Design and Operation of the GPS Receiver Onboard the CanX-2 Nanosatellite
NAVIGATION-JOURNAL OF THE INSTITUTE OF NAVIGATION
Authors: Kahr, Erin; O'Keefe, Kyle P. G.; Skone, Susan; Bradbury, Laura
Abstract
Among its payloads, the Canadian Advanced Nanospace eXperiment 2 (CanX-2) nanosatellite is carrying a commercial off-the-shelf GPS receiver, which offers advantages in terms of cost, size and power, and overall continues to perform well more than four years after launch. However, at orbital velocity and with low signal power the receiver is unable to acquire a position fix quickly using its standard acquisition algorithm. In order to effectively collect GPS data over short time intervals, the receiver is manually warm started by pre-assigning channels with PRN and Doppler information. Uploading warm start scripts to the satellite allows for reliable acquisition in an average of 3.5 min compared to a cold start of approximately 20 min, and avoids the need for complex onboard warm start capability. The data collection capability has in turn enabled a variety of scientific results to be obtained. Copyright (C) 2013 Institute of Navigation.
Depletion of endogenous miRNA-378-3p increases peak cell density of CHO DP12 cells and is correlated with elevated levels of ubiquitin carboxyl-terminal hydrolase 14
JOURNAL OF BIOTECHNOLOGY
Authors: Costello, Alan; Coleman, Orla; Lao, Nga T.; Henry, Michael; Meleady, Paula; Barron, Niall; Clynes, Martin
Abstract
miRNAs are potent molecular regulators of cellular behaviour. The manipulation of these small non-coding RNAs has been used to enhance industrially relevant phenotypes in Chinese Hamster Ovary (CHO) cells. We investigated the stable depletion of six miRNAs; miR-204-5p, 338-3p, 378-3p, 409-3p, 455-3p and 505-3p, robustly associated with cell growth rate from a previous profiling study. Inhibition of endogenous miR-378-3p function by miRNA-sponge-decoy improved peak cell density by 59%. Quantitative label free LC-MS/MS proteomic analysis of the fractionated cell cultures at day 4 and 8 of batch culture found 216 cytosolic and 114 membrane-associated proteins differentially expressed with stable miR-378-3p depletion. qRT-PCR of 8 genes; Clic4, Hnrnpa1, Prdx1, Actn4, Usp14, Srxn1, Canx and Gnb1, with unidirectional differential protein expression over the two time points of analysis was carried out. In-silico predictive algorithms; TargetScan and miRDB, were used to decipher possible direct targets of miR-378-3p. The Ubiquitin carboxyl-terminal hydrolase 14 (Usp14) protein was identified in the cytosolic fractions at both timepoints as differentially expressed with an increased abundance of 1.58-fold in the miR-378-3p depleted cells on day 8. Usp14 is a deubiquitinase (DUB) with previous reports of its up-regulation leading to increased proliferation of cancer cells. Overexpression of Usp14 in CHO cells had significant effects on cell growth supporting a role for Usp14 in the increased peak cell density seen with miR-378-3p depletion. This study highlights miR-378-3p as a novel engineering candidate for improving CHO cell growth. The use of subcellular fractionation also improved proteome coverage in the identification of novel miRNA targets.