MicroR159 regulation of most conserved targets in Arabidopsis has negligible phenotypic effects

BACKGROUND A current challenge of microRNA (miRNA) research is the identification of biologically relevant miRNA:target gene relationships. In plants, high miRNA:target gene complementarity has enabled accurate target predictions, and slicing of target mRNAs has facilitated target validation through rapid amplification of 5' cDNA ends (5'-RACE) analysis. Together, these approaches have identified more than 20 targets potentially regulated by the deeply conserved miR159 family in Arabidopsis, including eight MYB genes with highly conserved miR159 target sites. However, genetic analysis has revealed the functional specificity of the major family members, miR159a and miR159b is limited to only two targets, MYB33 and MYB65. Here, we examine the functional role of miR159 regulation for the other potential MYB target genes. RESULTS For these target genes, functional analysis failed to identify miR159 regulation that resulted in any major phenotypic impact, either at the morphological or molecular level. This appears to be mainly due to the quiescent nature of the remaining family member, MIR159c. Although its expression overlaps in a temporal and spatial cell-specific manner with a subset of these targets in anthers, the abundance of miR159c is extremely low and concomitantly a mir159c mutant displays no anther defects. Examination of potential miR159c targets with conserved miR159 binding sites found neither their spatial or temporal expression domains appeared miR159 regulated, despite the detection of miR159-guided cleavage products by 5'-RACE. Moreover, expression of a miR159-resistant target (mMYB101) resulted predominantly in plants that are indistinguishable from wild type. Plants that displayed altered morphological phenotypes were found to be ectopically expressing the mMYB101 transgene, and hence were misrepresentative of the in vivo functional role of miR159. CONCLUSIONS This study presents a novel explanation for a paradox common to plant and animal miRNA systems, where among many potential miRNA-target relationships usually only a few appear physiologically relevant. The identification of a quiescent miR159c:target gene regulatory module in anthers provides a likely rationale for the presence of conserved miR159 binding sites in many targets for which miR159 regulation has no obvious functional role. Remnants from the demise of such modules may lead to an overestimation of miRNA regulatory complexity when investigated using bioinformatic, 5'-RACE or transgenic approaches.RSA was funded by an ANU postgraduate scholarship and by a CSIRO Emerging Science Initiative. JL is the recipient of an ANU international student postgraduate scholarship. This research was supported by an Australian Research Council grant DP0773270

125 - 211 GHz low noise MMIC amplifier design for radio astronomy

To achieve the low noise and wide bandwidth required for millimeter wavelength astronomy applications, superconductor-insulator-superconductor (SIS) mixer based receiver systems have typically been used. This paper investigates the performance of high electron mobility transistor (HEMT) based low noise amplifiers (LNAs) as an alternative approach for systems operating in the 125 — 211 GHz frequency range. A four-stage, common-source, unconditionally stable monolithic microwave integrated circuit (MMIC) design is presented using the state-of-the-art 35 nm indium phosphide HEMT process from Northrop Grumman Corporation. The simulated MMIC achieves noise temperature (T_e) lower than 58 K across the operational bandwidth, with average T_e of 38.8 K (corresponding to less than 5 times the quantum limit (hf/k) at 170 GHz) and forward transmission of 20.5 ± 0.85 dB. Input and output reflection coefficients are better than -6 and -12 dB, respectively, across the desired bandwidth. To the authors knowledge, no LNA currently operates across the entirety of this frequency range. Successful fabrication and implementation of this LNA would challenge the dominance SIS mixers have on sub-THz receivers

gem-Dibromocyclopropanes and enzymatically derived cis-1,2-dihydrocatechols as building blocks in alkaloid synthesis

The application of the title building blocks, the 6,6-dibromobicyclo[3.1.0]hexanes and the cis-1,2-dihydrocatechols, to the total synthesis of crinine and lycorinine alkaloids is described.We thank the Australian Research Council and the Institute of Advanced Studies for generous financial support

Tests of the Las Campanas Distant Cluster Survey from Confirmation Observations for the ESO Distant Cluster Survey

The ESO Distant Cluster Survey (EDisCS) is a photometric and spectroscopic study of the galaxy cluster population at two epochs, z~0.5 and z~0.8, drawn from the Las Campanas Distant Cluster Survey (LCDCS). We report results from the initial candidate confirmation stage of the program and use these results to probe the properties of the LCDCS. Of the 30 candidates targeted, we find statistically significant overdensities of red galaxies near 28. Of the ten additional candidates serendipitously observed within the fields of the targeted 30, we detect red galaxy overdensities near six. We test the robustness of the published LCDCS estimated redshifts to misidentification of the brighest cluster galaxy (BCG) in the survey data, and measure the spatial alignment of the published cluster coordinates, the peak red galaxy overdensity, and the brightest cluster galaxy. We conclude that for LCDCS clusters out to z~0.8, 1) the LCDCS coordinates agree with the centroid of the red galaxy overdensity to within 25'' (~150 h^{-1} kpc) for 34 out of 37 candidates with 3\sigma galaxy overdensities, 2) BCGs are typically coincident with the centroid of the red galaxy population to within a projected separation of 200 h^{-1} kpc (32 out of 34 confirmed candidates), 3) the red galaxy population is strongly concentrated, and 4) the misidentification of the BCG in the LCDCS causes a redshift error >0.1 in 15-20% of the LCDCS candidates. These findings together help explain the success of the surface brightness fluctuations detection method.Comment: 10 pages, 9 figures, accepted for publication in the November 10 issue of Ap

Lensed CMB power spectra from all-sky correlation functions

Weak lensing of the CMB changes the unlensed temperature anisotropy and polarization power spectra. Accounting for the lensing effect will be crucial to obtain accurate parameter constraints from sensitive CMB observations. Methods for computing the lensed power spectra using a low-order perturbative expansion are not good enough for percent-level accuracy. Non-perturbative flat-sky methods are more accurate, but curvature effects change the spectra at the 0.3-1% level. We describe a new, accurate and fast, full-sky correlation-function method for computing the lensing effect on CMB power spectra to better than 0.1% at l<2500 (within the approximation that the lensing potential is linear and Gaussian). We also discuss the effect of non-linear evolution of the gravitational potential on the lensed power spectra. Our fast numerical code is publicly available.Comment: 16 pages, 4 figures. Changes to match PRD version including new section on non-linear corrections. CAMB code available at http://camb.info

Exploring the role of BMP7 gene expression in an In Vitro model of aging human skeletal muscle.

Sarcopenia is an age-related condition associated with rapid loss of skeletal muscle (SKM) tissue that affects mobility and quality of life of geriatric individuals. Mechanistic Target of Rapamycin (mTOR) and Protein Kinase B (AKT) have significant roles in SKM hypertrophy with responses to DNA damage and repair within SKM. However, mTOR and AKT expression is significantly decreased with age. Upstream of AKT, Bone Morphogenetic Protein (BMP7) is a member of the TGF-β signaling family that has been reported as a positive regulator of muscle hypertrophy through the Bmp–Smad1/5/8 signaling axis. PURPOSE: To use an in vitro model of aging muscle cells to investigate the role of BMP7 expression on protein synthesis. METHODS: Human SKM myoblasts were cultured and grown beyond mature myotube formation (typically day 6) to emulate aged SKM tissue (extracted on day 18). Groups included control cells (D6) and aged SKM myotubes (D18). Total RNA was extracted at the respective time points (days 6 & 18) and gene expression for BMP7, mTOR, and AKT was determined by qPCR. RESULTS: BMP7 expression was 7.73 fold greater for D18 compared to D6 (p \u3c 0.05). No differences were reported for AKT or mTOR. Data are expressed as fold changes. CONCLUSION: BMP7 expression, thought to be a positive regulator of muscle hypertrophy, was increased in the aging muscle cells of our model, despite our hypothesis that it would be decreased. However, BMP7’s downstream targets related to increased protein synthesis, mTOR and AKT, did not similarly increase from D6 to D18, which is constant with the phenomena of sarcopenia. This leads us to speculate that there may be additional mechanisms related to BMP7 activation and, despite increased signaling, may block protein synthesis at the level of AKT

The impact of naive agents in heterogeneous trust-aware societies

Autonomous agents require trust and reputation concepts in order to identify communities of agents with which to interact reliably in ways analogous to humans. Agent societies are invariably heterogeneous, with multiple decision making policies and actions governing their behaviour. Through the introduction of naive agents, this paper shows empirically that while learning agents can identify malicious agents through direct interaction, naive agents compromise utility through their inability to discern malicious agents. Moreover, the impact of the proportion of naive agents on the society is analyzed. The paper demonstrates that there is a need for witness interaction trust to detect naive agents in addition to the need for direct interaction trust to detect malicious agents. By proposing a set of policies, the paper demonstrates how learning agents can isolate themselves from naive and malicious agents

Towards distribution-based control of social networks

Background: Complex networks are found in many domains and the control of these networks is a research topic that continues to draw increasing attention. This paper proposes a method of network control that attempts to maintain a specified target distribution of the network state. In contrast to many existing network control research works, which focus exclusively on structural analysis of the network, this paper also accounts for user actions/behaviours within the network control problem. Methods: This paper proposes and makes use of a novel distribution-based control method. The control approach is applied within a simulation of the real-valued voter model, which could have applications in problems such as the avoidance of consensus or extremism. The network control problem under consideration is investigated using various theoretical network types, including scale free, random, and small world. Results: It is argued that a distribution-based control approach may be more appropriate for several types of social control problems, in which the exact state of the system is of less interest than the overall system behaviour. The preliminary results presented in this paper demonstrate that a standard reinforcement learning approach is capable of learning a control signal selection policy to prevent the network state distribution from straying far from a specified target distribution. Conclusions: In summary, the results presented in this paper demonstrate the feasibility of a distribution-based control solution within the simulated problem. Additionally, several interesting questions arise from these results and are discussed as potential future work

Robust resource allocation in weather data processing systems

Includes bibliographical references (pages [9-10]).Reliability of weather data processing systems is of prime importance to ensure the efficient operation of space-based weather monitoring systems. This work defines a heterogeneous weather data processing system that is susceptible to uncertainties in data set arrival times. The resource allocation must be robust with respect to these uncertainties. The tasks to be executed by the data processing system are classified into three broad categories: telemetry, tracking and control (high priority); data processing (medium priority); and data research (low priority).The high priority tasks must be completed before considering medium and low priority tasks. The goal of this research is to find a resource allocation that minimizes makespan of the high priority tasks, and to find a mapping that maximizes a function of the completion time and priority of the medium and low priority tasks. Different heuristic techniques to find near optimal solutions are studied, and their performance is evaluated