Autophagy protein Rubicon mediates phagocytic NADPH oxidase activation in response to microbial infection or TLR stimulation

Phagocytosis and autophagy are two important and related arms of the host's first-line defense against microbial invasion. Rubicon is a RUN domain containing cysteine-rich protein that functions as part of a Beclin-1-Vps34-containing autophagy complex. We report that Rubicon is also an essential, positive regulator of the NADPH oxidase complex. Upon microbial infection or Toll-like-receptor 2 (TLR2) activation, Rubicon interacts with the p22phox subunit of the NADPH oxidase complex, facilitating its phagosomal trafficking to induce a burst of reactive oxygen species (ROS) and inflammatory cytokines. Consequently, ectopic expression or depletion of Rubicon profoundly affected ROS, inflammatory cytokine production, and subsequent antimicrobial activity. Rubicon's actions in autophagy and in the NADPH oxidase complex are functionally and genetically separable, indicating that Rubicon functions in two ancient innate immune machineries, autophagy and phagocytosis, depending on the environmental stimulus. Rubicon may thus be pivotal to generating an optimal intracellular immune response against microbial infection.     

Vertical distribution of bacterial community is associated with the degree of soil organic matter decomposition in the active layer of moist acidic tundra

The increasing temperature in Arctic tundra deepens the active layer, which is the upper layer of permafrost soil that experiences repeated thawing and freezing. The increasing of soil temperature and the deepening of active layer seem to affect soil microbial communities. Therefore, information on soil microbial communities at various soil depths is essential to understand their potential responses to climate change in the active layer soil. We investigated the community structure of soil bacteria in the active layer from moist acidic tundra in Council, Alaska. We also interpreted their relationship with some relevant soil physicochemical characteristics along soil depth with a fine scale (5 cm depth interval). The bacterial community structure was found to change along soil depth. The relative abundances of Acidobacteria, Gammaproteobacteria, Planctomycetes, and candidate phylum WPS-2 rapidly decreased with soil depth, while those of Bacteroidetes, Chloroflexi, Gemmatimonadetes, and candidate AD3 rapidly increased. A structural shift was also found in the soil bacterial communities around 20 cm depth, where two organic (upper Oi and lower Oa) horizons are subdivided. The quality and the decomposition degree of organic matter might have influenced the bacterial community structure. Besides the organic matter quality, the vertical distribution of bacterial communities was also found to be related to soil pH and total phosphorus content. This study showed the vertical change of bacterial community in the active layer with a fine scale resolution and the possible influence of the quality of soil organic matter on shaping bacterial community structure.     

Optimization of expression,purification, and NMR measurement for structural studies of transmembrane region of amyloid β protein

The amyloid precursor protein (APP) is an integral transmembrane protein which has been suggested to play a central role in the pathogenesis of Alzheimer’s disease. Despite the enormous amount of research conducted on amyloid protein, the precise mechanism of its toxic effect is not yet fully understood. To better understand the mechanism and function of amyloid protein, it is critical to elucidate the three-dimensional structure of the single transmembrane spanning region of human APP (hAPP-TM). Unfortunately, it is difficult to prepare the peptide sample because hAPP-TM is a membrane-bound protein that transverses the lipid bilayer of the cell membrane. Generally, the preparation of a transmembrane peptide is very difficult and time-consuming. In fact, high yield production of transmembrane peptides has been limited by experimental difficulties related to insufficient yields and the low solubility of such peptides. In this study, we describe experimental processes developed to optimize the expression, purification, and NMR measurement conditions for hAPP-TM transmembrane peptide.     

Distribution of the Ussur Brown Katydid,Paratlanticus ussuriensis,in South Korea

This study was conducted to monitor the abundance and distribution of the ussur brown katydid, Paratlanticus ussuriensis in South Korea, and to gather basic information about potential outbreak areas of this species. P. ussuriensis samples were collected from April to July in 2009 and 2010 using the transect method at the city or gun level. P. ussuriensis were identified in 86 cities or guns, and eight guns were determined to be potential risk areas of P. ussuriensis outbreaks. The current distribution of P. ussuriensis is well matched with the distribution of broadleaf trees. Their distribution and population density are expected to increase due to the expanding distribution of Quercus spp., the major food source of P. ussuriensis.     

Two new records of the genus Cryptaphis Hille Ris Lambers (Hemiptera: Aphididae) from Korea

The genus Cryptaphis Hille Ris Lambers 1947 is described for the first time in Korea with new records of two species, Cryptaphis geranicola (Shinji 1935) and Cryptaphis menthae Takahashi 1961. Cryptaphis geranicola was collected from Geranium thunbergii (Lamiaceae) and C. menthae was collected from Isodon inflexus (Lamiaceae). Important characteristics are re-described, illustrated, and measured in apterous and alate viviparous females.     

A novel light‐dependent selection marker system in plants

Photosensitizers are common in nature and play diverse roles as defense compounds and pathogenicity determinants and as important molecules in many biological processes. Toxoflavin, a photosensitizer produced by Burkholderia glumae, has been implicated as an essential virulence factor causing bacterial rice grain rot. Toxoflavin produces superoxide and H₂O₂ during redox cycles under oxygen and light, and these reactive oxygen species cause phytotoxic effects. To utilize toxoflavin as a selection agent in plant transformation, we identified a gene, tflA, which encodes a toxoflavin‐degrading enzyme in the Paenibacillus polymyxa JH2 strain. TflA was estimated as 24.56 kDa in size based on the amino acid sequence and is similar to a ring‐cleavage extradiol dioxygenase in the Exiguobacterium sp. 255‐15; however, unlike other extradiol dioxygenases, Mn²⁺and dithiothreitol were required for toxoflavin degradation by TflA. Here, our results suggested toxoflavin is a photosensitizer and its degradation by TflA serves as a light‐dependent selection marker system in diverse plant species. We examined the efficiencies of two different plant selection systems, toxoflavin/tflA and hygromycin/hygromycin phosphotransferase (hpt) in both rice and Arabidopsis. The toxoflavin/tflA selection was more remarkable than hygromycin/hpt selection in the high‐density screening of transgenic Arabidopsis seeds. Based on these results, we propose the toxoflavin/tflA selection system, which is based on the degradation of the photosensitizer, provides a new robust nonantibiotic selection marker system for diverse plants.