A comprehensive evolutionary scenario for the origin and neofunctionalization of the Drosophila speciation gene Odysseus (OdsH).

Odysseus (OdsH) was the first speciation gene described in Drosophila related to hybrid sterility in offspring of mating between Drosophila mauritiana and Drosophila simulans. Its origin is attributed to the duplication of the gene unc-4 in the subgenus Sophophora. By using a much larger sample of Drosophilidae species, we showed that contrary to what has been previously proposed, OdsH origin occurred 62 MYA.

Reactivation of a somatic errantivirus and germline invasion in Drosophila ovaries.

Most Drosophila transposable elements are LTR retrotransposons, some of which belong to the genus Errantivirus and share structural and functional characteristics with vertebrate endogenous retroviruses. Like endogenous retroviruses, it is unclear whether errantiviruses retain some infectivity and transposition capacity. We created conditions where control of the Drosophila ZAM errantivirus through the piRNA pathway was abolished leading to its de novo reactivation in somatic gonadal cells.

More than just an inert dense region.

A newly discovered protein helps define a subset of heterochromatin regions that can silence harmful mobile genetic elements in the genome of fruit flies.

Adult T-Cell Leukemia: a Comprehensive Overview on Current and Promising Treatment Modalities.

Purpose Of The Review: Adult T-cell leukemia (ATL) is an aggressive chemo-resistant malignancy secondary to HTLV-1 retrovirus. Prognosis of ATL remains dismal. Herein, we emphasized on the current ATL treatment modalities and their drawbacks, and opened up on promising targeted therapies with special focus on the HTLV-1 regulatory proteins Tax and HBZ.

Loss of interleukin-10 activates innate immunity to eradicate adult T-cell leukemia-initiating cells.

Adult T cell leukemia/lymphoma (ATL) is associated to chronic human T cell leukemia virus type 1 (HTLV-1) infection and carries a poor prognosis. Arsenic trioxide (AS) and interferon-alpha (IFNα) together selectively trigger Tax viral oncoprotein degradation and cure Tax-driven murine ATL. AS/IFNα/zidovudine treatment achieves a high response rate in patients with chronic ATL.

In vivo antagonistic role of the Human T-Cell Leukemia Virus Type 1 regulatory proteins Tax and HBZ.

Adult T cell leukemia (ATL) is an aggressive malignancy secondary to chronic infection by the human T-cell leukemia virus type 1 (HTLV-1) infection. Two viral proteins, Tax and HBZ, play central roles in ATL leukemogenesis. Tax expression transforms T cells in vitro and induces ATL-like disease in mice.

Mouse Models That Enhanced Our Understanding of Adult T Cell Leukemia.

Adult T cell Leukemia (ATL) is an aggressive lymphoproliferative malignancy secondary to infection by the human T-cell leukemia virus type I (HTLV-I) and is associated with a dismal prognosis. ATL leukemogenesis remains enigmatic. In the era of precision medicine in oncology, mouse models offer one of the most efficient tools for the understanding of the disease biology and developing novel targeted therapies.

Piwi Is Required during Drosophila Embryogenesis to License Dual-Strand piRNA Clusters for Transposon Repression in Adult Ovaries.

Most piRNAs in the Drosophila female germline are transcribed from heterochromatic regions called dual-strand piRNA clusters. Histone 3 lysine 9 trimethylation (H3K9me3) is required for licensing piRNA production by these clusters. However, it is unclear when and how they acquire this permissive heterochromatic state.

MicroRNA-Dependent Transcriptional Silencing of Transposable Elements in Drosophila Follicle Cells.

RNA interference-related silencing mechanisms concern very diverse and distinct biological processes, from gene regulation (via the microRNA pathway) to defense against molecular parasites (through the small interfering RNA and the Piwi-interacting RNA pathways). Small non-coding RNAs serve as specificity factors that guide effector proteins to ribonucleic acid targets via base-pairing interactions, to achieve transcriptional or post-transcriptional regulation. Because of the small sequence complementarity required for microRNA-dependent post-transcriptional regulation, thousands of microRNA (miRNA) putative targets have been annotated in Drosophila.

Variable expression levels detected in the Drosophila effectors of piRNA biogenesis.

piRNAs (piwi-interacting RNAs) are a class of small interfering RNAs that play a major role in the regulation of transposable elements (TEs) in Drosophila and are considered of fundamental importance in gonadal development. Genes encoding the effectors of the piRNA machinery are thus often thought to be highly constrained. On the contrary, as actors of genetic immunity, these genes have also been shown to evolve rapidly and display a high level of sequence variability.

Maternally deposited germline piRNAs silence the tirant retrotransposon in somatic cells.

Transposable elements (TEs), whose propagation can result in severe damage to the host genome, are silenced in the animal gonad by Piwi-interacting RNAs (piRNAs). piRNAs produced in the ovaries are deposited in the embryonic germline and initiate TE repression in the germline progeny. Whether the maternally transmitted piRNAs play a role in the silencing of somatic TEs is however unknown.

A comparative analysis of the amounts and dynamics of transposable elements in natural populations of Drosophila melanogaster and Drosophila simulans.

Genes are important in defining genetic variability, but they do not constitute the largest component of genomes, which in most organisms contain large amounts of various repeated sequences including transposable elements (TEs), which have been shown to account for most of the genome size. TEs contribute to genetic diversity by their mutational potential as a result of their ability to insert into genes or gene regulator regions, to promote chromosomal rearrangements, and to interfere with gene networks. Also, TEs may be activated by environmental stresses (such as temperature or radiation) that interfere with epigenetic regulation systems, and makes them powerful mutation agents in nature.

tirant, a newly discovered active endogenous retrovirus in Drosophila simulans.

Endogenous retroviruses have the ability to become permanently integrated into the genomes of their host, and they are generally transmitted vertically from parent to progeny. With the exception of gypsy, few endogenous retroviruses have been identified in insects. In this study, we describe the tirant endogenous retrovirus in a subset of Drosophila simulans natural populations.