Search results for "INTERFERENCE"

Molecular basis of adaptive convergence in experimental populations of RNA viruses

2002

Abstract Characterizing the molecular basis of adaptation is one of the most important goals in modern evolutionary genetics. Here, we report a full-genome sequence analysis of 21 independent populations of vesicular stomatitis ribovirus evolved on the same cell type but under different demographic regimes. Each demographic regime differed in the effective viral population size. Evolutionary convergences are widespread both at synonymous and nonsynonymous replacements as well as in an intergenic region. We also found evidence for epistasis among sites of the same and different loci. We explain convergences as the consequence of four factors: (1) environmental homogeneity that supposes an id…

Linker histone H1 is essential for Drosophila development, the establishment of pericentric heterochromatin, and a normal polytene chromosome structu…

2009

We generated mutant alleles of Drosophila melanogaster in which expression of the linker histone H1 can be down-regulated over a wide range by RNAi. When the H1 protein level is reduced to ∼20% of the level in wild-type larvae, lethality occurs in the late larval – pupal stages of development. Here we show that H1 has an important function in gene regulation within or near heterochromatin. It is a strong dominant suppressor of position effect variegation (PEV). Similar to other suppressors of PEV, H1 is simultaneously involved in both the repression of euchromatic genes brought to the vicinity of pericentric heterochromatin and the activation of heterochromatic genes that depend on their pe…

A single type of cadherin is involved inBacillus thuringiensistoxicity inPlutella xylostella

2015

Cadherins have been described as one the main functional receptors for the toxins of the entomopathogenic bacterium, Bacillus thuringiensis (Bt). With the availability of the whole genome of Plutella xylostella, different types of cadherins have been annotated. In this study we focused on determining those members of the cadherin-related proteins that potentially play a role in the mode of action of Bt toxins. For this, we mined the genome of P. xylostella to identify these putative cadherins. The genome screening revealed 52 genes that were annotated as cadherin or cadherin-like genes. Further analysis revealed that six of these putative cadherins had three motifs common to all Bt-related …

RNA-based regulation of transposon expression

2015

Throughout the domains of life, transposon activity represents a serious threat to genome integrity and evolution has realized different molecular mechanisms that aim to inhibit the transposition of mobile DNA. Small noncoding RNAs that function as guides for Argonaute effector proteins represent a key feature of so-called RNA interference (RNAi) pathways and specialized RNAi pathways exist to repress transposon activity on the transcriptional and posttranscriptional level. Transposon transcription can be diminished by targeted DNA methylation or chromatin remodeling via repressive Histone modifications. Posttranscriptional transposon silencing bases on degradation of transposon transcripts…

2015

Piwi-interacting (pi-) RNAs guide germline-expressed Piwi proteins in order to suppress the activity of transposable elements (TEs). But notably, the majority of pachytene piRNAs in mammalian testes is not related to TEs. This raises the question of whether the Piwi/piRNA pathway exerts functions beyond TE silencing. Although gene-derived piRNAs were described many times, a possible gene-regulatory function was doubted due to the absence of antisense piRNAs. Here we sequenced and analyzed piRNAs expressed in the adult testis of the pig, as this taxon possesses the full set of mammalian Piwi paralogs while their spermatozoa are marked by an extreme fitness due to selective breeding. We provi…

RNAi knock-down mice: an emerging technology for post-genomic functional genetics

2003

RNA interference (RNAi) has been extensively used for sequence-specific silencing of gene function in mammalian cells. The latest major breakthrough in the application of RNAi technology came from experiments demonstrating RNAi-mediated gene repression in mice and rats. After more than two decades of functional mouse research aimed at developing and continuously improving transgenic and knock-out technology, the advent of RNAi knock-down mice represents a valuable new alternative for studying gene function in vivo. In this review we provide some basic insight as to how RNAi can induce gene silencing to then focus on recent findings concerning the applicability of RNAi for regulating gene fu…

CENPA overexpression promotes genome instability in pRb-depleted human cells

2009

Abstract Background Aneuploidy is a hallmark of most human cancers that arises as a consequence of chromosomal instability and it is frequently associated with centrosome amplification. Functional inactivation of the Retinoblastoma protein (pRb) has been indicated as a cause promoting chromosomal instability as well centrosome amplification. However, the underlying molecular mechanism still remains to be clarified. Results Here we show that pRb depletion both in wild type and p53 knockout HCT116 cells was associated with the presence of multipolar spindles, anaphase bridges, lagging chromosomes and micronuclei harbouring whole chromosomes. In addition aneuploidy caused by pRb acute loss was…

Ligophorus pilengas n. sp. (monogenea: ancyrocephalidae) from the introduced so-iuy mullet, mugil soiuy (teleostei: mugilidae), in the sea of Azov an…

2004

The monogenean Ligophorus chabaudi was originally described on the gills of the flathead mullet, Mugil cephalus, and was subsequently reported on the So-iuy mullet, Mugil soiuy. However, the morphology of sclerotized parts and multivariate statistical analyses suggest that the form from the So-iuy mullet represents a new species. This study provides a description of the new species Ligophorus pilengas n. sp. and provides additional morphological data concerning the morphology of the ventral bar that might be useful for the diagnosis of Ligophorus. Ligophorus pilengas n. sp. is the second species of Ligophorus reported on the So-iuy mullet. Zoogeographical records indicate that L. pilengas n…

Cohen syndrome is associated with major glycosylation defects

2014

International audience; Cohen syndrome (CS) is a rare autosomal recessive disorder with multisytemic clinical features due to mutations in the VPS13B gene, which has recently been described encoding a mandatory membrane protein involved in Golgi integrity. As the Golgi complex is the place where glycosylation of newly synthesized proteins occurs, we hypothesized that VPS13B deficiency, responsible of Golgi apparatus disturbance, could lead to glycosylation defects and/or mysfunction of this organelle, and thus be a cause of the main clinical manifestations of CS. The glycosylation status of CS serum proteins showed a very unusual pattern of glycosylation characterized by a significant accum…

MicroRNAs in solid organ and vascularized composite allotransplantation: Potential biomarkers for diagnosis and therapeutic use

2020

Abstract Nowadays, solid organ transplantation (SOT) is an established treatment for patients with end-organ dysfunction, which dramatically improves the quality-of-life. Vascularized composite allotransplants (VCAs) including hand and face have been reported worldwide over the last 20 years. However, VCAs, differently to SOT, are life-enhancing instead of life-saving and are not routinely performed due to the risk of immune rejection and the adverse effects of immunosuppression. Over the past decade, although considerable improvements in short-term outcomes after allotransplantation have been registered, these results have not been translated into major progress in long-term allograft acce…