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1.
Experimental data suggest that the P transposable element has invaded the Drosophila melanogaster genome after a horizontal
transfer from the phylogenetically distant species Drosophila willistoni. The differences between P element phylogeny and
that of the Drosophila genus could in part be explained by horizontal transfers. In vivo experiments show that P elements
are able to transpose in the genomes of other Drosophila species. This suggests that horizontal transmission of P elements
could have taken place in many species of this genus. The regulation, transposition, and deleterious effects of the P element
in D. melanogaster were formalized and integrated in a global model to produce a simulation program that simulates a P element
invasion. The simulations show that our knowledge of the P element in D. melanogaster can explain its behavior in the Drosophila
genus. The equilibrium state of the invaded population of a new species depends on its ability to repair damage caused by
P element activity. If repair is efficient, the equilibrium state tends to be of the P type state, in which case the element
could subsequently invade other populations of the species. Conversely, the equilibrium state is of the M′ type state when
the ability to repair damage is low. The invasion of the P element into other populations of this new species can then only
occur by genetic drift and it is likely to be lost. The success of a P element invasion into a new species thus greatly depends
on its ability to produce dysgenic crosses.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
2.
Molecular analysis suggests that the pomace fly Drosophila melanogaster acquired the P family of transposable elements from another Drosophila species, D. willistoni. Since the two species are distantly related, it has been assumed that transmission of P element DNA from D. willistoni to D. melanogaster was mediated by a vector. The possibility of an alternative mode of transmission was assessed by characterizing the sexual behaviors of D. willistoni males and females, then observing D. willistoni and D. melanogaster males and females to see whether males from one species interacted sexually with females from the other species in a laboratory setting. We observed that D. melanogaster males court D. willistoni females vigorously and, in some cases, stimulate the females to be receptive to copulation. However, D. willistoni males perform relatively little courtship in response to D. melanogaster females and do not attempt to copulate. Thus, it is unlikely that sexual interactions effected the transmission of P element DNA from D. willistoni to D. melanogaster in the flies' natural habitat. 相似文献
3.
A phylogenetic survey using the polymerase chain reaction (PCR) has
identified four major P element subfamilies in the saltans and willistoni
species groups of Drosophila. One subfamily, containing about half of the
sequences studied, consists of elements that are very similar to the
canonical (and active) P element from D. melanogaster. Within this
subfamily, nucleotide sequence differentiation among different copies from
the same species and among elements from different species is relatively
low. This observation suggests that the canonical elements are relatively
recent additions to the genome or, less likely, are evolving slowly
relative to the other subfamilies. Elements belonging to the three
noncanonical lineages are distinct from the canonical elements and from one
another. Furthermore, there is considerably more sequence variation, on the
average, within the noncanonical subfamilies compared to the canonical
elements. Horizontal transfer and the coexistence of multiple,
independently evolving element subfamilies in the same genome may explain
the distribution of P elements in the saltans and willistoni species
groups. Such explanations are not mutually exclusive, and each may be
involved to varying degrees in the maintenance of P elements in natural
populations of Drosophila.
相似文献
4.
G M Simmons 《Molecular biology and evolution》1992,9(6):1050-1060
The hobo family of transposable elements, one of three transposable-element families that cause hybrid dysgenesis in Drosophila melanogaster, appears to be present in all members of the D. melanogaster species complex: D. melanogaster, D. simulans, D. mauritiana, and D. sechellia. Some hobo-hybridizing sequences are also found in the other members of the melanogaster subgroup and in many members of the related montium subgroup. Surveys of older isofemale lines of D. melanogaster suggest that complete hobo elements were absent prior to 50 years ago and that hobo has recently been introduced into the species by horizontal transfer. To test the horizontal transfer hypothesis, the 2.6-kb XhoI fragments of hobo elements from D. melanogaster, D. simulans, and D. mauritiana were cloned and sequenced. The DNA sequences reveal an extremely low level of divergence and support the conclusion that the active hobo element has been horizontally transferred into or among these species in the recent past. 相似文献
5.
D Anxolabehere 《Comptes rendus des séances de la Société de biologie et de ses filiales》1992,186(6):641-655
The P transposable element family in Drosophila melanogaster is responsible for the syndrome of hybrid dysgenesis which includes chromosomal rearrangements, male recombination, high mutability and temperature sensitive agametic sterility (called gonadal dysgenesis sterility). P element activity is controlled by a complex regulation system, encoded by the elements themselves, which keeps their transposition rate low within the strain bearing P elements and limits copy number by genome. A second regulatory mechanism, which acts on the level of RNA processing, prevents P mobility to somatic cells. The oldest available strains, representing most major geographical regions of the world, exhibited no detectable hybridization to the P-element. In contrast, all recently collected natural populations that were tested carried P-element sequences. The available evidence is consistent with the hypothesis of a worldwide P-element invasion of D. melanogaster during the past 30 years. Timing and direction of the invasion are discussed. The lack of P-element in older strains of Drosophila melanogaster as well as in the species must closely related to Drosophila melanogaster, suggests that P entered the Drosophila melanogaster genome recently, probably by horizontal transfer from an other species. The analysis of P-element elsewhere in the genus Drosophila reveals that several more distantly related species carried transposable elements with sequences quite similar to P. The species with the best-matching P-element is D. willistoni. A P-element from this species was found to match all but one of the 2907 nucleotides of the Drosophila melanogaster P-element. The phylogenic distributions and the likely horizontal transfers of the two other Drosophila transposable elements are discussed. 相似文献
6.
The phylogenetic distribution of transposable families, P, gypsy, hobo, I, and mariner has been analyzed in 33 species of
11 groups of neotropical Drosophila and a Drosophilidae species Zygotrica vittimaculosa, using squash blot and dot blot. Genomic
DNA of almost all neotropical species tested hybridized with gypsy probe and some species showed a particularly strong hybridization
signal, as D. gaucha, D. virilis, and species of flavopilosa group. The hobo element was restricted to melanogaster group
and some strains of D. willistoni. Only D. simulans DNA showed hybridization to mariner probe in all species tested and D.
simulans and D. melanogaster showed hybridization with I element probe. P element homologous sequence was present in D. melanogaster
and all species and strains of the willistoni and saltans groups tested. The presence of at least one P-homologous sequence
was detected in Drosophila mediopunctata. This one was the only P-bearing species of all six tested from the tripunctata group.
Four different pairs of primers homologous to segments of the canonical sequence of D. melanogaster's P were used to amplify
specific sequences from D. mediopunctata DNA, showing the occurrence of seemingly well-conserved P-homologous sequences.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
7.
Horizontal transfer and selection in the evolution of P elements 总被引:2,自引:0,他引:2
The roles of selection and horizontal transfer in the evolution of the canonical subfamily of P: elements were studied in the saltans and willistoni species groups of the genus Drosophila (subgenus Sophophora). We estimate that the common ancestor of the canonical P: subfamily dates back 2-3 Myr at the most, despite the much older age (more than 40 Myr) of the P: family as a whole. The evolution of the canonical P: subfamily is characterized by weak selection at nonsynonymous sites. These sites have evolved at three quarters the rate of synonymous sites, in which no selective constraints were detected. Their recent horizontal transfer best explains the high degree of similarity among canonical P: elements from the saltans and willistoni species groups. These results are consistent with a model of P:-element evolution in which selective constraints are imposed at the time of horizontal transfer. Furthermore, it is estimated that the spread and diversification of the canonical subfamily involved a minimum of 11 horizontal transfer events among the 18 species surveyed within the past 3 Myr. The presence of multiple P: subfamilies in the saltans and willistoni species groups is likely to be the result of multiple invasions that have previously swept through these taxa in a succession of horizontal transfer events. These results suggest that horizontal transfer among eukaryotes might be more common than anticipated. 相似文献
8.
9.
Evolution of the Adh locus in the Drosophila willistoni group: the loss of an intron, and shift in codon usage 总被引:1,自引:0,他引:1
We report here the DNA sequence of the alcohol dehydrogenase gene (Adh)
cloned from Drosophila willistoni. The three major findings are as follows:
(1) Relative to all other Adh genes known from Drosophila, D. willistoni
Adh has the last intron precisely deleted; PCR directly from total genomic
DNA indicates that the deletion exists in all members of the willistoni
group but not in any other group, including the closely related saltans
group. Otherwise the structure and predicted protein are very similar to
those of other species. (2) There is a significant shift in codon usage,
especially compared with that in D. melanogaster Adh. The most striking
shift is from C to U in the wobble position (both third and first
position). Unlike the codon-usage-bias pattern typical of highly biased
genes in D. melanogaster, including Adh, D. willistoni has nearly 50% G + C
in the third position. (3) The phylogenetic information provided by this
new sequence is in agreement with almost all other molecular and
morphological data, in placing the obscura group closer to the melanogaster
group, with the willistoni group farther distant but still clearly within
the subgenus Sophophora.
相似文献
10.
Sequences homologous to the P element of Drosophila melanogaster were previously identified in Drosophila mediopunctata, a member of the tripunctata group, subgenus Drosophila. We report here that the P element is present in about three to five copies in the D. mediopunctata genome. While one of the insertion sites appears to be fixed, others may be polymorphic, indicating relatively recent P element activity. Phylogenetic analysis revealed that the D. mediopunctata element belongs to the canonical subfamily of P elements and that divergence of the D. mediopunctata element from other members of this subfamily ranges from 2% to 5% at the nucleotide level. This is the first report of a canonical P element outside the subgenus Sophophora. Based primarily on the striking incongruence between P element and host species phylogenies, the presence of a canonical P element in D. mediopunctata is most likely explained by horizontal transfer between species. 相似文献
11.
Powell JR Dion K Papaceit M Aguadé M Vicario S Garrick RC 《Molecular biology and evolution》2011,28(1):825-833
Rate of recombination is a powerful variable affecting several aspects of molecular variation and evolution. A nonrecombining portion of the genome of most Drosophila species, the "dot" chromosome or F element, exhibits very low levels of variation and unusual codon usage. One lineage of Drosophila, the willistoni/saltans groups, has the F element fused to a normally recombining E element. Here, we present polymorphism data for genes on the F element in two Drosophila willistoni and one D. insularis populations, genes previously studied in D. melanogaster. The D. willistoni populations were known to be very low in inversion polymorphism, thus minimizing the recombination suppression effect of inversions. We first confirmed, by in situ hybridization, that D. insularis has the same E + F fusion as D. willistoni, implying this was a monophyletic event. A clear gradient in codon usage exists along the willistoni F element, from the centromere distally to the fusion with E; estimates of recombination rates parallel this gradient and also indicate D. insularis has greater recombination than D. willistoni. In contrast to D. melanogaster, genes on the F element exhibit moderate levels of nucleotide polymorphism not distinguishable from two genes elsewhere in the genome. Although some linkage disequilibrium (LD) was detected between polymorphic sites within genes (generally <500 bp apart), no long-range LD between F element loci exists in the two willistoni group species. In general, the distribution of allele frequencies of F element genes display the typical pattern of expectations of neutral variation at equilibrium. These results are consistent with the hypothesis that recombination allows the accumulation of nucleotide variation as well as allows selection to act on synonymous codon usage. It is estimated that the fusion occurred ~20 Mya and while the F element in the willistoni lineage has evolved "normal" levels and patterns of nucleotide variation, equilibrium may not have been reached for codon usage. 相似文献
12.
Vázquez-Manrique RP Hernández M Martínez-Sebastián MJ de Frutos R 《Molecular biology and evolution》2000,17(8):1185-1193
The Ty3/gypsy family of retroelements is closely related to retroviruses, and some of their members have an open reading frame resembling the retroviral gene env. Sequences homologous to the gypsy element from Drosophila melanogaster are widely distributed among Drosophila species. In this work, we report a phylogenetic study based mainly on the analysis of the 5' region of the env gene from several species of the obscura group, and also from sequences already reported of D. melanogaster, Drosophila virilis, and Drosophila hydei. Our results indicate that the gypsy elements from species of the obscura group constitute a monophyletic group which has strongly diverged from the prototypic D. melanogaster gypsy element. Phylogenetic relationships between gypsy sequences from the obscura group are consistent with those of their hosts, indicating vertical transmission. However, D. hydei and D. virilis gypsy sequences are closely related to those of the affinis subgroup, which could be indicative of horizontal transmission. 相似文献
13.
Two novel families of miniature inverted repeat transposable elements (MITEs), Vege and Mar, are described from Drosophila willistoni. Based on their structures, both element families are hypothesized to belong to the hAT superfamily of transposable elements. Both elements have perfect, inverted terminal repeats and 8-bp target site duplications and were found to have inserted within fixed copies of nonautonomous P elements. Vege is present in all studied D. willistoni populations and appears to have a relatively low copy number. Mar was identified in only a single D. willistoni population, and its copy number is presently unknown. Although MITEs occupy relatively large proportions of the genomes of a broad range of organisms, this may be their first unambiguous identification in any species of the genus Drosophila. 相似文献
14.
Horizontal transmission, vertical inactivation, and stochastic loss of mariner-like transposable elements 总被引:13,自引:5,他引:8
Horizontal transmission has been well documented as a major mechanism for
the dissemination of mariner-like elements (MLEs) among species. Less well
understood are mechanisms that limit vertical transmission of MLEs
resulting in the "spotty" or discontinuous distribution observed in closely
related species. In this article we present evidence that the genome of the
common ancestor of the melanogaster species subgroup of Drosophila
contained an MLE related to the mellifera (honey bee) subfamily. Horizontal
transmission, approximately 3-10 MYA, is strongly suggested by the
observation that the sequence of the MLE in Drosophila erecta is 97%
identical in nucleotide sequence with that of an MLE in the cat flea,
Ctenocephalides felis. The D. erecta MLE has a spotty distribution among
species in the melanogaster subgroup. The element has a high copy number in
D. erecta and D. orena, a moderate copy number in D. teissieri and D.
yakuba, and was apparently lost ("stochastic loss") in the lineage leading
to D. melanogaster, D. simulans, D. mauritiana, and D. sechellia. In D.
erecta, most copies are concentrated in the heterochromatin. Two copies
from D. erecta, denoted De12 and De19, were cloned and sequenced, and they
appear to be nonfunctional ("vertical inactivation"). It therefore appears
that the predominant mode of MLE evolution is vertical inactivation and
stochastic loss balanced against occasional reinvasion of lineages by
horizontal transmission.
相似文献
15.
ABSTRACT: BACKGROUND: During the evolutionary history of transposable elements, some processes, such as ancestral polymorphisms and horizontal transfer of sequences between species, can produce incongruences in phylogenies. We investigated the evolutionary history of the transposable elements Bari and 412 in the sequenced genomes of the Drosophila melanogaster group and in the sibling species D. melanogaster and D. simulans using traditional phylogenetic and network approaches. RESULTS: The maximum likelihood (ML) phylogenetic analyses revealed incongruences and unresolved relationships for both the Bari and 412 elements. The DNA transposon Bari within the D. ananassae genome is more closely related to the element of the melanogaster complex than to the sequence in D. erecta, which is inconsistent with the species phylogeny. Divergence analysis and the comparison of the rate of synonymous substitutions per synonymous site of the Bari and host gene sequences explain the incongruence as an ancestral polymorphism inherited stochastically by the derived species. Unresolved relationships were observed in the ML phylogeny of both elements involving D. melanogaster, D. simulans and D. sechellia. A network approach was used to attempt to resolve these relationships. The resulting tree suggests recent transfers of both elements between D. melanogaster and D. simulans. The divergence values of the elements between these species support this conclusion. CONCLUSIONS: We showed that an ancestral polymorphism and recent invasion of genomes due to introgression or horizontal transfer between species occurred during the evolutionary history of the Bari and 412 elements in the melanogaster group. These invasions likely occurred in Africa during the Pleistocene, before the worldwide expansion of D. melanogaster and D. simulans. 相似文献
16.
Distribution and conservation of mobile elements in the genus Drosophila 总被引:13,自引:1,他引:12
Essentially nothing is known of the origin, mode of transmission, and
evolution of mobile elements within the genus Drosophila. To better
understand the evolutionary history of these mobile elements, we examined
the distribution and conservation of homologues to the P, I, gypsy, copia,
and F elements in 34 Drosophila species from three subgenera. Probes
specific for each element were prepared from D. melanogaster and hybridized
to genomic DNA. Filters were washed under conditions of increasing
stringency to estimate the similarity between D. melanogaster sequences and
their homologues in other species. The I element homologues show the most
limited distribution of all elements tested, being restricted to the
melanogaster species group. The P elements are found in many members of the
subgenus Sophophora but, with the notable exception of D. nasuta, are not
found in the other two subgenera. Copia-, gypsy-, and F-element homologues
are widespread in the genus, but their similarity to the D. melanogaster
probe differs markedly between species. The distribution of copia and P
elements and the conservation of the gypsy and P elements is inconsistent
with a model that postulates a single ancient origin for each type of
element followed by mating-dependent transmission. The data can be
explained by horizontal transmission of mobile elements between
reproductively isolated species.
相似文献
17.
18.
Introduction of a functional P element into the germ-line of Drosophila hawaiiensis 总被引:10,自引:0,他引:10
When a plasmid carrying a P-transposable element (derived from Drosophila melanogaster) is injected into young embryos of D. hawaiiensis, the P-element sequence from the plasmid transposes into the germ-line chromosomes. The introduction of this P element into D. hawaiiensis provides an opportunity to study the behavior of the transposable element in a novel context. Germ-line transposition and numerical increase of the P elements are readily detected in D. hawaiiensis. Thus these aspects of P-element function do not require chromosomal or cytoplasmic properties that are unique to D. melanogaster. Since D. hawaiiensis is among those Drosophila that are most distantly related to D. melanogaster, these results suggest that P-element-mediated transformation may function in many species. 相似文献
19.
Phylogenetic relationships were determined for 76 partial P-element
sequences from 14 species of the melanogaster species group within the
Drosophila subgenus Sophophora. These results are examined in the context
of the phylogeny of the species from which the sequences were isolated.
Sequences from the P-element family fall into distinct subfamilies, or
clades, which are often characteristic for particular species subgroups.
When examined locally among closely related species, the evolution of P
elements is characterized by vertical transmission, whereby the P-element
phylogeny traces the species phylogeny. On a broader scale, however, the
P-element phylogeny is not congruent with the species phylogeny. One
feature of P-element evolution in the melanogaster group is the presence of
more than one P-element subfamily, differing by as much as 36%, in the
genomes of some species. Thus, P elements from several individual species
are not monophyletic, and a likely explanation for the incongruence between
P-element and species phylogenies is provided by the comparison of
paralogous sequences. In certain instances, horizontal transfer seems to be
a valid alternative explanation for lack of congruence between species and
P-element phylogenies. The canonical P-element subfamily, which represents
the active, autonomous transposable element, is restricted to D.
melanogaster. Thus, its origin clearly lies outside of the melanogaster
species group, consistent with the earlier conclusion of recent horizontal
transfer.
相似文献
20.
Gypsy is an endogenous retrovirus of Drosophila melanogaster. Phylogenetic studies suggest that occasional horizontal transfer events of gypsy occur between Drosophila species. gypsy possesses infective properties associated with the products of the envelope gene that might be at the origin of these interspecies transfers. We report here the existence of DNA sequences putatively encoding full-length Env proteins in the genomes of Drosophila species other than D. melanogaster, suggesting that potentially infective gypsy copies able to spread between sexually isolated species can occur. The ability of gypsy to invade the genome of a new species is conditioned by its capacity to be expressed in the naive genome. The genetic basis for the regulation of gypsy activity in D. melanogaster is now well known, and it has been assigned to an X-linked gene called flamenco. We established an experimental simulation of the invasion of the D. melanogaster genome by gypsy elements derived from other Drosophila species, which demonstrates that these non- D. melanogaster gypsy elements escape the repression exerted by the D. melanogaster flamenco gene. 相似文献