The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
A syndrome of abnormal genetic effects, resembling Drosophila hybrid dysgenesis, occurs in Ceratitis capitata when strains of different origin are mated. The pattern of abnormal traits observed appears to be the phenotypic expression of a complex interacting dysgenic system of inducer and suppressor effects; probably more than one system is activated in the crosses. This suggests that different systems...
It is recognized that a stable number of transposable element (TE) copies per genome is maintained in natural populations of D. melanogaster as a result of the dynamic equilibrium between transposition to new sites and natural selection eliminating copies. The force of natural selection opposing TE multiplication is partly relaxed in inbred laboratory lines of flies. The average rate of TE transposition...
Several families of transposable elements (TEs), most of them belonging to the retrotransposon catagory, are particularly enriched in Drosophila melanogaster constitutive heterochromatin. The enrichment of TE-homologous sequences into heterochromatin is not a peculiar feature of the Drosophila genome, but appears to be widespread among higher eukaryotes. The constitutive heterochromatin of D. melanogaster...
In our search for transposable elements in barley, Hordeum vulgare, we have isolated and cloned two BamHI-fragments of 4.7 and 4.2 kb in length containing very abundant DNA sequences. The 4.7 kb fragment is homologous to the extended region, including more than half of the 5′-LTR and some part of the coding domain of BARE-1, a member of copia-like retrotransposon family of barley. The 4.2 kb fragment,...
To investigate the main forces controlling the containment of transposable elements (TE) in natural populations, we analyzed the copia, mdg1, and 412 elements in various populations of Drosophila melanogaster and D. simulans. A lower proportion of insertion sites on the X chromosome in comparison with the autosomes suggests that selection against the detrimental effects of TE insertions is the major...
CM-gag elements constitute an homogeneous family of sequences that are reiterated in the genome of Culex pipiens strains from different continents. Apparently complete 1.75 kb CM-gag copies are flanked by target-site duplications and have a polyadenylation signal near their 3′ end. They potentially contain a unique gene encoding a putative protein that displays homologies with nucleic acid binding...
The mariner/ Tc1 superfamily of transposable elements is widely distributed in animal genomes and is especially prevalent in insects. Their wide distribution results from their ability to be disseminated among hosts by horizontal transmission and also by their ability to persist in genomes through multiple speciation events. Although a great deal is known about the molecular mechanisms of transposition...
The mobile element ZAM, recently identified in Drosophila melanogaster, is similar in structure and coding potential to vertebrate retroviruses. In this paper, we analyze the insertional and structural polymorphism of this element and show that members of this family appear to have a long evolutionary history in the genome of Drosophila. It is present in all the species of the D. melanogaster subgroup...
The transposable elements (TEs) identified in fungal genomes reflect the whole spectrum of eukaryotic transposable elements. Most of our knowledge comes from species representing different ecological situations: plant pathogens, industrial, and field strains, most of them lacking the sexual stage. A number of changes in gene structure and function has been shown to be TE-mediated: inactivation of...
The S1 element is a plant SINE (Short INterspersed Element) that was first described and studied in Brassica napus and is widely distributed among Cruciferae, especially in species of the Brassiceae tribe. We propose that S1 amplification in Cruciferae could represent a good eukaryotic model to study retroposition. This is based on the fact that S1 elements share clear structural and evolutionary...
R1 and R2 are non-long terminal repeat (non-LTR) retrotransposable elements that specifically insert in the 28S ribosomal RNA (rRNA) genes of insects. Using the Drosophila genus, which includes some of the best characterized insect taxa, we have conducted a number of studies on the evolution of these elements. We find that R1 and R2 are subject to the same recombinational forces that give rise to...
The genomic organisation and diversity of the Ty1-copia group retrotransposons has been investigated in several crop plants and their relatives from both dicotyledonous and monocotyledonous families, including potato ( Solanum tuberosum), faba beans ( Vicia faba), Vicia melanops, Vicia sativa, barley ( Hordeum vulgare), rye ( Secale cereale), and onion ( Allium cepa). Extreme heterogeneity in the...
The study of gypsy elements in Drosophila subobscura (gypsyDs) indicated that they are transcriptionally active and mobile. From the comparative analysis of a complete gypsyDs element with the canonical gypsy sequence from D. melanogaster (gypsyDm) it can be deduced that while the whole structure is maintained, the gypsyDs ORF3 encodes a non-functional Env protein. The PCR amplification and sequencing...
The BARE-1 copia-like retrotransposon constitutes nearly 7% of the barley (Hordeum vulgare L.) genome as a family of more than 2 × 104 mostly full-length copies dispersed on all chromosomes. BARE-1 elements are transcribed in barley tissues from promoters within the LTR (long terminal repeat). The predicted, translated polyprotein contains conserved domains for GAG, aspartic proteinase, integrase,...
In Drosophila melanogaster, crossing males carrying autonomous P elements with females devoid of P copies results in hybrid dysgenesis in the germline of progeny. The reciprocal cross produces non-dysgenic progeny due to a maternally inherited state non-permissive for P transposition. The capacity of a P copy to repress transposition depends on both its structure and its chromosomal location. Naturally...
The gypsy element of Drosophila melanogaster is the first retrovirus identified so far in invertebrates. According to phylogenetic data, gypsy belongs to the same group as the Ty3 class of LTR-retrotransposons, which suggests that retroviruses evolved from this kind of retroelements before the radiation of vertebrates. There are other invertebrate retroelements that are also likely to be endogenous...
Transposable elements are abundant in the genomes of higher organisms but are usually thought to affect cells only incidentally, by transposing in or near a gene and influencing its expression. Telomeres of Drosophila chromosomes are maintained by two non-LTR retrotransposons, HeT-A and TART. These are the first transposable elements with identified roles in chromosome structure. We suggest that these...
The integrases of retrotransposons (class I) and retroviruses and the transposases of bacterial type elements (class II) were compared. The DDE signature that is crucial for the integration of these elements is present in most of them, except for the non-LTR retrotransposons and members of the hAT and P super-families. Alignment of this region was used to infer the relationships between class II elements,...
In most reports in which the activity of numerous Drosophila transposon families has been studied, only a subset of the families tested appears mobile. A comparison of these data shows that there are no transposons inherently more unstable than others and suggests that host factors regulate the activity of transposable elements. Consistent with this conclusion are the properties of Bari 1 elements,...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.