Invasion and Dispersion of the Exotic Species Procambarus clarkii (Decapoda Cambaridae) in Yeongsan River Basin, South Korea.

The introduction of exotic species negatively affects the distribution and interactions within local biological communities in an ecosystem and can threaten ecosystem health. This study aimed to provide the basic data required to manage P. clarkii in the Yeongsan River basin. We identified the dispersion pattern and evaluated the ecosystem risk of this newly introduced species. The distribution survey investigated Procambarus clarkii populations at 25 sites in the Yeongsan River basin over a four-year period. The initial introduction occurred in Jiseok Stream. The larvae of P. clarkii were most abundant in areas with a dense aquatic plant cover, whereas adults preferred silt/clay areas. The alterations in the water flow by the river refurbishment project (carried out in 2012) increased their preferred habitats and contributed to P. clarkii dispersion. However, stable isotope analysis showed that the dispersion has had little effect on the freshwater ecosystem. The interrelationship between P. clarkii (i.e., larvae and adults) and other biological communities has been limited. Although the rapid dispersion by P. clarkii in the Yeongsan River basin has not impacted the freshwater ecosystem, further ecological information is required on how to manage P. clarkii beyond this early stage of invasion.

Habitat Preferences and Trophic Position of Brachydiplax chalybea flavovittata Ris, 1911 (Insecta: Odonata) Larvae in Youngsan River Wetlands of South Korea.

In freshwater ecosystems, habitat heterogeneity supports high invertebrate density and diversity, and it contributes to the introduction and settlement of non-native species. In the present study, we identified the habitat preferences and trophic level of Brachydiplax chalybea flavovittata larvae, which were distributed in four of the 17 wetlands we examined in the Yeongsan River basin, South Korea. Larval density varied across four microhabitat types: open water area, and microhabitats dominated by Myriophyllum aquaticum, Paspalum distichum, and Zizania latifolia. Microhabitats dominated by M. aquaticum had the highest larval density, followed by those dominated by P. distichum. The larvae were more prevalent in silt sediments than in plant debris or sand. Stable isotope analysis showed that B. chalybea flavovittata is likely to consume, as a food source, other species of Odonata larvae. We conclude that successful settlement of B. chalybea flavovittata can be attributed to their habitat preferences. As temperature increases due to climate change, the likelihood of B. chalybea flavovittata spreading throughout South Korea increases. We, therefore, recommend continued monitoring of the spread and ecological impacts of B. chalybea flavovittata.

Transglutaminase 2 Inhibition Reverses Mesenchymal Transdifferentiation of Glioma Stem Cells by Regulating C/EBPß Signaling.

Necrosis is a hallmark of glioblastoma (GBM) and is responsible for poor prognosis and resistance to conventional therapies. However, the molecular mechanisms underlying necrotic microenvironment-induced malignancy of GBM have not been elucidated. Here, we report that transglutaminase 2 (TGM2) is upregulated in the perinecrotic region of GBM and triggered mesenchymal (MES) transdifferentiation of glioma stem cells (GSC) by regulating master transcription factors (TF), such as C/EBPß, TAZ, and STAT3. TGM2 expression was induced by macrophages/microglia-derived cytokines via NF-κB activation and further degraded DNA damage-inducible transcript 3 (GADD153) to induce C/EBPß expression, resulting in expression of the MES transcriptome. Downregulation of TGM2 decreased sphere-forming ability, tumor size, and radioresistance and survival in a xenograft mouse model through a loss of the MES signature. A TGM2-specific inhibitor GK921 blocked MES transdifferentiation and showed significant therapeutic efficacy in mouse models of GSC. Moreover, TGM2 expression was significantly increased in recurrent MES patients and inversely correlated with patient prognosis. Collectively, our results indicate that TGM2 is a key molecular switch of necrosis-induced MES transdifferentiation and an important therapeutic target for MES GBM. Cancer Res; 77(18); 4973-84. ©2017 AACR.

Effects of combined radiofrequency field exposure on amyloid-beta-induced cytotoxicity in HT22 mouse hippocampal neurones.

Alzheimer's disease (AD) is the most common progressive and irreversible neurodegenerative disease and it is caused by neuronal death in the brain. Recent studies have shown that non-ionizing radiofrequency (RF) radiation has some beneficial cognitive effects in animal models of AD. In this study, we examined the effect of combined RF radiation on amyloid-beta (Aß)-induced cytotoxicity in HT22 rat hippocampal neurons. Treatment with Aß suppressed HT22 cell proliferation in a concentration-dependent manner. RF exposure did not affect cell proliferation, and also had a marginal effect on Aß-induced suppression of growth in HT22 cells. Cell cycle analysis showed that Aß decreased the G1 fraction and increased the subG1 fraction, indicating increased apoptosis. Accordingly, Aß increased the annexin V/propidium iodide (PI)-positive cell fraction and the degradation of poly (ADP ribose) polymerase and caspase-3 in HT22 cells. However, RF alone and the combination of Aß and RF did not affect these events significantly. Aß increased reactive oxygen species (ROS) generation, thereby suppressing cell proliferation. This was abrogated by N-acetylcysteine (NAC) treatment, indicating that Aß-induced ROS generation is the main cause of suppression of proliferation. NAC also restored Aß-induced annexin V/PI-positive cell populations. However, RF did not have a significant impact on these events. Finally, Aß stimulated the ataxia telangiectasia and Rad3-related protein/checkpoint kinase 1 DNA single-strand breakage pathway, and enhanced beta-site amyloid precursor protein expression; RF had no effect on them. Taken together, our results demonstrate that RF exposure did not significantly affect the Aß-induced decrease of cell proliferation, increase of ROS production, or induction of cell death in these cells.

Red Ginseng-containing diet helps to protect mice and ferrets from the lethal infection by highly pathogenic H5N1 influenza virus.

The highly pathogenic (HP) H5N1 influenza virus is endemic in many countries and has a great potential for a pandemic in humans. The immune-enhancing prowess of ginseng has been known for millennia. We aimed to study whether mice and ferrets fed with Red Ginseng could be better protected from the lethal infections of HP H5N1 influenza virus than the infected unfed mice and ferrets. We fed mice and ferrets with Red Ginseng prior to when they were infected with HP H5N1 influenza virus. The mice and ferrets fed with a 60-day diet containing Red Ginseng could be protected from lethal infections by HP H5N1 influenza virus (survival rate of up to 45% and 40%, respectively). Interferon-α and -γ antiviral cytokines were significantly induced in the lungs of mice fed Red Ginseng, compared to mice fed an unsupplemented diet. These data suggest that the diet with the immune-enhancing Red Ginseng could help humans to overcome the infections by HP H5N1 influenza virus.

Transmissibility of novel H7N9 and H9N2 avian influenza viruses between chickens and ferrets.

Previous studies have shown that the H7N9 avian influenza virus cannot be transmitted efficiently between ferrets via respiratory droplets. Here, we studied the infectivity of the H7N9 avian influenza virus in chickens and its transmissibility from infected to naïve chickens and ferrets. The H7N9 virus (A/Anhui/1/2013) replicated poorly in chickens and could not be transmitted efficiently from infected chickens to naïve chickens and ferrets. H7N9 virus was shed from chicken tracheae for only 2 days after infection and from chicken cloacae for only 1 day after infection, while the H9N2 avian influenza virus, which is endemic in chickens in many Asian countries, was shed from tracheae and cloacae for 8 days after infection. Taken together, our results suggest that chickens may be a poor agent of transmission for the H7N9 virus to other chickens and to mammals, including humans.

Severe pathogenesis of influenza B virus in pregnant mice.

The study on pathogenesis of influenza B virus during pregnancy is limited. Here, we showed using a mouse model that influenza B virus could cause severe disease including death during pregnancy. Infected pregnant mice resulted in 40% mortality, but infected age-matched non-pregnant mice did not show any death. Infected pregnant mice contained high viral loads in lungs with the elevated inductions of inflammatory cytokines and chemokines than infected non-pregnant mice. Infected pregnant mice delivered lower number of neonates than uninfected pregnant mice, suggesting adverse effects of influenza B virus on fetuses. Progesterone which is important for maintaining pregnancy was reduced in uteruses of infected pregnant mice than in those of uninfected pregnant mice. Taken together, our results suggest that influenza B virus can cause severe disease during pregnancy, and that preventive measures including vaccination may be important for protecting women during pregnancy.

Comparison of properties of poly(vinyl alcohol) nanocomposites containing two different clays.

Morphologies, thermo-optical properties, and gas barriers of poly(vinyl alcohol) (PVA) hybrid films containing two different clays are compared. Saponite (SPT) and hydrophilic bentonite (BTT) were used as the reinforcing filler in the fabrication of PVA hybrid films, which were synthesized from aqueous solutions and were solvent-cast at room temperature under vacuum, yielding 20-31-µm-thick PVA hybrid films with varying clay contents. The addition of small amounts of clay is sufficient to improve the thermal properties and gas barriers of PVA hybrid films. Even polymers with a low clay content (3-10 wt%) were found to exhibit much higher transition temperature values than pure PVA. The addition of BTT was more effective than the addition of SPT for improving the thermal properties and gas barrier in the PVA matrix. The PVA hybrid films containing 5 wt% SPT were equibiaxially stretched, with stretching ratios ranging from 150% to 250%. Clay dispersion, morphology, optical transparency, and gas permeability were then examined as a function of the equibiaxial stretching ratio. PVA hybrid films with a stretching ratio of ≥ 150% displayed homogeneously dispersed clay within the polymer matrix and exfoliated nanocomposites.

The severe pathogenicity of alveolar macrophage-depleted ferrets infected with 2009 pandemic H1N1 influenza virus.

The in vivo role of alveolar macrophages in the infections with 2009 pandemic H1N1 influenza virus is not as yet known. Ferret study shows that alveolar macrophages are critical for lowering the risk of severe outcomes in 2009 pandemic H1N1 influenza virus infections. Up to 40% of the infected ferrets depleted of alveolar macrophages died, with elevated body temperature and major loss of body weight in contrast to infected ferrets not depleted of alveolar macrophages. The higher viral titers in the lungs were detected in infected ferrets depleted of alveolar macrophages than infected ferrets not depleted of alveolar macrophages 5 days after infection. The inflammatory chemokines were induced at greater levels in the lungs of infected ferrets depleted of alveolar macrophages than in those of infected ferrets not depleted of alveolar macrophages. Our study implies that alveolar macrophages are important for controlling the infections of 2009 pandemic H1N1 influenza virus.