Soon Young Jung

A two-photon fluorescent probe for lipid raft imaging : C-laurdan

The lipid‐rafts hypothesis proposes that naturally occurring lipid aggregates exist in the plane of membrane that are involved in signal transduction, protein sorting, and membrane transport. To understand their roles in cell biology, a direct visualization of such domains in living cells is essential. For this purpose, 6‐dodecanoyl‐2‐(dimethylamino)naphthalene (laurdan), a membrane probe that is sensitive to the polarity of the membrane, has often been used. We have synthesized and characterized 6‐dodecanoyl‐2‐[N‐methyl‐N‐(carboxymethyl)amino]naphthalene (C‐laurdan), which has the advantages of greater sensitivity to the membrane polarity, a brighter two‐photon fluorescence image, and reflecting the cell environment more accurately than laurdan. Lipid rafts can be visualized by two‐photon microscopy by using C‐laurdan as a probe. Our results show that the lipid rafts cover 38 % of the cell surface.

TRIM72, a novel negative feedback regulator of myogenesis, is transcriptionally activated by the synergism of MyoD (or myogenin) and MEF2.

TRIM72 is known to be involved in the negative feedback regulation of myogenesis by targeting insulin receptor substrate-1. Here, we found that TRIM72 was more highly expressed in oxidative muscle with the higher activity of MEF2, compared to glycolytic muscle. Indeed, TRIM72 promoter contained an evolutionarily conserved MEF2 site juxtaposed to E-box. TRIM72 promoter activity was decreased by the site-directed mutagenesis of either E-boxes or a MEF2 site and synergistically enhanced by MyoD (or myogenin) and MEF2, which were associated with proximal E-box, and MEF2 site of the TRIM72 promoter, respectively. Taken together all these data, we concluded that the synergism of MyoD (or myogenin) and MEF2 is necessary for TRIM72 expression during C2C12 differentiation.

Lipid raft proteome reveals that oxidative phosphorylation system is associated with the plasma membrane

Although accumulating proteomic analyses have supported the fact that mitochondrial oxidative phosphorylation (OXPHOS) complexes are localized in lipid rafts, which mediate cell signaling, immune response and host–pathogen interactions, there has been no in-depth study of the physiological functions of lipid-raft OXPHOS complexes. Here, we show that many subunits of OXPHOS complexes were identified from the lipid rafts of human adipocytes, C2C12 myotubes, Jurkat cells and surface biotin-labeled Jurkat cells via shotgun proteomic analysis. We discuss the findings of OXPHOS complexes in lipid rafts, the role of the surface ATP synthase complex as a receptor for various ligands and extracellular superoxide generation by plasma membrane oxidative phosphorylation complexes.

A resource manager for optimal resource selection and fault tolerance service in Grids

In this paper, we address the issues of resource management and fault tolerance in Grids. In Grids, the state of the selected resources for job execution is a primary factor that determines the computing performance. Specifically, we propose a resource manager for optimal resource selection. The resource manager automatically selects the optimal resources among candidate resources using a genetic algorithm. Typically, the probability of failure is higher in Grid computing than in a traditional parallel computing and the failure of resources affects job execution fatally. Therefore, a fault tolerance service is essential in computational Grids and Grid services are often expected to meet some minimum levels of quality of service (QoS) for desirable operation. To address this issue, we also propose fault tolerance service to satisfy QoS requirements. We extend the definition of failures, such as process failure, processor failure, and network failure, and design the fault detector and fault manager. The simulation results indicate that our approaches are promising in that (1) our resource manager finds the optimal set of resources that guarantees the optimal performance; (2) the fault detector detects the occurrence of resource failures; and (3) the fault manager guarantees that the submitted jobs complete and improves the performance of job execution due to job migration even if some failures happen.

Group-based dynamic computational replication mechanism in peer-to-peer grid computing

A peer-to-peer grid computing is complicated by heterogeneous capabilities, failures, volatility, and lack of trust because it is based on desktop computers at the edge of the Internet. In order to improve the reliability of computation and gain better performance, a replication mechanism must adapt to these distinct features. In other words, it is required to classify volunteers into groups that have similar properties and then dynamically apply different replication algorithms to each group. However, existing mechanisms do not provide such a replication mechanism on a per group basis. As a result, they cause a high overhead and poor performance. To solve the problems, we propose a new group-based computational replication mechanism to adapt to an unstable, untrusted, dynamic peer-to-peer grid computing environment. Our mechanism can reduce the number of redundancy and therefore complete many tasks by adaptively replicating computations on the basis of the properties of volunteer group such as availability, credibility, and volunteering service time.

Mitochondrial oxidative phosphorylation system is recruited to detergent‐resistant lipid rafts during myogenesis

Since detergent‐resistant lipid rafts play important roles in the signal transduction for myogenesis, their comprehensive proteomic analysis could provide new insights to understand their function in myotubes. Here, the detergent‐resistant lipid rafts were isolated from C2C12 myotubes and analyzed by capillary RPLC/MS/MS. Among the 327 proteins (or protein groups) identified, 28% were categorized to the plasma membrane or raft proteins, 29% to mitochondria, 20% to microsomal proteins, 10% to other proteins, and 13% to unknown proteins. The localization of oxidative phosphorylation (OXPHOS) complexes in the sarcolemma lipid rafts was further confirmed from C2C12 myotubes by cellular fractionation, surface‐biotin labeling, immunofluorescence, and lipid raft fractionation. After adding exogenous cytochrome c, the sarcolemma isolated from myotubes had an ability to consume oxygen in the presence of NADH or succinate. The generation of NADH‐dependent extracellular superoxide was increased by inhibiting or downregulating OXPHOS I, III, and IV in myotubes, indicating that OXPHOS proteins are major sources for extracellular ROS in skeletal muscle. With all these data, we can conclude that OXPHOS proteins are associated with the sarcolemma lipid rafts during C2C12 myogenesis to generate extracellular ROS.

Scheduling Scheme based on Dedication Rate in Volunteer Computing Environment

A volunteer node can join and leave a volunteer computing system freely. However, existing volunteer computing systems suffer from interruptions of job execution, delays of execution time, and increases of total execution time, since they do not consider dynamic scheduling properties (i.e. volatilities), such as leave, join, and suspension. Therefore, dynamic execution properties of volunteer node should be considered in scheduling schemes, in order to design a stable and reliable volunteer computing system. This paper proposes a new scheduling scheme based on the dedication rate (DR), which reflects the dynamic properties of a volunteer. The scheduling scheme improves the completeness and reliability of execution, while also decreasing delay and total execution time. In addition, an implementation of the proposed scheduling scheme on top of Korea@Home is described, as well as performance evaluation

Nearest surrounder searching in mobile computing environments

SUMMARY The key issue in mobile computing environments (MCEs) is how to relieve communication congestion and provide accurate information through location-based services (LBSs). The nearest surrounder (NS) query, used to find all visible objects around a given location, is a type of spatial query that suggests broad application base in LBS domain. However, because existing works for NS query only take into account static query points, the application of the NS query is limited to various LBSs in MCEs requiring frequent location updates. Motivated by this limitation, this paper introduces the continuous nearest surrounder (CNS) query, which uses a decentralized system framework to continuously maintain updated query results in MCEs. In this framework, the LBS server executes an initial NS query to prepare a region, termed non-provoked polygon (NPP), defines a set of visible objects that cannot be changed. Conversely, a client caches the NPP and does not update request unless it leaves its NPP. We performed extensive experiments using synthetic and real datasets with various data cardinality, and query mobility to validate the accurate performance of the proposed strategy. The results show that the CNS algorithm outperforms NS, in terms of computation and communication costs as well as scalability.Copyright

A new conflict relation for concurrency control and recovery in object-based databases

This paper proposes preservation as a new conflict relation in an object-based database. By explicitly including reverse-operations which bridge the gap between concurrency control and recovery, preservation can be used independently of execution contexts to which different recovery algorithms and/or object models give rise, and further it forms a basis for formulating semantics-based recovery. This paper also makes a t wo-dimensional( i.e., execution cent exts and operations’ specifications) comparison bet ween preservation and other conflict relations. Irr each execution cent ext, our formal comparison reveala that preservationbased concurrency control achieves more concurrency than commutativity-based one.

Practical firewall policy inspection using anomaly detection and its visualization

Due to the increasing cyber threats, firewall has become the one of the core elements in network security. The effectiveness of firewall security is dependent on providing policy management techniques. For this reason, it is highly required to have an automatic tool that is real applicable to running firewalls and it should help administrators use in easy. This paper represents a first step toward a practically applicable tool called Firewall Policy Checker for firewall policy inspection based on four anomaly types. It also focuses on detecting dangerous services such as telnet, ftp and so on which many administrators set as time goes and detecting illegal servers. In addition, this tool supports a large number of rules with the high speed using efficient N-ary tree module. The experimental results using real organizations’ rules are introduced. Finally, this paper illustrates an easy 3D visualization even for non experts.