Outbreaks of type C botulism in waterfowl in Japan

Four outbreaks of botulism in waterfowl were encountered over a five-year period of 1973 to 1977 in Japan. In all the outbreaks toxin was detected from all 12 sera, twenty-three of 24 gizzard contents from diseased or dead birds and one of three maggots. It was neutralized with Clostridium botulinum type C antitoxin serum, regardless of its origin. By using CO2 gas jet method, C. botulinum was isolated from four of 11 gizzards from diseased birds, five of 7 ones from dead birds, one of one maggot and one of one sludge sample, that is, eleven of 20 specimens in total. All 20 strains were identical with C. botulinum type C in biological properties. Most of the isolates showed a toxin titer ranging from 1,000 to 200,000 LD50 for mice. Four of them were identified as type C by mouse neutralization tests with antitoxin sera. The toxic suspensions of a strain 1-15 were administered orally to Chinese spot-billed ducks, which died when more than 200,000 LD50 mouse toxin was administered. Environmental conditions for occurrences of waterfowl botulism were discussed.     

Investigation of animal botulism outbreaks by PCR and standard methods

Abstract A double PCR procedure is proposed for identification of Clostridium botulinum C and D. This method consists of a first PCR amplification with a degenerate primer pair able to amplify a 340 bp common DNA fragment from botulinum neurotoxin (BoNT) C1 and D genes, followed by two subsequent PCR amplifications with two primer pairs specific for BoNT/C1 and D respectively (198 bp DNA fragment). This method was found to be specific for C. botulinum C and D, amongst 81 strains of C. botulinum and 21 different species of other Clostridium and bacteria tested. The detection limit ranged from 10 to 10³ bacteria in the reaction volume according to the C. botulinum C and D strains. In 160 naturally contaminated animal and food samples submitted to a 48 h enrichment culture, the double PCR showed an 89.4% correlation rate with the standard mouse bioassay. A clear distinction between botulism type C and D was obtained. The double PCR provides a reliable alternative for detection and identification of C. botulinum C and D in clinical and food samples.     

Prevalence of human T‐lymphotropic virus type 1 carriers among pregnant women in Hokkaido,Japan

As there is a risk of MTCT of HTLV‐1, the HSGP HTLV‐1 MTCT was organized in 2011. To determine how many pregnant women are infected with HTLV‐1 in Hokkaido, which is the northernmost and the second largest island in Japan with a population of 5 467 000 and 39 392 newborns in 2011, the HSGP HTLV‐1 MTCT asked all facilities that may care for pregnant women in Hokkaido in July 2013 to provide information on the number of pregnant women who underwent screening for anti‐HTLV‐1 antibody using particle agglutination or chemiluminescent enzyme immunoassay, and the numbers of those with positive, equivocal, and negative test results in the screening and confirmation tests using western blotting or PCR methods in 2012, respectively. A total of 111 facilities participated in this study and provided information on 33 617 pregnant women who underwent screening in 2012, corresponding to approximately 85% of all pregnant women who gave birth in Hokkaido in 2012. Of 81 candidates for a confirmation test because of positive (n = 77) or equivocal (n = 4) results on screening, 63 (78%) underwent the confirmation test and, finally, 34 (0.1%) and 33 563 (99.8%) women were judged to be HTLV‐1 carriers and non‐carriers, respectively. It was concluded that the prevalence rate of HTLV‐1 carriers was low, one per 1000 pregnant women in Hokkaido. Approximately 40 infants are born yearly to mothers infected with HTLV‐1 in Hokkaido.     

Biochemical identification of a brackish water type ofPungitius pungitius,and its morphological and ecological features in Hokkaido,Japan

A brackish water type ofPungitius pungitius (Gasterosteidae) is newly reported from Japan. Genetic differences, based on 13 loci of 6 enzymes and muscle protein, were examined between fresh and brackish water types in the Biwase River in the eastern part of Hokkaido. The alleles onGpd, Pgi andPgm were displaced between them, even though their distributions partially overlapped in the river. The brackish water type was also statistically different from the fresh water type on the basis of three morphological characters, such as number of dorsal spines, gill-rakers and vertebrae, although ranges overlapped. Segregation of spawning sites and differing nuptial colors of the male were found between fresh and brackish water types. These facts suggest that the brackish water type is reproductively isolated from the fresh water type and that both types should be regarded as independent species.     

Long-term growth dynamics of natural forests in Hokkaido,northern Japan

Abstract. The long-term growth dynamics of natural forest stands on the island of Hokkaido were described on the basis of an analysis of data from 38 permanent plots spanning 15–22 yr. Stand structure was characterized by basal area, stem density and tree size variability. To detect trends in stand structure, regression models for recruitment rate (per ha per yr), mortality rate and the rate of change in stem density and tree size variability were developed by a stepwise method using initial basal area, stem density, tree size variability, species composition summarized by LNMDS ordination, altitude, annual mean temperature, annual precipitation, type of understorey vegetation, topography and slope aspect as candidates for predictor variables. The same analyses were conducted for basal area increment (net growth) and its components: survivor growth = basal area gain by growth of surviving individuals and mortality = basal area loss by death of individuals. Stem density remained generally unchanged; recruitment was relatively low even in very sparse stands. Stand basal area generally increased as survivor growth was approximately double the mortality. Recruitment rate was strongly affected by the presence of dwarf bamboo (Sasa spp.) vegetation on the forest floor which inhibited tree regeneration. Mortality rate was density-dependent; dense stands had higher mortality than sparse stands. Density change rate (recruitment rate - mortality rate) was, therefore, determined by both the type of understorey vegetation and stem density. Survivor growth was high in stands with high stem density and basal area. Mortality was dependent on basal area and altitude. Net basal area increment (net growth) was dependent only on stem density with other factors that influenced survivor growth and mortality omitted. Tree size variability decreased in stands with high tree size variability whereas it increased in stands with low size variability. Based on the obtained models for density change rate and net basal area increment, trajectories of stands were illustrated on a log-log diagram of stem density and basal area. The predicted differences in trajectories as affected by the understorey vegetation type indicated the importance of dwarf bamboo vegetation for forest dynamics on Hokkaido.     

The population dynamics of the voleClethrionomys rufocanus in Hokkaido, Japan

Population dynamics of the gray sided-vole,Clethrionomys rufocanus, in Hokkaido, Japan were described on the basis of 225 time series (being from 12 to 31 years long); 194 of the time series have a length of 23 years or longer. The time series were classified into 11 groups according to geographic proximity and topographic characteristics of the island of Hokkaido. Mean abundance varied among populations from 1.07 to 21.07 individuals per 150 trap-nights. The index of variability for population fluctuation (s-index) ranged from 0.204 to 0.629. Another index for population variability (amplitude on log-10 scale) ranged from 0.811 to 2.743. Mean abundance and variability of populations were higher in the more northern and eastern regions of the island. Most populations, except for the southernmost populations, exhibited significant direct density-dependence in population growth. Detection rate for delayed density-dependence varied among groups from 0% to 22.6%. Both direct and delayed density-dependence tended to be stronger in the more northern and eastern populations. The proportion of cyclic populations was higher in the northern-eastern areas than that in the southern-western areas. There was a clear gradient from the asynchronous populations in southwest, to the highly synchronized populations in the northeast.     

日本北海道地区细石叶技术研究概述

细石叶技术是晚更新世晚期东北亚和西北美新的变革性剥坯技术和适应手段。北海道地区拥有丰富、多样的细石器遗存,相关材料最早可以追溯到距今约2.5万年前,持续了约1.2万年。以北海道具有明显技术复杂性和多样性特点的细石器为材料,学者们基于技术式"阅读"和拼合研究划分出一系列细石核工艺类型和剥坯技法;岛内以楔形细石核为代表的细石器工业传统在不断延续的同时,也表现出明显的阶段性变化,并在一定程度上显示出与气候环境变化较强的相关性。本文对北海道地区晚更新世末次盛冰期以来的气候、环境背景以及细石器的发现与研究历程进行介绍。在此基础上,厘清北海道细石核工艺类型的划分,并对细石器群的阶段性演变进行系统梳理,以期对我国相关研究有所裨益。     

The regeneration process in a mixed forest in central Hokkaido,Japan

The regeneration process in a mixed forest was investigated in Nopporo National Forest, Hokkaido. The analysis of age structure in an 80 m×80 m plot revealed that almost all of the species regenerated intermittently. In eleven gaps observed in the plot, the regeneration of a boreal conifer (Abies sachalinensis) was seldom observed. Temperate hardwoods, even climax species (Acer mono, Quercus mongolica var. grosseserrata, Tilia japonica), regenerated vigorously in the gaps. The age structure in ten additional plots scattered all over the forest showed that Abies tended to regenerate synchronously. From previous records, regeneration of Abies could be ascribed to catastrophic storms causing serious windfalls. On the other hand, regeneration of the temperate hardwoods was not synchronous but independent in different places within the forest. They could regenerate not only after those catastrophic storms but also after less severe disturbances which caused the death and fall of one or several trees. It is concluded that the coexistence of boreal coniferous species and temperate deciduous broad-leaved species in mixed forests may be maintained not only by the difference in habitat but also by the balance between the less frequent large disturbances, and the more frequent smaller ones.     

Three new freshwater ascomycetes from rivers in Akkeshi, Hokkaido, northern Japan

Three lignicolous freshwater ascomycetes from rivers in Akkeshi, Hokkaido, northern Japan are reported. All of these are new species belonging to the Lophiostomataceae and described as Lophiostoma breviappendiculatum, Massarina clionina, and Massariosphaeria maxima. Morphological differences between each species and its similar taxa are noted. All three species have been observed to produce only ascomatal states in artificial culture.     

Mode of infection of Hokkaido virus (Genus Hantavirus) among grey red-backed voles, Myodes rufocanus, in Hokkaido, Japan

Hokkaido virus (HOKV) is a member of the genus Hantavirus, in the family Bunyaviridae. To investigate HOKV infection in the host Myodes rufocanus, the grey red-backed vole, 199 animals were captured at Tobetsu (October 2004 and July 2005) and Nakagawa (October 2004) in Hokkaido, Japan, for detection of antibody, antigen, and viral RNA. In the surveys in Tobetsu (2004) and Nakagawa (2004), seropositive animals were detected at a frequency of 6.0% (5/84) and 10.4% (5/48), respectively. No seropositive animals were detected in Tobetsu in 2005. Seroprevalence in males in Tobetsu and Nakagawa in 2004 was 25% (1/4) and 45.5% (5/11), respectively, which was higher than in females, at 5.0% (4/80) and 0% (0/37), respectively (P<0.01). These results suggest that male animals play an important role in the maintenance of HOKV in M. rufocanus. Two females were seronegative but viral RNA-positive, indicating that these animals had acute infections before antibody was produced. Another five infected animals in Nakagawa were all male and had high levels of antibodies and viral RNA, suggesting that they had persistent infections. Viral RNA copies in organs of infected animals in Nakagawa were quantified by real-time polymerase chain reaction. Two acutely infected animals had > or = 10 times the number of RNA copies in their lungs compared to those of persistently infected animals. In most cases, lungs or spleen had the highest RNA copy number, regardless of infection status.     

Seasonal migration patterns of female sika deer in eastern Hokkaido,Japan

Fifty-seven female sika deer (Cervus nippon yesoensis), captured at the wintering area in the Shiranuka Hills in eastern Hokkaido, Japan, were radio-tracked during 1997–2001 to examine the factors affecting seasonal migration at the individual-landscape level. Ten of the 57 deers migrated between low-altitude summer home ranges and intermediate-altitude winter home ranges (the upward migrants). Twenty-nine migrated between high-altitude summer home ranges and intermediate-altitude winter home ranges (the downward migrants). Twelve used the intermediate-altitude home ranges all year round (the non-migrants). The remaining six were unknown. The summer home ranges of deer were widely scattered over an area of 5734km². Migration distances ranged between 7.2 and 101.7km. Deer showed high site fidelities to their seasonal home ranges. The upward migrants wintered in areas of less snow, higher quality of bamboo grass, and more coniferous cover than their summer home ranges. The downward migrants wintered in areas of less snow, higher quality of bamboo grass, higher winter temperature, and more southern slopes, but less coniferous cover than their summer home ranges. The non-migrants used year-round ranges with little snow, high quality of bamboo grass, and sufficient coniferous cover. We suggest that snow cover and bamboo grass are the factors affecting seasonal migration of the population and that coniferous cover is another factor for the upward migration.