Artificial and Epigenetic Regulation of the I Factor, a Nonviral Retrotransposon of Drosophila melanogaster

Genetics ◽  
2000 ◽  
Vol 156 (4) ◽  
pp. 1867-1878 ◽  
Author(s):  
Emmanuel Gauthier ◽  
Christophe Tatout ◽  
Hubert Pinon
Keyword(s):  
Drosophila Melanogaster ◽  
Maternal Effect ◽  
Copy Number ◽  
Hybrid Dysgenesis ◽  
Female Sterility ◽  
Paternal Effects ◽  
Transgene Copy Number ◽  
Paternal Effect ◽  
Two Generations ◽  
I Factor

Abstract The I factor (IF) is a LINE-like transposable element from Drosophila melanogaster. IF is silenced in most strains, but under special circumstances its transposition can be induced and correlates with the appearance of a syndrome of female sterility called hybrid dysgenesis. To elucidate the relationship between IF expression and female sterility, different transgenic antisense and/or sense RNAs homologous to the IF ORF1 have been expressed. Increasing the transgene copy number decreases both the expression of an IF-lacZ fusion and the intensity of the female sterile phenotype, demonstrating that IF expression is correlated with sterility. Some transgenes, however, exert their repressive abilities not only through a copy number-dependent zygotic effect, but also through additional maternal and paternal effects that may be induced at the DNA and/or RNA level. Properties of the maternal effect have been detailed: (1) it represses hybrid dysgenesis more efficiently than does the paternal effect; (2) its efficacy increases with both the transgene copy number and the aging of sterile females; (3) it accumulates slowly over generations after the transgene has been established; and (4) it is maintained for at least two generations after transgene removal. Conversely, the paternal effect increases only with female aging. The last two properties of the maternal effect and the genuine existence of a paternal effect argue for the occurrence, in the IF regulation pathway, of a cellular memory transmitted through mitosis, as well as through male and female meiosis, and akin to epigenetic phenomena.

scholarly journals Properties of transgenic strains of Drosophila melanogaster containing I transposable elements from Drosophila teissieri

1993 ◽  
Vol 61 (2) ◽  
pp. 81-90 ◽  
Author(s):  
Chantal Vaury ◽  
Alain Pélisson ◽  
Pierre Abad ◽  
Alain Bucheton
Keyword(s):  
Drosophila Melanogaster ◽  
Transposable Elements ◽  
Reverse Transcription ◽  
Copy Number ◽  
Hybrid Dysgenesis ◽  
P Element ◽  
I Factor ◽  
Transgenic Strains ◽  
Drosophila Teissieri

SummaryI factors are transposable elements of Drosophila melanogaster similar to mammalian LINEs, that transpose by reverse transcription of an RNA intermediate and are responsible for the I–R system of hybrid dysgenesis. There are two categories of strains in this species: inducer, that contain about 15 I elements at the various sites on chromosomal arms, and reactive, that lack active I factors. I elements occur in various Drosophila species. Potentially functional I factors from Drosophila teissieri can transpose when introduced by P-element-mediated transformation in a reactive strain of Drosophila melanogaster. We have studied the properties of Drosophila melanogaster strains into which such an I factor from Drosophila teissieri, named Itei, was introduced. Typical hybrid dysgenesis is produced when males carrying Itei are crossed with reactive females. However, more than one copy of the element seems necessary to produce dysgenic traits, whereas only one I factor of Drosophila melanogaster seems to be sufficient. The copy number of Itei in transformed lines maintained by endogamous crosses increases rapidly and stabilizes at values similar to those observed in inducer strains. As Drosophila teissieri contains much fewer copies than the Drosophila melanogaster strains, this suggests that the copy number of I elements is not simply regulated by sequences present in the element itself.

scholarly journals GERMLINE HYPERMUTABILITY IN DROSOPHILA AND ITS RELATION TO HYBRID DYSGENESIS AND CYTOTYPE

Genetics ◽  
1981 ◽  
Vol 98 (3) ◽  
pp. 565-587
Author(s):  
William R Engels
Keyword(s):  
Cell Survival ◽  
Chromosomal Rearrangements ◽  
Stable State ◽  
Hybrid Dysgenesis ◽  
Mutation Rates ◽  
Female Sterility ◽  
Genetic Element ◽  
Two Generations ◽  
The Mean ◽  
P Factor

ABSTRACT In its hypermutable state, an unstable singed allele, snw, mutates in the germline to two other alleleic forms at a total frequency usually between 40 and 60%. In its stable state, the mutation rate of snw is essentially zero. Its state depends on an extrachromosomal condition indistinguishable from a property called cytotype previously studied as a component of hybrid dysgenesis. Of the two known systems of hybrid dysgenesis, denoted P-M and I-R, snw hypermutability is determined by the P-M system and appears to be independent of the I-R system. Cytotype, as defined by the control of snw mutability, is self-reproducing in the cytoplasm or nucleoplasm of the germline through at least two generations. However, it is not entirely autonomous, being ultimately determined by the chromosomes after sufficiently many generations of backcrossing. This combination of chromosomal and extrachromosomal transmission agrees well with previous studies on cytotype. Temperature differences have little effect on the mean mutation rates, but they have a pronounced effect on the intrinsic variance among individuals. The latter effect suggests that high temperatures reduce germ-cell survival during the development of dysgenic flies. Chromosomal rearrangements produce no apparent effects on the behavior of snw. Hypermutability is thought to be caused by the excision or other alteration of an inserted genetic element in the snw gene. This element might be a copy of the "P factor," which is though to be a mobile sequence capable of causing female sterility and other dysgenic traits in the P-M system.

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

1989 ◽  
Vol 54 (1) ◽  
pp. 13-22 ◽  
Author(s):  
Stéphane Ronsseray ◽  
Monique Lehmann ◽  
Georges Periquet
Keyword(s):  
Drosophila Melanogaster ◽  
Copy Number ◽  
Gonadal Dysgenesis ◽  
Mixed Cultures ◽  
Hybrid Dysgenesis ◽  
P Elements ◽  
Copy Numbers ◽  
P Factor ◽  
P Type

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.

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

Genetics ◽  
1990 ◽  
Vol 124 (3) ◽  
pp. 663-676 ◽  
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.

scholarly journals NON-MENDELIAN FEMALE STERILITY IN DROSOPHILA MELANOGASTER: HEREDITARY TRANSMISSION OF I FACTOR

Genetics ◽  
1976 ◽  
Vol 83 (1) ◽  
pp. 107-123
Author(s):  
G Picard
Keyword(s):  
Drosophila Melanogaster ◽  
Female Sterility ◽  
Female Progeny ◽  
Two Factors ◽  
I Factor

ABSTRACT Systematic crosses between various strains of Drosophila melanogaster lead in some cases to partly sterile F1 females. Two main classes of strains, inducer and reactive, may be recognized on the basis of the fertility of F1 female progeny. Females which may show incomplete sterility (SF ♀) arise only when reactive females are crossed with inducer males, other crosses, including the reciprocal, producing only fertile F1 females. SF sterility appears as the result of an interaction between two factors, R brought into the initial cross by the reactive mother and maternally inherited, and I brought by the inducer father. The present paper reports on the hereditary transmission of I factor. It is shown that when transmitted through heterozygous males, bearing chromosomes of both inducer and reactive origin, I factor may be strictly linked to any one of the three major chromosomes of inducer strains. Such chromosomes carrying I factor were called inducer chromosomes. When transmitted through heterozygous females, this Mendelian behavior fails to hold, and non-inducer chromosomes coming from reactive strains may become inducer independently of the production of recombined gametes. This phenomenon was called chromosomal contamination. This contamination occurs even between nonhomologous chromosomes.

scholarly journals Hybrid Dysgenesis in Drosophila Melanogaster: A Possible Explanation in Terms of Spatial Organization of Chromosomes

1976 ◽  
Vol 29 (4) ◽  
pp. 375 ◽  
Author(s):  
JA Sved
Keyword(s):  
Drosophila Melanogaster ◽  
Spatial Organization ◽  
Wild Population ◽  
Laboratory Strain ◽  
Male Parent ◽  
Hybrid Dysgenesis ◽  
Female Sterility ◽  
Wild Type

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.

The molecular basis of I-R hybrid Dysgenesis in drosophila melanogaster: Identification, cloning, and properties of the I factor

Cell ◽  
1984 ◽  
Vol 38 (1) ◽  
pp. 153-163 ◽  
Author(s):  
A. Bucheton ◽  
R. Paro ◽  
H.M. Sang ◽  
A. Pelisson ◽  
D.J. Finnegan
Keyword(s):  
Drosophila Melanogaster ◽  
Molecular Basis ◽  
Hybrid Dysgenesis ◽  
I Factor

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

1991 ◽  
Vol 57 (3) ◽  
pp. 213-226 ◽  
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.

scholarly journals IR hybrid dysgenesis increases the frequency of recombination in Drosophila melanogaster

1995 ◽  
Vol 65 (3) ◽  
pp. 167-174 ◽  
Author(s):  
Marie-Christine Chaboissier ◽  
Françoise Lemeunier ◽  
Alain Bucheton
Keyword(s):  
Drosophila Melanogaster ◽  
Transposable Element ◽  
High Frequency ◽  
Germ Line ◽  
Hybrid Dysgenesis ◽  
High Rate ◽  
I Factor

SummaryThe I factor is a LINE-like transposable element responsible for the I-R system of hybrid dysgenesis in Drosophila melanogaster. Inducer strains of this species contain several I factors whereas reactive strains do not. I factors are stable in inducer strains, but transpose at high frequency in the germ-line of females, known as SF females, produced by crossing reactive females and inducer males. Various abnormalities occur in SF females, most of which result from this high rate of transposition. We report here that recombination is increased in the germ-line of these females. This is a new characteristic of the I-R system of hybrid dysgenesis that might also be associated with transposition of the I factor.

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