the eight dysgenic selection lines, and ten individuals from each of the eight nondysgenic selection lines. Variation among and within the selection lines and the parental P strain in P element insertion sites was exceptionally high. A total of 601 sites were identified, but there was no difference in total number of sites per line, mean number of sites per individual, mean copy number per individual, or site frequency between dysgenic and nondysgenic selection lines, or between lines selected for high and low bristle score. Transposition following nondysgenic crosses may explain additional observations of accelerated selection responses in nondysgenic selection lines. It was not possible to deduce which, if any, of the several hundred insertions in the dysgenic selection lines were responsible for their extreme bristle phenotypes.

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P-Element Repression in Drosophila melanogaster by Variegating Clusters of P-lacZ-white Transgenes

Genetics ◽

10.1093/genetics/159.4.1631 ◽

2001 ◽

Vol 159 (4) ◽

pp. 1631-1642 ◽

Cited By ~ 4

Author(s):

Stéphane Ronsseray ◽

Antoine Boivin ◽

Dominique Anxolabéhère

Keyword(s):

Drosophila Melanogaster ◽

X Chromosome ◽

Maternal Effect ◽

P Element ◽

Lacz Reporter ◽

X Ray ◽

Subtelomeric Heterochromatin ◽

P Elements ◽

In Trans ◽

Element Activity

Abstract In Drosophila, clusters of P transgenes (P-lac-w) display a variegating phenotype for the w marker. In addition, X-ray-induced rearrangements of chromosomes bearing such clusters may lead to enhancement of the variegated phenotype. Since P-lacZ transgenes in subtelomeric heterochromatin have some P-element repression abilities, we tested whether P-lac-w clusters also have the capacity to repress P-element activity in the germline. One cluster (T-1), located on a rearranged chromosome (T2;3) and derived from a line bearing a variegating tandem array of seven P-lac-w elements, partially represses the dysgenic sterility (GD sterility) induced by P elements. This cluster also strongly represses in trans the expression of P-lacZ elements in the germline. This latter suppression shows a maternal effect. Finally, the combination of variegating P-lac-w clusters and a single P-lacZ reporter inserted in subtelomeric heterochromatic sequences at the X chromosome telomere (cytological site 1A) leads to strong repression of dysgenic sterility. These results show that repression of P-induced dysgenic sterility can be elicited in the absence of P elements encoding a polypeptide repressor and that a transgene cluster can repress the expression of a single homologous transgene at a nonallelic position. Implications for models of transposable element silencing are discussed.

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