Alternative polyadenylation of antisense RNAs and flowering time control
BIOCHEMICAL SOCIETY TRANSACTIONS
Authors: Hornyik, Csaba; Duc, Celine; Rataj, Katarzyna; Terzi, Lionel C.; Simpson, Gordon G.
Abstract
Flowering time is controlled by precision in gene regulation mediated by different pathways. Two Arabidopsis thallium, components of the autonomous flowering pathway, FCA and FPA, function as genetically independent frons-acting regulators of alternative cleavage and polyadenylation. FCA and FPA directly associate with chromatin at the locus encoding the floral repressor FLC, but appear to control FLC transcription by mediating alternative polyadenylation of embedded non-coding antisense RNAs. These findings prompt the re-examination of how other factors control FLC expression, as it is formally possible that they function primarily to control alternative processing of antisense RNAs. As co-expressed sense and antisense gene pairs are wide spread in eukaryotes, alternative processing of antisense RNAs may represent a significant form of gene regulation.
Super-resolved parallel MRI by spatiotemporal encoding
MAGNETIC RESONANCE IMAGING
Authors: Schmidt, Rita; Baishya, Bikash; Ben-Eliezer, Noam; Seginer, Amir; Frydman, Lucio
Abstract
Recent studies described an "ultrafast" scanning method based on spatiotemporal (SPEN) principles. SPEN demonstrates numerous potential advantages over EPI-based alternatives, at no additional expense in experimental complexity. An important aspect that SPEN still needs to achieve for providing a competitive ultrafast MRI acquisition alternative, entails exploiting parallel imaging algorithms without compromising its proven capabilities. The present work introduces a combination of multi-band frequency-swept pulses simultaneously encoding multiple, partial fields-of-view, together with a new algorithm merging a Super-Resolved SPEN image reconstruction and SENSE multiple-receiving methods. This approach enables one to reduce both the excitation and acquisition times of sub-second SPEN acquisitions by the customary acceleration factor R, without compromises in either the method's spatial resolution, SAR deposition, or capability to operate in multi-slice mode. The performance of these new single-shot imaging sequences and their ancillary algorithms were explored and corroborated on phantoms and human volunteers at 3 T. The gains of the parallelized approach were particularly evident when dealing with heterogeneous systems subject to major T-2/T-2* effects, as is the case upon single-scan imaging near tissue/air interfaces. (C) 2014 Elsevier Inc. All rights reserved.