Molecular genetic and pathogenic characterization of psittacid herpesvirus type 1 isolated from a captive galah (Eolophus roseicapillus) in Japan

Psittacid herpesvirus type 1 (PsHV-1) was isolated from a captive galah (Eolophus roseicapillus) in Japan that was suspected of having Pacheco's disease (PD), an acute fatal disease in psittacine birds. PsHV-1 has been classified into four genotypes based on the UL16 gene sequence. In the present study, we investigated the genetic and pathogenic characteristics of the isolated virus, FOY-1, compared with a reference strain, RSL-1. The FOY-1 strain was classified into PsHV-1 genotype 2. The FOY-1 strain was found to be less pathogenic to budgerigars than RSL-1, which was classified as genotype 4 in an in vivo study. This is the first report regarding the classification of originally isolated PsHV-1 in Japan and its characterization by animal infection experiment.     

Reactivity and prevalence of neutralizing antibodies against Japanese strains of bovine viral diarrhea virus subgenotypes

Bovine viral diarrhea virus (BVDV) field isolates show genetic and antigenic diversity. At least 14 subgenotypes of BVDV-1 and 4 of BVDV-2 have been identified in Artiodactyla worldwide. Of these, 6 subgenotypes of BVDV-1 and 1 of BVDV-2 have been isolated in Japan. Previously, we reported that each subgenotype virus expresses different antigenic characteristics. Here we investigated the reactivity of neutralizing antibodies against representative strains of Japanese BVDV subgenotypes using sera from 266 beef cattle to estimate the prevalence of this epidemic virus among cattle in Japan. Antibody titers at concentrations at least 4-fold higher than antibodies against other subgenotype viruses were considered subgenotype specific. Subgenotype-specific antibodies were detected from 117 (80.7%) of 145 sera samples (69.7% against BVDV-1a, 1.4% against BVDV-1b, 8.3% against BVDV-1c, and 1.4% against BVDV-2a). The results suggest that neutralization tests are useful in estimating currently epidemic subgenotypes of BVDV in the field.     

Virological surveillance and phylogenetic analysis of the PB2 genes of influenza viruses isolated from wild water birds flying from their nesting lakes in Siberia to Hokkaido, Japan in autumn

Recent introduction of H5N1 highly pathogenic avian influenza virus (HPAIV) in wild birds from poultry in Eurasia signaled the possibility that this virus may perpetuate in nature. Surveillance of avian influenza especially in migratory birds, therefore, has been conducted to provide information on the viruses brought by them to Hokkaido, Japan, from their nesting lakes in Siberia in autumn. During 2008-2009, 62 influenza viruses of 21 different combinations of hemagglutinin (HA) and neuraminidase (NA) subtypes were isolated. Up to September 2010, no HPAIV has been found, indicating that H5N1 HPAIV has not perpetuated at least dominantly in the lakes where ducks nest in summer in Siberia. The PB2 genes of 54 influenza viruses out of 283 influenza viruses isolated in Hokkaido in 2000-2009 were phylogenetically analysed. None of the genes showed close relation to those of H5N1 HPAIVs that were detected in wild birds found dead in Eurasia on the way back to their northern territory in spring.     

早期鸡胚抗氧化活性物质的变化研究

通过检测鸡胚在早期发育过程中的抗氧化能力指数、脂质过氧化产物丙二醛、维生素C及谷胱甘肽的含量和超氧化物歧化酶活性,探讨内源性抗氧化活性物质变化,旨在为胚胎的抗氧化系统形成提供参考.结果显示,鸡胚在发育初期,胚胎内维生素C、谷胱甘肽、丙二醛含量及超氧化物歧化酶活性均有不同程度的提高,而卵黄内的抗氧化能力指数水平则逐渐降低.此外,试验结果还提示每克组织内的抗氧化指标在孵育前期呈递增趋势,发育至13日龄时随着体内抗氧化功能的健全而单位组织内的抗氧化水平趋于下降.以上结果说明,鸡胚内的抗氧化系统是在早期发育过程中逐渐形成并日益完善的,可能在胚胎发育过程中发挥着重要的生理意义.     

A simplified PCR assay for fast and easy mycoplasma mastitis screening in dairy cattle

A simplified polymerase chain reaction (PCR) assay was developed for fast and easy screening of mycoplasma mastitis in dairy cattle. Species of major mycoplasma strains [Mycoplasma (M.) bovis, M. arginini, M. bovigenitalium, M. californicum, M. bovirhinis, M. alkalescens and M. canadense] in cultured milk samples were detected by this simplified PCR-based method as well as a standard PCR technique. The minimum concentration limit for detecting mycoplasma by the simplified PCR was estimated to be about 2.5 × 10³ cfu/mL and was similar to that of the standard PCR. We compared the specificity and sensitivity of the simplified PCR to those of a culture method. Out of 1,685 milk samples cultured in mycoplasma broth, the simplified PCR detected Mycoplasma DNA in 152 that were also positive according to the culture assay. The sensitivity and specificity of the simplified PCR were 98.7% and 99.7%, respectively, for detecting mycoplasma in those cultures. The results obtained by the simplified PCR were consistent with ones from standard PCR. This newly developed simplified PCR, which does not require DNA purification, can analyze about 300 cultured samples within 3 h. The results from our study suggest that the simplified PCR can be used for mycoplasma mastitis screening in large-scale dairy farms.     

Asian-common strains of ‘<Emphasis Type="Italic">Candidatus</Emphasis> Liberibacter asiaticus’ are distributed in Northeast India,Papua New Guinea and Timor-Leste

‘Candidatus Liberibacter asiaticus’ is the most widespread of the three species of ‘Ca. Liberibacter’ that cause citrus greening disease (huanglongbing). To ascertain the phylogenetic relationships among Indian isolates that have higher diversity in the 16S rDNA than Asian isolates of this species, we collected symptomatic leaves from Northeast India, Papua New Guinea and Timor-Leste (East Timor) and detected ‘Ca. L. asiaticus’ by PCR using primers specific for nusG–rplK genes and 16S rDNA. Phylogenetic analysis with 16S rDNA sequences and single nucleotide polymorphisms of the omp gene region revealed that the Northeast Indian isolates were genetically closer to Asian-common isolates from Japan, Taiwan, and Vietnam than to Indian isolates reported previously. Thus, the Asian-common strains of ‘Ca. L. asiaticus’ are apparently also present in Northeast India.     

Process to extinction and genetic structure of a threatened Japanese conifer species, <Emphasis Type="Italic">Picea koyamae</Emphasis>

Since the end of the glacial age, Picea koyamae has been sparsely distributed in Japan as a relict species and is presently threatened with extinction. We investigated the population structure and genetic structure of nine populations of P. koyamae. Population size was assessed at 9–135 individuals in habitats ranging from 0.5 to 11.5 ha, and seedlings and saplings were observed in all but one particular population, which had a Sasa-type (bamboo grass) forest floor. The effective number of alleles per locus (N _e) within peripheral populations in the Yatsugatake Mountains was 1.8–2.7, much lower than that of core populations in the Akaishi Mountains (2.8–4.3) using five nuclear simple sequence repeat loci. This finding suggests that genetic variation in these populations has been reduced by isolation from other populations. The standardized genetic differentiation among populations (G′ _st ) was 0.410 and higher than that found in other Japanese conifers, suggesting that isolation and inbreeding have progressed in this species. In two isolated populations at the Yatsugatake Mountains, the fixation index (F _is ) was 0.315–0.354, much higher than the values determined for the other populations (−0.188 to 0.263). This suggests that these two populations have survived several generations while increasing the degree of inbreeding. However, the highest seedling density was in a population with low genetic variation and high F _is . The most serious problems at present appear to be the declining number of mature trees and the deterioration of suitable environments for seedling establishment.     

Strain analysis of lumber containing a knot during tensile failure

We analyzed the strain distribution of lumber containing a knot under a tensile load. The local tensile strain near the knot was measured using the digital image correlation method. Fracture often initiated near the knot where the fiber orientation changed in a three-dimensional manner. The fiber direction in this zone was different from that in the clear part, coinciding with the thickness direction and not with the longitudinal direction of the specimen. Our results disagree with those of previous models that assumed the longitudinal direction of lumber as the direction of crack propagation. Strain analysis showed that a nonlinear region existed around the knot just before ultimate fracture occurred. The results indicated that nonlinear characterization is necessary to determine the failure mechanism of lumber containing a knot, despite the brittleness fracture at the macroscopic scale.     

Engineered interface of magnetic oxides

Interface-selective probing of magnetism is a key issue for the design and realization of spin-electronic junction devices. Here, magnetization-induced second-harmonic generation was used to probe the local magnetic properties at the interface of the perovskite ferromagnet La(0.6)Sr(0.4)MnO3 with nonmagnetic insulating layers, as used in spin-tunnel junctions. We show that by grading the doping profile on an atomic scale at the interface, robust ferromagnetism can be realized around room temperature. The results should lead to improvements in the performance of spin-tunnel junctions.