Comparison of the regulation of P elements in M and M′ strains of Drosophila melanogaster

SummaryM and M′ strains of Drosophila melanogaster in the P-M system of hybrid dysgenesis were compared in two series of tests, with the following results. (1) The singed-weak hypermutability regulation test showed that M′ strains had lower P excision rates than M strains, suggesting that P-elements repression must occur in M′ strains although it is not detectable by gonadal dysgenesis assays. (2) The evolution of mixed P + M and mixed P + M′ populations was compared, using a strong P strain. The P + M cultures invariably evolved in a few generations into strong P cultures, while the P + M′ cultures evolved into P-type cultures with reduced P-factor potentials. However, after 30 generations of culture, both these types of mixed cultures had similar P copy numbers, suggesting that regulation of copy number had occurred in them.

Download Full-text

Repression of P element-mediated hybrid dysgenesis in Drosophila melanogaster.

Genetics ◽

10.1093/genetics/124.3.663 ◽

1990 ◽

Vol 124 (3) ◽

pp. 663-676 ◽

Cited By ~ 2

Author(s):

M J Simmons ◽

J D Raymond ◽

K E Rasmusson ◽

L M Miller ◽

C F McLarnon ◽

...

Keyword(s):

Drosophila Melanogaster ◽

Maternal Effect ◽

Gonadal Dysgenesis ◽

De Novo ◽

Inbred Lines ◽

Hybrid Dysgenesis ◽

P Element ◽

P Elements ◽

Hybrid Offspring ◽

Element Movement

Abstract Inbred lines derived from a strain called Sexi were analyzed for their abilities to repress P element-mediated gonadal dysgenesis. One line had high repression ability, four had intermediate ability and two had very low ability. The four intermediate lines also exhibited considerable within-line variation for this trait; furthermore, in at least two cases, this variation could not be attributed to recurring P element movement. Repression of gonadal dysgenesis in the hybrid offspring of all seven lines was due primarily to a maternal effect; there was no evidence for repression arising de novo in the hybrids themselves. In one of the lines, repression ability was inherited maternally, indicating the involvement of cytoplasmic factors. In three other lines, repression ability appeared to be determined by partially dominant or additive chromosomal factors; however, there was also evidence for a maternal effect that reduced the expression of these factors in at least two of the lines. In another line, repression ability seemed to be due to recessive chromosomal factors. All seven lines possessed numerous copies of a particular P element, called KP, which has been hypothesized to produce a polypeptide repressor of gonadal dysgenesis. This hypothesis, however, does not explain why the inbred Sexi lines varied so much in their repression abilities. It is suggested that some of this variation may be due to differences in the chromosomal position of the KP elements, or that other nonautonomous P elements are involved in the repression of hybrid dysgenesis in these lines.

Download Full-text

Genetic and molecular analysis of repression in the P–M system of hybrid dysgenesis in Drosophila melanogaster

Genetics Research ◽

10.1017/s0016672300029360 ◽

1991 ◽

Vol 57 (3) ◽

pp. 213-226 ◽

Cited By ~ 8

Author(s):

Ellen M. Heath ◽

Michael J. Simmons

Keyword(s):

Drosophila Melanogaster ◽

Maternal Effects ◽

X Chromosome ◽

Gonadal Dysgenesis ◽

Inbred Lines ◽

Hybrid Dysgenesis ◽

P Element ◽

P Elements ◽

Two Generations ◽

Highly Correlated

SummaryTwelve inbred lines derived from an M′ strain of Drosophila melanogaster were used to study the repression of P-element-mediated hybrid dysgenesis. Initial assessments indicated that the lines differed in the ability to repress gonadal dysgenesis, and that this ability was highly correlated with the ability to repress snw hypermutability. Later assessments indicated that most of the lines with low or intermediate repression potential evolved to a state of higher repression potential; however, Southern analyses failed to reveal significant changes in the array of genomic P elements that could account for this evolution. In addition, none of the lines possessed the incomplete P element known as KP, which has been proposed to explain repression in some D. melanogaster strains. One of the lines maintained intermediate repression potential throughout the period of study (52 generations), indicating that the intermediate condition was not intrinsically unstable. Genetic analyses demonstrated that in some of the lines, repression potential was influenced by factors that were inherited maternally through at least two generations; however, these factors were not as influential as those in a classic P cytotype strain. Additional tests with a dysgenesis-inducing X chromosome called T-5 indicated that repression itself was mediated by a combination of maternal effects and paternally inherited factors that were expressed after fertilization. These tests also suggested that in some circumstances, the P transposase, or its message, might be transmitted through the maternal cytoplasm.

Download Full-text

Hybrid dysgenesis in Drosophila melanogaster: the elimination of P elements through repeated backcrossing to an M-type strain

Genome ◽

10.1139/g87-033 ◽

1987 ◽

Vol 29 (1) ◽

pp. 195-200 ◽

Cited By ~ 2

Author(s):

Allen G. Good ◽

Donal A. Hickey

Keyword(s):

Drosophila Melanogaster ◽

Dna Hybridization ◽

Copy Number ◽

Natural Populations ◽

Hybrid Dysgenesis ◽

P Element ◽

P Elements ◽

Element Activity ◽

Equivalent Reduction ◽

Replicative Transposition

The rapid increase in the frequency of P elements in natural populations of Drosophila melanogaster has led to the suggestion that these elements can spread in nature through replicative transposition. In an attempt to model the introduction of a small number of P flies into an M population we backcrossed P flies and their offspring to M flies. Two components of dysgenesis, P element activity and P element copy number (measured by DNA hybridization), were monitored each generation. In these experiments P elements were not capable of spreading rapidly enough to maintain 30–50 copies per fly and were rapidly lost from the population. We also found that the reduction in a fly's ability to induce gonadal dysgenesis was matched by an equivalent reduction in P element copy number as measured by DNA hybridization. These results are discussed in terms of the conventional mechanisms of selection or segregation; the conclusion is that there are conditions under which P elements can be lost from a population. Key words: hybrid dysgenesis, P element, transposable elements, Drosophila.

Download Full-text

STERILITY AND HYPERMUTABILITY IN THE P-M SYSTEM OF HYBRID DYSGENESIS IN DROSOPHILA MELANOGASTER

Genetics ◽

10.1093/genetics/114.4.1147 ◽

1986 ◽

Vol 114 (4) ◽

pp. 1147-1163

Author(s):

Gordon J Kocur ◽

Eric A Drier ◽

Michael J Simmons

Keyword(s):

Drosophila Melanogaster ◽

Gonadal Dysgenesis ◽

Hybrid Dysgenesis ◽

P Element ◽

Insertion Mutation ◽

Eastern United States ◽

X Chromosomes ◽

P Elements ◽

Y Chromosomes ◽

Wild Strains

ABSTRACT Inbred wild strains of Drosophila melanogaster derived from the central and eastern United States were used to make dysgenic hybrids in the P-M system. These strains possessed P elements and the P cytotype, the condition that represses P element transposition. Their hybrids were studied for the mutability of the P element insertion mutation, snw, and for the incidence of gonadal dysgenesis (GD) sterility. All the strains tested were able to induce hybrid dysgenesis by one or both of these assays; however, high levels of dysgenesis were rare. Sets of X chromosomes and autosomes from the inbred wild strains were more effective at inducing GD sterility than were sets of Y chromosomes and autosomes. In two separate analyses, GD sterility was positively correlated with snw mutability, suggesting a linear relationship. However, one strain appeared to induce too much GD sterility for its level of snw destabilization, indicating an uncoupling of these two manifestations of hybrid dysgenesis.

Download Full-text

Amplification of KP elements associated with the repression of hybrid dysgenesis in Drosophila melanogaster.

Genetics ◽

10.1093/genetics/120.4.1003 ◽

1988 ◽

Vol 120 (4) ◽

pp. 1003-1013

Author(s):

M S Jackson ◽

D M Black ◽

G A Dover

Keyword(s):

Drosophila Melanogaster ◽

Copy Number ◽

Natural Populations ◽

Selective Advantage ◽

Complex Interaction ◽

Hybrid Dysgenesis ◽

P Element ◽

Deletion Derivative ◽

P Elements ◽

The Way

Abstract Mobile P elements in Drosophila melanogaster cause hybrid dysgenesis if their mobility is not repressed. One type of repression, termed P cytotype, is a complex interaction between chromosomes carrying P elements and cytoplasm and is transmitted through the cytoplasm only of females. Another type of repression is found in worldwide M' strains that contain approximately 30 copies per individual of one particular P element deletion-derivative termed the KP element. This repression is transmitted equally through both sexes. In the present study we show that biparentally transmitted repression increases in magnitude together with a rapid increase in KP copy-number in genotypes starting with one or a few KP elements and no other deletion-derivatives. Such correlated increases in repression and KP number per genome occur only in the presence of complete P elements, supporting the interpretation that they are probably a consequence of the selective advantage enjoyed by flies carrying the highest numbers of KP elements. Analysis of Q strains also reveals the presence of qualitative differences in the way the repression of dysgenesis is transmitted. In general, Q strains not containing KP elements have the P cytotype mode of repression, whereas Q strains with KP elements transmit repression through both sexes. This difference among Q strains further supports the existence of at least two types of repression of P-induced hybrid dysgenesis in natural populations of D. melanogaster.

Download Full-text

A hobo Transgene That Encodes the P-Element Transposase in Drosophila melanogaster: Autoregulation and Cytotype Control of Transposase Activity

Genetics ◽

10.1093/genetics/161.1.195 ◽

2002 ◽

Vol 161 (1) ◽

pp. 195-204 ◽

Cited By ~ 1

Author(s):

Michael J Simmons ◽

Kevin J Haley ◽

Craig D Grimes ◽

John D Raymond ◽

Jarad B Niemi

Keyword(s):

Drosophila Melanogaster ◽

Gonadal Dysgenesis ◽

P Element ◽

Hsp70 Gene ◽

Alternate Splicing ◽

Male And Female ◽

P Elements ◽

Male Germline ◽

Female Germline ◽

Transposase Expression

Abstract Drosophila were genetically transformed with a hobo transgene that contains a terminally truncated but otherwise complete P element fused to the promoter from the Drosophila hsp70 gene. Insertions of this H(hsp/CP) transgene on either of the major autosomes produced the P transposase in both the male and female germlines, but not in the soma. Heat-shock treatments significantly increased transposase activity in the female germline; in the male germline, these treatments had little effect. The transposase activity of two insertions of the H(hsp/CP) transgene was not significantly greater than their separate activities, and one insertion of this transgene reduced the transposase activity of P(ry+, Δ2-3)99B, a stable P transgene, in the germline as well as in the soma. These observations suggest that, through alternate splicing, the H(hsp/CP) transgene produces a repressor that feeds back negatively to regulate transposase expression or function in both the somatic and germline tissues. The H(hsp/CP) transgenes are able to induce gonadal dysgenesis when the transposase they encode has P-element targets to attack. However, this ability and the ability to induce P-element excisions are repressed by the P cytotype, a chromosomal/cytoplasmic state that regulates P elements in the germline.

Download Full-text

A novel repressor of P element transposition in Drosophila melanogaster

Genetics Research ◽

10.1017/s0016672397003066 ◽

1998 ◽

Vol 71 (1) ◽

pp. 21-30 ◽

Cited By ~ 4

Author(s):

RICHARD M. BADGE ◽

JOHN F. Y. BROOKFIELD

Keyword(s):

Drosophila Melanogaster ◽

Inbred Line ◽

Gonadal Dysgenesis ◽

Full Length ◽

P Element ◽

Temperature Dependent ◽

P Elements

We have discovered, in an inbred line (Loua) of Drosophila melanogaster from Zaïre, a third chromosome showing unusual P element repression. Repression of P element transposition by this chromosome, named Loua3, is dominant zygotic and has three unusual properties. Firstly, its repression of the gonadal dysgenesis caused by a strong P haplotype is strongly temperature-dependent, being most evident at higher rearing temperatures. Secondly, subdivision of Loua3 by recombination abolishes repression: the effect is apparently a function of the intact chromosome. Finally, Loua3 also diminishes somatic lethality when chromosomes carrying many ‘ammunition’ elements (Birmingham2) are exposed to the constitutive transposase source Δ2-3(99B). The chromosome has 17 P elements, none full-length, located in at least 12 dispersed positions.

Download Full-text

A particular P-element insertion is correlated to the P-induced hybrid dysgenesis repression in Drosophila melanogaster

Genetics Research ◽

10.1017/s0016672300030627 ◽

1992 ◽

Vol 60 (1) ◽

pp. 15-24 ◽

Cited By ~ 5

Author(s):

Dominique Higuet ◽

Dominique Anxolabéhére ◽

Danielle Nouaud

Keyword(s):

Drosophila Melanogaster ◽

Promoter Activity ◽

Hybrid Dysgenesis ◽

P Element ◽

P Elements ◽

Element Insertion ◽

Element Number

SummaryTransposable P elements in Drosophila melanogaster cause hybrid dysgenesis if their mobility is not repressed. The ability to regulate the dysgenic activity of the P elements depends on several mechanisms, one of which hypothesized that a particular deleted P element (the KP element) results in a non-susceptibility which is biparentally transmitted. In this study totally nonsusceptible lines, and susceptible lines containing exclusively KP elements (IINS2 line and IIS2 line) were isolated from a M' strain. We show that non-susceptibility is correlated with a particular insertion of one KP element located at the cytological site 47D1. The repression ability of the GD sterility is determined by a recessive chromosomal factor, and cannot be due to the KP-element number. Here the repression of the P mobility is associated with reduction of the P transcripts and the inhibition of P promoter activity.

Download Full-text

Molecular analysis of the P-M gonadal dysgenesis cline in eastern Australian Drosophila melanogaster.

Genetics ◽

10.1093/genetics/119.4.889 ◽

1988 ◽

Vol 119 (4) ◽

pp. 889-902

Author(s):

I A Boussy ◽

M J Healy ◽

J G Oakeshott ◽

M G Kidwell

Keyword(s):

Drosophila Melanogaster ◽

Transposable Element ◽

Gonadal Dysgenesis ◽

Molecular Techniques ◽

P Element ◽

Latitudinal Cline ◽

Deletion Derivative ◽

P Elements ◽

Regulatory Ability ◽

Eastern Australia

Abstract The latitudinal cline in P-M gonadal dysgenesis potential in eastern Australia has been shown to comprise three regions which are, from north to south respectively, P, Q, and M, with the P-to-Q and Q-to-M transitions occurring over relatively short distances. The P element complements of 30 lines from different regions of the cline were determined by molecular techniques. The total amount of P element-hybridizing DNA was high in all lines, and it did not correlate in any obvious way with the P-M phenotypes of individual lines. The number of potentially full-sized P elements per genome was high in lines from the P regions, but variable or low among lines from the Q and M regions, and thus declined overall from north to south. A particular P element deletion-derivative, the KP element, occurred in all the tested lines. The number of KP elements was low in lines from the P region, much higher in lines from the Q region, and highest among lines from the M region, thus forming a cline reciprocal to that of the full-sized P elements. Another transposable element, hobo, which has been described as causing dysgenic traits similar to those of P-M hybrid dysgenesis, was shown to be present in all lines and to vary among them in number, but not in any latitudinal pattern. The P-M cline in gonadal dysgenesis potential can be inferred to be based on underlying clinal patterns of genomic P element complements. P activity of a line was positively correlated with the number of full-sized P elements in the line, and negatively correlated with the number of KP elements. Among Q and M lines, regulatory ability was not correlated with numbers of KP elements.

Download Full-text

The distribution of transposable elements within and between chromosomes in a population of Drosophila melanogaster. I. Element frequencies and distribution

Genetics Research ◽

10.1017/s0016672300030792 ◽

1992 ◽

Vol 60 (2) ◽

pp. 103-114 ◽

Cited By ~ 65

Author(s):

Brian Charlesworth ◽

Angela Lapid ◽

Darlene Canada

Keyword(s):

Population Dynamics ◽

Drosophila Melanogaster ◽

Linkage Disequilibrium ◽

Transposable Elements ◽

Copy Number ◽

Polytene Chromosomes ◽

Chromosome Band ◽

High Frequencies ◽

Copy Numbers

SummaryData were collected on the distribution of nine families of transposable elements among second and third chromosomes isolated from a natural population of Drosophila melanogaster, by means of in situ hybridization of element probes to polytene chromosomes. It was found that the copy numbers per chromosome in the distal sections of the chromosome arms followed a Poisson distribution. Elements appeared to be distributed randomly along the distal sections of the chromosome arms. There was no evidence for linkage disequilibrium in the distal sections of the chromosomes, but some significant disequilibrium was detected in proximal regions. There were many significant correlations between different element families with respect to the identity of the sites that were occupied in the sample. There were also significant correlations between families with respect to sites at which elements achieved relatively high frequencies. Element frequencies per chromosome band were generally low in the distal sections, but were higher proximally. These results are discussed in the light of models of the population dynamics of transposable elements. It is concluded that they provide strong evidence for the operation of a force or forces opposing transpositional increase in copy number. The data suggest that the rate of transposition perelement per generation is of the order of 10−4, for the elements included in this study.

Download Full-text