The N-end rule proteolytic system in autophagy

The N-end rule pathway is a cellular proteolytic system that utilizes specific N-terminal residues as degradation determinants, called N-degrons. N-degrons are recognized and bound by specific recognition components (N-recognins) that mediate polyubiquitination of low-abundance regulators and selective proteolysis through the proteasome. Our earlier work identified UBR4/p600 as one of the N-recognins that promotes N-degron-dependent proteasomal degradation. In this study, we show that UBR4 is associated with cellular cargoes destined to autophagic vacuoles and is degraded by the lysosome. UBR4 loss causes multiple misregulations in autophagic pathways, including an increased formation of LC3 puncta. UBR4-deficient mice die during embryogenesis primarily due to defective vascular development in the yolk sac (YS), wherein UBR4 is associated with a bulk lysosomal degradation system that absorbs maternal proteins from the YS cavity and digests them into amino acids. Our results suggest that UBR4 plays a role not only in selective proteolysis of short-lived regulators through the proteasome, but also bulk degradation through the lysosome. Here, we discuss a possible mechanism of UBR4 as a regulatory component in the delivery of cargoes destined to interact with the autophagic core machinery.     

Ultrasmall Plasmonic Cavity for Chemical Sensing

We propose an ultrasmall plasmonic cavity based on the channel waveguides for chemical sensing. The plasmonic mode gap due to cutoff angular frequency enables strong optical confinement in a subwavelength volume and suppression of radiation loss. Due to strong field overlap of the surface plasmon polariton mode with environmental material, large sensitivity (1,100 nm/refractive index unit) and a high figure of merit (330) are achieved in the plasmonic cavity with a small physical size of 600?×?800?×?2,500 nm having a telecommunication resonant wavelength. This plasmonic cavity can introduce a broad range of applications including biochemical sensing and strong light–matter interactions.     

High genetic diversity within the morphologically conservative dwarf loach, Kichulchoia brevifasciata (Teleostei: Cobitidae), an endangered freshwater fish from South Korea

The dwarf loach, Kichulchoia brevifasciata, is a primary freshwater fish endemic to South Korea (Republic of Korea). Due to its limited geographic range, special habitat requirements, and scarcity, this species has been considered one of the most endangered cobitid loaches in the world. Gene tree and species tree reconstruction derived from mitochondrial and nuclear sequence data supports the exclusivity of K. brevifasciata and the existence of two highly distinct genetic lineages (eastern and western lineages). Intraspecific genetic variation based on the corrected genetic distance ranged from 0.0013 to 0.0017 (cytochrome b) and 0–0.0012 (nuclear loci) within each lineage and 0.0349 (cytochrome b) and 0.0037–0.0104 (nuclear loci) between the lineages. Although morphologically homogeneous, eastern and western lineages were estimated to have diverged roughly 2.79 million years ago (4.25–1.42, 95 % HPD). Future conservation efforts for K. brevifasciata should consider these genetically distinct lineages as separate evolutionary entities and adopt conservation efforts accordingly.     

Testing of divergent patterns of butterfly niche breadth in a peninsula

The butterfly fauna on the Korean peninsula are comprised of both the Palearctic and Oriental species. We hypothesized that the Oriental species (immigrated across the sea) tend to have a wider niche breadth compared with the Palearctic species (immigrated from the continent) since the former migrates long distances across the sea and has to adapt to new environments. We tested this hypothesis using Korean butterfly data on distribution, habitat, food and life history traits. The distribution and ecological traits such as habitat breadth, overwintering stage, and voltinism of the Oriental species were found to be significantly different from the Palearctic species. However, the diet breadth and food plant type were not different. These results partly confirm the peninsula niche breadth hypothesis, which predicted that Oriental species have a broader niche breadth than Palearctic species.     

LOCALIZATION OF CA2+-STIMULATED ATPASE IN THE COCCOLITH-PRODUCING COMPARTMENT OF CELLS OF PLEUROCHRYSIS SP. (PRYMNESIOPHYCEAE)1

Cell homogenates of Pleurochrysis sp. (CCMP299) were fractionated by means of sucrose gradients. Ca²⁺-stimulated ATPase (EC 3.6.1.3., ATP phosphohydrolase) was associated primarily with the plasma membrane, Golgi, and high density (1.21 g·cm^?3) membranous structures. Ca²⁺-stimulated ATPase was highly enriched in the latter. Based on treatments with Triton X-100 and NBD ceramide, we conclude that the high-density structures were membrane-delimited organelles. These vesicle-like organelles contained complex polysaccharides, a high concentration of calcium, and, upon microscopic examination, structures resembling coccoliths. These findings are consistent with observations on the known composition of coccoliths and the presumed mineralizing function of the sub-cellular coccolith-producing compartment. The high-density vesicles were linked to the Golgi by means of colchicine-sensitive materials, presumably microtubules. These data and prior ultrastructural observations by other investigators indicating vectorial assembly and secretion suggest that the subcellular movement of the newly formed coccoliths may be directed and/or powered by colchicine-sensitive cytoskeletal elements. We interpret the data to mean that the high-density vesicles represent the coccolith-producing compartment previously observed by others in electron micrographs.     

Factors that Predict Negative Results of QuantiFERON-TB Gold In-Tube Test in Patients with Culture-Confirmed Tuberculosis: A Multicenter Retrospective Cohort Study

Background

Interferon-γ release assays such as the QuantiFERON-TB Gold In-Tube Test (QFT-GIT) are designed to detect Mycobacterium tuberculosis infections, whether latent or manifesting as disease. However, a substantial number of persons with culture-confirmed tuberculosis (TB) have negative QFT-GITs. Information on host factors contributing to false-negative and indeterminate results are limited.

Methods

A multicenter retrospective cohort study was performed with 1,264 culture-confirmed TB patients older than 18 years who were subjected to the QFT-GIT at one of the six hospitals between May 2007 and February 2014. Patients with human immunodeficiency virus infection were excluded. Clinical and laboratory data were collected in South Korea.

Results

Of all patients, 87.6% (1,107/1,264) were diagnosed with pulmonary TB and 12.4% (157/1,264) with extrapulmonary TB. The rate of negative results was 14.4% (182/1,264). The following factors were highly correlated with false-negative results in the QFT-GIT: advanced age (age ≥ 65 years, odds ratio [OR] 1.57, 95% confidence interval [CI] 1.03–2.39), bilateral disease as determined by chest radiography (OR 1.75, 95% CI 1.13–2.72), malignancy (OR 2.42, 95% CI 1.30–4.49), and lymphocytopenia (total lymphocyte count < 1.0 × 10⁹/L, OR 1.86, 95% CI 1.21–2.87).

Conclusions

Consequently, QFT-GIT results need to be interpreted with caution in patients with these host risk factors such as the elderly, bilateral disease on chest radiography, or malignancy, or lymphocytopenia.     

Repurposing Salicylanilide Anthelmintic Drugs to Combat Drug Resistant Staphylococcus aureus

Staphylococcus aureus is a Gram-positive bacterium that has become the leading cause of hospital acquired infections in the US. Repurposing Food and Drug Administration (FDA) approved drugs for antimicrobial therapy involves lower risks and costs compared to de novo development of novel antimicrobial agents. In this study, we examined the antimicrobial properties of two commercially available anthelmintic drugs. The FDA approved drug niclosamide and the veterinary drug oxyclozanide displayed strong in vivo and in vitro activity against methicillin resistant S. aureus (minimum inhibitory concentration (MIC): 0.125 and 0.5 μg/ml respectively; minimum effective concentration: ≤ 0.78 μg/ml for both drugs). The two drugs were also effective against another Gram-positive bacteria Enterococcus faecium (MIC 0.25 and 2 μg/ml respectively), but not against the Gram-negative species Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa and Enterobacter aerogenes. The in vitro antimicrobial activity of niclosamide and oxyclozanide were determined against methicillin, vancomycin, linezolid or daptomycin resistant S. aureus clinical isolates, with MICs at 0.0625-0.5 and 0.125-2 μg/ml for niclosamide and oxyclozanide respectively. A time-kill study demonstrated that niclosamide is bacteriostatic, whereas oxyclozanide is bactericidal. Interestingly, oxyclozanide permeabilized the bacterial membrane but neither of the anthelmintic drugs exhibited demonstrable toxicity to sheep erythrocytes. Oxyclozanide was non-toxic to HepG2 human liver carcinoma cells within the range of its in vitro MICs but niclosamide displayed toxicity even at low concentrations. These data show that the salicylanilide anthelmintic drugs niclosamide and oxyclozanide are suitable candidates for mechanism of action studies and further clinical evaluation for treatment of staphylococcal infections.     

4-1BB Signaling Enhances Primary and Secondary Population Expansion of CD8+ T Cells by Maximizing Autocrine IL-2/IL-2 Receptor Signaling

4-1BB (CD137), a member of the tumor necrosis factor receptor superfamily (TNFRSF), is primarily expressed on activated T cells and is known to enhance proliferation of T cells, prevent activation-induced cell death, and promote memory formation of CD8⁺ T cells. In particular, it is well acknowledged that 4-1BB triggering preferentially enhances the expansion of CD8⁺ T cells rather than CD4⁺ T cells, but the underlying mechanism remains unclear. Here we found that 4-1BB triggering markedly increased IL-2Rα (CD25) and IL-2 expressions of CD8+ T cells but minimally for CD4⁺ T cells. Proliferation of CD8⁺ T cells was moderately enhanced by direct 4-1BB triggering in the absence of signaling through IL-2Rα/IL-2 interactions, but further promoted in the presence of IL-2Rα/IL-2 interactions. Among the TNFRSF members including OX40, GITR, CD30, and CD27, 4-1BB was superior in the ability to induce IL-2Rα expression on CD8+ T cells. When the primary and secondary expansions of CD8⁺ T cells in vivo were examined by adoptively transferring OVA-specific CD8⁺ T cells along with the treatment with agonistic anti-4-1BB and/or antagonistic anti-CD25 F(ab’)₂ mAb, 4-1BB triggering enhanced both primary and secondary expansion of CD8⁺ T cells in vivo, and the 4-1BB effects were moderately suppressed in primary expansion while completely abolished in secondary expansion of OVA-specific CD8⁺ T cells by blocking IL-2Rα. These results suggest that 4-1BB-mediated increases of IL-2Rα and IL-2 prolong the effects of transient TCR- and 4-1BB-mediated signaling in CD8⁺ T cells, and that 4-1BB triggering preferentially enhances the expansion of CD8⁺ T cells through the amplification of autocrine IL-2/IL-2R signaling loop.