The effects of gene disruption of Kre6-like proteins on the phenotype of β-glucan-producing Aureobasidium pullulans

Applied Microbiology and Biotechnology - Killer toxin resistant 6 (Kre6) and its paralog, suppressor of Kre null 1 (Skn1), are thought to be involved in the biosynthesis of cell wall...     

Protection of Coral Larvae from Thermally Induced Oxidative Stress by Redox Nanoparticles

Coral reefs are one of the most biologically diverse and economically important ecosystems on earth. However, the destruction of coral reefs has been reported worldwide owing to rising seawater temperature associated with global warming. In this study, we investigated the potential of a redox nanoparticle (RNP^O) to scavenge reactive oxygen species (ROS), which are overproduced under heat stress and play a crucial role in causing coral mortality. When reef-building coral (Acropora tenuis) larvae, without algal symbionts, were exposed to thermal stress at 33 °C, RNP^O treatment significantly increased the survival rate. Proteome analysis of coral larvae was performed using nano-liquid chromatography-tandem mass spectrometry for the first time. The results revealed that several proteins related to ROS-induced oxidative stress were specifically identified in A. tenuis larvae without RNP^O treatment, whereas these proteins were absent in RNP^O-treated larvae, which suggested that RNP^O effectively scavenged ROS from A. tenuis larvae. Results from this study indicate that RNP^O treatment can reduce ROS in aposymbiotic coral larvae and would be a promising approach for protecting corals from thermal stress.     

Cantharidin world in air: Spatiotemporal distributions of flying canthariphilous insects in the forest interior

The natural community in which the members interact using a toxic terpenoid cantharidin is named the “cantharidin world.” In previous studies, however, the members of this world have been surveyed only on the forest floor by setting pitfall traps with cantharidin as an attractant. In this study, we set cantharidin traps at various heights above the forest floor to investigate the structure and functional diversity of the canthariphilous flying insect community in the forest above‐ground space. A total of 3,168 arthropods were collected by the traps; among them, six species were more attracted to cantharidin than to control traps. Pseudopyrochroa brevitarsis and P. laticollis (Colecoptera: Pyrochroidae) both appeared for a short time during spring, but the latter species tended to use a lower layer of the forest. Clavicollis fugiens (Coleoptera: Anthicidae) also appeared in spring and flew near the ground. In these beetles, the attracted individuals were mostly males; they may use the obtained cantharidin for nuptial gifts to the female. Atrichopogon femoralis, A. insularis and Atrichopogon sp. (Diptera: Ceratopogonidae) were collected widely in the forest above‐ground space. These midges were almost females, probably because only females of these insects use chemical cues, including cantharidin, for searching for arthropods from which to suck hemolymph.     

Comparative analysis of microbial diversity and bacterial seedling disease‐suppressive activity in organic‐farmed and standardized commercial conventional soils for rice nursery cultivation

The outbreak of rice plant diseases can be effectively suppressed in organic farming systems. However, the mechanisms of disease suppression by organic farming systems are not well understood. When Burkholderia‐infected rice seeds were sown and cultivated on nine organic‐farmed soils which were supplied by nine independent organic rice farmers or standardized commercial conventional soils, the emergence of bacterial seedling diseases was suppressed to equivalent degrees in nine organic‐farmed soils, whereas the diseases occurred in two commercial conventional soils. In any organic or commercial conventional soil sown with healthy rice seeds as a control, the diseases did not appear. Upon physicochemical analysis of the nine organic‐farmed soils, component common to these organic‐farmed soils seemed to not be directly associated with disease‐suppressive activity. However, microbiome analyses indicated that the bacterial population in these nine organic‐farmed soils was more diverse than those in commercial conventional soils. Intriguingly, the diverse bacterial population structures of organic‐farmed soils were preserved after irrigating and sowing rice seeds, but that of commercial conventional soils was clearly changed by them. Thus, organic‐farmed soils seem to maintain robust bacterial populations despite the irrigation and seedling growth. Indeed, pathogenic Burkholderia in infected rice seeds also did not proliferate in the seedling grown on organic‐farmed soils. Taken together, the common feature of organic‐farmed soils might be the correlation between bacterial seedling disease‐suppressive activity and higher robustness of the diversified microbiome.     

Mouse Homolog of Poliovirus Receptor-Related Gene 2 Product, mPRR2, Mediates Homophilic Cell Aggregation

Poliovirus receptor (PVR) is a cell surface glycoprotein that belongs to the immunoglobulin superfamily. Although MPH was initially reported as the mouse homolog of human PVR, recent data strongly suggest that MPH is the mouse homolog of human PRR2, a PVR-related gene 2 product, and not that of human PVR. Thus MPH is renamed mPRR2 in this study. Physiological functions of the PVR-related gene products have not been elucidated, although PVR has been well characterized as the poliovirus receptor. In this study, a possible function of mPRR2 (MPH), which is not a functional receptor for poliovirus, was investigated. Mouse L cells expressing mPRR2 were prepared. Those mouse cells showed a higher activity of cell aggregation than the parental mouse L cells. Enhancement of cell aggregation was also observed for insect Sf9 cells infected with recombinant baculovirus carrying mPRR2 cDNA. On the other hand, L cells expressing human PVR or monkey PVR (AGMα1 or AGMα2) did not show increased cell aggregation. The cell aggregation activity of L cells expressing mPRR2 was inhibited by the addition of anti-mPRR2 monoclonal antibodies or a soluble mPRR2 molecule produced by the baculovirus expression system. An immunofluorescence study revealed that mPRR2 protein was localized to the cell–cell contact sites between cells expressing mPRR2. A similar localization of mPRR2 was observed for intrinsic mPRR2 molecules of the mouse neuroblastoma cell line NS20Y. The contact site-specific localization of mPRR2 was not observed on the border between mPRR2-expressing and nonexpressing HeLa cells. Furthermore, mPRR2 proteins directly bound to each otherin vitro.mPRR2 was detected on various types of cultured cells of mouse origin and in various mouse tissues. These results suggest that mPRR2 is an intercellular adhesion molecule with a homophilic binding manner.     

Role of Curdlan Sulfate in the Binding of HIV-1 gp120 to CD4 Molecules and the Production of gp120-Mediated TNF-α

To clarify the mechanism by which curdlan sulfate (CRDS) inhibits human immunodeficiency virus (HIV)-1 infection, we examined its influence on the binding of gp120 to CD4 molecules on T cells and macrophages, as well as on the production of TNF-α by gp120-stimulated macrophages (which promotes HIV-1 replication). CRDS treatment of cells not only inhibited the binding of HIV-1 gp120 to CD4⁺ cells, but also inhibited TNF-α production induced by gp120. Inhibition of HIV-1 infection by CRDS may be related to these two actions.     

Effects of carp serum on the growth of goldfish fin cells in early passage

The culture medium supplemented with carp serum and fetal bovine serum (FBS) promoted cell growth significantly and induced morphological change of goldfish fin cells in early passage as compared to the medium containing FBS alone. However, these effects were not observed in RBCF-1, a cell line established from the goldfish fin. The sensitivity of the cells in early passage to carp serum suggests the following possibilities: (1) cells in early passage retain the ability to respond to growth-promoting factors specifically included in carp serum; and (2) this ability is lost during the process of long-term culture and/or long-term culture in FBS eliminates cell groups showing high dependency of cell growth on carp serum.     

Crystallization and Preliminary X-Ray Analysis of Neuropsin, a Serine Protease Expressed in the Limbic System of Mouse Brain

Neuropsin (M_r25 032) is a serine protease expressed in the limbic system of mouse brain. It has been implicated in various neurological processes including formation of memory and may be important as a drug target in the treatment of epilepsy. The recombinant protein was produced using a baculovirus expression system and was purified. Two crystal forms were obtained by a hanging-drop vapor-diffusion method with polyethylene glycol. Preliminary X-ray crystallographic analysis revealed that crystal form I belongs to triclinic space groupP1 with unit cell dimensionsa= 97.16 Å,b= 97.12 Å,c= 46.75 Å and α = 99.17°, β = 99.77°, γ = 117.35°. Self-rotation function analysis of these data of form I indicates the position of a noncrystallographic threefold axis. There are six molecules in the crystallographic asymmetric unit. Crystal form II also belongs to triclinic space groupP1 but has unit cell dimensions ofa= 38.40 Å,b= 55.16 Å,c= 65.37 Å and α = 95.38°, β = 89.98°, γ = 110.46° with two molecules in the crystallographic asymmetric unit. Form II has a noncrystallographic twofold axis. Intensity data to 3.1 Å resolution for form I and to 2.2 Å resolution for form II have been collected.