N. G. Kim

Improvement of Task Retrieval Performance Using AMGA in a Large-Scale Virtual Screening

In this paper, we address performance and scalability issues when AMGA (ARDA Metadata Grid Application) is used as a metadata service for task retrieval in the WISDOM (Wide in Silico Docking on Malaria) environment, and propose optimization techniques to deal with the issues. First, to deal with the performance problem due to the communication overhead caused by the need for jobs to call a series of AMGA operations in order for them to retrieve a task from the AMGA server in the WISDOM environment, we propose a new AMGA operation which allows jobs deployed on the Grid to retrieve a task in a single operation instead of calling series of existing AMGA operations. According to the performance study that we have done, the throughput of task retrieval using the new AMGA operation can be as much as 70 times higher than the throughput of using the existing AMGA operations. Second, to address the scalability problem when thousands of jobs running have access to the single AMGA server concurrently in an attempt to grab available tasks, we propose the use of multiple AMGA servers for the purpose of task retrieval. Our test results demonstrate that throughput can be improved linearly in proportion to the number of AMGA servers set up for load balancing.

Comparative Analyses of Tomato yellow leaf curl virus C4 Protein-Interacting Host Proteins in Healthy and Infected Tomato Tissues

Tomato yellow leaf curl virus (TYLCV), a member of the genus Begomovirus, is one of the most important viruses of cultivated tomatoes worldwide, mainly causing yellowing and curling of leaves with stunting in plants. TYLCV causes severe problems in sub-tropical and tropical countries, as well as in Korea. However, the mechanism of TYLCV infection remains unclear, although the function of each viral component has been identified. TYLCV C4 codes for a small protein involved in various cellular functions, including symptom determination, gene silencing, viral movement, and induction of the plant defense response. In this study, through yeast-two hybrid screenings, we identified TYLCV C4-interacting host proteins from both healthy and symptom-exhibiting tomato tissues, to determine the role of TYLCV C4 proteins in the infection processes. Comparative analyses of 28 proteins from healthy tissues and 36 from infected tissues showing interactions with TYLCV C4 indicated that TYLCV C4 mainly interacts with host proteins involved in translation, ubiquitination, and plant defense, and most interacting proteins differed between the two tissues but belong to similar molecular functional categories. Four proteins—two ribosomal proteins, S-adenosyl-L-homocysteine hydrolase, and 14-3-3 family protein—were detected in both tissues. Furthermore, the identified proteins in symptom-exhibiting tissues showed greater involvement in plant defenses. Some are key regulators, such as receptor-like kinases and pathogenesis-related proteins, of plant defenses. Thus, TYLCV C4 may contribute to the suppression of host defense during TYLCV infection and be involved in ubiquitination for viral infection.

Cooperative interactions between seed-borne bacterial and air-borne fungal pathogens on rice

Bacterial-fungal interactions are widely found in distinct environments and contribute to ecosystem processes. Previous studies of these interactions have mostly been performed in soil, and only limited studies of aerial plant tissues have been conducted. Here we show that a seed-borne plant pathogenic bacterium, Burkholderia glumae (Bg), and an air-borne plant pathogenic fungus, Fusarium graminearum (Fg), interact to promote bacterial survival, bacterial and fungal dispersal, and disease progression on rice plants, despite the production of antifungal toxoflavin by Bg. We perform assays of toxoflavin sensitivity, RNA-seq analyses, lipid staining and measures of triacylglyceride content to show that triacylglycerides containing linolenic acid mediate resistance to reactive oxygen species that are generated in response to toxoflavin in Fg. As a result, Bg is able to physically attach to Fg to achieve rapid and expansive dispersal to enhance disease severity.Interactions between bacteria and fungi are common and contribute to ecosystem processes. Here, Jung et al. show that the interaction between two plant pathogens (a seed-borne bacterium and an air-borne fungus) promotes their own survival and dispersal, as well as disease progression on rice plants.