Two strains ofVibrio cholerae non-O1 possessing somatic (O) antigen factors in common withV. cholerae serogroup O139 synonym “Bengal”

Two strains (O22 reference strain, 169–68, and strain 490–93 isolated from a patient with diarrhea in Thailand) ofVibrio cholerae non-O1 possessing somatic (O) antigen factors in common withV. cholerae O139 synonym Bengal are described. The O antigens of these two strains were closely related to that ofV. cholerae O139 in an a,b-a,c type of relationship, but were not completely identical with serogroup O139. Therefore, both these strains are not classified into the O139 serogroup ofV. cholerae, because they have their own major antigens. As the strain 490–93 could not be placed into any of the 154 established O serogroups ofV. cholerae, this strain was assigned to a new serogroup, O155. For practical use, the diagnostic antiserum prepared against the O139 reference strain (MO45, ATCC 51394) ofV. cholerae must be absorbed with reference strains 169–68 and 490–93 representing serogroups O22 and O155 ofV. cholerae to remove cross-reacting agglutinins of the O22 and O155 strains, respectively.     

Plasma-mediated enhancement of enzyme secretion in Aspergillus oryzae

Technical bottlenecks in protein production and secretion often limit the efficient and robust industrial use of microbial enzymes. The potential of non-thermal atmospheric pressure plasma to overcome these technical barriers was examined. Spores of the fermenting fungus Aspergillus oryzae (A. oryzae) were submerged in potato dextrose broth (PDB) (5 × 10⁶ per ml) and treated with micro dielectric barrier discharge plasma at an input voltage of 1.2 kV and current of 50 to 63 mA using nitrogen as the feed gas. The specific activity of α-amylase in the broth was increased by 7.4 to 9.3% after 24 and 48 h of plasma treatment. Long-lived species, such as NO₂⁻ and NO₃⁻, generated in PDB after plasma treatment may have contributed to the elevated secretion of α-amylase. Observations after 24 h of plasma treatment also included increased accumulation of vesicles at the hyphal tip, hyphal membrane depolarization and higher intracellular Ca²⁺ levels. These results suggest that long-lived nitrogen species generated in PDB after plasma treatment can enhance the secretion of α-amylase from fungal hyphae by depolarizing the cell membrane and activating Ca²⁺ influx into hyphal cells, eventually leading to the accumulation of secretory vesicles near the hyphal tips.     

Selection of rub trees by brown bears (Ursus arctos) in Hokkaido, Japan

Tree rubbing by brown bears (Ursus arctos) is a well-known behavior throughout the animal’s distribution. There is still insufficient information on the characteristics and function of the behavior. We investigated seasonal frequency of tree rubbing by brown bears, characteristics and reasons for selection of rub trees, and characteristics of bear signs on and around rub trees in a mixed coniferous–broad-leaved deciduous forest in Hokkaido, Japan. Between 1998 and 2009, we found 172 rub trees and confirmed 995 tree rubbings. We found that the rub trees were used repeatedly by bears within a year and for multiple years (more than 10 years). Tree rubbing by brown bears was observed from April to November, with a peak between May and June that corresponds to the mating season of brown bears. Abies sachalinensis was selected and broad-leaved trees were avoided for tree rubbing based on estimated availability in natural forest. The preference for Abies sachalinensis might be because the strong odor of resin attracts bears for rubbing their head and neck in resinous substances and for increasing the detectability of their markings by receptor bears. Selected trees for rubbing were located right beside the trail on relatively level ground among trees along roads or trails. Trees had a relatively large diameter at breast height. These characteristics would also serve to increase the access and detectability of their markings. Series of pad-shaped depressions was the most frequently observed (70 %) indication of bear rubbing, followed by debarking (51 %) and clawing (30 %). In terms of visual and olfactory signal amplification, physical damage by bears to the trees might have a function to enhance the smell as a result of increase in outflow of the resin. We conclude that tree rubbing behavior is associated with the mating season of brown bears and that the main purpose of this behavior is scent marking to communicate intraspecifically during the mating season.     

Multiple spatial scale factors affecting mirid bug abundance and damage level in organic rice paddies

Mirid bugs, major insect pests in rice production, have dramatically expanded their range in Japan, resulting in increased economic losses especially for organic rice farmers. In this study, the within-field and landscape-scale factors affecting the bug and its damage to crops were examined in organic rice farms. Bug densities and crop damage levels showed significant positive relationships with weed densities (Schoenoplectus juncoides and Echinochloa crus-galli) within individual fields. Bug densities were negatively associated with Tetragnatha spp. and Pachygnatha clercki densities, indicating that these spiders act as biological control agents that help to decrease crop damage levels. At the landscape scale, bug densities increased with the proportion of the area that was fallow within a 400-m radius around focal fields. Fallows represent important source habitat for the bug and the spatial extent at which bug abundance was affected indicates the mobility of these insects. These results suggest that the combination of biological control by natural enemies, and weed management within individual paddies and surrounding landscapes inside a buffer zone of less than half a kilometre may be effective in controlling mirid bugs and the damage they cause in organic paddy fields.     

Increased urinary 1,N6-ethenodeoxyadenosine and 3,N4-ethenodeoxycytidine excretion in thalassemia patients: markers for lipid peroxidation-induced DNA damage

Thalassemic diseases including homozygous beta-thalassemia and beta-thalassemia/Hb E (beta-Thal/Hb E) are prevalent in Southeast Asia. Iron overload is a common complication in beta-thalassemia patients which induces intracellular oxidative stress and lipid peroxidation (LPO). LPO end products generate miscoding etheno adducts in DNA which after their repair are excreted in urine. We investigated whether urinary levels of 1,N6-ethenodeoxyadenosine (epsilondA) and 3,N4-ethenodeoxycytidine (epsilondC) can serve as putative cancer risk markers in beta-Thal/Hb E patients. epsilondA and epsilondC levels were assayed in collected urine samples by immunoprecipitation-HPLC-fluorescence and 32P-postlabeling TLC, respectively. Mean epsilondA (fmol/micromol creatinine) levels in urine of beta-Thal/Hb E patients ranged from 4.8 to 120.4 (33.8+/-3.9; n=37) and were 8.7 times higher compared to asymptomatic controls (1.4-13.8; 3.9+/-0.8; n=20). The respective epsilondC levels ranged from 0.15 to 32.5 (5.2+/-1.3; n=37) and were increased some 13 times over controls (0.04-1.2; 0.4+/-0.7; n=20). epsilondC levels were correlated positively with NTBI (r=0.517; P=0.002), whereas epsilondA showed only a trend (r=0.257; P=0.124). We conclude that the strongly increased urinary excretion of etheno adducts indicates elevated LPO-induced DNA damage in internal organs such as the liver. These highly promutagenic lesions may contribute to the increased risk of thalassemia patients to develop hepatocellular carcinoma.     

Ochratoxin A-induced teratogenesis in rats: partial protection by phenylalanine

Ochratoxin A (OA), an important foodborne mycotoxin, is a potent teratogenic and nephrotoxic agent produced by several species of Aspergillus and Penicillium. OA is a known inhibitor of protein synthesis via competition with phenylalanine (Phe) in the phenylalanyl-tRNA synthetase-catalyzed reaction. It also has been reported that a variety of toxic effects of OA can be prevented by Phe. This study was designed to determine whether Phe could prevent or diminish the teratogenic effects of OA in rats. Pregnant Sprague-Dawley rats were injected with a single individual dose of OA (1.75 mg/kg) alone or in combination with a single dose of Phe (20 mg/kg) or in combination with either a single or daily dose of Phe (25 mg/kg). OA dissolved in 5% sodium bicarbonate and Phe dissolved in normal saline were administered subcutaneously on gestation day 7 to rats. The incidences of OA-induced fetal malformations (gross and skeletal) were significantly diminished in the presence of added Phe. These results indicate that coadministered Phe provides partial prenatal protection from the teratogenic effects of OA.     

The ubiquitin-selective segregase VCP/p97 orchestrates the response to DNA double-strand breaks

Unrepaired DNA double-strand breaks (DSBs) cause genetic instability that leads to malignant transformation or cell death. Cells respond to DSBs with the ordered recruitment of signalling and repair proteins to the site of lesion. Protein modification with ubiquitin is crucial for the signalling cascade, but how ubiquitylation coordinates the dynamic assembly of these complexes is poorly understood. Here, we show that the human ubiquitin-selective protein segregase p97 (also known as VCP; valosin-containing protein) cooperates with the ubiquitin ligase RNF8 to orchestrate assembly of signalling complexes and efficient DSB repair after exposure to ionizing radiation. p97 is recruited to DNA lesions by its ubiquitin adaptor UFD1-NPL4 and Lys-48-linked ubiquitin (K48-Ub) chains, whose formation is regulated by RNF8. p97 subsequently removes K48-Ub conjugates from sites of DNA damage to orchestrate proper association of 53BP1, BRCA1 and RAD51, three factors critical for DNA repair and genome surveillance mechanisms. Impairment of p97 activity decreases the level of DSB repair and cell survival after exposure to ionizing radiation. These findings identify the p97-UFD1-NPL4 complex as an essential factor in ubiquitin-governed DNA-damage response, highlighting its importance in guarding genome stability.     

Contrasting responses of web-building spiders to deer browsing among habitats and feeding guilds

We examined web-building spider species richness and abundance in forests across a deer density gradient to determine the effects of sika deer browsing on spiders among habitats and feeding guilds. Deer decreased the abundance of web-building spiders in understory vegetation but increased their abundance in the litter layer. Deer seemed to affect web-building spiders in the understory vegetation by reducing the number of sites for webs because vegetation complexity was positively correlated with spider density and negatively correlated with deer density. In contrast, the presence of vegetation just above the litter layer decreased the spider density, and deer exerted a negative effect on this vegetation, possibly resulting in an indirect positive effect on spider density. The vegetation just above the litter layer may be unsuitable as a scaffold for building webs if it is too flexible to serve as a reliable web support, and may even hinder spiders from building webs on litter. Alternatively, the negative effect of this vegetation on spiders in the litter may be as a result of reduced local prey availability under the leaves because of the reduced accessibility of aerial insects. The response to deer browsing on web-building spiders that inhabit the understory vegetation varied with feeding guild. Deer tended to affect web-invading spiders, which inhabit the webs of other spiders and steal prey, more heavily than other web-building spiders, probably because of the accumulated effects of habitat fragmentation through the trophic levels. Thus, the treatment of a particular higher-order taxon as a homogeneous group could result in misleading conclusions about the effects of mammalian herbivores.     

Intraspecific variations in life history traits of two pecky rice bug species from Japan: Mapping emergence dates and number of annual generations

The mirid bugs Stenotus rubrovittatus and Trigonotylus caelestialium, which cause pecky rice, have become a threat to rice cultivation in Asia. Damage caused by these pests has rapidly become frequent since around 2000 in Japan. Their expansion pattern is not simple, and predicting their future spread remains challenging. Some insects with wide ranges have locally adapted variations in life‐history traits. We performed laboratory rearing experiments to assess the geographical scale of intraspecific variations in life‐history traits of S. rubrovittatus and T. caelestialium. The experiments were aimed at increasing the accuracy of occurrence estimates and the number of generations per year. These results were compared with previous research, and differences in development rates were observed between populations of different latitudes, but not of the same latitude. Finally, plotting the timing of adult emergence and the potential number of generations per year on maps with a 5‐km grid revealed that they differed greatly locally at the same latitude. These maps can be used for developing more efficient methods of managing mirid bugs in integrated pest management.     

Each Conserved Active Site Tyr in the Three Subunits of Human Isocitrate Dehydrogenase Has a Different Function

The human NAD-dependent isocitrate dehydrogenase (IDH) is a heterotetrameric mitochondrial enzyme with 2α:1β:1γ subunit ratio. The three subunits share 40–52% identity in amino acid sequence and each includes a tyrosine in a comparable position: αY126, βY137, and γY135. To study the role of the corresponding tyrosines of each of the subunits of human NAD-IDH, the tyrosines were mutated (one subunit at a time) to Ser, Phe, or Glu. Enzymes were expressed with one mutant and two wild-type subunits. The results of characterization of the mutant enzymes suggest that βY137 is involved in NAD binding and allosteric activation by ADP. The αY126 is required for catalytic activity and likely acts as a general acid in the reaction. The γY135 is also required for catalytic activity and may be involved in proper folding of the enzyme. The corresponding tyrosines in the three dissimilar subunits of NAD-IDH thus have distinctive functions.