Dimerisation of the PICTS complex via LC8/Cut-up drives co-transcriptional transposon silencing in Drosophila

In animal gonads, the PIWI-interacting RNA (piRNA) pathway guards genome integrity in part through the co-transcriptional gene silencing of transposon insertions. In Drosophila ovaries, piRNA-loaded Piwi detects nascent transposon transcripts and instructs heterochromatin formation through the Panoramix-induced co-transcriptional silencing (PICTS) complex, containing Panoramix, Nxf2 and Nxt1. Here, we report that the highly conserved dynein light chain LC8/Cut-up (Ctp) is an essential component of the PICTS complex. Loss of Ctp results in transposon de-repression and a reduction in repressive chromatin marks specifically at transposon loci. In turn, Ctp can enforce transcriptional silencing when artificially recruited to RNA and DNA reporters. We show that Ctp drives dimerisation of the PICTS complex through its interaction with conserved motifs within Panoramix. Artificial dimerisation of Panoramix bypasses the necessity for its interaction with Ctp, demonstrating that conscription of a protein from a ubiquitous cellular machinery has fulfilled a fundamental requirement for a transposon silencing complex

Dimerisation of the PICTS complex via LC8/Cut-up drives co-transcriptional transposon silencing in Drosophila

In animal gonads, the PIWI-interacting RNA (piRNA) pathway guards genome integrity in part through the co-transcriptional gene silencing of transposon insertions. In Drosophila ovaries, piRNA-loaded Piwi detects nascent transposon transcripts and instructs heterochromatin formation through the Panoramix-induced co-transcriptional silencing (PICTS) complex, containing Panoramix, Nxf2 and Nxt1. Here, we report that the highly conserved dynein light chain LC8/Cut-up (Ctp) is an essential component of the PICTS complex. Loss of Ctp results in transposon de-repression and a reduction in repressive chromatin marks specifically at transposon loci. In turn, Ctp can enforce transcriptional silencing when artificially recruited to RNA and DNA reporters. We show that Ctp drives dimerisation of the PICTS complex through its interaction with conserved motifs within Panoramix. Artificial dimerisation of Panoramix bypasses the necessity for its interaction with Ctp, demonstrating that conscription of a protein from a ubiquitous cellular machinery has fulfilled a fundamental requirement for a transposon silencing complex

The Western Crete geodetic infrastructure: Long-range power-law correlations in GPS time series using detrended fluctuation Analysis

Summarization: The Global Positioning System makes it possible, nowadays, to measure crustal displacements with unprecedented accuracy. These measurements can improve our understanding of the spatio-temporal evolution of motion along tectonic plate boundaries, as well as deepen our comprehension for the nature of earthquake fault behavior and earthquake cycle. The Hellenic subduction zone and the earthquake-prone Crete, with large crustal motions of 3–4 cm/yr, may provide such a natural laboratory for this type of investigation. In this work, we examine the statistical structure and behavior of time series, as produced by permanent GPS sites, established on the islands of Crete and Gavdos. At first, we investigate the crustal motion based on daily displacements as monitored by a regional GPS network, established on either sides of faults, in Gavdos and Crete. Secondly, we reconstruct the missing data in the time series of two GPS stations, which contain the longest observations, by selecting an appropriate autoregressive stochastic model. This is accomplished by representing the state-space behavior of the signal using a Kalman filter. Finally, the Detrended Fluctuation Analysis has been applied on the residuals for the North and East components of the GPS displacements. In conclusion, there seems to exist strong evidence, at least for the period of measurements of 7.5 years, that both investigated stations show similar statistical behavior in the form of power law and exhibit the same (∼0.9–1.0) long-range correlation.Presented on: Advances in Space Researc

Absolute calibration of Jason satellite radar altimeters at Gavdos Cal/Val facility using independent techniques

Summarization: The Gavdos calibration facility for satellite radar altimeters has been operational as of 2004. The island is located along repeating ground tracks of Jason-1 and Jason-2 satellites (crossover point for passes No.109 ascending and No.018 descending and adjacent to Envisat), and because of its small size, both altimeter and radiometer measurements are not significantly contaminated by land. This makes Gavdos an ideal place for the calibration of satellite altimeters. In this work, three different techniques have been applied for calibrating the Jason altimeter measurements at Gavdos Cal/Val facility. These are: (i) The conventional: In-situ observations made by tide gauges, GNSS receivers, meteorological and other sensors in conjunction with precise geoid models are applied for determining the altimeter bias; (ii) The MSS: instead of the geoid, the mean sea level, provided by the CLS10_MSS model, is used as a reference surface for estimating the bias; and (iii) Microwave transponder measurements are implemented and examined over the cross over point on land to produce the altimeter bias as well. This paper presents the results regarding these calibration techniques.Presented on