Conformational features of the human U2-U6 snRNA complex

The splicing of precursor messenger (pre-m) RNA, during which noncoding intervening sequences are excised and flanking coding regions ligated, is an integral reaction of gene expression. In eukaryotes, it is carried out by a dynamic RNA-protein complex called the spliceosome, in which five small nuclear (sn) RNA components are actively involved in recognition and chemical aspects of the process. A complex formed between U2 and U6 snRNAs is implicated in the chemistry of pre-mRNA splicing. The catalytic activity of the U2-U6 snRNA complex is dependent on the presence of Mg2+ ions, and the complex has been shown to have several specifically bound Mg2+ binding sites in vitro. The overall goal of this research is to characterize the conformational changes of the human U2-U6 snRNA complex upon addition of Mg2+. In order to pursue this question, we attempted to characterize the lowest energy structure of the complex in the absence of spliceosomal proteins using a combination of biophysical and biochemical techniques in the solution state. We first used enzymatic structure probing to evaluate the secondary structural fold of protein-free human U2-U6 snRNA complex. Cleavage patterns resulting from probing reactions were consistent with formation of four stem regions surrounding the junction, therefore favoring the four-helix model consistent with previous results of in vivo studies of the human U2-U6 snRNA complex. However, 19F NMR studies from our laboratory also identified a lesser fraction (up to 14%) of a three- helix conformation. Upon addition of up to 100 mM Mg2+, a slight increase in cleavage by enzymes specific for both single-stranded and double-stranded regions was observed at the junction region, suggesting that this region is becoming more accessible, perhaps because of an increase in the fraction of the three-helix conformation. Analytical ultracentrifugation studies revealed that the Stokes radius of the RNA complex decreased slightly from 31.3 Ã? to 27.9 Ã? in the presence of 100 mM Mg2+, suggesting a slight compaction of the tertiary structure in the presence of divalent metal ions. Hydroxyl radical footprinting experiments on this complex showed signs of increased protection in some areas near and more distant from the junction upon addition of Mg2+, suggesting a change in three-dimensional conformation. Therefore, it appears that Mg2+ induces a small three-dimensional conformational change on human U2-U6 snRNA complex. In order to build a three-dimensional model for the four-helix conformation, we designed a mutant that favors the formation of four-helix conformation and performed SAXS experiments on it. The preliminary SAXS studies suggest that the human U2-U6 snRNA complex and the mutant complex may also be amenable to further study by SAXS. These results act as a good starting point to characterize further the overall global conformation of human U2-U6 snRNA complex and effects of spliceosomal proteins on it

Goal Flexibility as a Predictor of Depression, Rumination and Homesickness in Students

Objective: Theoretical and empirical evidence in the field of self-regulation and goal adjustment posits that being able to disengage from goals that are no longer attainable and reengage with new ones is related to improved wellbeing. Transition to university involves being able to successfully disengage from previous goals that have become unattainable and identify and engage in meaningful new goals, however research in this area is sparse. The current study therefore predicted that greater difficulties with goal disengagement in students would be associated with increased depressive symptoms, rumination and homesickness at the beginning of term. Difficulties with goal adjustment was further predicted to be associated with increased depressive symptoms at the end of term and this would partly be mediated by increased homesickness from the beginning to middle of term. Methods: New undergraduates completed self-report assessments on goal adjustment capacities, depressive symptoms, rumination and homesickness at baseline (N = 221) and a four-month follow up (N = 198). Data was analysed using hierarchical multiple regression and mediation analysis. Results: Goal disengagement was not significant in predicting depressive symptoms, rumination or homesickness at baseline in students. Goal reengagement was also not significant in predicting rumination or homesickness at baseline; however, it was significant in predicting depressive symptoms at baseline. Only goal reengagement was found to significantly predict fewer reported symptoms of depression at time 3. Further analysis revealed that residualised change in homesickness from baseline to time 2 did not mediate goal adjustment and depressive symptoms at the end of term. Conclusion: Despite the lack of support for goal disengagement, findings indicate that identifying and engaging in meaningful and attainable goals may be beneficial for depressive symptoms among university students during the first term

A comparative analysis of the hydrological performance of reconstructed and natural watersheds

An example of watershed disturbance activity undertaken to gain access to the oil sands is large scale mining in the Athabasca basin, Alberta, Canada. One of the remedial activities of this disturbance is the reclamation of the disturbed lands. In the process of reclamation, the overburden soil is placed back into the mined pits and reformed with soil covers (alternatively called reconstructed watersheds). In the design process of reclamation, a major concern is hydrological sustainability, which includes the soil’s ability to store enough moisture for the water requirements of vegetation growth and land-atmospheric moisture fluxes. Typically, the goal of the reclamation is to restore the disturbed watersheds, so that they mimic the natural watersheds in terms of the ecological sustainability. Therefore, a comparative evaluation of the hydrological sustainability of the reconstructed watersheds with natural watersheds is required.The considered reconstructed watershed in this study (the flat top of the South Bison Hill, Fort McMurray, Alberta, which is about 6 years old) constitutes a thin layer of a peat-mineral mix (20 cm thick) overlying an 80 cm thick secondary (glacial till) layer on the shale formation, mimicking the natural soil horizons of undisturbed watersheds. As the reconstructed watershed is located in the boreal forest region, a mature boreal forest (Old Aspen site, about 88 years old) located in the Southern Study Area (SSA), BOREAS, Saskatchewan, Canada, is considered as a representative of natural watershed. The A-horizon with 25 cm of sandy loam texture, the B-horizon with 45 cm-thick sandy clay loam, and the C-horizon with 40 cm of a mixture of sandy clay loam and loam are considered in this study.An existing System Dynamics Watershed (SDW) model (lumped and site-specific) is modified and adapted to model the hydrological processes of the reconstructed and natural watersheds, such as soil moisture, evapotranspiration, and runoff. The models are calibrated and validated on daily time scale using two years data (growing season) in each case. The hydrological processes are simulated reasonably well despite the high complexity involved in the processes of soil moisture dynamics and the evapotranspiration, for both study areas. Using the modified and calibrated models, long term simulations (48 years) are carried out on both the reconstructed and natural watersheds. Vegetation properties are switched between the reconstructed and natural watersheds and two scenarios are generated. Consequently, long term simulations are performed. With the help of a probabilistic approach, the daily soil moisture results are used to address the comparative soil moisture storage capability of the watersheds.The results indicate that the selected reconstructed watershed is able to provide its designed store-and-release moisture of 160 mm (a requirement of the land capability classification for forest ecosystems in the oil sands) for the vegetation and meteorological moisture demands at a non-exceedance probability of 93%. The comparative study shows that the reconstructed watershed provides less moisture for evapotranspiration requirements than the natural watershed. The reconstructed watershed is able to provide less moisture than the natural watershed for both small and also mature vegetation scenarios. A possible reason for this may be that the reconstructed site is still in the process of restoration and that it may take a few more years to get closer to natural watersheds in terms of the hydrological sustainability. The study also demonstrates the utility of the system dynamics approach of modeling the case study under consideration. The future addition of a vegetation growth model to the hydrological model, and the development of a generic watershed modeling technique would be helpful in decision making and management practices of watershed reclamation

SISO System Model Reduction and Digital Controller Design using Nature Inspired Heuristic Optimisation Algorithms

This research article explores an algorithm to reduce the order of a SISO system and thereby to design a digital controller. The reduced order modelling of a large complex system eases out the analysis of the system. AGTM (Approximate Generalised Time Moments) method was implemented wherein the responses were matched at different time instants to achieve the reduced system. This research work devises a new method, Ensemble Framework for Optimized System (EFOS), resulting into a reduced system with better performance as compared to conventional techniques. The research also efforts towards effective utilization of various heuristic algorithms like Genetic Algorithm, Particle Swarm Optimization and Luus Jaakola Algorithm, their implementation and a comparison with other techniques based on relative mean square error and time complexity. It was observed that the proposed transfer learning based approach, EFOS, combining the advantages of Luus Jaakola and Genetic algorithms depicted better results than their individual counterparts on diverse performance parameters like speed of convergence and optimal convergence to global minima. The percentage improvement achieved in the time taken for design of the digital controller was 85.3%, with no change in delta value

A study of surgical management of distal femoral fractures in adults using locking compression plate

Background: The introduction of locking compression plates with option of locked screws has provided the means to increase the stability of fracture fixation.Methods: In this study, 30 distal femoral fractures were treated using the distal femoral locking compression plate. All fractures were fresh, closed and operated within 12 days. Follow up duration ranged from 6 to 18 months.Results: In this study, 20 patients were males and 10 were females. The 23 of the fractures (76.66%), were caused by road traffic accidents, 3 were due to accidental falls (10%), one was due to assault and 3 were due to fall from height.9 patients had associated injuries.  All patients were treated with open reduction and internal fixation using Locking Compression Plate. 6 to 9 holed plates were used. Out of 30 patients 2 went for delayed union and 3 went for non-union. Average knee flexion was 109o having knee range of motion more than 100 with 50% patients. Average knee extensor lag was 2.4 degrees with only 4 patients with lag more than 5. 2 patients developed 2 cm shortening. 4 patients had less than 5 degrees of malalignment. 2 patients had deep infection. Functional outcome was measured using NEER's scoring system and was done at the end of 5- 7 months (average of 6 months).  Excellent results- 17 (56.66%) good results-8 (26.66%) fair results-2 (6.66%) poor results-3 (10%).Conclusions: LCP condylar plate represents an evolutionary approach to the surgical management and is an important armamentarium in distal femur fracture fixation, especially when fracture is severely comminuted and in situations of osteoporosis.

Detection of Motion Vector-Based Video Steganography by Adding or Subtracting One Motion Vector Value

In last decades the Steganography is an tremendous progress, at the same time there exist issues to detect the steganalysis in motion based video where the substance is reliably in motion conduct that makes that to detect it. Analyzing the difference between the rated motion value plays a crucial role that enables us to focus on difference between the locally optimal SAD and actual SAD after adding-or-subtracting-one operation on the motion value. Based on the motion vectors to play out the classification and extraction process at last, two features sets are been used based on the fact that most motion vectors are locally optimal for most video codec’s to complete this process. The conventional approaches announced the technique for proposed prevails to meet the requirement applications and detecting the steganalysis in videos compare in the literature